Department of Medicine, University of Udine, Udine, ITALY.
Experimental Laboratory for Auxo-endocrinological Research, Istituto Auxologico Italiano, IRCCS, Milan and Piancavallo (VB), ITALY.
Med Sci Sports Exerc. 2021 May 1;53(5):986-993. doi: 10.1249/MSS.0000000000002551.
"Slow components" of heart rate (HR) kinetics, occurring also during moderate-intensity constant work rate exercise, represent a problem for exercise prescription at fixed HR values. This problem, described in young healthy subjects, could be more pronounced in obese patients.
Sixteen male obese patients (age, 22 ± 7 yr; body mass, 127 ± 19 kg; body mass index, 41.6 ± 3.9 kg·m-2) were tested before (PRE) and after (POST) a 3-wk multidisciplinary body mass reduction program, entailing moderate-intensity exercise. They performed on a cycle ergometer an incremental exercise to voluntary exhaustion (to determine peak pulmonary oxygen uptake (V˙O2peak) and gas exchange threshold (GET)) and constant work rate exercises: moderate-intensity (MODERATE; 80% of GET determined in PRE), heavy-intensity (HEAVY; 120% of GET determined in PRE), and "HRCLAMPED" exercise, in which work rate was continuously adjusted to maintain a constant HR corresponding to that at 120% of GET. Breath-by-breath V˙O2 and HR were determined.
V˙O2peak and GET (expressed as a percent of V˙O2peak) were not significantly different in PRE versus POST. In POST versus PRE, the HR slow component disappeared (MODERATE) or was reduced (HEAVY). In PRE, work rate had to decrease by 20% over a 15-min task in order to keep HR constant; this decrease was significantly smaller (5%) in POST.
In obese patients, a 3-wk multidisciplinary body mass reduction intervention i) increased exercise tolerance by eliminating (during MODERATE) or by reducing (during HEAVY) the slow component of HR kinetics, and ii) facilitated exercise prescription by allowing to translate a fixed submaximal HR value into a work rate slightly above GET.
心率（HR）动力学的“缓慢成分”也会在中等强度恒功运动中出现，这给以固定 HR 值进行运动处方制定带来了问题。在年轻健康受试者中描述的这个问题，在肥胖患者中可能更为明显。
16 名男性肥胖患者（年龄 22 ± 7 岁；体重 127 ± 19kg；体重指数 41.6 ± 3.9kg·m-2）在进行为期 3 周的多学科减肥计划（包括中等强度运动）前后（PRE 和 POST）进行了测试。他们在自行车测力计上进行了递增至力竭的运动测试（以确定峰值肺氧摄取量（V˙O2peak）和气体交换阈值（GET））以及恒功运动测试：中等强度（MODERATE；在 PRE 中测定的 GET 的 80%）、高强度（HEAVY；在 PRE 中测定的 GET 的 120%）和“HRCLAMPED”运动，其中通过连续调整功量以保持与 120%GET 相对应的恒定 HR。通过逐口气测量 V˙O2 和 HR。
在 PRE 与 POST 相比，V˙O2peak 和 GET（表示为 V˙O2peak 的百分比）没有显著差异。在 POST 与 PRE 相比，HR 缓慢成分消失（在 MODERATE 中）或减少（在 HEAVY 中）。在 PRE 中，为了保持 HR 恒定，需要在 15 分钟的任务中降低约 20%的功量；而在 POST 中，这种降低明显较小（约 5%）。
在肥胖患者中，3 周的多学科减肥干预措施 i）通过消除（在 MODERATE 期间）或减少（在 HEAVY 期间）HR 动力学的缓慢成分，增加了运动耐量，ii）通过允许将固定的亚最大 HR 值转换为略高于 GET 的功量，从而使运动处方的制定变得更加容易。
