Beating the Bonk: A Practical Guide to Carbohydrate Strategy

Introduction

Picture the last 10 km of a marathon or the final climb of a 120 km sportive. Legs heavy. Pace slipping. You’re not “out of fitness.” You’re running out of carbohydrate. Glycogen and blood glucose underpin sustained power and fast finishes, while fat mostly carries the load at lower intensities. When the race goes long or hard, carbohydrate availability decides whether you press or fade. This article distils the physiology and the practice, so you can plan daily intake, pre-race loading, in-session fueling, and rapid recovery. We also show where a research-led formula like Carb Accelerator fits in to support absorption and comfort when you push higher carb intakes.

The Problem 

Most athletes know carbs matter, but three things are routinely missed:

1. Daily carbohydrate needs should scale to training load by g per kg, not by vague percentages.

2. During exercise, the gut limits absorption unless you use the right carbohydrate mix and train the gut. 

3. Recovery carbohydrate timing and dose determine how quickly glycogen rebounds for tomorrow’s session.

These aren’t academic details; they are performance levers. Guidance is clear on dose ranges, yet many athletes still underfuel day to day and over-concentrate drinks on race day, inviting gastrointestinal distress. 

Science Deep Dive

Carbohydrate supports higher rates of ATP resynthesis than fat, especially as intensity rises, which is why high-intensity efforts lean on glycogen and blood glucose. Typical stores are roughly 300–400 g in muscle and 70–100 g in liver, making carbohydrate a limited fuel you must manage. 

Daily availability matters and we need to scale intake to training: roughly 3–5 g/kg on light days, 5–7 g/kg for moderate training, and 7–12 g/kg for heavy endurance blocks. The target is to match glycogen use with intake across the week. 

During exercise, performance benefits track carbohydrate delivery to the working muscle. With glucose-only feeds, intestinal SGLT1 transport saturates near 60 g/h. Combining multiple transportable carbohydrates, typically glucose and fructose, engages GLUT5 as well and lifts exogenous oxidation toward 90 g/h and sometimes beyond. This is why blends outperform single sugars in long events. 

Could you go even higher? Recent work shows 120 g/h can be tolerable and yields very high exogenous oxidation, yet may not further spare endogenous glycogen versus 90 g/h. Translation: some athletes can push higher intakes, but the extra return is not guaranteed, and gut tolerance becomes the limiter. 

The gut adapts. Regularly practising your race-day carb plan increases transporter expression and raises exogenous carbohydrate oxidation rates. Controlled studies show higher oxidation after weeks of higher-carb feeding, and emerging trials indicate “gut training” can reduce symptoms. 

Recovery is a race against the clock. After hard or long sessions, glycogen resynthesis is fastest when you consume 1.0–1.2 g/kg/h of carbohydrate for the first 3–4 hours. Adding protein in the 0.2–0.5 g/kg/h range may help when carbohydrate intake is suboptimal. 

Practical Application

Here are some practical tips that you can personalise:

• Daily carbohydrate planning

  • Light/skills day: ~3–5 g/kg

  • Moderate endurance: ~5–7 g/kg

  • Heavy block or race week: ~7–12 g/kg
    Adjust up within these bands when volume or intensity spikes. 

• Before training or racing

  • 1–4 g/kg in the 1–4 hours pre-session. Choose familiar, low-fibre foods to reduce gut load. 

• During

  • Up to ~60 g/h for sessions ≈1–2.5 h using glucose-based options.

  • 60–90 g/h for events >2.5 h using glucose plus fructose blends.

  • Consider 90–120 g/h only if you’ve trained the gut and tested in race-like conditions. Keep total fluid and sodium appropriate for conditions to avoid over-concentrated bottles. 

• Gut training

  • Practise your target intake 1–2 times per week in key sessions for at least 3–4 weeks before racing. Start at the lower end of the range and step up in 10–15 g/h increments. Watch for symptoms and adjust texture, osmolality, and feed frequency. 

• After

  • Aim for 1.0–1.2 g/kg/h carbohydrate for 3–4 h post-session, especially with two-a-days or back-to-back key workouts. Where appetite is low, liquid or semi-solid carbohydrate can help; adding 0.2–0.5 g/kg/h protein is reasonable. 

When you push toward the higher end of during-exercise targets, the practical limit is the gut. Formulation details matter, as do strategies that support digestion. Carb Accelerator is developed with this reality in mind: it is designed to support carbohydrate absorption and comfort at moderate to high intakes typical harder efforts in training and racing. The formulation includes a digestive-enzyme complex used to hydrolyse starches, disaccharides, and selected oligosaccharides during high-carb feeding, alongside botanical aids commonly used for GI comfort. These components are positioned to complement gut training by supporting the breakdown of a mixed carbohydrate matrix during sustained intake.

For athletes targeting 60–90 g/h with mixed glucose–fructose sources, Carb Accelerator can be layered into your routine during key gut-training sessions to evaluate individual tolerance and pacing of feeds. That means practising bottle concentration, feed timing, and total hourly grams while monitoring symptoms, so race day feels familiar rather than experimental. 

Conclusion

Endurance performance is limited by many things, but carbohydrate availability is one you can control. Scale daily intake to load. Prime before sessions. Deliver the right carbohydrates during, in the right amounts. Refill rapidly after. Train the gut, not just the legs. Then use supportive formulation details to help you tolerate ambitious, but evidence-based, carbohydrate targets. Start conservative, practise relentlessly, and arrive on the start line with both fitness and fuel systems ready to go.

References

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