Heavy legs around 15 km? This is what happens in your body

Many walkers recognise it while preparing for the 4Daagse. The first kilometres feel easy, but somewhere around 15 to 20 kilometres your legs start to feel heavier.

Your pace drops slightly, your muscles feel stiffer and the effort seems greater. That is no coincidence. During prolonged exertion, various processes take place in your muscles and in your brain.

What happens in your muscles during a long walk?

During longer walks your body mainly uses carbohydrates and fats as its energy source. The longer the effort lasts, the more the glycogen stores in your muscles gradually decline. Glycogen is the stored form of carbohydrates and an important fuel for muscle activity.

Research into endurance exercise shows that lower glycogen availability can contribute to muscle fatigue and a heavier feeling in the legs. Studies of glycogen availability and muscle performance show that reduced glycogen stores are an important factor in fatigue during prolonged exertion.

In addition, prolonged exertion causes small amounts of damage to muscle fibres. This process, also known as exercise-induced muscle damage, is a normal part of training. During recovery the body repairs these fibres and adapts, so that muscles ultimately become stronger and more resilient.

Research into prolonged walking shows that over distances of 15 to 50 kilometres, markers of muscle damage and muscle fatigue rise clearly after sustained exertion.

This is exactly why recovery plays such an important role when preparing for the 4Daagse.

Sources:

Fatigue is not just in your legs

During prolonged exertion, the nervous system also plays a role. When energy stores fall and muscles tire, the brain receives signals that the effort is becoming hard.

This can lead to:

This combination of physical and mental fatigue is a well-known phenomenon in endurance exercise.

Why recovery is so important

The kilometres you cover matter, but real training progress happens during recovery.

In the hours and days after a training session:

Sufficient recovery helps prevent fatigue from building up, so you can start your next training session with fresh legs.

Practical tips for recovery and energy

Hydration: more than just water

During long walks you lose fluid through sweating. You also lose electrolytes such as sodium and potassium. These play an important role in fluid balance and muscle function.

Practical tips:

Energy while walking

During prolonged exertion the body mainly uses carbohydrates as fuel.

During longer training sessions it can help to take in small amounts of energy while walking, for example:

This helps to top up energy stores and delay fatigue.

Nutrition after training

After training, the body needs building blocks for recovery.

A combination of carbohydrates and protein can help with:

For example:

Walking it off and stretching

After a long walk, a short cool-down can help bring the body gradually to rest.

A few minutes of easy walking helps keep the circulation going and supports muscle recovery. After that, light stretching can help reduce muscle tension and maintain mobility.

Rest and recovery methods

Sleep and relaxation are essential for the recovery of both muscles and the nervous system. In addition, many walkers use various recovery methods to stimulate circulation and help muscles relax, such as:

Compression
For example with recovery boots or compression sleeves to support circulation in the legs.

Massage
Massage can help reduce muscle tension. You can use a massage mat or, for example, a massage gun.

Heat
Heat can contribute to muscle relaxation and stimulate circulation. Some athletes use an infrared sauna blanket for this, for example.

Cold therapy
Cold baths or ice baths are sometimes used to reduce inflammatory responses and muscle soreness after strenuous exertion. The effect can vary from person to person, but in certain situations cold therapy can contribute to recovery after intensive exertion.

Recovery as part of your 4Daagse preparation

When preparing for the 4Daagse, the focus is often on clocking up the kilometres. Yet the balance between load and recovery is at least as important.

By paying deliberate attention to recovery through nutrition, hydration, rest and recovery methods, you help your body adapt to the training load. That way you are working not only on strong legs, but also on a fresh mind for the next training kilometres.

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