Carbohydrate Timing for Performance: Daily Intake, Intra-Workout Fuel, and Glycogen

1) Glycogen basics: what it is and why carbs matter for moderate-to-high intensity work

Glycogen is the storage form of carbohydrate in your body. It’s stored mainly in muscle (used locally by that muscle during exercise) and in the liver (helps maintain blood glucose, especially between meals and during longer sessions).

When training intensity rises (tempo, intervals, hills, heavy lifting circuits, repeated sprints), your muscles rely more on carbohydrate because it can produce energy quickly. Fat can support lower-to-moderate intensities well, but it cannot match carbohydrate’s speed when you need to sustain or repeat hard efforts.

What “carbohydrate availability” means

Carbohydrate availability is simply: how much usable carbohydrate you have on board (muscle glycogen + liver glycogen + blood glucose) relative to the demands of the session. Higher availability generally supports:

• Better training quality (holding target pace/power, completing planned reps)
• More total work (volume) at a given perceived effort
• More consistent technique late in sessions (less “fade”)

Low availability tends to show up as: early fatigue, heavy legs, declining power/pace, increased perceived exertion, and cravings later in the day.

Glycogen use: practical cues

• Short easy sessions often don’t require special carb strategies.
• Moderate-to-high intensity sessions use glycogen faster (intervals, tempo, long lifts with short rest, team-sport practice).
• Long sessions can deplete glycogen even at moderate intensity, making “late-session” fueling important.

2) Daily carbohydrate ranges: match intake to training volume and goal

Daily carbohydrate needs vary widely. A practical way to set a target is to use grams per kilogram of body weight per day (g/kg/day) and adjust based on training load and goals.

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How to adjust without overthinking

• Hard day = higher carbs: add carbs at 1–2 meals and/or add intra-workout carbs for long/hard sessions.
• Easy day = moderate carbs: keep carbs but reduce portions slightly, especially at meals far from training.
• Goal: performance: bias carbs toward training windows and key sessions; avoid chronic under-fueling.
• Goal: fat loss while training: keep carbs higher around workouts and reduce them more at other meals rather than cutting them evenly across the day.

Quick math example

If you weigh 70 kg and train moderately, a starting range is 3–5 g/kg/day = 210–350 g carbs/day. On a long/hard day you might move toward the top of the range; on a rest day, toward the bottom.

3) Carb timing: pre-, during-, and post-workout (with clear thresholds)

This section focuses on when intra-workout carbs are worth it and how to time carbs to support training quality and glycogen.

Pre-workout: top up availability (without repeating meal templates)

Think of pre-workout carbs as a way to ensure you start the session with adequate liver glycogen and stable blood glucose, especially if you’re training early, training hard, or training long.

• 1–4 hours pre: a carb-containing meal supports higher glycogen availability for quality sessions.
• 0–60 minutes pre: a small carb “top-up” can help if you’re starting hard or you haven’t eaten recently.

Practical step-by-step (pre-workout decision)

1. Look at the session: is it hard (intervals/tempo/repeats) or long (>75–90 min)?
2. Check time since last carb-containing meal: if it’s been >3–4 hours, plan a carb top-up.
3. If you’re prone to GI discomfort, choose lower-fiber, lower-fat carb sources closer to training.

During workout: when intra-workout carbs are beneficial

Intra-workout carbs are most useful when they help you maintain intensity, delay fatigue, and protect glycogen late in the session.

Clear thresholds (duration/intensity cues)

• Usually not necessary: sessions <60 minutes at easy-to-moderate intensity (unless you’re training fasted, doing very intense intervals, or you struggle with low energy).
• Often beneficial: sessions 60–90 minutes that include sustained moderate-to-high intensity, repeated hard efforts, or high total work (e.g., long tempo, tough group ride, hard team practice).
• Strongly recommended: sessions >90 minutes, especially if intensity is moderate-to-high or conditions are hot/humid.

How much carbohydrate per hour?

• 30–45 g/hour: a solid starting point for 60–120 minute sessions or for athletes new to fueling.
• 45–60 g/hour: common target for longer or harder sessions.
• 60–90 g/hour: for 2.5+ hour endurance sessions or very high output; best achieved with a mix of carb types (e.g., glucose + fructose) and requires practice.

Practical step-by-step (during-workout plan)

1. Estimate session length and intensity.
2. Choose a carb target (e.g., 30 g/hour for 90 minutes; 60 g/hour for 2+ hours).
3. Start early: begin carbs at 15–30 minutes rather than waiting until you feel depleted.
4. Divide into small doses every 10–20 minutes to reduce gut load.
5. Pair carbs with fluids and sodium for longer sessions (see below).

Post-workout: replenish glycogen based on what’s next

Post-workout carbs matter most when you need to restore glycogen for another demanding session soon (same day or next morning) or when the session was long/hard.

• When recovery time is short (<24 hours): prioritize carbs soon after training and include them in the next meals.
• When recovery time is long (24–48+ hours): total daily carbs matter more than minute-by-minute timing, but a carb-containing meal still supports recovery.

Practical target: after long/hard sessions, aim for a carb-forward meal/snack in the first few hours, then continue normal meals to reach your daily carb range.

4) Food-based carbs vs sports products (gels/drinks): how to choose

Both approaches can work. The best choice depends on convenience, gut tolerance, and how hard you’re working.

Food-based options (often best for lower intensity or when you can chew)

• Bananas, applesauce pouches
• Rice cakes, jam/honey sandwiches
• Dates, dried fruit (watch fiber if sensitive)
• Boiled potatoes with salt (great for long steady sessions)

Pros: cheaper, more satisfying, can include sodium naturally (e.g., salted potatoes). Cons: harder to carry, slower to eat, may be harder to tolerate at high intensity.

Sports products (best for high intensity and precise dosing)

• Sports drinks (carbs + fluid; sometimes sodium)
• Gels/chews (compact, fast carbs)
• Drink mixes with multiple carb types (useful for higher g/hour targets)

Pros: easy to dose, quick to digest, convenient during hard efforts. Cons: can cause GI issues if too concentrated or if you’re not used to them; cost adds up.

How to decide (simple checklist)

• Intensity high / breathing hard? Prefer drinks/gels over solid foods.
• Need 60+ g/hour? Sports drink + gel/chews is often easiest.
• GI sensitive? Start with lower doses (20–30 g/hour), choose lower-fiber options, and avoid very concentrated mixes.
• Cold weather / low thirst? Gels/chews + small sips can be easier than relying on drink calories alone.

Gut tolerance: train it

Your gut adapts. Practice fueling on easier long sessions before using higher carb targets in races or key workouts.

• Increase carbs by 10–15 g/hour every 1–2 weeks as tolerated.
• Keep doses small and frequent.
• Match carb concentration to fluid intake (too little fluid with lots of carbs increases GI risk).

Sample fueling plans (45 minutes, 90 minutes, 2+ hours)

These examples assume you’ve eaten normally earlier in the day. Adjust upward if you’re training early or starting under-fueled.

Plan A: ~45 minutes session

Goal: maintain quality without overcomplicating.

• During: usually water only.
• Optional (if very intense intervals, or you feel flat): 10–20 g carbs total (e.g., a few sips of sports drink or half a gel) starting around minute 15–20.

Example: 45 min hard intervals (optional support)  - Minute 15: ~10 g carbs (sports drink)  - Finish: normal meal later to meet daily carb target

Plan B: ~90 minutes session

Goal: prevent late-session drop and support output.

• During: target 30–45 g carbs/hour = 45–70 g total.
• Timing: start at 15–30 minutes, then every 15–20 minutes.

Example: 90 min moderate-to-hard  - Minute 20: 1 gel (~25 g) + water  - Minute 45: sports drink (~15–25 g depending on bottle)  - Minute 70: 1 gel or chews (~20–25 g)  Total: ~60–75 g carbs

Plan C: 2+ hours session

Goal: sustain performance, protect glycogen, and pair carbs with sodium/fluid.

• During: target 45–75 g carbs/hour (advanced: up to 90 g/hour with practice).
• Start early: within the first 15–20 minutes.
• Use a combo: drink mix + gels/chews or food + drink mix.

Example: 2.5 hours endurance  Target: ~60 g carbs/hour (~150 g total)  - Bottle 1 (first hour): sports drink mix ~30 g carbs + sodium  - Hour 1: 1 gel (~25 g)  - Bottle 2 (second hour): sports drink mix ~30 g carbs + sodium  - Hour 2: chews (~25 g)  - Hour 2 to 2.5: gel (~25 g) + water as needed  Total: ~165 g carbs

Pairing carbs with sodium/fluid in longer sessions (practical guidance)

For longer sessions, carbs work best when you can also maintain hydration and sodium balance. Use this as a simple field guide:

• If you’re using sports drink: check the label for carbs per bottle and sodium per bottle. Build your hourly plan from those numbers.
• If you’re using gels: take them with water, and consider a sodium source (sports drink, electrolyte tabs, or salty foods) during long/hot sessions.
• Avoid overly concentrated bottles unless you’re deliberately using a “concentrate + water” strategy and you know your gut tolerates it.

Step-by-step for a 2+ hour session

1. Pick your carb target (e.g., 60 g/hour).
2. Decide delivery: 30 g/hour from drink + 30 g/hour from gels/chews is a common, gut-friendly split.
3. Ensure sodium is present across the hour (via drink mix or an added sodium source), especially if you’re a salty sweater or it’s hot.
4. Set a timer for every 15–20 minutes: small carb dose + a few sips.