For decades, the standard advice for endurance athletes was to aim for 60 to 90 grams of carbohydrates per hour during strenuous activity. However, recent breakthroughs in sports science and professional racing have shifted the goalposts. We are now entering the era of the '120g carbohydrate revolution,' a strategy that promises to sustain high-intensity performance for longer than ever before. As a running coach, I have seen first-hand how mastering this fuel intake can be the difference between hitting the wall at mile 20 and finishing with a flourish.

Why More Fuel Means Better Performance

The primary limitation for most endurance athletes isn't just physical fatigue; it is the depletion of glycogen stores. By increasing carbohydrate intake to 120g per hour, you are effectively providing a constant stream of glucose to your working muscles. This shift helps to spare your endogenous glycogen, prevent premature muscle breakdown, and keep your mental focus sharp when the race gets tough. It is not just about eating more; it is about keeping your 'engine' perfectly topped up during the most demanding phases of your workout.

The Art of Gut Training

You cannot simply jump from 60g to 120g of carbohydrates overnight. Your digestive system is a highly adaptable muscle that requires specific training to handle higher concentrations of fuel. I advise my athletes to increase their intake incrementally, perhaps by 10g per week during long, low-intensity 'zone 2' training runs. This 'gut training' allows your body to express more glucose transporters in the intestine, making the absorption of higher carbohydrate loads a seamless process rather than a recipe for gastric distress.

Mastering the Dual-Source Strategy

To hit the 120g mark without suffering from bloating or nausea, you must use a dual-source carbohydrate strategy. The body has different transporters for glucose and fructose; by combining these in a specific ratio—usually 1:0.8 or 2:1—you avoid saturating a single transport pathway. This is why many elite athletes are moving away from traditional gels toward high-concentration sports drinks and hydrogels. By diversifying your fuel sources, you minimise the risk of gut issues while ensuring your cells get the energy they desperately need.

Applying the Technique to Your Long Run

When you head out for your weekly long run, treat it as a dress rehearsal for your race-day nutrition strategy. Don't just focus on your cadence or heart rate; focus on your fuel timing. I recommend setting a recurring alert on your sports watch to consume a set amount of calories every 20 minutes. Consistency is the secret weapon here. If you wait until you feel hungry or fatigued, you have already waited too long. By the time the hunger signal hits, your blood sugar is likely already trending downward.

The Role of Hydration and Electrolytes

It is worth noting that higher carbohydrate intake requires sufficient hydration to maintain optimal gastric emptying. If you do not drink enough fluid, the high concentration of sugar in your stomach can cause a 'sloshing' sensation and delay absorption. Pair your 120g carbohydrate goal with a robust electrolyte strategy, focusing on sodium intake. Sodium acts as a catalyst for carbohydrate absorption in the small intestine, acting like a key that unlocks the door for energy to enter your bloodstream.

Precision and Patience

Remember, this is a transition that requires patience. If you experience discomfort during your practice runs, dial the intake back by 10g and spend an extra week adapting. Every athlete is biochemically unique, and the 120g threshold is an aspirational ceiling, not a universal requirement for every individual. The goal is to find the maximum amount of fuel your unique system can process while you perform at your absolute peak.

Top 10 Tips for Endurance Fuelling Success

1. Start by logging your current intake to establish a baseline.
2. Increase your carbohydrate intake by 5-10g per week to train your gut.
3. Use a 1:0.8 ratio of glucose to fructose to maximise absorption.
4. Prioritise liquid fuels for easier digestion during high-intensity sessions.
5. Set an 'eat every 20 minutes' timer on your watch to maintain consistency.
6. Always test your chosen nutrition products during long, race-pace runs.
7. Balance your carbohydrate intake with sufficient water to prevent bloating.
8. Include sodium-rich electrolyte tablets to assist with glucose transport.
9. Avoid high-fibre or high-fat foods in the 48 hours before long efforts.
10. Listen to your body; if you feel discomfort, reduce the concentration slightly.