The severity of performance fatigability and the capacity to recover from activity are profoundly influenced by skeletal muscle energetics, specifically the ability to buffer fatigue-inducing ions produced from anaerobic metabolism. Mechanisms responsible for buffering these ions result in the production of excess carbon dioxide (CO2) that can be measured as expired CO2 ( $$ \dot{\mathrm{V}} $$ CO2) during cardiopulmonary exercise testing (CPET). The primary objective of this study was to assess the feasibility of select assessment procedures for use in planning and carrying out interventional studies, which are larger interventional studies investigating the relationships between CO2 expiration, measured during and after both CPET and submaximal exercise testing, and performance fatigability. Cross-sectional, pilot study design. Seven healthy subjects (30.7±5.1 years; 5 females) completed a peak CPET and constant work-rate test (CWRT) on separate days, each followed by a 10-min recovery then 10-min walk test. Oxygen consumption ( $$ \dot{\mathrm{V}} $$ O2) and $$ \dot{\mathrm{V}} $$ CO2 on- and off-kinetics (transition constant and oxidative response index), excess- $$ \dot{\mathrm{V}} $$ CO2, and performance fatigability severity scores (PFSS) were measured. Data were analyzed using regression analyses. All subjects that met the inclusion/exclusion criteria and consented to participate in the study completed all exercise testing sessions with no adverse events. All testing procedures were carried out successfully and outcome measures were obtained, as intended, without adverse events. Excess- $$ \dot{\mathrm{V}} $$ CO2 accounted for 61% of the variability in performance fatigability as measured by $$ \dot{\mathrm{V}} $$ O2 on-kinetic ORI (ml/s) (R2=0.614; y = 8.474x − 4.379, 95% CI [0.748, 16.200]) and 62% of the variability as measured by PFSS (R2=0.619; y = − 0.096x + 1.267, 95% CI [−0.183, −0.009]). During CPET, $$ \dot{\mathrm{V}} $$ CO2 -off ORI accounted for 70% (R2=0.695; y = 1.390x − 11.984, 95% CI [0.331, 2.449]) and $$ \dot{\mathrm{V}} $$ CO2 -off Kt for 73% of the variability in performance fatigability measured by $$ \dot{\mathrm{V}} $$ O2 on-kinetic ORI (ml/s) (R2=0.730; y = 1.818x − 13.639, 95% CI [0.548, 3.087]). The findings of this study suggest that utilizing $$ \dot{\mathrm{V}} $$ CO2 measures may be a viable and useful addition or alternative to $$ \dot{\mathrm{V}} $$ O2 measures, warranting further study. While the current protocol appeared to be satisfactory, for obtaining select cardiopulmonary and performance fatigability measures as intended, modifications to the current protocol to consider in subsequent, larger studies may include use of an alternate mode or measure to enable control of work rate constancy during performance fatigability testing following initial CPET.

中文翻译：

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测量过量 \( \dot{\mathrm{V}} \)CO2 和恢复 \( \dot{\mathrm{V}} \)CO2 作为运动期间表现疲劳指数：一项试点研究


表现疲劳的严重程度和从活动中恢复的能力深受骨骼肌能量的影响，特别是缓冲无氧代谢产生的疲劳诱导离子的能力。负责缓冲这些离子的机制会导致产生过量的二氧化碳 (CO2)，在心肺运动测试 (CPET) 期间可将其测量为过期二氧化碳 ( $$ \dot{\mathrm{V}} $$ CO2)。本研究的主要目的是评估用于规划和开展介入研究的选定评估程序的可行性，这些研究是较大的介入研究，调查 CPET 和次最大运动测试期间和之后测量的二氧化碳呼气量与表现之间的关系疲劳性。横断面试点研究设计。 7 名健康受试者（30.7±5.1 岁；5 名女性）在不同的日子完成了峰值 CPET 和恒定工作率测试 (CWRT)，然后分别进行 10 分钟恢复和 10 分钟步行测试。耗氧量 ( $$ \dot{\mathrm{V}} $$ O2) 和 $$ \dot{\mathrm{V}} $$ CO2 开启和关闭动力学（转变常数和氧化反应指数），过量 -测量了$$ \dot{\mathrm{V}} $$ CO2 和表现疲劳严重程度评分（PFSS）。使用回归分析对数据进行分析。所有符合纳入/排除标准并同意参加研究的受试者完成了所有运动测试，没有出现不良事件。所有测试程序均按预期成功进行，并获得了结果测量，没有发生不良事件。过量 - $$ \dot{\mathrm{V}} $$ CO2 占性能疲劳性变异的 61%，通过 $$ \dot{\mathrm{V}} $$ O2 动态 ORI (ml/ s) (R2=0.614；y=8。474x − 4.379，95% CI [0.748, 16.200]）和 PFSS 测量的 62% 变异性（R2=0.619；y = − 0.096x + 1.267，95% CI [−0.183，−0.009]）。在 CPET 期间，$$ \dot{\mathrm{V}} $$ CO2 -off ORI 占 70% (R2=0.695; y = 1.390x − 11.984, 95% CI [0.331, 2.449]) 和 $$ \dot {\mathrm{V}} $$ CO2 -off Kt，通过 $$ \dot{\mathrm{V}} $$ O2 动态 ORI (ml/s) 测量，性能疲劳性变化为 73% (R2= 0.730；y = 1.818x - 13.639，95% CI [0.548，3.087]）。本研究的结果表明，利用 $$ \dot{\mathrm{V}} $$ CO2 措施可能是 $$ \dot{\mathrm{V}} $$ O2 措施的可行且有用的补充或替代方案，保证进一步研究。虽然当前的协议似乎令人满意，但为了按预期获得选定的心肺和性能疲劳测量，对当前协议的修改要考虑在后续的、更大规模的研究中可能包括使用替代模式或措施来控制性能期间的工作速率恒定性初始 CPET 后进行疲劳测试。