AGE AND GENDER EFFECTS ON RECIPROCAL MOMENT RATIOS IN KNEE MUSCLE CONTRACTIONS

Fifteen young and 17 older females (29.5 +/- 4.6 and 58.2 +/- 6.1 year s 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 an d gender effects on reciprocal moment ratios in knee muscle groups. Su bjects completed 4 consecutive maximal contractions of dominant knee e xtensor and flexor muscles at 60 degrees/s for the concentric (CON) an d 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) contr actions at a 60 degrees angle and 0 degrees/s velocity for knee extens ors. The results demonstrated that (a) ECC strength, particularly in m ales, was less influenced than ISM and CON strength by aging factors, (b) older groups, particularly females, prossessed greater capacity fo r 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 g roups.