Effects of Power Training on Mechanical Muscle Output in Old and Very Old Elderly Women

Abstract

Decline in explosive force (i.e. contractile rate of force development RFD) and mechanical muscle power with aging has been reported to correlate with reduced ability to maintain postural control and balance recovery after tripping and to predict falls in community-dwelling old adults. It was therefore recently suggested to develop strength training programmes aimed at maximising maximal muscle power and RFD. Different training protocols have been implemented with older people but no study has been designed as power training with heavy loading (75-80% 1RM) for very old individuals. PURPOSE: To evaluate the effect of low frequency (twice a week), 12-weeks power training with heavy-loading (75-80 % of 1RM) using fast-to-explosive execution of the movements on maximal voluntary contraction (MVC), explosive force characteristics (RFD and impulse) and mechanical muscle power during multi-joint motor tasks in two age-groups of community-dwelling elderly women (TG60, TG80, age-groups 60 and 80, respectively). METHODS: Elderly women from two age-groups, 60 (62.7 2.2 years, n=40) and 80 (81.8 2.7 years, n=25) were randomized (matched) into two training and two control groups (TG60, n=20; TG80, n=12) (CG 60, n=20; CG80, n=13). MVC, RFD, normalized RFD (RFD/MVC) and impulse (during 5 time intervals from onset of contraction separated by 100ms) were obtained during a maximal multi-joint isometric leg press. Mechanical muscle power was assessed in a countermovement jump (CMJ) as jump height, (JH), peak power (Ppeak), velocity and force at Ppeak (Vppeak, Fppeak, respectively). RESULTS: RFD, relative RFD, impulse, MVC, Ppeak, JH, and Vppeak increased with training (between 5 and 50%) in both age-groups whereas no changes occurred in the CG. The gains in RFD, impulse and MVC for TG 80 were of such a magnitude that the difference observed pre intervention with the age-group 60 was abolished after training. CONCLUSION: The present findings indicate that power training with heavy loading is highly effective in inducing adaptive changes in maximal and explosive mechanical muscle output in old and very old healthy women even in the 8th decade of life. Importantly, this training type seems safe and suitable in healthy older adults.