Ferguson Carrie, Wylde Lindsey A, Benson Alan P, Cannon Daniel T, Rossiter Harry B
School of Biomedical Sciences and Multidisciplinary Cardiovascular Research Centre, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom;
Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California; and School of Exercise and Nutritional Sciences, San Diego State University, San Diego, California.
J Appl Physiol (1985). 2016 Jan 1;120(1):70-7. doi: 10.1152/japplphysiol.00662.2015. Epub 2015 Nov 12.
During whole body exercise in health, maximal oxygen uptake (V̇o2max) is typically attained at or immediately before the limit of tolerance (LoT). At the V̇o2max and LoT of incremental exercise, a fundamental, but unresolved, question is whether maximal evocable power can be increased above the task requirement, i.e., whether there is a "power reserve" at the LoT. Using an instantaneous switch from cadence-independent (hyperbolic) to isokinetic cycle ergometry, we determined maximal evocable power at the limit of ramp-incremental exercise. We hypothesized that in endurance-trained men at LoT, maximal (4 s) isokinetic power would not differ from the power required by the task. Baseline isokinetic power at 80 rpm (Piso; measured at the pedals) and summed integrated EMG from five leg muscles (ΣiEMG) were measured in 12 endurance-trained men (V̇o2max = 4.2 ± 1.0 l/min). Participants then completed a ramp incremental exercise test (20-25 W/min), with instantaneous measurement of Piso and ΣiEMG at the LoT. Piso decreased from 788 ± 103 W at baseline to 391 ± 72 W at LoT, which was not different from the required ramp-incremental flywheel power (352 ± 58 W; P > 0.05). At LoT, the relative reduction in Piso was greater than the relative reduction in the isokinetic ΣiEMG (50 ± 9 vs. 63 ± 10% of baseline; P < 0.05). During maximal ramp incremental exercise in endurance-trained men, maximum voluntary power is not different from the power required by the task and is consequent to both central and peripheral limitations in evocable power. The absence of a power reserve suggests both the perceptual and physiological limits of maximum voluntary power production are not widely dissociated at LoT in this population.
在健康人群进行全身运动时，最大摄氧量（V̇o2max）通常在耐受极限（LoT）时或即将达到耐受极限之前达到。在递增运动的V̇o2max和LoT时，一个基本但尚未解决的问题是，最大可唤起功率是否能增加到超过任务要求，即LoT时是否存在“功率储备”。通过从与踏频无关（双曲线）的等动自行车测功仪进行瞬时切换，我们测定了递增运动极限时的最大可唤起功率。我们假设，在耐力训练的男性达到LoT时，最大（4秒）等动功率与任务所需功率无差异。在12名耐力训练男性（V̇o2max = 4.2 ± 1.0升/分钟）中测量了80转/分钟时的基线等动功率（Piso；在踏板处测量）以及来自五条腿部肌肉的积分肌电图总和（ΣiEMG）。参与者随后完成递增运动测试（20 - 25瓦/分钟），并在LoT时瞬时测量Piso和ΣiEMG。Piso从基线时的788 ± 103瓦降至LoT时的391 ± 72瓦，这与所需的递增飞轮功率（352 ± 58瓦；P > 0.05）无差异。在LoT时，Piso的相对降低大于等动ΣiEMG的相对降低（分别为基线的50 ± 9%和63 ± 10%；P < 0.05）。在耐力训练男性进行最大递增运动时，最大自主功率与任务所需功率无差异，这是由可唤起功率的中枢和外周限制共同导致的。功率储备的缺乏表明，在该人群中，最大自主功率产生的感知和生理极限在LoT时并没有广泛分离。
