工作周期对功率-时间关系的影响：观察结果与潜在机制。
Influence of duty cycle on the power-duration relationship: observations and potential mechanisms.
机构信息
Department of Kinesiology, Kansas State University, Manhattan, KS, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA.
Department of Kinesiology, Kansas State University, Manhattan, KS, USA; Department of Anatomy and Physiology, Kansas State University, Manhattan, KS, USA.
出版信息
Respir Physiol Neurobiol. 2014 Feb 1;192:102-11. doi: 10.1016/j.resp.2013.11.010. Epub 2013 Dec 17.
The highest sustainable rate of aerobic metabolism [critical power (CP)] and the finite amount of work that can be performed above CP (W' [curvature constant]) were determined under two muscle contraction duty cycles. Eight men completed at least three constant-power handgrip tests to exhaustion to determine CP and W' for 50% and 20% duty cycles, while brachial artery blood flow (Q̇BA) and deoxygenated-[hemoglobin + myoglobin] (deoxy-[Hb+Mb]) were measured. CP was lower for the 50% duty cycle (3.9 ± 0.9 W) than the 20% duty cycle (5.1 ± 0.8 W; p < 0.001), while W' was not significantly different (50% duty cycle: 452 ± 141 J vs. 20% duty cycle: 432 ± 130 J; p > 0.05). At the same power output, Q̇BA and deoxy-[Hb + Mb] achieved higher end-exercise values for the 20% duty cycle (9.87 ± 1.73 ml·s(-1); 51.7 ± 4.7 μM) than the 50% duty cycle (7.37 ± 1.76 ml·s(-1), p < 0.001; 44.3 ± 2.4 μM, p < 0.03). These findings indicate that blood flow influences CP, but not W'.
在两种肌肉收缩工作周期下，确定了有氧代谢的最高可持续率[临界功率 (CP)]和超过 CP 可完成的有限工作量 (W'[曲率常数])。八名男性完成了至少三次恒功率握力测试，直至力竭，以确定 50%和 20%工作周期的 CP 和 W'，同时测量肱动脉血流量 (Q̇BA)和去氧-[血红蛋白+肌红蛋白] (deoxy-[Hb+Mb])。50%工作周期的 CP 低于 20%工作周期 (3.9±0.9 W 比 5.1±0.8 W；p<0.001)，而 W' 没有显著差异 (50%工作周期：452±141 J 比 20%工作周期：432±130 J；p>0.05)。在相同的功率输出下，20%工作周期的 Q̇BA 和 deoxy-[Hb+Mb]达到了更高的运动末期值 (9.87±1.73 ml·s(-1)；51.7±4.7 μM)，高于 50%工作周期 (7.37±1.76 ml·s(-1)，p<0.001；44.3±2.4 μM，p<0.03)。这些发现表明血流量影响 CP，但不影响 W'。
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