Concentric isokinetic torque characteristics of the calf muscles of active women aged 20 to 84 years.
METHODS
Descriptive, comparative, and correlational study of nonimpaired, active women in 3 age groups.


OBJECTIVE
We described age-related concentric isokinetic torque of plantar flexion (PF) of active women and examined the proposal that PF torque at slow to rapid velocities would be influenced by age-related slower muscle contractile properties. We also examined the relationship of age to passive and active force characteristics of the calf muscle.


BACKGROUND
Aging is associated with decreased calf muscle strength, slower muscle contractile properties, and decreased dorsiflexion (DF) range of motion. Clinical methods of measuring these changes in the calf muscles have not been described adequately.


METHODS
24 younger women (20 to 39 years), 24 middle-aged women (40 to 59 years), and 33 older women (60 to 84 years) performed maximal concentric PF of the right ankle from maximal passive DF at randomly ordered velocities of 30 degrees.s-1, 60 degrees.s-1, 120 degrees.s-1, and 180 degrees.s-1. The peak and mean torques and "angular delay" (degree) from the onset of movement to peak torque were examined using ANOVA. Age was correlated (Pearson product moment r) with the peak and mean torques, "angular delay," velocity at peak torque for 180 degrees.s-1, and the maximal passive DF angle and torque.


RESULTS
The peak and mean torques decreased with increasing age and velocities. The angular delay at 180 degrees.s-1 decreased with increasing age. Age was negatively correlated with the peak and mean torques (range, r = -0.60 to -0.73), the "angular delay" at all velocities (range, r = -0.44 to -0.64), the maximal passive DF angle (r = -0.73) and torque (r = -0.60), and with the peak torque velocity at 180 degrees.s-1 (r = -0.29).


CONCLUSIONS
The results indicate age-related changes for the concentric isokinetic torque of the calf muscles of active women. The angular delay at 180 degrees.s-1 may show changes influenced by slower muscle contractile properties. Concurrent age-related declines in passive and active calf muscle force characteristics were demonstrated.
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000843:Ankle Joint / Q000502:physiology; D004576:Electromyography; D005260:Female; D005528:Foot / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D009119:Muscle Contraction / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013314:Stress, Mechanical; D013997:Time Factors; D019415:Torque