In brief:The accurate assessment of muscular strength, endurance, power, and flexibility through quantitative testing is important in the evaluation and rehabilitation of injured athletes. Test results must be compared to normal values to be properly interpreted. If healthy baseline data on an individual athlete is not available, the next most specific set of data would be a profile derived from athletes of the same sport, competitive level, and playing position. Inter-extremity comparisons are useful, but may be misleading even with unilateral involvement.