<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="6.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">David J Clark</style></author><author><style face="normal" font="default" size="100%">Carolynn Patten</style></author><author><style face="normal" font="default" size="100%">Kieran F Reid</style></author><author><style face="normal" font="default" size="100%">Robert J Carabello</style></author><author><style face="normal" font="default" size="100%">Edward M Phillips</style></author><author><style face="normal" font="default" size="100%">Roger A Fielding</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Muscle performance and physical function are associated with voluntary rate of neuromuscular activation in older adults</style></title><secondary-title><style face="normal" font="default" size="100%">The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">80 and over</style></keyword><keyword><style  face="normal" font="default" size="100%">Adult</style></keyword><keyword><style  face="normal" font="default" size="100%">Aged</style></keyword><keyword><style  face="normal" font="default" size="100%">Aging</style></keyword><keyword><style  face="normal" font="default" size="100%">Disability Evaluation</style></keyword><keyword><style  face="normal" font="default" size="100%">Electromyography</style></keyword><keyword><style  face="normal" font="default" size="100%">Female</style></keyword><keyword><style  face="normal" font="default" size="100%">Humans</style></keyword><keyword><style  face="normal" font="default" size="100%">Male</style></keyword><keyword><style  face="normal" font="default" size="100%">Middle Aged</style></keyword><keyword><style  face="normal" font="default" size="100%">Mobility Limitation</style></keyword><keyword><style  face="normal" font="default" size="100%">Muscle</style></keyword><keyword><style  face="normal" font="default" size="100%">Neuromuscular Junction</style></keyword><keyword><style  face="normal" font="default" size="100%">Skeletal</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2011</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/20829294</style></url></web-urls></urls><number><style face="normal" font="default" size="100%">1</style></number><volume><style face="normal" font="default" size="100%">66</style></volume><pages><style face="normal" font="default" size="100%">115–121</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">BACKGROUND
Muscle power is related to mobility function in older adults, and effective power production requires rapid neuromuscular activation. Accordingly, this study examines the association of neuromuscular activation rate with muscle performance in persons of different age and mobility function.
METHODS Participants were recruited to three experimental groups: middle-aged healthy adults {(MH),} older healthy adults {(OH),} and older adults with mobility limitations {(OML).} {OH} and {OML} were primarily differentiated by performance on the Short Physical Performance Battery {(SPPB).} Muscle performance (acceleration and power) and electromyography {(EMG)} were recorded during a maximal-effort leg press task at an absolute resistance (260 N) and at a relative resistance (70% of the one-repetition maximum [1 {RM]).} Neuromuscular activation rate was quantified as pre-movement time (duration between {EMG} onset and movement onset) and the rate of {EMG}rise.
RESULTS Pre-movement time, rate of {EMG} rise, leg press acceleration, and leg press power were lower in {OML} relative to {MH} and {OH} but did not differ between {OH} and {MH,} with the exception of power at 70% {1RM.} Across all older participants, rate of {EMG} rise was positively associated with acceleration, power, and the {SPPB} score.
CONCLUSIONS Slowing of neuromuscular activation rate is associated with compromised dynamic muscle performance, which may contribute to mobility limitations in some older adults. Future research should identify the precise neurophysiological impairments that contribute to declines in neuromuscular activation rate and mobility function with aging.</style></abstract><notes><style face="normal" font="default" size="100%">{PMID:} 20829294</style></notes></record></records></xml>