PURPOSE To determine if time-efficient, high-resistance inspiratory muscle strength training (IMST), comprising 30 inhalation-resisted breaths per day, improves cardiorespiratory fitness, exercise tolerance, physical function and/or regional body composition in healthy midlife and older adults. METHODS We performed a double-blind, randomized, sham-controlled clinical trial (NCT03266510) testing 6 weeks of IMST (30 breaths/day, 6 days/week, 55%-75% maximal inspiratory pressure) versus low-resistance sham training (15% maximal inspiratory pressure) in healthy men and women aged 50-79 years. Subjects performed a graded treadmill exercise test to exhaustion, physical performance battery (e.g., handgrip strength, leg press), and body composition testing (dual x-ray absorptiometry) at baseline and after 6 weeks of training. RESULTS Thirty-five participants (17 women, 18 men) completed high-resistance IMST (n = 17) or sham training (n = 18). Cardiorespiratory fitness (V̇O2peak) was unchanged, but exercise tolerance, measured as treadmill exercise time during a graded exercise treadmill test, increased with IMST (baseline: 539 ± 42 s, end-intervention: 606 ± 42 s; p = 0.01) but not sham training (baseline: 562 ± 39 s, end-intervention: 553 ± 38 s; p = 0.69). IMST increased peak respiratory exchange ratio (baseline: 1.09 ± 0.02, end-intervention: 1.13 ± 0.02; p = 0.012), peak ventilatory efficiency (baseline: 25.2 ± 0.8, end-intervention: 24.6 ± 0.8; p = 0.036) and improved submaximal exercise economy (baseline: 23.5 ± 1.1 ml/kg/min, end-intervention: 22.1 ± 1.1 ml/kg/min; p < 0.001); none of these factors were altered by sham training (all p > 0.05). Changes in plasma acylcarnitines (targeted metabolomics analysis) were consistently positively correlated with changes in exercise tolerance following IMST but not sham training. IMST was associated with regional increases in thorax lean mass (+4.4%; p = 0.06) and reductions in trunk fat mass (-4.8%; p = 0.04); however, peripheral muscle strength, muscle power, dexterity and mobility were unchanged. CONCLUSIONS These data suggest that high-resistance IMST is an effective, time-efficient lifestyle intervention for improving exercise tolerance in healthy midlife and older adults.

中文翻译：

---

省时、高阻力吸气肌力量训练可提高中年和老年人的运动耐力。

目的 确定省时、高阻力吸气肌力量训练 (IMST)（包括每天 30 次吸气阻力呼吸）是否可以改善健康中年人和老年人的心肺健康、运动耐量、身体功能和/或局部身体成分。方法 我们进行了一项双盲、随机、假对照临床试验 (NCT03266510)，测试 6 周的 IMST（每天 30 次呼吸，每周 6 天，55%-75% 最大吸气压）与低阻力假训练（ 50-79 岁健康男性和女性的最大吸气压力的 15%）。受试者在基线时和训练 6 周后进行分级跑步机运动测试，直至力竭、身体表现电池（例如握力、压腿）和身体成分测试（双 X 射线吸收测定法）。结果 35 名参与者（17 名女性，18 名男性）完成了高阻力 IMST（n = 17）或假训练（n = 18）。心肺健康 (V̇O2peak) 没有变化，但运动耐量（在分级运动跑步机测试中以跑步机运动时间测量）随着 IMST 的增加而增加（基线：539 ± 42 秒，最终干预：606 ± 42 秒；p = 0.01），但没有增加假训练（基线：562 ± 39 s，干预结束：553 ± 38 s；p = 0.69）。IMST 增加了峰值呼吸交换比（基线：1.09 ± 0.02，干预结束：1.13 ± 0.02；p = 0.012）、峰值通气效率（基线：25.2 ± 0.8，干预结束：24.6 ± 0.8；p = 0.036）并得到改善次最大运动经济性（基线：23.5 ± 1.1 ml/kg/min，最终干预：22.1 ± 1.1 ml/kg/min；p < 0.001）；这些因素均未因假训练而改变（所有 p > 0.05）。血浆酰基肉碱的变化（目标代谢组学分析）与 IMST 后运动耐量的变化始终呈正相关，但与假训练无关。IMST 与胸部去脂质量的区域增加（+4.4%；p = 0.06）和躯干脂肪量的减少（-4.8%；p = 0.04）相关；然而，周围肌肉力量、肌肉力量、灵活性和活动能力没有变化。结论 这些数据表明，高阻力 IMST 是一种有效、省时的生活方式干预措施，可提高健康中年人和老年人的运动耐量。