Recovery of muscular endurance following submaximal, isometric exercise.

Each of 22 subjects squeezed a hand-gripping device for as long as possible at a tension of 50% of his maximum voluntary contraction. When the prescribed tension could no longer be maintained, the subject was given a predetermined rest period and at its conclusion again squeezed the hand dynamometer in a second all-out bout. The length of the interbout rest period was either 5, 10, 20, 40, 80, 160, 320, 640, 1280, or 2560 sec. Each subject experienced every rest period with the order of administration assigned at random. At least three days intervened between successive testing sessions. The mean time the subjects persisted during the first bout was 120.25 sec. The percentage of recovery, calculated by dividing the holding time of the first bout into the time of the second, ranged from 20.3% after 5 sec of rest to 86.8% following the 2,560-sec rest interval. An analysis of the percentages of recovery at the various time periods revealed that the pattern of submaximal isometric endurance recovery folowed a three-component exponential curve.