Boys vs men differences in muscular fatigue, muscle and cerebral oxygenation during maximal effort isometric contractions: the effect of muscle blood flow restriction.
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引用次数: 0
Abstract
Purpose: To examine whether the children's superiority, over adults, to resist fatigue during repeated maximal-efforts depends on their often-cited oxidative advantage, attributed to greater muscle blood flow and O2-delivery. We also investigated the mechanisms underlying child-adult differences in muscle-oxygenation (due to O2-supply or O2-utilization) and examined if there are age-differences in cerebral-oxygenation response (a brain-activation index).
Methods: Eleven men (23.3 ± 1.8yrs) and eleven boys (11.6 ± 1.1 yrs) performed 15 maximal-effort handgrips (3-s contraction/3-s rest) under two conditions: free-flow circulation (FF) and arterial-occlusion (OCC). Force, muscle-oxygenation (TSImuscle) and cerebral-oxygenation (oxyhemoglobin-O2Hbcerebral; total hemoglobin-tHbcerebral; deoxyhemoglobin-HHbcerebral) were assessed.
Results: In boys, force declined less (- 26.3 ± 2.6 vs. - 34.4 ± 2.4%) and at slower rate (- 1.56 ± 0.16 vs. - 2.24 ± 0.17%·rep-1) vs. men in FF (p < 0.01-0.05; d = 0.60-1.24). However, in OCC there were no age-differences in the magnitude (- 38.3 ± 3.0 vs. - 37.8 ± 3.0%) and rate (- 2.44 ± 0.26 vs. - 2.54 ± 0.26%·rep-1) of force decline. Boys compared to men, exhibited less TSImuscle decline in both protocols, and lower muscle VO2 (p < 0.05). Boys, also, presented a smaller O2Hbcerebral and tHbcerebral rise than men in FF; exercising with OCC increased the O2Hbcerebral and tHbcerebral response in boys. Using MVIC as a covariate in FF condition, abolished boys-men differences in force and TSImuscle decline and O2Hbcerebral rise.
Conclusion: During repeated maximal-efforts: (i) blood flow is a significant contributor to children's superiority over adults to resist fatigue; (ii) age-difference in muscle hypoxia/deoxygenation is rather attributed to men's greater metabolic demand than to lower muscle-perfusion; and (iii) cerebral oxygenation/blood volume increase more in men than boys under free circulation, implying greater brain activation.
期刊介绍：
The European Journal of Applied Physiology (EJAP) aims to promote mechanistic advances in human integrative and translational physiology. Physiology is viewed broadly, having overlapping context with related disciplines such as biomechanics, biochemistry, endocrinology, ergonomics, immunology, motor control, and nutrition. EJAP welcomes studies dealing with physical exercise, training and performance. Studies addressing physiological mechanisms are preferred over descriptive studies. Papers dealing with animal models or pathophysiological conditions are not excluded from consideration, but must be clearly relevant to human physiology.
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