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Citation |
Mani D, Almuklass AM, Hamilton LD, Vieira TM, Botter A, Enoka RM. J. Neurophysiol. 2018; 120(4): 1988-1997. |
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Affiliation |
Department of Integrative Physiology, University of Colorado, United States. |
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Copyright |
(Copyright © 2018, American Physiological Society) |
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DOI |
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PMID |
30044670 |
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Abstract |
The purpose of our study was to examine the associations between the performance of older adults on four tests of mobility with the physical capabilities of the lower leg muscles. The assessments included measures of muscle strength, muscle activation, and perceived fatigability. Muscle activation was quantified as the force fluctuations-a measure of force steadiness-and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions. Perceived fatigability was measured as the rating of perceived exertion achieved during a test of walking endurance. Twenty participants (73 ± 4 yrs) completed 1-4 evaluation sessions that were each separated by at least 3 weeks. The protocol included a 400-m walk, 10-m walk at maximal and preferred speeds, a chair-rise test, and the strength, force steadiness, and the discharge characteristics of motor units detected by high-density electromyography of lower leg muscles. Multiple-regression analyses yielded statistically significant models that explained modest amounts of the variance in the four mobility tests. The variance explained by the regression models was 39% for 400-m walk time, 33% for maximal walk time, 42% for preferred walk time, and 27% for chair-rise time. The findings indicate that differences in mobility among healthy older adults were partially associated with the level of perceived fatigability (willingness of individuals to exert themselves) achieved during the test of walking endurance and the discharge characteristics of soleus, medial gastrocnemius, and tibialis anterior motor units during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. Language: en |
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Keywords |
aging; force steadiness; mobility; motor units; walking endurance |