Staying Mentally Sharp During Long Sessions

Endurance performance isn’t only about strong legs and lungs. Nutrition also plays a crucial role in maintaining focus, mood, and decision-making during long sessions.

When we exercise, we need to fuel the brain as well as the muscles. If you’ve ever experienced any of the symptoms below during training or racing, it’s likely that your brain wasn’t being adequately fuelled:

• Difficulty concentrating or staying present
• Slower reaction time or indecision
• Feeling overwhelmed by the effort or distance remaining
• Mentally “checking out”
• Headache or light-headedness
• A heavy or “foggy” feeling in the head
  

Why Does This Happen?

When we underfuel, it isn’t just the muscles that suffer the brain does too. These symptoms are often early warning signs that your nutrition strategy needs attention, not a lack of mental toughness.

So what’s going on?

Low Carbohydrate Availability

The brain relies on glucose, just like the muscles that allow us to move. When blood glucose drops, cognitive performance declines. This can increase perceived effort, reduce concentration, and impair decision-making, making pacing, fuelling, and race strategy much harder to manage.

How To Minimise This

• Fuel appropriately before sessions with a carbohydrate-rich meal or snack, regardless of session length.
• For sessions lasting longer than 60 minutes, consider taking on carbohydrates during exercise.
• Prioritise carbohydrate intake after training to replenish glycogen stores and support recovery for future sessions.
  

Dehydration And Electrolyte Loss

Dehydration leads to a reduction in blood volume, which limits the delivery of oxygen and nutrients to the brain. This can trigger mental fatigue, even when the muscles still feel capable. As dehydration progresses, the heart has to work harder, increasing overall stress and perceived effort.

High sweat losses also mean greater electrolyte loss, which can contribute to dizziness, confusion, and disorientation, particularly in warm conditions or long sessions.

How To Minimise This

• Start sessions well hydrated by sipping fluids consistently throughout the day.
• During exercise, respond to thirst cues and drink little and often.
• In hot conditions or during long sessions, consider adding electrolytes to fluids to replace sweat losses.
• If you struggle to drink during exercise, adding electrolytes can help improve fluid intake by stimulating thirst.
  

Caffeine Timing

Caffeine is one of the most researched ergogenic aids for performance, but only when used strategically. It can reduce perceived effort and improve alertness and motivation. However, timing and dose are key. Taking caffeine too early can lead to a crash later in the session, while excessive intake may increase anxiety, tunnel vision, or impulsive decision-making.

How To Maximise The Effect

• Performance benefits are typically seen with intakes of ~1.5–6 mg per kg of body weight, with no added benefit above this range.
• Caffeine should always be tested in training, as tolerance and side effects vary widely between individuals.
• Peak blood caffeine levels occur around 60 minutes after ingestion, or ~30 minutes when using chewing gum.
• In longer events, many athletes benefit most from caffeine later in the session, when perceived effort is highest.
• In shorter events (e.g. 5–10 km), earlier caffeine intake may be more appropriate.
• Experiment to find what timing works best for you and the demands of your event.
  

There’s a lot of messaging around fuelling for muscle performance, and rightly so. But fuelling also plays a vital role in keeping you mentally present, emotionally stable, and capable of making good decisions when fatigue sets in.

Supporting the brain with the right nutrition strategy helps ensure you don’t just keep moving, you keep thinking clearly throughout your session.