Effects of age on human muscle torque, velocity, and power in two muscle groups

Abstract

The purpose of this study was to test the hypotheses that, under isovelocity conditions, older compared with young humans would 1). be slower to reach target velocity and 2). exhibit a downward shift in the torque-velocity and power-velocity relationships in the ankle dorsiflexor and knee extensor muscles. We studied 12 young (26 +/- 5 yr, 6 men/6 women) and 12 older (72 +/- 6 yr, 6 men/6 women) healthy adults during maximal voluntary concentric contractions at preset target velocities (dorsiflexion: 0-240 degrees /s; knee extension: 0-400 degrees /s) using an isokinetic dynamometer. The time to target velocity was longer in older subjects in the dorsiflexors and knee extensors (both P <or= 0.02). Averaged across all velocities, older subjects produced approximately 26% less concentric torque and power in the dorsiflexors (P < 0.01) and approximately 32% less in the knee extensors (P < 0.01). The downward shift in the torque-velocity relationship persisted even when torque was expressed relative to each subject's maximum. In the knee extensors only, the age-related decrement in power increased with increasing velocities, suggesting that this muscle group may be more susceptible to age-related losses of function than the dorsiflexor muscles are. In support of our hypotheses, these results demonstrate an age-related impairment in the dynamic performance of two functionally distinct muscle groups in healthy older adults. With age, the impairment of dynamic performance appears to exceed the loss of isometric performance, particularly in the knee extensor muscles.

Longitudinal impact of aging on muscle quality in middle-aged men

“…2 Relationship between the individual changes in muscle quality based on basic strength (in % per year) and basic strength at baseline. More specifically, in a the relationship between muscle quality based on static strength and static strength at baseline is presented, whereas b shows the relationship between muscle quality based on dynamic strength at a low velocity of 60°/s and dynamic strength at a low velocity of 60°/s at baseline detrimental impact of the human aging process on dynamic muscle strength and muscle power is related to the age-associated slowing of contraction speed (Lanza et al 2003;Macaluso and De Vito 2004;Raj et al 2010). However, former longitudinal research in aging men and women between 46 and 85 years consistently reported higher decline rates (−1.18 to −3.42 % per year) in muscle strength and muscle power compared to the present study (Frontera et al 2000;Hughes et al 2001a;Goodpaster et al 2006;Delmonico et al 2009;Hicks et al 2012;Reid et al 2014).…”

“…Additionally, aging seems to have a more detrimental impact on the ability to generate torque at higher movement velocities (Izquierdo et al 1999;Lanza et al 2003). In this regard, higher decline rates were observed for dynamic muscle strength compared to static muscle strength (Lanza et al 2003). Moreover, muscle power is found to decline earlier and more precipitously than muscle strength (Macaluso and De Vito 2004;Kostka 2005).…”

“…The age-associated losses in muscle strength, or the maximum force generation capacity, are even higher amounting from −1 to −1.5 % per year to −3 % per year after the sixth decade (Skelton et al 1994;Macaluso and De Vito 2004;von Haehling et al 2010). Additionally, aging seems to have a more detrimental impact on the ability to generate torque at higher movement velocities (Izquierdo et al 1999;Lanza et al 2003). In this regard, higher decline rates were observed for dynamic muscle strength compared to static muscle strength (Lanza et al 2003).…”

Neuromuscular mechanics and hopping training in elderly

“…Generally, the movements in elderly can be characterized as weak (Candow and Chilibeck. 2005;Norris et al 2007), slow (Lanza et al 2003;Norris et al 2007) and less economical (Malatesta et al 2003;Mian et al 2006) when compared to those of the young. Part of these changes are due to the aging process itself (Pearson et al 2002) but may be partly explained by the decrease in physical activity level that typically occurs with aging (Hunter et al 2000), especially high intensity exercises that require rapid force production (Candow and Chilibeck 2005;Morse et al 2004).…”

Older men are more fatigable than young when matched for maximal power and knee extension angular velocity is unconstrained

“…However, angular velocity and work performed during shortening contractions are likely key factors which may ultimately explain some of these discrepant findings. Furthermore, maximal velocity and rate of angular velocity production in older adults are diminished when compared with young ) and can potentially limit their ability to attain the pre-set (absolute) angular velocity imposed by an isokinetic dynamometer (Lanza et al 2003;Callahan and KentBraun 2011). Failure to keep up with the isokinetic velocity hampers the development of maximal torque, thereby further confounding the assessment of fatigue and resulting in an overall limitation for meaningful comparisons among the limited studies using dynamic contractions with different conditions.…”