Fatigue and recovery contractile properties of young and elderly men

Abstract

The 24 h recovery pattern of contractile properties of the triceps surae muscle, following a period of muscle fatigue, was compared in physically active young (25 years, n = 10) and elderly (66 years, n = 7) men. The fatigue test protocol consisted of 10 min of intermittent submaximal 20 Hz tetani. The maximal twitch (Pt) and tetanic force at 3 frequencies (10, 20 and 50 Hz) were determined at baseline and at 15 min, 1, 4 and 24 h after fatiguing the muscle. Maximal voluntary contraction (MVC) and vertical jump (MVJ) were also assessed. The loss of force during the fatigue test was not significantly different between the young (18 +/- 13%) and elderly (22 +/- 15%). Both groups showed similar and significant reductions of Pt (15%), tetanic force (10 to 35%) and rate of force development (dp/dt) (20%) 15 min and 1 h into recovery. The loss of force was greater at the lower stimulation frequencies of 10 and 20 Hz. Time-to-peak tension was unchanged from baseline during recovery in either group. The average rate of relaxation of twitch force (-dPt/dt) was decreased (p less than 0.05) and half-relaxation time significantly increased at 15 min and 1 h in the elderly but not the young. The findings indicate that after fatiguing contractions, elderly muscle demonstrates a slower return to resting levels of the rate and time course of twitch relaxation compared to the young.

The Effect of Aging on Skeletal-Muscle Recovery from Exercise: Possible Implications for Aging Athletes

“…The delayed force recovery of skeletal muscle that has been observed in aging animals is concordant with the findings of several earlier studies in humans (Dedrick & Clarkson, 1990;Klein et al, 1988). Dedrick and Clarkson found that lengthening contractions in college-age women (23.6 ± 3.3 years) elicited the greatest strength loss immediately after the exercise, and thereafter strength demonstrated a progressive return to preexercise values after 3 days.…”

“…Using a fatiguing but not necessarily damaging exercise protocol in humans, Klein et al (1988) found there were no significant differences between young (19-32 years) and older (64-69 years) adults for loss of force during a fatigue test or the recovery of force during 1 hr of recovery in the triceps surae muscle. These researchers, however, reported that in the older participants there was a decrease in the rate of relaxation of twitch force and an increased half-relaxation time.…”

“…For example, Klein, Cunningham, Paterson, and Taylor (1988) examined the contractile properties of the triceps surae muscle after electrically evoked muscle fatigue in a group of physically active young (19-32 years) and aging (64-69 years) men. They reported that although the maximum voluntary contraction and vertical-jump height were reduced similarly in both groups after exercise, the rate of muscle relaxation after an electrically stimulated twitch contraction was significantly reduced in the aging group compared with the young participants for 1 hr after the fatiguing contractions, indicating impairment in functional recovery.…”

Effect of age on muscle functions investigated with surface electromyography

“…Results have been reported for both voluntary and electrically elicited contractions, but there are discrepancies among the published studies and comparison is difficult as different measures of fatigue have been used and different muscles have been investigated. Some investigators have reported higher fatigability in elderly subjects during electrically elicited contractions, 9,31 others found lower fatigability, 44 and others found no age-related change in muscle fatigability 23,41 or endurance during voluntary contractions. 30, 45 Merletti et al 41 found, with voluntary contractions of the tibialis anterior muscle, a lower level of myoelectric manifestations of muscle fatigue in a group of elderly subjects compared to a control group of young subjects.…”

Variable stimulation patterns for poststroke hemiplegia

“…46 In general, low-frequency stimulation (20 Hz) induces greater fatigue in older compared to younger adults, 16,17,40 whereas fatigue rates are similar during evoked contractions with higher frequencies (40 Hz) of stimulation. 16,36,44 It is not known whether muscles paralyzed by stroke in older adults would show the same responses to variable patterns of stimulation as those of young adults paralyzed by SCI.…”