Abstract

Going to failure - or not, have probably been one of the most debated issues during the history of strength training. However, few studies have directly compared the physiological effect of failure versus non-failure strength training. The purpose of this study was to evaluate muscle activation strategies with electromyography during heavy repetitions versus repetitions to failure with lighter resistance. 15 healthy untrained females performed a set with heavy loading (3 Repetition maximum) and a set of repetitions to failure with lower resistance (∼15 RM) during lateral raise with elastic tubing. Electromyographic (EMG) amplitude and median power frequency (MPF) of specific shoulder and neck muscles was analysed and the Borg CR10 scale was used to rate perceived loading immediately after each set of exercise. During the failure set normalized EMG was significantly lower during the first repetition and significantly higher during the latter repetitions compared with the heavy 3 RM set (P<0.05). Normalized EMG for the examined muscles increased throughout the set to failure in a curvilinear fashion - e.g. for the trapezius from 86% to 124% MVC (P<0.001) - and reached a plateau during the final 3-5 repetitions before failure. MPF for all examined muscles decreased throughout the set to failure in a linear fashion, indicating progressively increasing fatigue. In conclusion, going to complete failure during lateral raise is not necessary to recruit the entire motor unit pool in untrained women - i.e. muscle activity reached a plateau 3-5 repetitions from failure with an elastic resistance of approximately 15 RM. Further, strengthening exercises performed with elastic tubing seems to be an efficient resistance exercise and a feasible and practical alternative to traditional resistance equipment.