Ever wondered why Mealvana recommends 75 grams of carbs per hour for your long bike ride but only 55 for your tempo run? Or why your sodium targets are different from your training partner’s? Let’s pull back the curtain on the sports science that powers your personalized fueling recommendations.

The Short Version

Your fueling needs aren’t one-size-fits-all. They depend on:

  • How long you’re exercising
  • How hard you’re working
  • What sport you’re doing (bike vs. run vs. swim)
  • Your body (sweat rate, gut tolerance, weight)
  • The conditions (heat, humidity, altitude)

Mealvana combines decades of peer-reviewed sports nutrition research with your personal profile to generate recommendations tailored specifically to you. Here’s how it all works.

Part 1: Carbohydrates — Your Engine’s Fuel

Why Carbs Matter

During endurance exercise, your muscles burn a mix of carbohydrates and fat. The harder you go, the more you rely on carbs. A 2.5-hour workout at moderate-to-hard intensity can burn through 300-500 grams of stored carbohydrate (glycogen) — and your body can only store about 400-500 grams total (Jeukendrup, 2004).

The math is simple: If you don’t replace carbs during long or hard efforts, you’ll bonk.

The 60 g/hr Ceiling (And How to Break It)

Here’s something fascinating that researchers discovered: your gut can only absorb about 60 grams of a single type of carbohydrate per hour, no matter how much you consume.

This finding has been replicated across dozens of studies. As Dr. Asker Jeukendrup summarized in his landmark 2004 review: “A single CHO ingested during exercise will be oxidized at rates up to about 1 g/min, even when large amounts of CHO are ingested” (Jeukendrup, 2004, Nutrition).

Why? It comes down to intestinal transporters — specialized proteins that shuttle sugar from your gut into your bloodstream. The main transporter for glucose (called SGLT1) maxes out at roughly 1 gram per minute (Jeukendrup & Jentjens, 2000, Sports Medicine).

But here’s the game-changer: Fructose uses a different transporter (GLUT5). By combining glucose and fructose, you can essentially open a second absorption lane.

Carb Source Max Absorption Rate Research
Glucose only ~60 g/hr Jeukendrup, 2004
Glucose + Fructose 90-105 g/hr Jentjens & Jeukendrup, 2005
Trained gut + optimal ratio Up to 120 g/hr Hearris et al., 2022

This is why most sports nutrition products now use glucose:fructose blends (often listed as maltodextrin + fructose). The research from Jentjens & Jeukendrup (2005) showed that athletes can oxidize up to 105 g/hr with the right carb mix — representing a 75% increase over single-source carbohydrate (Jentjens & Jeukendrup, 2005, British Journal of Nutrition).

More recent work has pushed this further. Hearris and colleagues (2022) demonstrated that 120 g/hr is practically tolerable for athletes with trained guts using an optimized 1:0.8 glucose:fructose ratio (Hearris et al., 2022).

The Optimal Carbohydrate Ratio

Not all glucose:fructose ratios are equal. The research has evolved:

This ratio matters because fructose absorption can become the bottleneck at very high intake rates. Elite marathon runner Eliud Kipchoge reportedly uses a 1:0.8 ratio for his record attempts.

How Mealvana Calculates Your Carb Targets

We use duration and intensity as the primary drivers, following the evidence-based guidelines from the American College of Sports Medicine and International Olympic Committee consensus statements (Thomas et al., 2016, Journal of the Academy of Nutrition and Dietetics):

Base Recommendations by Duration:

Workout Duration Carb Target Scientific Rationale
Under 60 min 0-30 g total Glycogen stores sufficient; mouth rinse approach may help (Carter et al., 2004)
60-90 min 30-60 g/hr Maintains blood glucose (Burke et al., 2011)
90 min - 2.5 hr 45-60 g/hr Delays glycogen depletion
2.5 - 4 hr 60-90 g/hr Requires multiple transportable carbs (Jeukendrup, 2014)
4+ hr 80-100+ g/hr Maximum sustainable; must include real food (Pfeiffer et al., 2012)

Sources: Burke et al., 2011, Journal of Sports Sciences; Jeukendrup, 2014, Sports Medicine; Thomas et al., 2016

Your Personal Modifier:

In your Mealvana profile, you set your maximum carb tolerance — the most you can comfortably consume per hour without GI distress. We never recommend above this ceiling, even if the workout duration would otherwise call for it.

Research confirms this individual variation is real: a large field study of Ironman competitors found carbohydrate intake ranged from 6 to 136 g/hr across athletes, with higher intakes correlating to faster finish times (Pfeiffer et al., 2012, Medicine and Science in Sports and Exercise).

Example: If you’ve set your tolerance at 70 g/hr and you’re doing a 4-hour ride, we’ll recommend 70 g/hr (your max), not the 80-90 g/hr that duration might otherwise suggest.

Part 2: Pre-Workout Nutrition — Setting Up for Success

What you eat before your workout matters as much as what you consume during it. But the optimal pre-workout meal depends on timing, sport type, and workout intensity. Here’s how Mealvana calculates your pre-workout recommendations.

The Science of Pre-Exercise Fueling

Your pre-workout nutrition serves three purposes:

  1. Top off liver glycogen — Depleted overnight, liver glycogen fuels your brain and maintains blood glucose (Casey et al., 2000)
  2. Ensure adequate muscle glycogen — Your primary fuel for moderate-to-high intensity work (Hawley & Burke, 2010)
  3. Optimize hydration status — Start euhydrated, not playing catch-up (Sawka et al., 2007)

The challenge: eat enough to fuel performance, but not so much (or so close to exercise) that GI distress derails your workout.

Timing Windows: How Time Before Exercise Changes Everything

Research has established clear timing-based guidelines. The closer you get to your workout, the simpler and smaller your nutrition should be (Kerksick et al., 2017, Journal of the International Society of Sports Nutrition).

3-4 Hours Before: The Full Meal Window

Nutrient Target Rationale
Carbohydrate 1-4 g/kg body weight Tops off glycogen stores (Burke et al., 2011)
Protein 0.15-0.25 g/kg Supports muscle protein balance (Kerksick et al., 2017)
Fat 0.3-0.5 g/kg Acceptable; adequate digestion time
Fiber Moderate Can include vegetables, whole grains

Example for 70kg athlete: 70-280g carbs, 10-18g protein, 20-35g fat

This is your window for a “real meal” — oatmeal with banana and eggs, a bagel with peanut butter, rice with chicken and vegetables. The 3-4 hour buffer allows complete gastric emptying before exercise begins (Rehrer et al., 1992).

1-2 Hours Before: The Snack Window

Nutrient Target Rationale
Carbohydrate 1-2 g/kg body weight Maintain blood glucose (Ormsbee et al., 2014)
Protein 0-10g Optional; keep minimal
Fat <10g Slows gastric emptying; minimize (Rehrer et al., 1992)
Fiber Low Avoid GI bulk

Example for 70kg athlete: 70-140g carbs, minimal fat/protein

This is your window for easily digestible carbs — white bread with jam, a banana, rice cakes, a small bowl of cereal with low-fat milk. Fat and fiber should be minimized as they slow gastric emptying and increase GI distress risk.

30-60 Minutes Before: The Top-Up Window

Nutrient Target Rationale
Carbohydrate 0.5-1 g/kg Final glucose availability boost (Jeukendrup & Killer, 2010)
Protein 0g No time to digest
Fat 0g No time to digest
Fiber 0g Risk of GI distress

Example for 70kg athlete: 35-70g carbs from simple sources

This window is for simple, fast-digesting carbs only — a gel, sports drink, white bread with honey, or a ripe banana. Research shows that consuming carbohydrate in this window can enhance performance, particularly for sessions starting with low glycogen or lasting >60 minutes (Jeukendrup & Killer, 2010, Annals of Nutrition and Metabolism).

<30 Minutes Before: Proceed with Caution

Eating within 30 minutes of exercise is generally not recommended for most athletes. However, for early morning workouts where eating 2-3 hours prior isn’t practical, a small amount of easily digestible carbohydrate (15-30g) is better than training completely fasted for high-intensity or long sessions (Rothschild et al., 2020, Nutrients).

Sport-Specific Pre-Workout Guidelines

Your gut doesn’t respond the same way to cycling, running, and swimming. The mechanical and physiological demands of each sport create different tolerance windows.

Running: The Most Sensitive

Running creates the most GI stress due to:

  • Vertical oscillation and impact with each stride
  • Increased intra-abdominal pressure
  • Greater blood flow diversion from the gut compared to cycling at similar intensity

Research consistently shows runners experience more GI symptoms than cyclists (Peters et al., 1999). A survey of 606 Dutch endurance athletes found that “approximately 45% of runners reported GI problems during running, compared to 33% of cyclists” (de Oliveira & Burini, 2009, British Journal of Sports Medicine).

Mealvana’s Running Pre-Workout Adjustments:

Factor Adjustment
Last full meal 3-4 hours minimum before hard runs
Carb amount (1-2hr window) Lower end of range (1-1.5 g/kg)
Fat tolerance <10g in final 2 hours
Fiber tolerance Very low; avoid high-fiber foods day-of
High-intensity runs Extend digestion window by 30-60 min

Cycling: The Most Forgiving

Cyclists can generally tolerate more food, closer to exercise:

  • Stable torso position minimizes GI jostling
  • Aerodynamic posture doesn’t compress stomach
  • Lower relative blood flow diversion at equivalent heart rate

Studies show cyclists tolerate higher carbohydrate intake during exercise, and this tolerance extends to pre-exercise nutrition (Pfeiffer et al., 2012).

Mealvana’s Cycling Pre-Workout Adjustments:

Factor Adjustment
Last full meal 2-3 hours acceptable for most
Carb amount (1-2hr window) Full range acceptable (1-2 g/kg)
Fat tolerance Moderate amounts okay 2+ hours out
Fiber tolerance Moderate; more forgiving than running
Indoor trainer Same as outdoor; if anything, slightly more conservative due to heat

Swimming: Unique Considerations

Swimming presents different challenges:

  • Horizontal body position affects gastric emptying
  • Water pressure on the abdomen
  • Breathing pattern interruptions
  • Cold water can slow digestion

Research on swimming-specific pre-exercise nutrition is limited, but expert consensus suggests moderate caution. The triathlon-specific research from Jeukendrup et al. (2005) notes that “gastric emptying may be impaired by the change in body position” when transitioning between disciplines (Jeukendrup et al., 2005).

Mealvana’s Swimming Pre-Workout Adjustments:

Factor Adjustment
Last full meal 2-3 hours minimum
Carb amount (1-2hr window) Moderate (1-1.5 g/kg); avoid large volumes
Fat tolerance Low; horizontal position slows fat digestion
Fiber tolerance Low to moderate
Open water Allow extra time; cold water + nerves affect gut
Pool sessions Slightly more forgiving than open water

Intensity Matters: Hard Sessions Need More Buffer

Exercise intensity directly affects gastrointestinal function. Higher intensity means:

  • Greater blood flow diversion to working muscles
  • Reduced splanchnic (gut) blood flow — up to 80% reduction at maximal exercise (van Wijck et al., 2012)
  • Slower gastric emptying
  • Increased GI symptom risk

A systematic review found that “exercise intensity is considered one of the most important factors determining gastrointestinal disturbance during exercise” (de Oliveira et al., 2014, Sports Medicine).

Mealvana’s Intensity-Based Adjustments:

Workout Intensity Pre-Workout Window Carb Target Fat/Fiber Tolerance
Recovery/Easy (Z1-Z2) 1-2 hours okay 0.5-1 g/kg Moderate
Endurance (Z2-Z3) 2-3 hours preferred 1-2 g/kg Low-moderate
Tempo/Threshold (Z3-Z4) 3+ hours for full meal 1-2 g/kg Low
Intervals/VO2max (Z4-Z5) 3-4 hours for full meal 1.5-2 g/kg Very low
Race/key workout effort 3-4 hours minimum 2-4 g/kg Minimal

The Early Morning Workout Problem

Many athletes train at 5 or 6 AM. Waking at 2 AM to eat isn’t realistic. What does the research say?

Option 1: Train Fasted (Strategic Use)

Fasted training — exercising after an overnight fast without pre-workout food — has become popular for its potential metabolic benefits. But it’s not appropriate for every workout.

The Science: What Fasted Training Does

A 2016 meta-analysis found that aerobic exercise performed fasted induces significantly higher fat oxidation than exercise performed fed (Vieira et al., 2016, British Journal of Nutrition). The mechanism: without incoming carbohydrate, insulin levels remain low, allowing greater mobilization of fatty acids for fuel.

Research from Van Proeyen et al. (2011) demonstrated that 6 weeks of fasted training enhanced markers of fat metabolism, including increased fatty acid binding protein (FABPm) content and reduced glycogen breakdown during exercise (Van Proeyen et al., 2011).

However, there’s a critical caveat from Dr. Daniel Moore’s research at the University of Toronto: training with low carbohydrate availability increases protein requirements. In a carefully controlled study, Gillen, Moore and colleagues found that endurance exercise performed in a low-carbohydrate state resulted in significantly higher amino acid oxidation during recovery, suggesting a greater protein requirement to support whole-body protein synthesis (Gillen et al., 2019, Medicine & Science in Sports & Exercise).

“It is important to increase your protein intake if you are training with low-carbohydrate availability as the extra amino acids that are used as energy must be replaced through the diet.” — Dr. Daniel Moore, University of Toronto

Which Workouts Are Suitable for Fasted Training?

Not all workouts respond equally to fasted training. Here’s a research-backed breakdown:

Workout Type Fasted Suitability Rationale
Easy/Recovery runs (Z1-Z2) Good candidate Low glycogen demand, enhances fat adaptation
Moderate steady-state (Z2-Z3, <75 min) Acceptable Sustainable intensity, manageable glycogen needs
Long runs (>90 min) Not recommended Performance suffers, muscle breakdown increases
Tempo/Threshold (Z3-Z4) Not recommended Quality suffers without carbs; train these fueled
Intervals/VO2max (Z4-Z5) Avoid Glycolytic work requires glycogen; dangerous to perform depleted
Easy cycling (Z1-Z2) Good candidate Stable, low-impact; excellent for fat adaptation
Moderate cycling (<90 min) Acceptable Can sustain reasonable power fasted
High-intensity cycling Not recommended Sprint/interval work impaired without glycogen
Swimming Generally suitable Lower sweat rate, stable intensity, pool environment

Duration Guidelines for Fasted Training:

Duration Fasted Suitability Notes
<45 min Excellent Minimal glycogen depletion, low risk
45-60 min Good Most athletes tolerate well
60-75 min Marginal Individual tolerance varies; stay Z1-Z2
75-90 min Risky Performance decline likely; fuel if quality matters
>90 min Not recommended Significant muscle breakdown, cortisol elevation

A comprehensive review concluded: “We recommend that endurance athletes should avoid high intensity training while fasting” (Alghannam et al., 2020, Open Access Journal of Sports Medicine).

Sport-Specific Fasted Training Considerations:

Running:

  • Most suitable for easy/recovery runs under 60 minutes
  • GI system actually benefits from fasted training (no sloshing)
  • Higher muscle damage risk than cycling — prioritize post-workout protein
  • Avoid fasted running for any session where pace/quality matters

Cycling:

  • Generally more tolerant of fasted training than running
  • Can extend duration slightly (up to 75 min easy) due to no impact stress
  • Indoor trainer sessions work well fasted (controlled environment)
  • Avoid fasted cycling for any interval or tempo work

Swimming:

  • Well-suited for fasted training
  • Lower sweat rate reduces electrolyte concerns
  • Controlled environment; can exit pool if needed
  • Most pool sessions under 60 min work well fasted

The “Fuel for the Work Required” Framework: James Morton’s Approach

The most sophisticated approach to carbohydrate periodization comes from Professor James Morton (Liverpool John Moores University, former Head of Nutrition for Team Sky/INEOS Grenadiers) and colleagues. Their landmark 2018 paper introduced the “Fuel for the Work Required” paradigm and Glycogen Threshold Hypothesis — the scientific framework that powered Chris Froome’s famous race-winning attacks (Impey, Morton et al., 2018, Sports Medicine).

The Core Principle:

Rather than chronic low-carb diets OR always eating high-carb, Morton’s framework adjusts carbohydrate availability day-to-day and meal-by-meal according to the demands of each specific training session:

  • High-intensity/key sessions → High carb availability (fuel the quality)
  • Low-intensity/easy sessions → Low carb availability (enhance adaptation)
  • Competition → Always fully fueled

“CHO availability should be adjusted in accordance with the demands of the upcoming training session(s)… creating a metabolic milieu conducive to facilitating the endurance phenotype.” — Impey, Morton et al., 2018

The Glycogen Threshold Hypothesis

Morton’s research identified a critical glycogen “sweet spot” for training adaptations:

Muscle Glycogen Level Training Outcome
>500 mmol/kg dry wt Adaptations blunted; gene expression suppressed
300-500 mmol/kg dry wt Good zone for quality training
200-300 mmol/kg dry wt Optimal adaptation zone — enhanced cell signaling, gene expression
<200 mmol/kg dry wt Training intensity impaired; potential harm

The key insight: Start low enough to trigger adaptation, but not so low you can’t complete the work.

Their systematic review found that when training sessions were commenced with glycogen ≤300 mmol/kg dry weight:

  • 73% of studies showed augmented cell signaling
  • 75% showed enhanced gene expression
  • 78% showed increased oxidative enzyme activity

Practical “Train Low” Models from Morton’s Research:

Model How It Works Best For
Fasted training Morning session after overnight fast Easy aerobic sessions <75 min
Twice-daily training Second session done glycogen-depleted Doubling up easy + moderate sessions
Sleep low, train low Evening HIT → skip carbs → morning easy session Maximizing adaptation window
Post-exercise CHO restriction Delay carbs 3-4 hours after training Recovery sessions, easy days

The “Sleep Low, Train Low” Protocol in Detail

This specific model combines Morton’s framework with practical application:

The Protocol:

  1. Evening: Perform a high-intensity session (intervals, tempo) with full carb availability
  2. Post-workout: Skip or minimize carbs until the next morning (extend the low-glycogen window)
  3. Morning: Perform an easy/moderate session fasted (muscle glycogen already depleted from evening)
  4. Post-morning session: Resume normal carbohydrate intake

Marquet et al. (2016) found that trained triathletes using this “sleep low” strategy for 3 weeks improved 10-km running performance by 2.9%, improved cycling efficiency by 11.7%, and reduced body fat by 1.1% compared to athletes consuming the same total carbohydrates distributed evenly throughout the day (Marquet et al., 2016, Medicine & Science in Sports & Exercise).

What Proportion of Training Should Be “Train Low”?

Morton’s research suggests 30-50% of training sessions can be performed with reduced carbohydrate availability — not all of them. The remaining 50-70% should be fully fueled to:

  • Support high-quality interval/threshold work
  • Prevent chronic energy deficiency
  • Maintain immune function
  • Support bone health (emerging research suggests this is carb-dependent)

Putting It Together: A Sample Week

Day Session CHO Strategy
Mon Easy run 45min Train low (fasted or post-exercise restriction)
Tue Intervals 60min Train high — full carb availability
Wed Easy bike 60min Train low (fasted)
Thu Tempo run 50min Train high — full carb availability
Fri Recovery swim 30min Train low (fasted)
Sat Long run 2hr Train high — carbs before + during
Sun Rest Normal eating

In this example: 3 sessions train-low (43%), 3 sessions train-high (43%), 1 rest day

Mealvana’s Implementation of “Fuel for the Work Required”:

Mealvana applies Morton’s framework automatically by analyzing each workout:

If Your Workout Is… Mealvana Suggests…
Easy run, <60 min, Z1-Z2 Fasted/train-low option available
Easy bike, <75 min, Z1-Z2 Fasted/train-low option available
Any swim <60 min Fasted/train-low option available
Any workout with intervals Fuel this session (train high)
Any tempo/threshold work Fuel this session (train high)
Any session >75 min Fuel this session (train high)
Back-to-back day (fatigued) Fuel this session
Key workout or race simulation Fuel this session (train high)
Competition/race Always fully fueled

Critical: If You Train Low, Increase Post-Workout Protein

Based on Dr. Daniel Moore’s research, athletes who train with low carbohydrate availability should increase their post-workout protein intake to compensate for increased amino acid oxidation during the session:

Post-Workout Context Protein Target Timing
Standard recommendation 0.25-0.3 g/kg Within 1-2 hours
After train-low session 0.35-0.4 g/kg Within 30-60 min

Example for 70kg athlete: Standard post-workout = 18-21g protein; After train-low = 25-28g protein

Notably, consuming ~20g of protein before/during a train-low session can preserve the metabolic benefits while protecting muscle protein synthesis (Impey et al., 2016).

Option 2: Strategic Small Feeding (Best of Both Worlds)

If you want to avoid true fasted training but can’t eat a full meal, research supports consuming a small amount of easily digestible carbohydrate (25-50g) 15-30 minutes before exercise (Jeukendrup & Killer, 2010). This provides enough glucose to support quality work without requiring early wake-up.

Examples:

  • Half a banana (~15g carbs)
  • 200ml sports drink (~25g carbs)
  • 1 gel (25g carbs)
  • 1-2 medjool dates (~30g carbs)
  • Small handful of dried fruit

Option 3: Evening Carb Loading

For planned early morning key sessions, consuming extra carbohydrate the evening before can partially compensate for the abbreviated morning window. This doesn’t fully replace pre-exercise fueling but helps ensure adequate glycogen stores (Burke et al., 2011).

Mealvana generates multiple protocols for early morning workouts:

  1. A “fasted training” option for suitable easy sessions (with elevated post-workout protein)
  2. A minimal “wake and go” option with simple carbs only
  3. An evening-before carb emphasis to compensate for morning limitations
  4. A recommendation on which protocol best fits the specific workout

Pre-Workout Hydration and Sodium: Start Ahead

Hydration status at the start of exercise significantly impacts performance and thermoregulation. Starting even slightly dehydrated (2% body mass deficit) can impair endurance performance by 5-10% (Cheuvront & Kenefick, 2014, Comprehensive Physiology).

The ACSM recommends:

“Prehydrating with beverages, if needed, should be initiated at least several hours before the exercise task to enable fluid absorption and allow urine output to return to normal levels” (Sawka et al., 2007).

Practical Pre-Workout Hydration Guidelines:

Timing Fluid Target Sodium Target Notes
2-4 hours before 5-7 ml/kg (~350-500ml for 70kg) 300-600mg Allows time for absorption and urination
1-2 hours before 3-5 ml/kg (~200-350ml for 70kg) 200-400mg Sip gradually, don’t chug
10-20 min before 200-300ml 100-200mg Final top-up

Why Sodium Matters Pre-Workout

Plain water is poorly retained by the body — much of it ends up as urine before you even start exercising. Adding sodium dramatically improves fluid retention.

Research by Sims et al. (2007) demonstrated that consuming a high-sodium beverage (164 mmol/L, or ~3,800 mg/L) before exercise in the heat expanded plasma volume and improved cycling time trial performance by 3% compared to a low-sodium placebo (Sims et al., 2007, Medicine and Science in Sports and Exercise).

The mechanism: Sodium increases plasma osmolality, which:

  1. Triggers greater fluid retention (less urination)
  2. Expands blood plasma volume
  3. Provides a larger “reservoir” to draw from during exercise
  4. Delays the point at which dehydration impairs performance

Pre-Workout Sodium Loading Protocols:

Scenario Sodium Target Timing Research
Standard workout 300-600mg total 2-4 hours before Shirreffs & Sawka, 2011
Hot conditions (>25°C) 10-25 mg/kg body weight 2-3 hours before Sims et al., 2007
Known heavy sweater 500-1000mg total 2-4 hours before Baker & Jeukendrup, 2014
Long race (>3 hours) 10-20 mg/kg body weight With pre-race meal McCubbin et al., 2020

Example for 70kg athlete in hot conditions: 700-1,750mg sodium in the 2-3 hours before exercise

Practical Sodium Sources:

Source Approximate Sodium
1 tablet (e.g., SaltStick) 215mg
500ml sports drink 250-500mg
1 tsp table salt 2,300mg
Bouillon cube in water 800-1,000mg
Salted pretzels (30g) 400-500mg
Pickle juice (60ml) 400-500mg

Sport-Specific Pre-Workout Hydration

Running

Runners need to balance hydration with avoiding the “sloshing stomach” sensation. Excess fluid before running can cause GI discomfort due to the mechanical bouncing.

Factor Recommendation
Total fluid 2-4hr before 5-7 ml/kg (standard)
Final hour before Minimize — small sips only
Sodium strategy Include with earlier fluids, not last-minute
Urine check Pale yellow before starting

Cycling

Cyclists can generally tolerate more pre-workout fluid without GI issues. The stable position makes pre-hydration easier.

Factor Recommendation
Total fluid 2-4hr before 5-7 ml/kg (full range)
Final hour before 3-5 ml/kg acceptable
Sodium strategy Can continue closer to start
Indoor trainer Increase by 20-30% (heat consideration)

Swimming

Swimmers have unique considerations: pool access to fluids during the session is limited, and the sensation of thirst is blunted in water.

Factor Recommendation
Total fluid 2-4hr before 5-7 ml/kg
Final 30 min before Moderate — won’t have access during
Sodium strategy Standard; less critical due to lower sweat rate
Open water More aggressive pre-hydration; no during-swim access

Environmental Adjustments to Pre-Workout Hydration

Conditions matter enormously. A humid summer morning requires different preparation than a cool fall day.

Condition Fluid Adjustment Sodium Adjustment Rationale
Hot (>25°C / 77°F) +25-30% +50-100% (sodium loading) Higher sweat losses anticipated
Humid (>70%) +20% +25-50% Sweat evaporation impaired
Cold (<10°C / 50°F) Standard to -10% Standard Reduced but not eliminated sweat
Altitude (>2000m) +15-25% Standard Increased respiratory water loss
Indoor (no airflow) +20-30% +25-50% Dramatically higher sweat rate

Signs You’ve Pre-Hydrated Correctly

Good signs:

  • Urine is pale yellow (not clear, not dark)
  • You urinate 1-2 times in the 2 hours before exercise
  • No sensation of bloating or stomach fullness at start
  • Body weight is stable or slightly up from baseline

Warning signs of over-hydration:

  • Urine is completely clear
  • Frequent urination (>3 times in final 2 hours)
  • Bloated, heavy feeling
  • GI sloshing during warm-up

Warning signs of under-hydration:

  • Dark yellow or amber urine
  • No urination in 3+ hours
  • Thirst sensation before starting
  • Elevated morning heart rate

Mealvana’s Pre-Workout Hydration Logic

When generating your pre-workout fluid and sodium targets, Mealvana considers:

  1. Workout duration → Longer sessions justify more aggressive pre-hydration
  2. Your sweat rate profile → Heavy sweaters get higher targets
  3. Environmental conditions → Heat/humidity triggers sodium loading protocol
  4. Sport type → Running gets more conservative final-hour guidance
  5. Time of day → Morning workouts may need to compensate for overnight dehydration
  6. Your sodium loss rate → Salty sweaters get higher sodium targets

Summary: Mealvana’s Pre-Workout Decision Tree

When generating your pre-workout recommendations, Mealvana considers:

  1. How long until your workout? → Sets the macro composition and total volume
  2. What sport? → Running gets most conservative; cycling most forgiving
  3. What intensity? → Higher intensity = longer digestion window needed
  4. What’s your GI history? → Sensitive athletes get extended windows and reduced volumes
  5. Is it early morning? → Generates fasted protocol + evening-before option
  6. How long is the session? → Longer sessions justify more aggressive pre-fueling
  7. What are the conditions? → Heat/humidity triggers sodium loading protocol
  8. What’s your sweat profile? → Heavy/salty sweaters get adjusted fluid and sodium targets

The result: a pre-workout nutrition plan calibrated to your specific workout, not generic advice that ignores the difference between an easy spin and a VO2max session.

Part 3: Why Bike and Run Fueling Are Different

This is one of the most important concepts in triathlon and multisport nutrition: you can fuel more aggressively on the bike than on the run.

The Science

When you run, three things work against your gut:

  1. Mechanical jostling — Every footstrike sends a shockwave through your GI system
  2. Reduced blood flow — Running diverts more blood away from your digestive system than cycling at equivalent effort
  3. Body position — The upright running posture affects gastric emptying differently than cycling’s forward lean

These aren’t just theoretical concerns. In a study of gastrointestinal symptoms across different sports, Peters et al. (1999) found that “symptoms are more common in runners than in cyclists” — with mechanical impact identified as a primary cause (Peters et al., 1999, American Journal of Gastroenterology).

The difference becomes dramatic in longer events. Pfeiffer et al. (2012) documented that severe GI distress occurred in just 4% of marathon runners and cyclists, but in 32% of Ironman competitors — who must run a marathon after already stressing their gut for 5+ hours on the bike (Pfeiffer et al., 2012).

A systematic review on gastrointestinal distress noted that “an estimated 30-90% of endurance athletes engaging in marathons, triathlons, and running report experiencing GI symptoms during exercise” (ter Steege et al., 2008).

How This Affects Your Recommendations

Based on this research, Mealvana applies sport-specific adjustments:

Sport Practical Carb Ceiling Evidence Base
Cycling 80-120 g/hr Stable platform, no impact, can eat solids (Jeukendrup, 2011)
Running 50-70 g/hr GI jostling limits absorption (Peters et al., 1999)
Swimming Pre/post only Can’t fuel during; reduced sweat anyway (Jeukendrup et al., 2005)

The Brick Workout Penalty

If you’re doing a brick (bike → run), your run fueling should be even more conservative. Your gut has been working hard on the bike, blood flow patterns are shifting, and the sudden switch to running impact often triggers GI issues.

Research on triathlon-specific nutrition confirms this effect: “the change in body position among the three disciplines may impair gastric emptying and increase GI distress” (Jeukendrup, Jentjens & Moseley, 2005, Sports Medicine).

A study comparing gel vs. liquid carbohydrate during simulated long-distance triathlon found that 7 of 12 participants reported GI discomfort with gels, while none reported issues with liquid carbs (Sareban et al., 2016, International Journal of Sport Nutrition and Exercise Metabolism).

Mealvana automatically reduces your run carb target by 20-30% when it detects a brick workout pattern in your TrainingPeaks calendar.

Example:

  • Standalone 90-min tempo run: 55 g/hr recommendation
  • 90-min run off a 3-hour bike: 40-45 g/hr recommendation

Part 4: Sodium — More Personal Than You Think

Your Sweat Is Unique

Here’s a number that might surprise you: athletes can lose anywhere from 200 to 2,000 mg of sodium per liter of sweat. That’s a 10x difference between the saltiest and least salty sweaters.

This massive range has been documented across multiple studies. Baker et al. (2016) analyzed 506 athletes and found sweat sodium concentrations ranging from 230 to 1,840 mg/L, with a mean of 826 mg/L (Baker et al., 2016, Sports Medicine).

Your sweat sodium concentration is largely genetic — you’re either a salty sweater or you’re not. Heat acclimation helps reduce it somewhat, but the range between individuals remains enormous (Baker et al., 2017).

How Mealvana Calculates Your Sodium Needs

The formula:

Sodium Loss (mg/hr) = Sweat Rate (L/hr) × Sweat Sodium Concentration (mg/L)

This approach aligns with the ACSM Position Stand on Exercise and Fluid Replacement: “Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized fluid replacement programs are recommended” (Sawka et al., 2007, Medicine and Science in Sports and Exercise).

Example — Two Athletes, Same Workout:

Athlete Sweat Rate Sodium Concentration Hourly Loss
Sarah 1.2 L/hr 900 mg/L 1,080 mg/hr
Marcus 1.8 L/hr 1,400 mg/L 2,520 mg/hr

Marcus loses more than twice as much sodium as Sarah in the same workout. Their fueling plans need to reflect this.

This isn’t just academic. Baker et al. (2019) demonstrated significant sport-specific differences in sodium losses, with American football and endurance athletes showing the greatest need for deliberate replacement strategies (Baker et al., 2019, Journal of Sports Sciences).

Setting Your Profile

In Mealvana, you can input:

  • Sweat rate (L/hr) — Measure by weighing yourself before and after a 1-hour workout
  • Sodium loss rate (mg/L) — From a sweat test, or use our estimate based on your description

If you haven’t done a formal sweat test, we use research-based defaults from Baker et al. (2016):

  • Average sweat sodium: ~900 mg/L
  • Range for “salty sweater” profile: 1,200-1,500 mg/L
  • Range for “light sweater” profile: 400-600 mg/L

Sodium Replacement Guidelines

How much should you replace? Research suggests targeting 50-80% replacement during exercise is both practical and effective. The International Society of Sports Nutrition recommends 500-700 mg of sodium per liter of fluid for ultra-endurance events (Tiller et al., 2019, Journal of the International Society of Sports Nutrition).

For hot/humid conditions (>25°C and/or >60% humidity), intake should increase to 300-600 mg sodium per hour (Tiller et al., 2019).

Part 5: Fluid — Matching Your Sweat Rate

The Goal

The research consensus is clear: don’t lose more than 2-3% of your body weight from dehydration during exercise. Beyond that threshold, performance drops measurably (Sawka et al., 2007).

But here’s the flip side: don’t over-drink either. Hyponatremia (dangerously low blood sodium from drinking too much plain water) is a real risk in long events, particularly marathons and Ironman races (Hew-Butler et al., 2015).

Sweat Rate Variability

Just like sodium concentration, sweat rates vary dramatically. The research documents a range of 0.5 to 2.5+ L/hr depending on:

  • Exercise intensity
  • Environmental conditions (heat, humidity)
  • Body size
  • Fitness level and heat acclimation
  • Genetics

(Baker et al., 2016, Sports Medicine)

How Mealvana Calculates Fluid Targets

We start with your sweat rate and apply a practical replacement factor:

Fluid Target (ml/hr) = Sweat Rate (L/hr) × 1000 × Replacement Factor (0.7-0.9)

The replacement factor accounts for:

  1. Some fluid produced from metabolism
  2. Perfect 100% replacement isn’t necessary or practical
  3. You’ll consume additional fluid with food

Environmental Adjustments:

Research documents significant environmental effects on sweat rate and fluid needs:

Condition Fluid Adjustment Evidence
Hot (>25°C / 77°F) +25-40% Tiller et al., 2019
Humid (>70%) +20-30% Sawka et al., 2007
Cold (<10°C / 50°F) -30-50% Reduced but not eliminated sweat
Indoor trainer (no wind) +30-50% No convective cooling dramatically increases sweat
Altitude (>2000m) +15-25% Increased respiratory water loss

That indoor trainer adjustment is no joke — without wind cooling, sweat rates can nearly double. A German position statement on fluid replacement notes that athletes should pay particular attention to hydration during indoor training (Mosler et al., 2020, German Journal of Sports Medicine).

Part 6: Post-Workout Nutrition — Optimizing Recovery

What you eat after your workout determines how well you recover — and how ready you’ll be for tomorrow’s session. But recovery nutrition isn’t one-size-fits-all. The optimal approach depends on what you just did, when you’re training next, and your overall goals.

The Three Goals of Recovery Nutrition

Post-workout nutrition serves three primary purposes:

  1. Replenish glycogen stores — Restore the muscle fuel you just burned (Burke et al., 2004)
  2. Repair and build muscle — Provide amino acids for muscle protein synthesis (Moore et al., 2009)
  3. Rehydrate — Replace fluid and electrolytes lost through sweat (Shirreffs et al., 1996)

The relative importance of each goal depends on your workout and your schedule.

The Recovery Window: What the Research Actually Says

You’ve probably heard of the “anabolic window” — the idea that you must eat within 30-60 minutes post-exercise or miss out on recovery benefits. The truth is more nuanced.

Glycogen Resynthesis

Muscle glycogen resynthesis is indeed fastest in the first 30-60 minutes post-exercise, when the enzyme glycogen synthase is most active and muscles are highly insulin-sensitive (Ivy et al., 1988, Journal of Applied Physiology).

However, as a comprehensive review noted: “The importance of immediate post-exercise carbohydrate intake is dependent on the time until the next training session” (Beelen et al., 2010, International Journal of Sport Nutrition and Exercise Metabolism).

The Practical Takeaway:

  • <8 hours until next session: Timing matters. Start carbs immediately.
  • >24 hours until next session: Total daily intake matters more than precise timing.

Muscle Protein Synthesis

The protein timing window is wider than once thought. A meta-analysis by Schoenfeld et al. (2013) found that “the anabolic effect of exercise is long-lasting (at least 24 h), but likely diminishes with increasing time post-exercise” (Schoenfeld et al., 2013, Journal of the International Society of Sports Nutrition).

That said, consuming protein within 2 hours post-exercise is still recommended for optimal muscle protein synthesis, especially if you trained fasted or it’s been >4 hours since your last protein-containing meal (Aragon & Schoenfeld, 2013, Journal of the International Society of Sports Nutrition).

Post-Workout Carbohydrate: Refilling the Tank

How Much?

The rate of glycogen resynthesis maxes out at approximately 1.0-1.2 g/kg/hour for the first 4 hours post-exercise (Burke et al., 2004). Consuming more than this doesn’t speed up the process — it just gets stored as fat or oxidized.

Recovery Window Carb Target Rationale
0-30 min 1.0-1.2 g/kg Maximizes glycogen synthase activity (Ivy, 1988)
30-60 min 1.0-1.2 g/kg Continued rapid resynthesis
2-4 hours 1.0-1.2 g/kg/hr If rapid recovery needed
24-hour total 5-7 g/kg (moderate) to 7-12 g/kg (high volume) For full glycogen restoration (Burke et al., 2011)

Example for 70kg athlete after a depleting session: 70-84g carbs in first 30 min, repeated hourly for 4 hours if training again within 8 hours.

Carb Quality Matters

High glycemic index (GI) carbohydrates produce faster glycogen resynthesis in the immediate post-exercise period (Burke et al., 1993). Good choices include:

  • White rice, white bread, bagels
  • Potatoes (not sweet potatoes initially)
  • Sports drinks, fruit juice
  • Ripe bananas, dates
  • Rice cakes, pretzels

For the 2-24 hour window, a mix of high and moderate GI carbs is fine, and whole food sources become preferable for overall nutrition quality.

Post-Workout Protein: Building and Repairing

How Much?

Research consistently shows that 20-40g of high-quality protein (or 0.25-0.4 g/kg body weight) maximally stimulates muscle protein synthesis post-exercise (Moore et al., 2009).

A dose-response study found that 20g of egg protein stimulated muscle protein synthesis maximally in young men after resistance exercise, with 40g providing no additional benefit for whole-body protein synthesis (Witard et al., 2014, American Journal of Clinical Nutrition).

However, for older athletes (>40) or after particularly damaging exercise (long runs, eccentric work), higher doses of 40g may be beneficial (Moore et al., 2015).

Protein Quality: Leucine Is Key

Not all proteins are equal for muscle recovery. The amino acid leucine is the primary trigger for muscle protein synthesis. Research suggests a leucine threshold of 2.5-3g is needed to maximally stimulate this process (Churchward-Venne et al., 2012).

Protein Source Amount for ~3g Leucine
Whey protein 20-25g
Eggs 4-5 whole eggs
Chicken breast 120-140g
Greek yogurt 300-350g
Milk 750ml
Plant blend 30-40g (lower leucine density)

Source: van Vliet et al., 2015, Journal of Nutrition

The Carb + Protein Combination

Early research suggested that adding protein to carbohydrate enhanced glycogen resynthesis (Zawadzki et al., 1992). However, subsequent studies clarified that this benefit disappears when carbohydrate intake is already optimal (≥1.0-1.2 g/kg/hr) (Beelen et al., 2010).

The current consensus:

  • If you can consume adequate carbs (1.0-1.2 g/kg/hr), adding protein doesn’t accelerate glycogen resynthesis
  • However, protein is still valuable for muscle repair — so include it regardless
  • If appetite or stomach tolerance limits carb intake, adding protein can help compensate

Mealvana recommends both carbs AND protein post-workout — not because they’re synergistic for glycogen, but because you need both for complete recovery.

Sport-Specific Post-Workout Guidelines

Different sports create different recovery demands. A 90-minute easy spin doesn’t require the same recovery protocol as a marathon.

Running: Highest Muscle Damage

Running creates significant eccentric muscle damage from the repetitive impact and braking forces. Research shows that marathon running causes measurable muscle damage lasting 7-14 days (Howatson & van Someren, 2008).

Mealvana’s Running Recovery Adjustments:

Factor Adjustment Rationale
Protein priority Higher (0.3-0.4 g/kg) Greater muscle damage to repair
Protein timing Within 1-2 hours Support repair processes
Anti-inflammatory foods Encouraged Tart cherry, omega-3s may help (Howatson et al., 2010)
Long runs (>90 min) Aggressive carb replacement Significant glycogen depletion
Easy runs (<60 min) Moderate recovery meal Less depleting

Cycling: Primarily Metabolic Stress

Cycling causes less muscle damage than running (concentric-dominant movement) but can create significant glycogen depletion, especially in long or high-intensity sessions.

Mealvana’s Cycling Recovery Adjustments:

Factor Adjustment Rationale
Carb priority Higher emphasis Primary limiter is glycogen
Protein Standard (0.25-0.3 g/kg) Less muscle damage
Long rides (>3 hr) Aggressive carb: 1.2 g/kg/hr Major glycogen depletion
Intervals/VO2max Prioritize carbs High glycogen cost
Easy spins Minimal recovery focus Little depletion

Swimming: Unique Recovery Needs

Swimming involves upper body muscles often undertrained in runners/cyclists, creating a different recovery demand. Additionally, cold water immersion affects post-exercise appetite and metabolism.

Mealvana’s Swimming Recovery Adjustments:

Factor Adjustment Rationale
Protein Standard to slightly higher Upper body muscle repair
Carb Lower than equivalent land sessions Less glycogen depletion per hour
Timing May need reminder Cold water suppresses appetite
Chlorine exposure Emphasize antioxidants Oxidative stress consideration

When Time to Next Workout Changes Everything

This is perhaps the most important factor in recovery nutrition: when are you training again?

Scenario 1: >24 Hours Until Next Session

For most recreational athletes training once daily or every other day:

  • Timing is flexible — eat within 2 hours, but don’t stress
  • Focus on total daily carb and protein intake
  • A balanced meal is fine; no need for specific recovery products

“When a 24-h recovery period is available, the pattern of intake of CHO-rich meals and snacks is not as important as achieving total CHO intake targets” (Burke et al., 2011)

Scenario 2: 8-24 Hours Until Next Session (Two-a-Days, AM/PM Split)

Timing becomes more important:

  • Start carbs within 30 minutes: 1.0-1.2 g/kg
  • Include protein: 0.25-0.4 g/kg
  • Continue carb-rich meals/snacks every 2-3 hours
  • Prioritize sleep for hormonal recovery

Scenario 3: <8 Hours Until Next Session (Same-Day Doubles)

Aggressive recovery protocol needed:

  • Immediate (0-30 min): 1.2 g/kg carbs + 0.3 g/kg protein
  • Hourly for 4 hours: 1.0-1.2 g/kg carbs
  • High GI carbs preferred for speed
  • Fluid: 150% of losses (Shirreffs et al., 1996)
  • Consider liquid nutrition if appetite is suppressed

Intensity and Duration: Calibrating Recovery to Effort

Not every workout deserves the same recovery treatment. Mealvana adjusts recommendations based on what you actually did.

By Intensity:

Workout Type Carb Need Protein Need Recovery Priority
Recovery/Easy (Z1-Z2) Low (0.3-0.5 g/kg) Standard Normal meal timing fine
Endurance (Z2-Z3) Moderate (0.5-0.8 g/kg) Standard Within 2 hours
Tempo/Threshold (Z3-Z4) Moderate-High (0.8-1.0 g/kg) Standard Within 1-2 hours
Intervals (Z4-Z5) High (1.0-1.2 g/kg) Standard-High Within 1 hour
Race effort High (1.0-1.2 g/kg) High Immediate

By Duration:

Duration Glycogen Depletion Recovery Carb Target
<45 min Minimal (~10-20%) Normal meal; no special recovery needed
45-90 min Moderate (~30-50%) 0.5-0.8 g/kg within 2 hours
90-150 min Significant (~50-70%) 0.8-1.0 g/kg within 1 hour
>150 min Near-complete (>70%) 1.0-1.2 g/kg immediately + ongoing

Depletion estimates based on moderate-intensity exercise; higher intensity accelerates depletion (Hawley & Burke, 2010)

Post-Workout Hydration: The 150% Rule

You can’t fully rehydrate during exercise — you’re always playing catch-up. Post-workout is when you restore fluid balance.

Research by Shirreffs et al. (1996) established that athletes must consume 150% of fluid losses to achieve euhydration, because some fluid is lost to urine production during the rehydration process (Shirreffs et al., 1996, Medicine and Science in Sports and Exercise).

Practical Application:

  • Weigh yourself before and after exercise
  • Every 1 kg lost = 1 L fluid deficit
  • Consume 1.5 L for every 1 kg lost over 2-4 hours

Sodium Aids Retention

Plain water is poorly retained. Adding sodium (500-700 mg/L) significantly improves fluid retention post-exercise (Maughan et al., 1994).

Post-Workout Fluid Sodium Retention
Plain water 0 mg/L ~50% retained
Sports drink 400-500 mg/L ~70% retained
Oral rehydration solution 800-1000 mg/L ~80% retained
Milk ~500 mg/L + protein Excellent retention (Shirreffs et al., 2007)

Source: Evans et al., 2017, European Journal of Applied Physiology

Recovery Nutrition for Weight-Conscious Athletes

Some athletes are simultaneously trying to recover and manage body composition. This requires careful balancing.

Key Principles:

  • Never skip post-workout protein — muscle preservation is critical during caloric restriction
  • Carbs can be moderated if >24 hours to next hard session
  • After easy sessions, a normal meal is sufficient — no need for additional recovery calories
  • Prioritize recovery nutrition after key sessions; be more conservative after easy days

Research shows that protein timing becomes more important during caloric restriction, as the margin for error in muscle protein balance is smaller (Areta et al., 2014).

Summary: Mealvana’s Post-Workout Decision Tree

When generating your post-workout recommendations, Mealvana considers:

  1. When is your next workout? → <8 hours = aggressive; >24 hours = flexible timing
  2. What sport did you do? → Running = protein priority; Cycling = carb priority
  3. How long was the session? → Duration drives glycogen depletion estimate
  4. How hard was it? → Intensity affects both glycogen use and muscle damage
  5. What are your goals? → Performance vs. weight management affects carb recommendations
  6. What time of day? → Evening workouts get sleep-optimized recommendations

The result: recovery nutrition matched to what your body actually needs, not a generic “eat protein and carbs” recommendation.

Part 7: Putting It All Together — A Worked Example

Let’s walk through how Mealvana generates a complete fueling plan for a specific workout — before, during, and after. We’ll use a race example here, but the same calculation logic applies to your Tuesday brick session, Saturday long ride, or Wednesday track workout — just with different inputs.

The Workout

Olympic Triathlon Race

  • Swim: 1.5 km (~25 min)
  • Bike: 40 km (~65 min)
  • Run: 10 km (~50 min)
  • Total: ~2:20
  • Conditions: Warm day (26°C / 79°F), moderate humidity (55%)

The Athlete Profile

  • Weight: 68 kg
  • Sweat rate: 1.3 L/hr (increases to ~1.5 L/hr in heat)
  • Sweat sodium: 1,100 mg/L
  • Max carb tolerance: 80 g/hr
  • GI sensitivity: Low
  • Caffeine sensitive: No
  • Next workout: Easy recovery swim in 36 hours

PRE-WORKOUT CALCULATION

Timing Context: Race starts at 8:00 AM. Athlete wakes at 5:00 AM.

Pre-Workout Carbohydrate:

For a 2:20 race at high intensity, we want maximally topped-off glycogen stores.

Timing Target Calculation
3 hours before (5:00 AM) 2-3 g/kg = 136-204g carbs High end due to race intensity
10-20 min before 0.5 g/kg = 30-35g carbs Final top-up

Pre-Workout Protein & Fat:

Nutrient Target Timing Notes
Protein 15-20g 3 hours before Support, not priority
Fat <15g 3 hours before Minimize to speed gastric emptying
Fiber Minimal All day before Reduce GI risk

Pre-Workout Hydration:

Given the warm conditions (26°C), we apply the sodium loading protocol:

Timing Fluid Target Sodium Target Calculation
Evening before 500ml with dinner 500-800mg With salty meal
Wake up (5:00 AM) 400-500ml 400-600mg 6-7 ml/kg
1-2 hr before 200-300ml 200-300mg 3-4 ml/kg
10-20 min before 150-200ml 100-200mg Final sips
Total pre-race 1,250-1,500ml 1,200-1,900mg —

Sodium loading calculation for warm conditions: 15-20 mg/kg × 68 kg = 1,020-1,360mg in the 2-4 hours before. We hit the upper range given race importance.

Pre-Race Meal Example (5:00 AM):

  • 2 cups white rice with honey (80g carbs)
  • 1 banana (25g carbs)
  • 2 eggs (12g protein)
  • 500ml sports drink (30g carbs + 500mg sodium)
  • Salt on eggs + salty broth sipped
  • Total: ~135g carbs, ~15g protein, ~500-700mg sodium

Final Top-Up (7:40-7:50 AM):

  • 1 gel (25g carbs)
  • 200ml electrolyte drink (200mg sodium)
  • Small sips only — don’t overdo it

DURING-WORKOUT CALCULATION

Swim Leg:

  • Duration: 25 min
  • Fueling: None (can’t eat while swimming)
  • Sweat: Reduced in water (~50% of land rate) — approximately 0.3L total
  • Sodium loss: ~330mg
  • Note: Pre-race fueling carries you through (Jeukendrup et al., 2005)

T1 Transition:

  • Quick sip of water if available
  • No solid food — keep moving

Bike Leg:

  • Duration: 65 min
  • Intensity: Race pace (high)
  • Sweat rate in heat: 1.5 L/hr × 1.08 hr = ~1.6L
  • Sodium loss: 1.6L × 1,100 mg/L = ~1,760mg
  • Base carb recommendation: 60-75 g/hr for this duration/intensity (Burke et al., 2011)
  • Athlete tolerance: 80 g/hr (not limiting)
  • Bike carb target: 60-70g total (~55-65 g/hr)
  • Bike sodium target: ~1,500mg (aim to replace ~85%)
  • Bike fluid target: ~1,200-1,400ml (aim to replace ~80%)

T2 Transition:

  • Quick gel (25g carb) + electrolyte sip (200mg sodium)
  • This is your last easy fueling opportunity before GI-sensitive run

Run Leg:

  • Duration: 50 min
  • Intensity: Race pace
  • Sweat rate in heat: 1.5 L/hr × 0.83 hr = ~1.25L
  • Sodium loss: ~1,375mg
  • Base carb recommendation: 40-50 g/hr for 50-min race effort
  • Brick penalty applied: Reduce by 20% due to bike-to-run GI stress (Jeukendrup et al., 2005)
  • Run carb target: 30-40g total
  • Run sodium target: ~700mg (conservative due to GI sensitivity on run)
  • Run fluid target: ~500-600ml (from aid stations)

DURING-WORKOUT SUMMARY

Segment Carbs Sodium Fluid Products
Pre-race (3hr before) 135g 600mg 500ml Breakfast + sports drink
Pre-race (20min before) 25g 200mg 200ml Gel + electrolyte sips
Swim — — — —
T1 — — Quick sip —
Bike 60-70g 1,500mg 1,300ml 2 bottles high-sodium mix + 1 gel
T2 25g 200mg 100ml Gel + electrolyte sip
Run 30-40g 700mg 550ml 1-2 gels + aid station cups
RACE TOTAL 275-295g 3,200mg 2,650ml —

POST-WORKOUT CALCULATION

Context Assessment:

  • Total duration: 2:20 at race effort
  • Glycogen depletion: Near-complete (estimated 80-90%)
  • Muscle damage: Moderate-high (running component)
  • Fluid deficit: Estimated 1.5-2.0 kg body weight loss
  • Next workout: 36 hours away (recovery swim)
  • Priority: Full recovery, but no ultra-urgent timeline

Post-Race Carbohydrate:

Since the next session is 36 hours away, we don’t need the most aggressive protocol — but this was a depleting race, so we still prioritize recovery.

Timing Target Calculation Rationale
0-30 min 1.0 g/kg = 68g High GI priority Maximize glycogen synthase window
1-2 hours 0.8 g/kg = 54g With real meal Continue replenishment
Rest of day 5-6 g/kg total = 340-400g Spread across meals Full restoration by next day

Post-Race Protein:

Running causes more muscle damage than cycling. After a triathlon with a 10K run, protein is important.

Timing Target Source Preference
0-30 min 0.3-0.4 g/kg = 20-27g Fast-absorbing (whey, milk)
Each subsequent meal 0.25-0.3 g/kg = 17-20g Whole food sources
Daily total 1.6-2.0 g/kg = 110-136g Elevated for 24-48 hours

Higher protein recommendation due to running-induced muscle damage (Howatson & van Someren, 2008)

Post-Race Rehydration:

Apply the 150% rule (Shirreffs et al., 1996):

Metric Value Calculation
Estimated fluid deficit 1.5-2.0 kg Body weight loss
Rehydration target 2.25-3.0 L 150% of deficit
Timeline Over 2-4 hours Don’t chug — sip steadily
Sodium to include 1,500-2,000mg 500-700mg per liter

Post-Race Sodium:

Sodium is critical for fluid retention. Without it, much of what you drink ends up as urine.

Timing Sodium Target Source
0-30 min 500-700mg Recovery drink or salty snack
1-2 hours 500-800mg With meal (salt food liberally)
Rest of day Match sweat losses Normal salty eating

Anti-Inflammatory Considerations:

After the running component, consider foods that may support recovery:

  • Tart cherry juice: 8-12 oz (may reduce muscle soreness) (Howatson et al., 2010)
  • Omega-3 rich foods: Salmon, walnuts, chia seeds
  • Avoid NSAIDs: Ibuprofen impairs gut barrier and may slow recovery (Van Wijck et al., 2012)

POST-RACE RECOVERY PLAN

Immediate (0-30 min):

Nutrient Target Example
Carbs 68g (1.0 g/kg) Recovery shake + banana
Protein 25g (0.35 g/kg) Whey protein in shake
Fluid 500-750ml Sports drink or chocolate milk
Sodium 600mg In recovery drink + salty snack

Practical option: 500ml chocolate milk (50g carbs, 16g protein, 300mg sodium) + banana (25g carbs) + salted pretzels (15g carbs, 400mg sodium) + 250ml water

1-2 Hours Post (Recovery Meal):

Nutrient Target Example
Carbs 54g (0.8 g/kg) Rice, pasta, or potatoes
Protein 25-30g Chicken, fish, or eggs
Fat Moderate Acceptable now
Fluid 750ml-1L Water with meal + electrolyte drink
Sodium 700-1,000mg Salt food, salty sides

Practical option: Grilled chicken (30g protein) + large serving white rice (60g carbs) + steamed vegetables + soy sauce (sodium) + 8oz tart cherry juice + 500ml water

Evening/Rest of Day:

  • Continue eating carb-rich meals until ~350-400g total for day
  • Include protein at each meal (20-30g)
  • Continue hydrating until urine is pale yellow
  • Consider salty snacks if still feeling depleted
  • Prioritize sleep — hormonal recovery happens overnight

COMPLETE NUTRITION TIMELINE

Time Phase Carbs Protein Sodium Fluid
Night before Dinner 100g 25g 800mg 500ml
5:00 AM Pre-race meal 135g 15g 600mg 500ml
7:45 AM Final top-up 25g — 200mg 200ml
8:00-10:20 AM Race 115-135g — 2,400mg 1,950ml
10:20-10:50 AM Immediate recovery 68g 25g 600mg 650ml
12:00 PM Recovery meal 54g 30g 800mg 750ml
Rest of day Ongoing recovery 150-200g 60g 1,000mg 1,500ml
24-HOUR TOTAL — 650-720g 155g 6,400mg 6,050ml

This represents a high-carbohydrate race day protocol for optimal performance and recovery. Training days would typically be 30-50% lower in total carbohydrates depending on workout demands.

Part 8: Why Mealvana Is More Than a Lookup Table

You might be thinking: “This is just a table lookup. Duration goes in, carb recommendation comes out.” But that’s exactly what we don’t do. Here’s how Mealvana’s approach differs from the static tables you’ll find in textbooks and generic sports nutrition guides.

1. Continuous Functions, Not Arbitrary Cutoffs

Traditional guidelines use step functions with hard cutoffs:

Duration Traditional Recommendation
45-60 min 30 g/hr
60-90 min 30-60 g/hr
90-150 min 60-90 g/hr

See the problem? A 59-minute workout gets one recommendation. A 61-minute workout jumps to a completely different range. Your body doesn’t work in 60-minute increments.

Mealvana uses continuous algorithms that smoothly scale recommendations across the full duration spectrum. A 59-minute workout and a 61-minute workout get nearly identical recommendations — because physiologically, they’re nearly identical workouts.

The same applies to intensity. We don’t suddenly flip a switch at “Zone 3 vs. Zone 4.” We use your actual workout intensity (from TrainingPeaks TSS and IF data) to calculate recommendations on a smooth curve.

2. We Learn From Your Feedback

Research provides population-level ranges. But you’re not a population — you’re an individual.

When you log a workout and tell us:

  • “Fueling felt perfect”
  • “Stomach was a bit off”
  • “Bonked at mile 18”
  • “Could have eaten more”

…we learn. Over time, Mealvana narrows your personal band from the wide population range down to what actually works for you.

Example:

  • Population range for a 3-hour ride: 60-90 g/hr
  • After 10 logged rides with feedback: Your personalized range: 70-80 g/hr

This is the difference between generic advice and a system that knows you — your gut, your preferences, your tolerance.

3. Weight-Scaled Recommendations

Here’s something most tables ignore: body size matters.

A 55 kg runner and an 85 kg runner doing the same workout have different absolute needs. While carbohydrate oxidation rates are largely gut-limited (not body-size-limited), other factors do scale:

  • Fluid needs scale with body surface area and sweat rate
  • Sodium losses scale with sweat volume
  • Absolute glycogen stores are larger in bigger athletes
  • Practical tolerance often correlates with body size

Mealvana applies weight-based scaling within each recommendation band:

  • Lower-weight athletes start toward the lower end of ranges
  • Higher-weight athletes start toward the upper end

This isn’t just about being bigger — it’s about calibrating to your physiology from day one, then refining from there.

4. Multi-Variable Integration

Traditional tables handle one or two variables. Mealvana integrates all of them simultaneously:

Variable How We Use It
Duration Primary driver of total carb need
Intensity (TSS/IF) Modifies carb utilization rate
Sport type Bike vs. run vs. swim algorithms
Your carb tolerance Hard ceiling on recommendations
Your sweat rate Drives fluid/sodium targets
Your sodium concentration Personalizes electrolyte needs
Environmental conditions Heat/cold/humidity/altitude adjustments
Workout context Brick penalties, back-to-back days
Training phase Taper week carb loading vs. base building

No lookup table can handle this complexity. We calculate your recommendations fresh for every workout, with every variable weighted appropriately.

5. Training Context Awareness

Your Monday long run and your Friday long run might be identical on paper — but if you’ve done hard sessions Tuesday through Thursday, your Friday needs are different.

Mealvana reads your full TrainingPeaks calendar, not just the individual workout. We know:

  • Back-to-back hard days: Emphasize recovery nutrition and glycogen replenishment
  • Taper week: Carb loading protocols for the final days before your race
  • Build phase: Standard fueling, focus on training the gut
  • Two-a-days: Adjusted recovery windows between sessions

6. Ranges, Not False Precision

You’ll notice Mealvana gives you ranges (60-75 g/hr) rather than single numbers (67.3 g/hr).

This is intentional. The research gives us ranges. Your individual response varies day to day. Weather changes. Stress affects your gut. That gel you usually love might taste terrible at mile 20.

We give you a target band — precise enough to be actionable, honest enough to acknowledge uncertainty. Aim for the middle, and you have room to adjust based on how you feel.

7. Workout Intent Matters: Training Mode vs. Race Mode

A Tuesday tempo run and an A-race have different goals — and should have different fueling strategies.

In training mode, we optimize for development:

  • Room to experiment with products and quantities
  • Building gut tolerance gradually
  • Learning your personal limits through controlled trial
  • Sometimes intentionally under-fueling low-key sessions to enhance fat adaptation

In race/key workout mode, we optimize for performance:

  • Maximize output within your proven tolerance
  • Pre-workout protocols optimized for topped-off glycogen
  • Stick with what you’ve tested — no experiments
  • Contingency plans for GI distress

When you mark a workout as a race or key session in TrainingPeaks, Mealvana shifts its recommendations accordingly. Both modes matter — training fueling builds your capacity; race fueling unleashes it.

Part 9: Training Your Gut

Here’s something the research has proven: your gut adapts to what you ask of it.

A landmark study by Cox et al. (2010) showed that athletes who trained with high carbohydrate intake for 28 days significantly increased their ability to absorb and oxidize carbs during exercise. The high-carb group showed “higher exogenous carbohydrate oxidation rates during exercise than the low-carb group” — attributed to improved intestinal absorption (Cox et al., 2010, Journal of Applied Physiology).

This adaptation appears to involve upregulation of intestinal transporters (SGLT1 and GLUT5), meaning your gut literally builds more “lanes” for carbohydrate absorption with training (Jeukendrup, 2017).

As Jeukendrup summarized: “The gut is highly adaptable and endurance athletes should incorporate nutritional training into their training plans” (Jeukendrup & McLaughlin, 2011, Nestlé Nutrition Institute Workshop Series).

What This Means for You

  1. Start conservative — If you’re new to fueling during exercise, begin at 40-50 g/hr
  2. Build gradually — Add 5-10 g/hr every few weeks
  3. Practice your fueling strategy — Test products and quantities in training before key events
  4. Use long sessions to test tolerance — Long rides and runs are perfect for gut training

A systematic review on gut training concluded that “repeated exposure to high carbohydrate intake during training can impact physiological outcomes; specifically, substrate utilization” and can help prevent GI distress (Costa et al., 2023, Sports Medicine).

Mealvana tracks your training history and will gradually suggest higher carb targets as you demonstrate tolerance over time.

Part 10: When Things Go Wrong — GI Distress

Even with perfect planning, GI issues happen. Research suggests several risk factors, which Mealvana accounts for in its recommendations.

Known Risk Factors for GI Distress

Studies have identified several dietary and non-dietary correlates of GI distress during endurance events:

Risk Factor Evidence
History of GI issues Strongest predictor (ρ = 0.32-0.51) (Pfeiffer et al., 2012)
High fiber intake before workout Increases symptoms (Rehrer et al., 1992)
High fat/protein before workout Delays gastric emptying (Rehrer et al., 1992)
Concentrated carb solutions (>8%) Increases GI distress (de Oliveira et al., 2014)
NSAIDs (ibuprofen, etc.) Compromises gut barrier (Van Wijck et al., 2012)
Dehydration Exacerbates symptoms (Rehrer et al., 1992)

Source: Wilson, 2015, International Journal of Sport Nutrition and Exercise Metabolism

Red Flags That Trigger Conservative Recommendations

Factor Mealvana Adjustment
GI sensitivity: High Reduce carb ceiling by 20-30%
First time at this duration/intensity Conservative fueling, liquid calories preferred
Hot conditions Reduce carbs slightly, increase sodium/fluid
Brick run Reduce run carbs by 20-30%
Caffeine sensitive Remove caffeine from recommendations

The Backup Plan

For long workouts and races (3+ hours), Mealvana generates a GI distress contingency based on field experience from ultra-endurance research:

  • If nausea hits: Switch to simple carbs (cola, flat ginger ale) + broth only (Stuempfle & Hoffman, 2015)
  • Reduce intensity briefly to allow digestion
  • Reduce intake to 30 g/hr until symptoms resolve
  • Prioritize hydration over calories

In training, a GI blowup is a learning opportunity. In a race, it’s a crisis. Either way, having a plan B ready keeps a bad patch from becoming a DNF.

The Bottom Line

Your Mealvana nutrition plan isn’t a guess — it’s built on:

  • Peer-reviewed research from leading sports nutrition scientists
  • Your personal profile (weight, sweat rate, sodium loss, carb tolerance)
  • Your specific workout (duration, intensity, sport type)
  • Environmental conditions (heat, humidity, altitude)
  • Smart adjustments (brick penalties, GI sensitivity, caffeine restrictions)

The goal is simple: give you enough fuel to perform your best, without giving you so much that your stomach rebels.

Every recommendation comes with the reasoning behind it, so you understand not just what to eat, but why. Because the more you understand your fueling, the better you can adapt when your workout throws you a curveball.

Key References

Carbohydrate Oxidation & Guidelines

  1. Jeukendrup AE. (2004). Carbohydrate intake during exercise and performance. Nutrition, 20(7-8):669-677. PubMed
  2. Jeukendrup AE. (2014). A step towards personalized sports nutrition: Carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1):S25-S33. PubMed
  3. Jentjens RL, Jeukendrup AE. (2005). High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose. British Journal of Nutrition, 93(4):485-492. PubMed
  4. Burke LM, Hawley JA, Wong SH, Jeukendrup AE. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29(Suppl 1):S17-S27. PubMed
  5. Thomas DT, Erdman KA, Burke LM. (2016). Position of the Academy of Nutrition and Dietetics: Nutrition and Athletic Performance. Journal of the Academy of Nutrition and Dietetics, 116(3):501-528. PubMed
  6. Hearris MA et al. (2022). Graded carbohydrate ingestion rates… International Journal of Sport Nutrition and Exercise Metabolism. PubMed

Multiple Transportable Carbohydrates

  1. Jeukendrup AE. (2008). Carbohydrate feeding during exercise. European Journal of Sport Science, 8(2):77-86. Taylor & Francis
  2. Jeukendrup AE. (2010). Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4):452-457. PubMed
  3. Rowlands DS et al. (2015). Fructose-glucose composite carbohydrates and endurance performance. Sports Medicine, 45(3):381-400. PubMed
  4. Currell K, Jeukendrup AE. (2008). Superior endurance performance with ingestion of multiple transportable carbohydrates. Medicine and Science in Sports and Exercise, 40(2):275-281. PubMed

GI Distress & Sport Differences

  1. Peters HP et al. (1999). Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes. American Journal of Gastroenterology, 94(6):1570-1581. PubMed
  2. Pfeiffer B et al. (2012). Nutritional intake and gastrointestinal problems during competitive endurance events. Medicine and Science in Sports and Exercise, 44(2):344-351. PubMed
  3. Jeukendrup AE, Jentjens RL, Moseley L. (2005). Nutritional considerations in triathlon. Sports Medicine, 35(2):163-181. PubMed
  4. Sareban M et al. (2016). Carbohydrate intake in form of gel is associated with increased gastrointestinal distress. International Journal of Sport Nutrition and Exercise Metabolism, 26(2):114-122. PubMed

Sweat & Sodium

  1. Baker LB et al. (2016). Normative data for regional sweat sodium concentration. Journal of Sports Sciences, 34(4):358-368. PubMed
  2. Baker LB et al. (2017). Sweating rate and sweat sodium concentration in athletes: A review. Sports Medicine, 47(Suppl 1):111-128. PubMed
  3. Baker LB et al. (2019). Normative data for sweating rate, sweat sodium concentration, and sweat sodium loss: An update and analysis by sport. Journal of Sports Sciences, 37(20):2356-2366. Taylor & Francis

Hydration Guidelines

  1. Sawka MN et al. (2007). ACSM Position Stand: Exercise and fluid replacement. Medicine and Science in Sports and Exercise, 39(2):377-390. PubMed
  2. Tiller NB et al. (2019). ISSN Position Stand: Nutritional considerations for single-stage ultra-marathon training and racing. Journal of the International Society of Sports Nutrition, 16(1):50. PubMed
  3. Cheuvront SN, Kenefick RW. (2014). Dehydration: Physiology, assessment, and performance effects. Comprehensive Physiology, 4(1):257-285. PubMed
  4. Sims ST et al. (2007). Pre-exercise sodium loading aids fluid balance and endurance for women exercising in the heat. Journal of Applied Physiology, 103(2):534-541. PubMed
  5. McCubbin AJ et al. (2020). Sodium ingestion before and during exercise in the heat: A systematic review and meta-analysis. Sports Medicine, 50(2):225-244. PubMed
  6. Baker LB, Jeukendrup AE. (2014). Optimal composition of fluid-replacement beverages. Comprehensive Physiology, 4(2):575-620. PubMed

Gut Training

  1. Cox GR et al. (2010). Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation. Journal of Applied Physiology, 109(1):126-134. PubMed
  2. Jeukendrup AE, McLaughlin J. (2011). Carbohydrate ingestion during exercise: effects on performance, training adaptations and trainability of the gut. Nestlé Nutrition Institute Workshop Series, 69:1-12. PubMed
  3. Costa RJS et al. (2023). The effect of gut-training and feeding-challenge on markers of gastrointestinal status. Sports Medicine. Springer

Pre-Exercise Nutrition & Timing

  1. Kerksick CM et al. (2017). ISSN position stand: Nutrient timing. Journal of the International Society of Sports Nutrition, 14:33. PubMed
  2. Ormsbee MJ et al. (2014). Pre-exercise nutrition: The role of macronutrients, modified starches and supplements on metabolism and endurance performance. Nutrients, 6(5):1782-1808. PubMed
  3. Jeukendrup AE, Killer SC. (2010). The myths surrounding pre-exercise carbohydrate feeding. Annals of Nutrition and Metabolism, 57(Suppl 2):18-25. PubMed
  4. Rothschild JA et al. (2020). What should I eat before exercise? Pre-exercise nutrition and the response to endurance exercise: Current prospective and future directions. Nutrients, 12(11):3473. PubMed
  5. Rehrer NJ et al. (1992). Gastrointestinal complaints in relation to dietary intake in triathletes. International Journal of Sport Nutrition, 2(1):48-59. PubMed
  6. Hawley JA, Burke LM. (2010). Carbohydrate availability and training adaptation: Effects on cell metabolism. Exercise and Sport Sciences Reviews, 38(4):152-160. PubMed
  7. Van Proeyen K et al. (2011). Beneficial metabolic adaptations due to endurance exercise training in the fasted state. Journal of Applied Physiology, 110(1):236-245. PubMed
  8. de Oliveira EP, Burini RC. (2009). The impact of physical exercise on the gastrointestinal tract. Current Opinion in Clinical Nutrition and Metabolic Care, 12(5):533-538. PubMed
  9. van Wijck K et al. (2012). Exercise-induced splanchnic hypoperfusion results in gut dysfunction in healthy men. PLoS One, 7(1):e30724. PubMed
  10. Shirreffs SM, Sawka MN. (2011). Fluid and electrolyte needs for training, competition, and recovery. Journal of Sports Sciences, 29(Suppl 1):S39-S46. PubMed

Post-Exercise Recovery Nutrition

  1. Ivy JL et al. (1988). Muscle glycogen synthesis after exercise: effect of time of carbohydrate ingestion. Journal of Applied Physiology, 64(4):1480-1485. PubMed
  2. Beelen M et al. (2010). Nutritional strategies to promote postexercise recovery. International Journal of Sport Nutrition and Exercise Metabolism, 20(6):515-532. PubMed
  3. Burke LM et al. (2004). Carbohydrates and fat for training and recovery. Journal of Sports Sciences, 22(1):15-30. PubMed
  4. Burke LM et al. (1993). Muscle glycogen storage after prolonged exercise: effect of the glycemic index of carbohydrate feedings. Journal of Applied Physiology, 75(2):1019-1023. PubMed
  5. Moore DR et al. (2009). Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. American Journal of Clinical Nutrition, 89(1):161-168. PubMed
  6. Witard OC et al. (2014). Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. American Journal of Clinical Nutrition, 99(1):86-95. PubMed
  7. Moore DR et al. (2015). Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. Journals of Gerontology Series A, 70(1):57-62. PubMed
  8. Schoenfeld BJ et al. (2013). The effect of protein timing on muscle strength and hypertrophy: A meta-analysis. Journal of the International Society of Sports Nutrition, 10:53. PubMed
  9. Aragon AA, Schoenfeld BJ. (2013). Nutrient timing revisited: Is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition, 10:5. PubMed
  10. Churchward-Venne TA et al. (2012). Role of protein and amino acids in promoting lean mass accretion with resistance exercise and attenuating lean mass loss during energy deficit in humans. Amino Acids, 45(2):231-240. PubMed
  11. van Vliet S et al. (2015). The skeletal muscle anabolic response to plant- versus animal-based protein consumption. Journal of Nutrition, 145(9):1981-1991. PubMed
  12. Shirreffs SM et al. (1996). Post-exercise rehydration in man: effects of volume consumed and drink sodium content. Medicine and Science in Sports and Exercise, 28(10):1260-1271. PubMed
  13. Shirreffs SM et al. (2007). Milk as an effective post-exercise rehydration drink. British Journal of Nutrition, 98(1):173-180. PubMed
  14. Maughan RJ et al. (1994). Restoration of fluid balance after exercise-induced dehydration: effects of food and fluid intake. European Journal of Applied Physiology, 69(3):209-215. PubMed
  15. Evans GH et al. (2017). Optimizing the restoration and maintenance of fluid balance after exercise-induced dehydration. Journal of Applied Physiology, 122(4):945-951. PubMed
  16. Howatson G, van Someren KA. (2008). The prevention and treatment of exercise-induced muscle damage. Sports Medicine, 38(6):483-503. PubMed
  17. Howatson G et al. (2010). Influence of tart cherry juice on indices of recovery following marathon running. Scandinavian Journal of Medicine and Science in Sports, 20(6):843-852. PubMed
  18. Areta JL et al. (2014). Reduced resting skeletal muscle protein synthesis is rescued by resistance exercise and protein ingestion following short-term energy deficit. American Journal of Physiology, 306(8):E989-E997. PubMed

Fasted Training & Carbohydrate Periodization

  1. Vieira AF et al. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: A systematic review and meta-analysis. British Journal of Nutrition, 116(7):1153-1164. PubMed
  2. Gillen JB, West DWD, Williamson EP, Fung HJW, Moore DR. (2019). Low-carbohydrate training increases protein requirements of endurance athletes. Medicine & Science in Sports & Exercise, 51(11):2294-2301. PubMed
  3. Marquet LA et al. (2016). Enhanced endurance performance by periodization of carbohydrate intake: “Sleep Low” strategy. Medicine & Science in Sports & Exercise, 48(4):663-672. PubMed
  4. Alghannam AF et al. (2020). Exercise training and fasting: Current insights. Open Access Journal of Sports Medicine, 11:1-28. PubMed
  5. Impey SG, Hearris MA, Hammond KM, Bartlett JD, Louis J, Close GL, Morton JP. (2018). Fuel for the work required: A theoretical framework for carbohydrate periodization and the glycogen threshold hypothesis. Sports Medicine, 48(5):1031-1048. PubMed
  6. Moore DR et al. (2014). Beyond muscle hypertrophy: Why dietary protein is important for endurance athletes. Applied Physiology, Nutrition, and Metabolism, 39(9):987-997. PubMed
  7. Rothschild JA, Kilding AE, Plews DJ. (2020). Prevalence and determinants of fasted training in endurance athletes: A survey analysis. International Journal of Sport Nutrition and Exercise Metabolism, 30(5):345-356. PubMed
  8. Impey SG, Hammond KM, Shepherd SO, Sharples AP, Stewart C, Limb M, Smith K, Philp A, Jeromson S, Hamilton DL, Close GL, Morton JP. (2016). Fuel for the work required: A practical approach to amalgamating train-low paradigms for endurance athletes. Physiological Reports, 4(10):e12803. PubMed
  9. Hearris MA, Hammond KM, Fell JM, Morton JP. (2018). Regulation of muscle glycogen metabolism during exercise: Implications for endurance performance and training adaptations. Nutrients, 10(3):298. PubMed
  10. Hawley JA, Morton JP. (2014). Ramping up the signal: Promoting endurance training adaptation in skeletal muscle by nutritional manipulation. Clinical and Experimental Pharmacology and Physiology, 41(8):608-613. PubMed
  11. Bartlett JD, Hawley JA, Morton JP. (2015). Carbohydrate availability and exercise training adaptation: Too much of a good thing? European Journal of Sport Science, 15(1):3-12. PubMed

Questions about your personalized recommendations? Tap any nutrition target in Mealvana to see the calculation breakdown and the factors that influenced it.

Happy training — and happy fueling!

About Mealvana Endurance

Mealvana Endurance syncs with TrainingPeaks to automatically generate personalized nutrition plans for every workout on your calendar — from easy recovery spins to key brick sessions to your A-race. We translate sports science into practical, actionable fueling strategies so you can focus on training, not spreadsheets.