You know the moment. Kilometre twenty of a long run, the last set on the bench press, a hill that simply refuses to end. Your legs go heavy, your head starts negotiating, and suddenly walking home seems like a perfectly reasonable plan.

Fatigue in sport isn’t failure. It’s a signal. And once you know where it comes from, there’s a lot you can do about it.

Where fatigue comes from

During longer or harder efforts, several things happen at once. Your muscles burn through their glycogen, the carbohydrate stored in muscles and liver. You lose water and minerals through sweat. And your brain, which is busy keeping you safe, starts applying the brakes before the tank is actually empty.

Then there’s the fatigue that lingers. Poor sleep, heavy legs even after a rest day, a resting heart rate higher than usual, performances going down instead of up. That’s usually not one bad session but too little recovery. The best remedy is a few days off. And if the tiredness doesn’t lift even then, it’s worth seeing your GP.

Before training

Have your main meal two to three hours beforehand so it doesn’t sit heavy. If you’re training before you’ve had a chance to eat properly, a small snack 30 to 60 minutes before you start helps. Something with carbohydrates that you tolerate well and that won’t weigh you down.

That’s exactly what gfBar ORIGINAL is for: carbohydrates from wild blueberries and dates, fats from Brazil nuts and 40 mg of caffeine from guarana. One bar half an hour before training; keep the other for the journey home.

And drink. Start during the day, not in the changing room.

During training

For sessions under an hour, water is usually enough. On longer runs, rides or hikes, it pays to top up carbohydrates as you go. Endurance athletes typically aim for 30–60 g an hour, whether from gels, a banana or a bar. Test it in training – never for the first time on race day.

After training

This is where tomorrow is decided. Your body needs to refill its glycogen and get protein to repair and build muscle. The usual advice is 20–30 g of protein in your post-training meal.

A box of gfBar PROTEIN contains 12.4 g of protein from hemp. Protein contributes to a growth in muscle mass, but one box won’t cover the full amount on its own. Treat it as a quick first step until you can get to a proper meal. It goes well with a plain yoghurt or a glass of milk.

Why hemp protein rather than whey? We explain in Not all protein is created equal.

Your head is a muscle too

Fatigue has a mental side. If work is stressing you out, running will feel harder even when your body is fine. It helps to break a session into smaller chunks, breathe slowly and deeply, and think only about the next kilometre, not all the ones still to come.

And then there’s the cheapest supplement of all: sleep. Nothing does as much for recovery as seven to nine hours of it.

In short

Eat in good time, drink steadily, top up carbohydrates on long efforts, get protein in afterwards, and sleep. The rest is training.