Age and gender effects on reciprocal moment ratios in knee muscle contractions

Abstract

Fifteen young and 17 older females (29.5 +/- 4.6 and 58.2 +/- 6.1 years of age) and 14 young and 15 older males (27.2 +/- 3.3 and 56.5 +/- 5.7 years) volunteered as subjects for this study to investigate age and gender effects on reciprocal moment ratios in knee muscle groups. Subjects completed 4 consecutive maximal contractions of dominant knee extensor and flexor muscles at 60 degrees/s for the concentric (CON) and eccentric (ECC) torque tests and 20 consecutive maximal contractions at 180 degrees C/s and 120 degrees/s for the CON and ECC torque-work tests, respectively. Subjects also performed 5-s isometric (ISM) contractions at a 60 degrees angle and 0 degrees/s velocity for knee extensors. The results demonstrated that (a) ECC strength, particularly in males, was less influenced than ISM and CON strength by aging factors, (b) older groups, particularly females, prossessed greater capacity for ECC muscles action than CON compared to other groups, and (c) older groups, particularly females, had a lower ratio of CON extensors: ECC flexors and a greater ratio of ECC extensors: CON flexors than young groups.