EFFECTS OF MOTORIZED VS NON-MOTORIZED TREADMILL TRAINING ON HAMSTRING/QUADRICEPS STRENGTH RATIOS

Previous literature suggests that muscular involvement and biomechanical changes elicit different responses between overground and treadmill training. The objective of this study was to examine the effects of training on two different treadmill designs on the conventional (CR; concentric only) and functional (FR; eccentric to concentric) hamstring and quadriceps strength ratios. Fifteen men and sixteen women were randomly divided into three groups: motorized (MT), non-motorized (NMT) or control (C). Subjects completed pre and post-test isokinetic concentric and eccentric quadriceps and hamstring testing of both legs. Subjects completed 4 weeks of training on their respective treadmills with mileage increasing mile each week, beginning with 2 miles. The C group did not participate in any training. The CR revealed a significant two way interaction of group x time with MT increasing (pre: 0.80 ± 0.09 to post: 0.84 ± 0.09), NMT decreasing (pre: 0.76 ± 0.13 to post: 0.74 ± 0.10), and C showing no change (pre: 0.79 ± 0.10 to post: 0.79 ± 0.09. The FR revealed a significant two way interaction of speed x sex with the FR increasing as speeds increased for men (60 degrees.s-1: 1.04 ± 0.11; 180 degrees.s-1: 1.66 ± 0.27; 300 degrees.s-1: 2.36 ± 0.45) and women (60 degrees.s-1: 1.05 ± 0.16; 180 degrees.s-1: 1.90 ± 0.26; 300 degrees.s-1: 2.75 ± 0.47) but women increased greater relative to men. Training mode elicited a specific change in concentric hamstring and quadriceps strength resulting in specific changes to the CR; however, neither training mode had an effect on eccentric hamstrings nor the FR. Special attention should be given to the mode of endurance training when the goal is to alter the hamstring/quadriceps CR.