Types of Fatigue in Exercise and Sport
Let's dive into the fascinating world of fatigue - that feeling when your body just can't keep going during exercise. There are several distinct types of fatigue, each affecting performance in different ways.
1. Central Fatigue
Central fatigue occurs in your nervous system, specifically your brain and spinal cord. Think of it as your body's control center getting tired!
Key characteristics:
- Reduced neural drive to muscles
- Decreased motivation
- Altered perception of effort
- Reduced motor unit recruitment
During a marathon, runners often experience central fatigue in the later stages, leading to reduced running efficiency and that "hitting the wall" sensation, even though their muscles might still have more to give.
2. Peripheral Fatigue
This type occurs directly in the muscles themselves and can be broken down into several subtypes:
a) Metabolic Fatigue
- Caused by depletion of energy sources (ATP, glycogen)
- Build-up of metabolic by-products (lactate, hydrogen ions)
- Disruption of calcium regulation
Metabolic fatigue is particularly relevant in high-intensity activities like sprinting or weightlifting, where energy demands are extremely high.
b) Neural-Junction Fatigue
- Occurs at the neuromuscular junction
- Reduced neurotransmitter release
- Decreased receptor sensitivity
c) Contractile Fatigue
- Direct impairment of muscle fiber contractile mechanisms
- Damage to sarcomeres
