Differential increases in average isokinetic power by specific muscle groups of older women due to variations in training and testing

Background. As a person ages, leg speed and power decrease. These changes are associated with increased falls and reduced gait speed. It has been shown that upper leg training in younger persons results in increased strength and power at the specific speed at which resistance training is applied, although there are only limited data concerning speed-specific training effects on lower leg activity. However, because both upper and lower leg speed and power influence gait and balance, it is important to determine the training speeds that selectively improve these variables in older persons. Methods. No studies have examined selective speed-specific changes in performance for the upper and lower leg muscles in older individuals. Therefore, we compared shifts in the power-velocity relationship after high-speed (HS) and low-speed (LS) isokinetic training of knee extensors (KE) and flexors (KF), dorsiflexors (DF), and plantar flexors (PF) in community-dwelling women (ages 61 to 75). Subjects were randomly assigned to a HS training, LS training, or control (C) group. Training occurred three times a week for 12 weeks. HS training occurred at 4.73 rad(.)s(-1) (knee) and 3.14 rad(.)s(-1) (ankle); LS training for both joint actions was at 1.05 rad(.)s(-1). Results. HS training improved KE power at intermediate (3.14 rad(.)s(-1); p = .0007) and high (5.24 rad(.)s(-1) P = .0004) testing speeds. Neither the HS nor LS group showed any change in KF as a result of the training. Both LS and HS training improved DF power at all testing speeds; however, PF power improved only with LS training and only at 1.05 rad(.)s(-1) (p = .0132) and 3.14 rad(.)s(-1) (p = .0310). Conclusions. Our results suggest that, in older women, lower leg training should occur at lower training speeds than upper leg training. Additionally, attention to differential speed-specific training of knee and ankle actions could improve power production, mobility, balance, and other functional measures in older persons.