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Effects of aging and sex on voluntary activation and peak relaxation rate of human elbow flexors studied with motor cortical stimulation.
- Source :
-
Age (Dordrecht, Netherlands) [Age (Dordr)] 2013 Aug; Vol. 35 (4), pp. 1327-37. Date of Electronic Publication: 2012 Jun 01. - Publication Year :
- 2013
-
Abstract
- Data are equivocal on whether voluntary activation is preserved or decreased in old compared to young adults. Further, data are scant on the effect of age on the rate of muscle relaxation when the muscle is contracting voluntarily. Assessment of both measures with transcranial magnetic stimulation (TMS) yields information which cannot be obtained with traditional peripheral nerve stimulation. Hence, voluntary activation and peak relaxation rate of the elbow flexors were assessed with TMS during repeated maximal efforts in 30 men and 28 women between the ages of 22-84 years. Voluntary activation was similar for the two sexes (P = 0.154) and was not affected by age in men (96.2 ± 2.7 %; P = 0.887) or women (95.1 ± 3.0 %; P = 0.546). Men had a significantly faster peak rate of relaxation than women in absolute units (-880.0 ± 223.2 vs. -360.2 ± 78.5 Nm/ s, respectively; P < 0.001) and when normalized to subject strength (-12.5 ± 2.1 vs. -8.7 ± 1.0 s(-1), respectively; P < 0.001). Absolute and normalized relaxation rates slowed with age in men (P = 0.002 and P = 0.006, respectively), but not women (P = 0.142 and P = 0.950, respectively). Across the age range studied, all subjects, regardless of age or sex, were able to achieve high voluntary activation scores for the elbow flexors (~95 %). In contrast, peak relaxation rate was markedly faster in men than women and slowed with age in men but not women. Normalization of relaxation rates to strength did not affect the influence of age or sex.
- Subjects :
- Adult
Aged
Brachial Plexus physiology
Elbow Joint physiology
Electromyography
Evoked Potentials, Motor
Female
Humans
Isometric Contraction physiology
Male
Middle Aged
Muscle, Skeletal physiology
Transcranial Magnetic Stimulation methods
Aging physiology
Motor Cortex physiology
Muscle Fatigue physiology
Muscle Relaxation physiology
Muscle, Skeletal innervation
Subjects
Details
- Language :
- English
- ISSN :
- 1574-4647
- Volume :
- 35
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Age (Dordrecht, Netherlands)
- Publication Type :
- Academic Journal
- Accession number :
- 22653296
- Full Text :
- https://doi.org/10.1007/s11357-012-9435-5