Quantifying Continuous Exercise Using the Ratio of Work Completed to Endurance Limit Associated with Exercise-Induced Delayed-Onset Muscle Soreness

This study quantified training load of various exercises using a novel method developed by the authors and based on the ratio of work completed: endurance limit, associated with exercise-induced delayed-onset muscle soreness. Exercises were also quantified using the Training Impulse method. 8 runners performed a marathon and a 60-min. run at marathon velocity, and 9 rowers performed two maximal exercises (500 m and 2000 m) on a rowing ergometer. To examine the validity of the two methods, the relationships between the training loads provided by the Training Impulse and the Authors' methods, the direct comparison of the tasks performed, and the usability of the Authors' method components in regular training were assessed. Authors' method was significantly related to Training Impulse method (r = .83, p < .05) and was higher for running (r = .94, p < .05) but none was observed for rowing. In both methods, the marathon run resulted in high training load compared with the other tasks. When compared with the 60-min. run, the training load of the 2000-m row was slightly higher for the Authors' method, but lower for Training Impulse method. In the Authors' method, the delayed-onset muscle soreness component discriminates the marathon from the other tasks whereas the ration of work completed: endurance limit differentiates the 60-min. run from the 2000-m row. The duration component of the Training Impulse method could lead to overestimation of the training load of prolonged exercises compared with high intensity exercise. The relationship between the Training Impulse and the Authors' methods for prolonged exercises, the training load provided for each task, and the components of the Authors' method supported the validity of this new tool to describe exercise-induced fatigue.