Muza S R, Levine L, Latzka W A, Sawka M N
U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, USA.
Int J Sports Med. 1996 Jul;17(5):344-50. doi: 10.1055/s-2007-972858.
This study examined the effects of added inspiratory resistance (R5 5 cm H2O.L-1.S-1) on the relationship between exercise breathing pattern and resting hypercapnic ventilatory responsiveness (HCVR). Twelve men completed an HCVR test and two progressive intensity exercise tasks with minimal (R0) and elevated (R5) resistance. Peak oxygen uptake, and peak power output were not different, but peak VE was decreased with the R5 load. Exercise ventilation (VE was tightly coupled to VCO2 (r = 0.97) as was mean inspiratory flow rate (VT/TI, r = 0.95), but not duty cycle (TI/TTOT, r = 0.39). With imposition of R5, VT/TI was depressed (p < 0.05) at mild (approximately 40% VO2peak) to peak exercise intensities, whereas TI/TTOT was relatively unaffected. At both moderate (approximately 60% peak VO2) and peak exercise intensities, VE was positively correlated (r = 0.62, p < 0.05 and r = 0.82, p < 0.01, respectively) to subjects' HCVR. However, when normalized, VE.VCO2(-1) was significantly correlated to HCVR only at peak exercise ventilation during the R0 load. Analysis of the exercise breathing pattern revealed that at both moderate and peak exercise intensities, VT/TI was positively correlated to HCVR, but TI/TTOT was not. The imposition of R5 decreased the slope of the relationship between exercise VT/TI and HCVR at both moderate and peak exercise intensities, and weakened the positive correlation at the moderate exercise intensity. Our analysis indicates that: 1) the positive correlation between exercise hyperpnea and HCVR is mediated by the mean inspiratory flow rate rather than the duty cycle component of the breathing pattern and, 2) at moderate exercise the relationship between mean inspiratory flow rate and resting HCVR is more sensitive to added inspiratory resistance than minute ventilation per se. These findings suggest that the degree of influence resting HCVR has on exercise hyperpnea is dependent upon the magnitudes of both the ventilatory hyperpnea and mechanical loading placed on the ventilatory system.
本研究考察了增加吸气阻力（R5 = 5 cm H2O·L-1·S-1）对运动呼吸模式与静息高碳酸通气反应性（HCVR）之间关系的影响。12名男性完成了一项HCVR测试以及两项递增强度运动任务，分别为最小阻力（R0）和增加阻力（R5）的情况。峰值摄氧量和峰值功率输出无差异，但R5负荷时峰值每分通气量（VE）降低。运动通气（VE）与二氧化碳排出量（VCO2）紧密相关（r = 0.97），平均吸气流量（VT/TI，r = 0.95）也是如此，但呼吸比（TI/TTOT，r = 0.39）并非如此。施加R5后，在轻度（约40% VO2峰值）至峰值运动强度时，VT/TI降低（p < 0.05），而TI/TTOT相对未受影响。在中度（约60%峰值VO2）和峰值运动强度时，VE与受试者的HCVR均呈正相关（分别为r = 0.62，p < 0.05和r = 0.82，p < 0.01）。然而，经归一化后，仅在R0负荷的峰值运动通气时，VE·VCO2（-1）与HCVR显著相关。对运动呼吸模式的分析表明，在中度和峰值运动强度时，VT/TI与HCVR均呈正相关，但TI/TTOT并非如此。施加R5降低了中度和峰值运动强度时运动VT/TI与HCVR之间关系的斜率，并削弱了中度运动强度时的正相关。我们的分析表明：1）运动性通气过度与HCVR之间的正相关是由平均吸气流量介导的，而非呼吸模式的呼吸比成分；2）在中度运动时，平均吸气流量与静息HCVR之间的关系比每分通气量本身对增加的吸气阻力更敏感。这些发现表明，静息HCVR对运动性通气过度的影响程度取决于通气过度的程度以及施加于通气系统的机械负荷大小。
