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Variability Of Motor Unit Discharge And Force Fluctuations Across A Range Of Muscle Forces In Older Adults, Brian L. Tracy, Katrina S. Maluf, Jennifer L. Stephenson, Sandra K. Hunter
Variability Of Motor Unit Discharge And Force Fluctuations Across A Range Of Muscle Forces In Older Adults, Brian L. Tracy, Katrina S. Maluf, Jennifer L. Stephenson, Sandra K. Hunter
Exercise Science Faculty Research and Publications
Variability of motor unit discharge is a likely contributor to the greater force fluctuations observed in old adults at low muscle forces. We sought to determine whether the variability of motor unit discharge rate underlies the fluctuations in force during steady contractions across a range of forces in young (n = 11) and old (n = 14) adults. The coefficient of variation (CV) for discharge rate and force were measured during a force-matching task as the first dorsal interosseous muscle performed isometric contractions. The recruitment thresholds of the 78 motor units ranged from 0.04% to 34% of maximal …
Time To Task Failure Differs With Load Type When Old Adults Perform A Submaximal Fatiguing Contraction, Sandra K. Hunter, Ludovic Rochette, Ashley Critchlow, Roger M. Enoka
Time To Task Failure Differs With Load Type When Old Adults Perform A Submaximal Fatiguing Contraction, Sandra K. Hunter, Ludovic Rochette, Ashley Critchlow, Roger M. Enoka
Exercise Science Faculty Research and Publications
Young adults exhibit a longer time to task failure when performing a submaximal isometric contraction by pushing against a force transducer (force task) than when supporting an equivalent inertial load (position task). The purpose of this study was to compare the time to failure for old adults when they performed a force task and a position task with the elbow flexor muscles. Eighteen old adults (72 ± 4 years) performed the force and position tasks at 20% maximal voluntary contraction (MVC) force until task failure. The time to task failure was briefer for the position task (10.6 ± 6.1 min) …