Maximum number of repetitions at different percentages of maximum strength in older men: a crossover study

Abstract

Introduction: Based on the inverse relationship between the amount of weight lifted and the maximum number of repetitions (RM) performed, the intensity prescription method based on a percentage of maximum strength (%1RM) has been widely used in different populations, including older adults. However, considerable inter-individual variability in RM performed at a given %1RM has been reported in previous studies on this topic. Aim: To compare the number of repetitions performed at 60, 75, and 90%1RM in lower and upper limb resistance exercises in older adults. Methods: Fifteen men aged between 60 and 75 years performed two preliminary sessions (familiarization + and 1RM tests) and three experimental sessions (RM tests at 60, 75, and 90%1RM on knee extension and elbow flexion exercises). Movement velocity for each concentric and eccentric muscle action was 1.5-2 s. Statistical comparisons regarding the RM performed in each %1RM were tested using the Generalized Estimating Equations analysis. Results: The RM during knee extension exercise was significantly lower when compared to elbow flexion at 60% 1RM. On the other hand, the RM during knee extension exercise was significantly higher when compared to elbow flexion at 90%1RM. A similar number of repetitions at 75%1RM were performed in both exercises. Conclusion: Physically active older men can perform different RM at 60% and 90%1RM in knee extension and elbow flexion exercises, suggesting that the use of a specific RM range cannot be associated to the same percentage of 1RM in this individuals.