Heart rate response to graded exercise test of elderly subjects in different ranges of TSH levels

ABSTRACT Objective: Life expectancy is increasing worldwide and studies have been demonstrating that elevated serum thyroid stimulating hormone (TSH) concentration in elderly is associated with some better health outcomes. This elevation is somewhat physiological as aging. The aim of this study was to investigate the heart rate (HR) response during a graded exercise test and its recovery in healthy elderly, comparing subjects within serum TSH in the lower limit of reference range to those within the TSH in the upper limit. Subjects and methods: A cross-sectional study was conducted with 86 healthy elderly aged 71.5 ± 5.1 years, with serum TSH between 0.4 – 4.0 mUl/mL. The participants were divided into two groups according to TSH level: < 1.0 mUl/mL (n = 13) and ≥ 1.0 µUI/mL (n = 73). All participants performed an ergometric test on a treadmill. The HR was recorded and analyzed at rest, during exercise and during the three minutes immediately after exercise. Results: No differences were observed in relation to HR at peak of exercise (TSH < 1.0 µUI/mL: 133.9 ± 22.5 bpm vs. TSH ≥ 1.0 µUI/mL: 132.4 ± 21.3 bpm; p = 0.70) and during the first minute of recovery phase (TSH < 1.0 µUI/mL: 122.3 ± 23.1 bpm vs. TSH ≥ 1.0 µUI/mL: 115.7 ± 18.4 bpm p = 0.33). The groups also presented similar chronotropic index (TSH < 1.0 µUI/mL: 78.1 ± 30.6 vs. TSH ≥ 1.0 µUI/mL: 79.5 ± 26.4; p = 0.74). Conclusion: In this sample studied, there were no difference between lower and upper TSH level concerning HR response during rest, peak of exercise and exercise recovery.

摘要
目的：全球人口预期寿命持续延长，已有研究表明，老年人血清促甲状腺激素（thyroid stimulating hormone, TSH）水平升高与部分更佳的健康结局相关，该升高现象随衰老进程属于一定程度的生理变化。本研究旨在探究健康老年人在分级运动试验中的心率（heart rate, HR）反应及恢复特征，并对比血清TSH处于参考范围下限与上限的受试者之间的差异。
对象与方法：本研究为横断面研究，共纳入86名健康老年人，年龄为71.5±5.1岁，血清TSH水平介于0.4–4.0 mUl/mL。根据TSH水平将受试者分为两组：<1.0 mUl/mL组（n=13）与≥1.0 µUI/mL组（n=73）。所有受试者均在跑步机上完成功率代谢运动试验。于静息状态、运动过程中及运动后即刻3分钟内记录并分析心率数据。
结果：运动峰值心率方面，TSH<1.0 µUI/mL组为133.9±22.5次/分钟，TSH≥1.0 µUI/mL组为132.4±21.3次/分钟（p=0.70），两组无显著差异；恢复阶段第一分钟的心率分别为122.3±23.1次/分钟与115.7±18.4次/分钟（p=0.33），同样未观察到组间差异。此外，两组的变时性指数也无显著差异：TSH<1.0 µUI/mL组为78.1±30.6，TSH≥1.0 µUI/mL组为79.5±26.4（p=0.74）。
结论：在本研究纳入的样本中，血清TSH处于参考范围上下限的健康老年人在静息心率、运动峰值心率及运动后心率恢复方面均无显著差异。