Causes of Fatigue
Fatigue in physical activity or sports is a complex physiological response to various stressors. It can result from a combination of factors such as overheating, depletion of energy reserves, dehydration, and disturbances in electrolyte balance. Below are key causes of fatigue during physical exertion.
1. Overheating
The body’s core temperature rises beyond a level that can be effectively regulated, leading to impaired performance.
- Mechanism:
- When muscles work during exercise, they generate heat, which raises body temperature.
- Overheating causes the body to divert blood flow away from muscles to the skin for cooling, which reduces muscle function.
- Sweating: Although sweating is a cooling mechanism, it leads to fluid and electrolyte loss, further exacerbating fatigue.
- Consequences:
- Heat exhaustion: Symptoms include dizziness, nausea, and weakness.
- Heat stroke: Can be life-threatening, leading to confusion, unconsciousness, and organ damage.
- Prevention:
- Adequate hydration, cooling breaks, and appropriate clothing are essential.
2. Depletion in Acetylcholine
Acetylcholine is a neurotransmitter that plays a key role in transmitting nerve impulses to muscles.
- Mechanism:
- Acetylcholine is released at the neuromuscular junction to stimulate muscle contraction.
- Prolonged or intense physical activity can lead to the depletion of acetylcholine, impairing nerve-muscle communication.
- Consequences:
- A reduced release of acetylcholine leads to decreased muscle contraction efficiency, contributing to muscle weakness and fatigue.
- This effect is particularly noticeable in endurance sports or during prolonged high-intensity exercise.
- Prevention:
- Adequate rest, recovery, and proper nutrition (including choline-rich foods) can help maintain acetylcholine levels.
3. Depletion in Glycogen Reserves
Glycogen is the stored form of glucose in muscles and the liver, which provides energy during physical activity.
- Mechanism:
- During exercise, glycogen is broken down into glucose to provide energy.
- Intense or prolonged exercise depletes glycogen reserves, leading to "hitting the wall" or exhaustion.
- Consequences:
- Without sufficient glycogen, the body switches to less efficient fat oxidation for energy, leading to fatigue and a decline in performance.
- This is common in endurance sports such as marathon running.
- Prevention:
