Perceived exertion during isometric quadriceps contraction - A comparison between men and women

Background. 1) To examine the validity and accuracy of the CR-10 scale for evaluating perceived exertion, and 2) to assess gender differences in perce ived exertion across different levels of contraction intensity. Methods. Experimental design: cross-sectional, comparative design. Setting: Human Performance and Fatigue Laboratory, Eastern Washington University. S ubjects: 30 healthy, college age volunteers (15 males, 15 females). Measure s: All subjects were assessed for isometric torque and perceived exertion o f the quadriceps femoris muscles, via the CR-10 scale. One low anchor was a pplied under resting conditions with the knee flexed to 60 degrees, and a h igh anchor was applied during a maximal voluntary muscle contraction (MVC). Subjects performed five-second isometric contractions equivalent to 10%, 2 0%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% of their MVC, in a random order, and were assessed for perceived exertion by visually observing the CR-10 sc ale. One sample "t"-tests and 95% confidence intervals were calculated for perceived exertion at each relative torque level. A single factor ANOVA. wi th repeated measures was performed across all levels of exercise intensity Linearity for perceived exertion was assessed via regression analysis. Results. Perceived exertion at each exercise intensity were as follows: 10% : 1.87+/-1.14, 20%: 2.43+/-1.19, 30%: 3.5+/-1.36, 40%: 3.97+/-1.52, 50%: 4. 73+/-1.28, 60%: 5.53+/-1.28, 70%: 6.73+/-1.62, 80%: 7.57+/-1.72, and 90%: 8 .6+/-1.52. The increase in perceived exertion across the intensity spectrum was found to fit both linear and quadratic trends. There were no gender di fferences in perceived exertion across all levels of exercise intensity. Conclusions. The findings demonstrate that the CR-10 scale closely approxim ates perceived exertion of the quadriceps femoris muscles during sub-maxima l, static contractions, and is not gender specific.