Pain is not always associated with trauma. Pain from Taekwondo training may result from activity intolerance and fatigue. Activity intolerance is when a person has insufficient physical or psychological energy to endure or complete a required training activity. The frequency, intensity, and duration of training that people are able to withstand depends upon a balance between available energy and the energy required to complete the training.
Acute physical fatigue has a rapid onset and is a normal response to a high intensity and short duration activity. It occurs when insufficient oxygen or nutrients are delivered to muscles. It serves as a protective mechanism and is usually relieved when the activity ceases. Chronic fatigue differs from acute fatigue in terms of onset, intensity, perception, duration, and relief. It has a gradual and insidious onset, may last for days or weeks, and is not relieved by cessation of the activity.