Bomma Meghana, Lott Donovan, Forbes Sean, Shih Renata, Coppola John-Anthony, Christle Jeffrey W, Duong Tina, Russo Joseph, Pant Aditi, Leon-Astudillo Carmen, Berthy Julie, Cousins Christina, Corti Manuela, Byrne Barry, May James, Xue W, Taivassalo Tanja
Department of Physiology and Aging, University of Florida, Gainesville, FL, USA.
Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
J Neuromuscul Dis. 2025 Mar 4:22143602251319170. doi: 10.1177/22143602251319170.
Cardiopulmonary exercise testing (CPET) is the gold-standard for quantification of peak oxygen uptake (VO) and cardiorespiratory and muscle responses to exercise. Its application to Duchenne muscular dystrophy (DMD) has been scarce due to the notion that muscle weakness inherent to disease restricts the cardiorespiratory system from reaching maximal capacity.
To investigate the utility of CPET in DMD by 1) establishing whether patients can perform maximal-effort exercise for valid VO peak assessment; 2) quantifying VO peak repeatability; 3) characterizing muscle and cardiorespiratory responses; 4) comparing VO peak to 6-min walk distance (6MWD).
Twenty-seven DMD and eight healthy boys (6 years and older) underwent CPET using an incremental work-rate protocol for leg (ambulatory) or arm (non-ambulatory) cycling with measurement of heart rate (HR) and gas-exchange variables from rest to maximal-effort. The oxygen cost of work (ΔVO/Δwork-rate) was calculated, and peak exercise parameters (VO, HR, O pulse, ventilation (VE) and ventilatory threshold (VT)) were considered valid if the respiratory exchange ratio ≥1.01.
VO peak was valid (81.5% of patients), repeatable (intraclass correlation coefficient = 0.998) and low in ambulatory and non-ambulatory DMD compared to controls (19.0 ± 6.0; 10.7 ± 2; 35.2 ± 4.5 mL/kg/min respectively). VT was low (30.8 ± 10.7; 19.4 ± 3.0; 61.2 ± 6.9% VO peak) reflecting significant muscle metabolic impairment. Peak HR in ambulatory-DMD (172 ± 14 bpm) was similar to controls (183 ± 8.3 bpm), but O pulse was low (3.4 ± 1.0; 6.5 ± 1.1 mL/beat). Peak VE/VO (ambulatory = 42.1 ± 6.8; non-ambulatory = 42.2 ± 7.8; controls = 34.3 ± 4.6) and ΔVO/Δwork-rate were elevated (ambulatory = 12.4 ± 4.9; non-ambulatory = 19.0 ± 9.7; controls = 10.1 ± 0.8) revealing ventilatory and mechanical inefficiency. Despite strong correlation between VO peak and 6MWD, severity of impairment was discordant.
Valid CPET is feasible in DMD, revealing low VO peak due to abnormal muscle metabolic and cardiorespiratory responses during dynamic exercise. CPET reveals cardiorespiratory limitations in DMD boys with unremarkable 6MWD, and should be considered an integrative approach in clinical care and assessment of emerging therapeutics.
心肺运动试验（CPET）是定量测定峰值摄氧量（VO）以及评估心肺和肌肉对运动反应的金标准。由于认为该疾病固有的肌肉无力会限制心肺系统达到最大能力，所以CPET在杜氏肌营养不良症（DMD）中的应用较少。
通过以下方式研究CPET在DMD中的效用：1）确定患者是否能够进行最大努力运动以进行有效的VO峰值评估；2）量化VO峰值的可重复性；3）描述肌肉和心肺反应特征；4）比较VO峰值与6分钟步行距离（6MWD）。
27名DMD患儿和8名健康男孩（6岁及以上）采用递增工作率方案进行腿部（能行走的）或手臂（不能行走的）骑行CPET，测量从静息到最大努力运动期间的心率（HR）和气体交换变量。计算工作的氧耗（ΔVO/Δ工作率），如果呼吸交换率≥1.01，则认为峰值运动参数（VO、HR、氧脉搏、通气量（VE）和通气阈值（VT））有效。
VO峰值有效（81.5%的患者）、可重复（组内相关系数 = 0.998），与对照组相比，能行走和不能行走的DMD患者的VO峰值较低（分别为19.0±6.0；10.7±2；35.2±4.5 mL/kg/min）。VT较低（30.8±10.7；19.4±3.0；61.2±6.9%VO峰值），反映出明显的肌肉代谢受损。能行走的DMD患者的峰值HR（172±14 bpm）与对照组（183±8.3 bpm）相似，但氧脉搏较低（3.4±1.0；6.5±1.1 mL/次搏动）。峰值VE/VO（能行走的 = 42.1±6.8；不能行走的 = 42.2±7.8；对照组 = 34.3±4.6）和ΔVO/Δ工作率升高（能行走的 = 12.4±4.9；不能行走的 = 19.0±9.7；对照组 = 10.1±0.8），表明通气和机械效率低下。尽管VO峰值与6MWD之间存在强相关性，但损伤严重程度不一致。
有效的CPET在DMD中是可行的，揭示了动态运动期间由于异常的肌肉代谢和心肺反应导致VO峰值较低。CPET揭示了6MWD无明显异常的DMD男孩的心肺限制，应被视为临床护理和新兴疗法评估中的一种综合方法。
