Effects of maximal isometric and isokinetic resistance training on strength and functional mobility in older adults.

Background: The aim of the present study was to compare the changes in voluntary strength (isometric, concentric, and eccentric) and functional mobility in response to maximal isokinetic eccentric-only resistance training to those elicited by maximal isometric-only or maximal isokinetic concentric-only resistance training in older adults.

Methods: Twelve women (73 +/- 7 years) and 18 men (73 +/- 5 years) completed a 12-week training program (three times per week) using a Biodex System 3 dynamometer. Primary outcome measures included peak isometric and isokinetic (concentric and eccentric) knee extensor strength, concentric work, concentric power, stair ascent and descent, and gait speed. Participants were randomly assigned to one of three training groups: isometric-only, isokinetic concentric-only, or isokinetic eccentric-only.

Results: All three training groups demonstrated an increase in peak isometric and isokinetic concentric and eccentric strength following 12 weeks of training (p <.01). Step time was positively influenced (p <.03) by all three training modes; however, gait speed was unchanged following 12 weeks of training. All three training groups experienced a significant increase in peak concentric work and concentric power (p <.01) with the concentric training group demonstrating the largest increases in both peak concentric work and concentric power when compared to the isometric and eccentric training groups.

Conclusions: It was clear that all three resistance training programs (isometric, concentric, and eccentric) in older adults were effective in increasing strength, concentric work, and concentric power over the 12-week training period. Furthermore, 12 weeks of resistance training resulted in improved stair ascent and descent performance.