The clinical importance of the anaerobic energy system and its assessment in human performance.

The anaerobic energy system is involved in providing energy for all forms of physical activity. The relevance of this system to human performance and physical fitness throughout the age spectrum is underscored here and contrasted with the aerobic energy system. The anaerobic system responds to high-intensity training with biochemical, neural, and anatomic adaptations. Unlike the aerobic system, this response tends to be primarily a local phenomenon with little systemic adaptation. An important factor distinguishing anaerobic training from aerobic training is the intensity of the exercise dose. For anaerobic training to occur, the dose must be of high intensity and performed to near-exhaustion. The anaerobic system can be indirectly assessed by performance tests, such as a vertical jump or stair climb, or more directly by supramaximal bicycle tests. The impact of recent research regarding the trainability of the anaerobic system, particularly in the elderly population, is encouraging. The elderly respond to anaerobic training and, as a result, their independence, quality of life, and safety from falls can be improved. While little is known about anaerobic rehabilitation after injury, it is known that isokinetic and performance tests may be considered normal after rehabilitation, despite incomplete rehabilitation of the anaerobic system. Thus, appropriate application of the anaerobic system assessments and training principles is an important aspect of sports medicine practice.