Age-Related Changes in Neuromuscular Properties of Human Quadriceps970

Roos, Martin R.; Rice, Charles L.

doi:10.1097/00005768-199605001-00968

Cited by 5 publications

(7 citation statements)

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“…For example, Vandervoort and McComas 122 have shown that elbow and knee extensor muscles in men, 104 and the knee extensors and flexors in women, 49,[101][102][103]123 that healthy aged men and women between 60 and 100 years of age were able to activate maximally their age-related decrements in strength are less remarkable during isokinetic eccentric contractions than ankle plantar and dorsiflexor muscles during isometric MVC. Furthermore, Roos and Rice 110 have shown during concentric contractions.…”

Section: Age-related Changes In Muscle Functionmentioning

confidence: 95%

“…In addition, MU firing although other limb muscles have also received attention. 50,110 At threshold, there are no consistent age-rates may be affected by age-related limitations in excitability of the corticospinal tract 111 and MNs, 37 or related changes in firing rate 44,50,93 (Fig. 1).…”

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 98%

“…Any additional force elicited with these superimposed shocks riceps femoris group. 49,73,89,95,102,104,110,117,123 Studies using concentric isokinetic contractions of the knee exten-implies that the muscle is not fully activated. Classically, it has been stated that young healthy adults are sors 73,89,90 and ankle plantar flexors 28 have shown that aging is associated with a 20-40% loss in strength in able to activate virtually all of their skeletal muscle mass during brief isometric maximal voluntary con-both males and females.…”

Section: Age-related Changes In Muscle Functionmentioning

confidence: 99%

“…However, the process of recording individual MU action potentials at high age-related change in MU discharge rate. However, preliminary data which have been published in ab-force levels is technically challenging due to difficulties with discriminating the discharge patterns of indi-stract form 110 indicate that at 75% of MVC in vastus medialis of older males (75-80 years), MU discharge vidual units. As a result, very few meaningful data are available concerning discharge properties at force rates are significantly (33%) slower than in young males.…”

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 99%

“…Although some work has been age-related changes in MU firing rates do not occur until force levels are greater than ȁ50% MVC. 56,110 done to elucidate the causes of MU firing rate reductions in acute conditions such as fatigue, considerably In the earliest attempt to study human age-related differences in MU discharge patterns, it was sug-less has been done in chronic conditions such as aging and neuromuscular disease. Reductions in re-gested that as force in extensor digitorum brevis increased from threshold to MVC, more MUs were corded MU discharge rate in the elderly may simply be due to larger MUs in the elderly, which are inner-observed in older people which tended to discharge at intermediate rates, as opposed to high rates.…”

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 99%

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Age-related changes in motor unit function

1997

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This review focuses on the functional relationship between age‐related morphological and physiological changes at the level of the motor unit (MU). It is well established that older humans are weaker than younger people, exhibit reduced force control, and have slower neuromuscular contractile properties. Older people may also exhibit a decrease in MU discharge rate, and an increase in variability of MU discharge at high force levels. The matching of MU discharge and contractile properties may be an age‐related neurophysiological strategy adopted to optimize motor control, similar to that observed in acute conditions such as fatigue. Because muscle force output is modulated partially by MU discharge behavior, the study of these properties may offer insights into the physiology of muscular weakness and motor function in older people. In turn, this will allow the implementation of optimal exercise and rehabilitation programs to reduce the degree of dependence associated with aging. © 1997 John Wiley & Sons, Inc. Muscle Nerve, 20, 679–690, 1997.

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Section: Age-related Changes In Muscle Functionmentioning

confidence: 95%

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 98%

Section: Age-related Changes In Muscle Functionmentioning

confidence: 99%

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 99%

Section: Age-related Changes In Mu Discharge Behaviormentioning

confidence: 99%

See 3 more Smart Citations

Age-related changes in motor unit function

1997

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Comparison of power and EMG during 6-s all-out cycling between young and older women

Duffy

Stewart

Pecoraro

et al. 2012

Journal of Sports Sciences

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To investigate the effects of ageing on the neural control strategies governing sprint cycling on a friction-loaded cycle-ergometer, 10 older (aged 70-83 yr) and 8 young (aged 19-35 yr) healthy women completed seven 6-s all-out cycling trials against varying loads. Root mean square (RMS), median frequency and muscle fibre conduction velocity were determined from the vastus lateralis of the dominant limb during each pedal stroke. Peak power was 43% lower in the older group compared to the younger (p < 0.001) and was accompanied by a significantly lower RMS (p < 0.05). No differences were observed in the other electromyography (EMG) parameters between the groups (p > 0.05). ΔRMS from the first to the sixth second during each trial was found to increase significantly with the development of power output in both groups (p < 0.05). For the first time during an all-out 6-s cycle trial, it has been demonstrated that older women's lower mechanical power output was accompanied by a significantly lower RMS, which indicates a decline in either the number of active of motor units or a reduced discharge rate. Hence, changes in motor units can be regarded as a contributory factor to the decline of muscle power with advancing age. Overall, though, similar neural strategies are adopted in both younger and older populations.

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