Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and The University of Texas Southwestern Medical Center, Dallas, TX.
Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas and The University of Texas Southwestern Medical Center, Dallas, TX.
Chest. 2013 Oct;144(4):1330-1339. doi: 10.1378/chest.12-3022.
Alterations in respiratory mechanics predispose healthy obese individuals to low lung volume breathing, which places them at risk of developing expiratory flow limitation (EFL). The high ventilatory demand in endurance-trained obese adults further increases their risk of developing EFL and increases their work of breathing. The objective of this study was to investigate the prevalence and magnitude of EFL in fit obese (FO) adults via measurements of breathing mechanics and ventilatory dynamics during exercise.
Ten (seven women and three men) FO (mean ± SD, 38 ± 5 years, 38% ± 5% body fat) and 10 (seven women and three men) control obese (CO) (38 ± 5 years, 39% ± 5% body fat) subjects underwent hydrostatic weighing, pulmonary function testing, cycle exercise testing, and the determination of the oxygen cost of breathing during eucapnic voluntary hyperpnea.
There were no differences in functional residual capacity (43% ± 6% vs 40% ± 9% total lung capacity [TLC]), residual volume (21% ± 4% vs 21% ± 4% TLC), or FVC (111% ± 13% vs 104% ± 15% predicted) between FO and CO subjects, respectively. FO subjects had higher FEV1 (111% ± 13% vs 99% ± 11% predicted), TLC (106% ± 14% vs 94% ± 7% predicted), peak expiratory flow (123% ± 14% vs 106% ± 13% predicted), and maximal voluntary ventilation (128% ± 15% vs 106% ± 13% predicted) than did CO subjects. Peak oxygen uptake (129% ± 16% vs 86% ± 15% predicted), minute ventilation (128 ± 35 L/min vs 92 ± 25 L/min), and work rate (229 ± 54 W vs 166 ± 55 W) were higher in FO subjects. Mean inspiratory (4.65 ± 1.09 L/s vs 3.06 ± 1.21 L/s) and expiratory (4.15 ± 0.95 L/s vs 2.98 ± 0.76 L/s) flows were greater in FO subjects, which yielded a greater breathing frequency (51 ± 8 breaths/min vs 41 ± 10 breaths/min) at peak exercise in FO subjects. Mechanical ventilatory constraints in FO subjects were similar to those in CO subjects despite the greater ventilatory demand in FO subjects.
FO individuals achieve high ventilations by increasing breathing frequency, matching the elevated metabolic demand associated with high fitness. They do this without developing meaningful ventilatory constraints. Therefore, endurance-trained obese individuals with higher lung function are not limited by breathing mechanics during peak exercise, which may allow healthy obese adults to participate in vigorous exercise training.
呼吸力学的改变使健康肥胖个体容易出现低肺容积呼吸，从而使他们有发展为呼气流量受限（EFL）的风险。耐力训练肥胖成年人的高通气需求进一步增加了他们发展 EFL 的风险，并增加了他们的呼吸功。本研究的目的是通过测量运动期间的呼吸力学和通气动力学来研究健康肥胖（FO）成年人中 EFL 的患病率和程度。
10 名（7 名女性和 3 名男性）FO（平均 ± 标准差，38 ± 5 岁，38% ± 5%体脂）和 10 名（7 名女性和 3 名男性）对照肥胖（CO）（38 ± 5 岁，39% ± 5%体脂）受试者接受了静水称重、肺功能测试、循环运动测试以及在 eucapnic 自愿性 hyperpnea 期间确定呼吸的耗氧量。
FO 和 CO 受试者的功能残气量（43% ± 6%比 40% ± 9%总肺容量[TLC]）、残气量（21% ± 4%比 21% ± 4%TLC）或 FVC（111% ± 13%比 104% ± 15%预测）均无差异。FO 受试者的 FEV1（111% ± 13%比 99% ± 11%预测）、TLC（106% ± 14%比 94% ± 7%预测）、呼气峰流量（123% ± 14%比 106% ± 13%预测）和最大自愿通气量（128% ± 15%比 106% ± 13%预测）均高于 CO 受试者。峰值摄氧量（129% ± 16%比 86% ± 15%预测）、分钟通气量（128 ± 35 L/min 比 92 ± 25 L/min）和工作率（229 ± 54 W 比 166 ± 55 W）在 FO 受试者中更高。FO 受试者的平均吸气（4.65 ± 1.09 L/s 比 3.06 ± 1.21 L/s）和呼气（4.15 ± 0.95 L/s 比 2.98 ± 0.76 L/s）流量更大，这导致 FO 受试者在运动峰值时呼吸频率更高（51 ± 8 次/分钟比 41 ± 10 次/分钟）。尽管 FO 受试者的通气需求较高，但 FO 受试者的机械通气限制与 CO 受试者相似。
FO 个体通过增加呼吸频率来实现高通气，从而与较高的运动能力相关的代谢需求相匹配。他们这样做而不会产生有意义的通气限制。因此，具有较高肺功能的耐力训练肥胖个体在峰值运动期间不受呼吸力学的限制，这可能允许健康肥胖成年人参加剧烈运动训练。
