Rapid contractile measures such as rate of velocity (RVD), torque (RTD) and power (RPD) development dramatically decrease with age, but have rarely been concurrently investigated. Further, few studies have examined the relationship between these parameters and functional performance.
PURPOSE: To compare rapid contractile parameters of the knee extensors in middle-aged and older males, and examine correlates of 5-chair rise (5CR) performance.
METHODS: As part of a larger ongoing investigation, twelve healthy untrained, middle-aged (n = 6, age = 46 ± 2.90 yrs) and older (n = 6, age = 69 ± 3.10 yrs) males completed a familiarization visit followed by one testing visit. Using a Biodex System 4 dynamometer, participants performed three maximal voluntary isometric contractions of the right knee extensors followed by three maximal isotonic contractions at 40% of isometric peak torque. Participants were instructed to “kick out as hard and fast as possible” prior to each contraction. The torque and velocity signals were acquired and the power curve was derived from multiplying torque and velocity. RVD and RPD were obtained from isotonic contractions, as the linear slope of the velocity- and power-time curve, respectively. RTD was calculated for the first 50 ms of the isometric torque-time curve. In addition, 5CR, the time to rise 5 times from a chair as quickly as possible was recorded. Groups were compared with independent samples t-tests, while Pearson correlation coefficients were used to examine relationships between age, RVD, RPD, RTD, and 5CR.
RESULTS: RVD (32.15%; p = 0.004) and RPD (53.27%; p = 0.03) were decreased in older males, but not RTD (p = 0.497). In addition, only RVD was correlated with 5CR (r = -0.588; p = 0.044).
CONCLUSIONS: While preliminary, these data suggest that dynamic, rapid contractile measures are preferentially affected by age as compared to RTD, and only RVD was related to 5CR performance.