COMPARISON OF STRENGTH AND PEAK FORCE BETWEEN YOUNGER AND OLDER MALES DURING A LEG PRESS

Abstract

Muscle strength and peak force measures are important functional determinates for meeting the physical challenges in activities of daily living, sports and response to both emergency and non-emergency type situations. The purpose of this study was to compare leg strength and peak force measures of both younger and older subjects during a leg press at 90% subjects single repetition maximums (1-RM). Twelve younger males (Age: 21.41 ± 2.1 yrs., HT: 176 ± 12 cm., WT: 80 ± 9.2 kg) and twelve older males (Age: 50.66 ± 6.5 yrs., HT: 179 ± 10.4 cm., WT: 85.6 ± 10.8 kg) volunteered for this study. Subjects were classified as untrained by Godin leisure time activity questionnaire and apparently healthy according to both a general health screening and physical readiness activity questionnaires. Lower body strength was assessed using a 1-RM protocol on a Cybex seated leg press machine. Leg press peak force was assessed by a modified accelerometer, developed to measure relative peak force and velocity patterns of human movement. A load equaling 90% of the subjects' 1-RMs was used to assess peak force developed during each repetition. Subjects were given approximately 5 seconds rest between each repetition and instructed to perform each repetition as forcefully as possible. Independent t-tests examined between group measures on strength and peak force variables between groups for each independent variable. Mean 1-RM values for the young were 134 ± 29kg and 118 ± 25kg for older subjects. This 12% difference in the older group was not significant (t = 1.402; df = 22; p = .088). However, the cumulative peak force group means for the young was 24,223 Newtons and 16,986 Newtons respectfully, indicating a 30% performance decrease in the older group (t = 2.629; df = 22; p = .007). This study indicates that this sample of older adults did not have significant differences in the absolute measures of leg strength during a leg press when compared to younger adults. However, during heavy and continuous work represented by cumulative peak force group means revealed that significant differences between groups exist.