Accession Number : AD0714190

Title :   Serial Isometric Fatigue Functions with Variable Intertrial Intervals.

Descriptive Note : Progress rept.,

Corporate Author : ARMY MEDICAL RESEARCH LAB FORT KNOX KY

Personal Author(s) : Caldwell,Lee S.

Report Date : 05 AUG 1970

Pagination or Media Count : 19

Abstract : The objective of this study was to measure the effects of repeated maximal isometric exertions with various intertrial intervals on the shape of the fatigue function, and to examine the relationship between strength and relative decrement. The maximum voluntary strength of 60 subjects was measured during ten successive 25-sec trials separated by rest periods of 25, 50, or 100 sec. The intertrial intervals within a session were constant. Response strength was recorded at 3-sec intervals from the beginning of the contraction thus yielding eight scores per trial and 80 scores per session for each subject. The adjustment to the various work-rest schedules occurred early in the trial series. When the reduction in mean output was taken as 100% for each rest condition, the loss between the first two trials was 33%, 35%, and 24% for the 25-, 50-, and 100-sec conditions, respectively. An equation derived by a multiple regression analysis with the number of previous trials, intertrial intervals, and contraction time as independent variables produced a set of predicted values which correlated .99 with the actual means. This analysis indicated that the fatigue functions may be assumed to b identical in form for the various trials at the different intertrial intervals. Strength was found to be significantly correlated with absolute decrement but not with relative decrement. (Author)

Descriptors :   (*MUSCLES, FATIGUE(PHYSIOLOGY)), CONTRACTION, STRENGTH(PHYSIOLOGY), ENDURANCE(PHYSIOLOGY), PERFORMANCE(HUMAN), STRESS(PHYSIOLOGY)

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE