Quackenbush Joseph, Duquin Aubrey, Helfer Samuel, Pendergast David R
Center for Research and Education in Special Environments, Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.
Aerosp Med Hum Perform. 2016 Jan;87(1):18-25. doi: 10.3357/AMHP.4420.2016.
Hiking and trekking often occur at altitudes up to 12,000 ft altitude. The hypoxia-induced hyperventilation at altitude paradoxically reduces arterial CO2 (Paco2). A reduction in Paco2 results in vasoconstriction of the blood vessels of the brain and thus in local hypoxia. The local hypoxia likely affects cognitive function, which may result in reduced performance and altitude accidents. Recent publications have demonstrated that voluntary isocapnic hyperventilatory training of the respiratory muscles (VIHT) can markedly enhance exercise endurance as it is associated with reduced ventilation and its energy cost. VIHT may be useful in blunting the altitude-induced hyperventilation leading to higher Paco2 and improved cognitive function.
This study examined the effects of VIHT, compared to control (C) and placebo (PVIHT) groups, on selected measures of executive functioning, including working memory and processing speed (i.e., Stroop Test, Symbol Digit Modalities Test, and Digit Span Forward) at simulated altitude up to 12,000 ft. Associated physiological parameters were also measured.
The Digit Span Forward Test did not show improvements after VIHT in any group. The VIHT group, but not C or PVIHT groups, improved significantly (17-30%) on the Stroop Test. Similarly the VIHT group, but not the C and PVIHT groups, improved correct responses (26%) and number of attempts (24%) on the Symbol Digit Modalities Test. In addition, reaction time was also improved (16%).
VIHT improved processing speed and working memory during exercise at altitude.
徒步旅行和长途跋涉通常发生在海拔高达12000英尺的地方。海拔高度引起的低氧性通气过度反而会降低动脉血二氧化碳分压（Paco2）。Paco2降低会导致脑血管收缩，进而导致局部缺氧。局部缺氧可能会影响认知功能，这可能会导致表现下降和高原事故。最近的出版物表明，呼吸肌的自愿等碳酸通气过度训练（VIHT）可以显著提高运动耐力，因为它与通气量及其能量消耗的减少有关。VIHT可能有助于减轻海拔高度引起的通气过度，从而导致更高的Paco2和改善认知功能。
本研究考察了VIHT与对照组（C）和安慰剂组（PVIHT）相比，在模拟海拔高达12000英尺时对包括工作记忆和处理速度（即Stroop测试、符号数字模态测试和数字广度顺背）等执行功能选定指标的影响。还测量了相关的生理参数。
数字广度顺背测试在任何组的VIHT后均未显示出改善。VIHT组在Stroop测试中显著改善（17%-30%），而C组和PVIHT组则没有。同样，VIHT组在符号数字模态测试中的正确反应（26%）和尝试次数（24%）有所改善，而C组和PVIHT组则没有。此外，反应时间也有所改善（16%）。
VIHT改善了高原运动期间的处理速度和工作记忆。
