Relationships among grip strength, work capacity, and recovery.

The relationship between strength, fatigue, and work capacity is a central issue for occupational rehabilitation. Musculoskeletal impairments often are expressed functionally as a loss of strength. For work tasks that require strength, such impairments may have a detrimental effect on work capacity that is sufficient to be disabling. How important is strength as a component of work capacity? How do work capacity and strength affect recovery time from repetitive forceful upper extremity work ? A sample of 40 healthy subjects comprised of 20 males and 20 females was studied in a model that used the isotonic strength of each subject to set exercise levels for subsequent forceful repetitive gripping tasks. Resistance levels of 75%, 50%, and 25% of maximum were used for one-per-second repetitions until the subject could not maintain that pace. Isometric grip strength was measured after 1 minute of rest and after 5, 10, and 20 minutes. Results indicate that males and females do not differ in terms of their rate of recovery and that the best predictor of recovery time is the immediate measurement of strength loss following cessation of work activity.