Physiological reductions in perfusion pressure (hand above heart level) increased muscle fatigue in 5 of 7 subjects, accompanied by a proportional rise in central blood pressure.
Does reduced arterial perfusion pressure increase fatigue in a working human hand muscle?
Physiological reductions in perfusion pressure can increase human muscle fatigue, which is accompanied by a proportional compensatory rise in central blood pressure.
The effects of changes in arterial perfusion across the physiological range on the fatigue of a working human hand muscle were studied in seven normal subjects. With the hand above heart level, subjects made repeated isometric contractions of the adductor pollicis muscle at 50% of maximal voluntary contraction in a 6-s on, 4-s off cycle. To assess fatigue, a maximal isometric twitch was elicited in each "off" period by electrical stimulation of the ulnar nerve. The experiment was repeated at least 2 days later with the hand at heart level. Five subjects showed faster fatigue with the arm elevated, and two subjects showed little difference in fatigue for the two conditions. Central blood pressure rose in proportion to fatigue for the subjects overall and returned quickly to its initial level afterwards. We conclude that human muscle fatigue can be increased by physiological reductions in perfusion pressure. Central blood pressure increases as the muscle fatigues, a response that may partially offset declining muscle performance.
Wright et al. (Mon,) conducted a other in Healthy (n=7). Hand above heart level vs. Hand at heart level was evaluated on Muscle fatigue assessed by maximal isometric twitch. Physiological reductions in perfusion pressure (hand above heart level) increased muscle fatigue in 5 of 7 subjects, accompanied by a proportional rise in central blood pressure.
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