The effects of rest interval on quadriceps torque and perceived exertion in healthy males

Background. The ability to generate maximal muscular force is dependant upo n time mediated mechanisms of fatigue. Interset rest interval length may no t only affect force production but may also manifest changes in ratings of perceived exertion (RPE), The purpose of this study was to examine the effe cts of rest interval on quadriceps torque and RPE during multiple sets of r esisted knee extensions. Methods, 14 healthy male volunteers were assessed for concentric isokinetic quadriceps peak torque, total work, and average power on the Biodex System II Isokinetic Dynamometer at a preset angular velocity of 180 deg.sec(-1). Perceived exertion was measured with a modified category-ratio scale (CR-1 0), Under isometric conditions the perceptual range was anchored with one h igh and two low anchors. Subjects were randomly assigned to one of two grou ps: short rest interval (Group 1, 40 sec) and long rest interval (Group 2, 160 sec), All subjects performed 4 sets of 20 maximal isokinetic contractio ns with an inter-set rest interval that corresponded to their group assignm ent, Following the completion of each set subjects were asked to assign a r ating out of 10 to the feelings in their quadriceps by visually observing a chart of the CR-10 scale, Results. The results demonstrated a significantly greater decline in quadri ceps peak torque (p<0.05), total work (p<0.05), and average power (p<0.05) by Group 1 as compared to Group 2, Changes in RPE across the 4 sets of exer cise did not show a significant difference between the 2 groups, Conclusions. The generation of quadriceps torque is a function of rest inte rval length, whereas perceived exertion appears to be unaffected.