The Effects Of Power Training Frequency On Functional Performance In Healthy, Older, Untrained Women.

Abstract

Power training (PT) in older adults can improve muscle power and functional performance. The majority of studies have utilized higher intensities for training (≥ 60% of maximum strength) and have included combined results for older men and women. Less is known about the effects of low-intensity PT on muscle performance and function in older, healthy women. In addition, the dose-response of PT on power and function with 1, 2, or 3 days/week in older adults has not been determined. PURPOSE: The purpose of this study was to investigate the impact of different weekly frequencies of low-intensity PT on muscle strength, power, and function in healthy, older, untrained women. METHODS: Older women (n = 54) were randomized to PT 1 (n = 14), 2 (n = 17), or 3 (n = 17) days/week or wait-control, C (n = 15). Participants undertook 12 weeks of PT using lower-body resistance training machines at an intensity of 40% of the 1-repetition maximum (1RM), and performed the concentric phase of the exercises ‘as fast as possible’. The primary outcome was functional performance (Short Physical Performance Battery, stair climb, 30 second chair stands, and 400-meter walk) and secondary outcomes were strength (leg-press 1RM) and power (knee-extension power at 40% of maximal isometric strength). RESULTS: Within-group analyses (pre-post time points) indicated that strength improved in all PT groups (p < 0.05) with a 23.7%, 23.3%, 34.8%, and 9.8% increase from baseline for PT1, PT2, PT3 and C, respectively. Pre-post power improved significantly in PT2 and PT3 (p < 0.05) by 9.6% and 12.2%, respectively. For pre-post function, all PT groups improved in 3 of 4 functional tests (p < 0.05) with improvements ranging from 4.0 - 21.7% and with no differences observed between groups. Although the control group showed small but significant improvement in some aspects of function over the course of the study, effects sizes for all PT groups suggest small to large improvements above that observed in the controls. The large intra-individual variability in the data might have limited statistical power to detect differences between the groups. CONCLUSIONS: PT of 2 days/week or more is recommended for improving muscle power, however, 1 session weekly might be sufficient for improving functional performance.