Renggli Andrea S, Verges Samuel, Notter Dominic A, Spengler Christina M
Exercise Physiology, Institute for Human Movement Sciences, ETH Zurich, Switzerland.
Respir Physiol Neurobiol. 2008 Dec 31;164(3):366-72. doi: 10.1016/j.resp.2008.08.008. Epub 2008 Aug 30.
To assess the development of inspiratory and expiratory muscle fatigue during normocapnic hyperpnoea, we studied fourteen healthy men performing 8min hyperpnoea, 6min pause, 8min hyperpnoea, etc., until task failure. Twitch transdiaphragmatic (P(di,tw)) and gastric (P(ga,tw)) pressures were measured during cervical and thoracic magnetic nerve stimulation, before hyperpnoea, after every 8min of hyperpnoea, and at task failure (i.e., at 25.3+/-4.7min). P(di,tw) decreased during the first 16min (-28+/-7%, p<0.001) and P(ga,tw) during the first 8min (-20+/-7%, p<0.001) of hyperpnoea without further change until task failure. During inspiration, the pressure-time-product of oesophageal pressure (PTP(oes)) increased relative to PTP(di) during the first 16min (+11+/-21%, p<0.05). Similarly, during expiration, PTP(oes) increased relative to PTP(ga) during the first 8min (+10+/-16%, p<0.05). Also, blood lactate concentration and respiratory sensations significantly increased during the first 8min (+1.0+/-0.5mmoll(-1), p<0.001) and 16min (breathlessness +1.6+/-1.8 points, respiratory effort +5.9+/-2.2points, p<0.001), respectively. We conclude that, during hyperpnoea, contractile fatigue of the diaphragm and abdominal muscles develops long before task failure and may trigger an increased recruitment of rib cage muscles.
为评估在正常碳酸血症性通气过度期间吸气和呼气肌疲劳的发展情况，我们对14名健康男性进行了研究，他们进行8分钟通气过度、6分钟暂停、8分钟通气过度等操作，直至任务失败。在通气过度前、每8分钟通气过度后以及任务失败时（即25.3±4.7分钟），在颈部和胸部磁神经刺激期间测量跨膈压（P(di,tw)）和胃内压（P(ga,tw)）。在通气过度的前16分钟，P(di,tw)下降（-28±7%，p<0.001），在前8分钟，P(ga,tw)下降（-20±7%，p<0.001），直至任务失败前无进一步变化。在吸气过程中，食管压力的压力-时间乘积（PTP(oes)）在最初16分钟相对于PTP(di)增加（+11±21%，p<0.05）。同样，在呼气过程中，PTP(oes)在最初8分钟相对于PTP(ga)增加（+10±16%，p<0.05）。此外，血乳酸浓度和呼吸感觉在最初8分钟（+1.0±0.5mmol·l(-1)，p<0.001）和16分钟（呼吸急促增加1.6±1.8分，呼吸用力增加5.9±2.2分，p<0.001）时分别显著增加。我们得出结论，在通气过度期间，膈肌和腹肌的收缩性疲劳在任务失败前很早就已出现，并可能引发胸廓肌肉募集增加。
