Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada.
Faculty of Health and Sport Sciences, University of Tsukuba, Japan.
J Therm Biol. 2022 Dec;110:103344. doi: 10.1016/j.jtherbio.2022.103344. Epub 2022 Sep 24.
Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (T) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite T not being different between groups, T was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury.
目前劳动力人口结构正在发生变化，预计从事体力要求高的职业的老年人数量将持续增加，而这些职业往往在高温下进行。由于与年龄相关的全身热量损失下降，老年人患热损伤的风险增加，而高血压（HTN）和 2 型糖尿病（T2D）可能会使这种风险加剧。升高的鸢尾素产生可能在减轻与高温下体力劳动相关的过度氧化应激和急性炎症方面发挥作用。然而，HTN 和 T2D 对这种反应的影响仍不清楚。因此，我们评估了 12 名健康老年人（平均年龄 ± 标准差；59 ± 4 岁）、10 名高血压男性（60 ± 4 岁）和 9 名 2 型糖尿病男性（60 ± 5 岁）在中等强度运动（代谢率：200 W/m）前、后 3 小时和运动后 60 分钟恢复期结束时在温和（湿球温度球温度（WBGT）16°C）和高热应激（WBGT 32°C）环境下的血清鸢尾素水平，运动持续时间为 3 小时。核心温度（T）连续测量。在高温下，高血压男性和 2 型糖尿病男性的总运动时间明显更短（均 p ≤ 0.049）。尽管各组之间的 T 没有差异，但与温和条件相比，所有组在高温下的 T 更高（p < 0.001）。同样，在任何一种条件下，各组之间的血清鸢尾素浓度均无差异，但在高温下运动后和恢复期结束时均高于温和条件（分别升高 93.9 pg/mL SEM 26 和 70.5 pg/mL SEM 38；均 p ≤ 0.014）。因此，我们的研究结果表明，与健康、年龄匹配的对照组相比，高血压和 2 型糖尿病患者的鸢尾素反应相似，尽管在高温下长时间运动时的运动耐量降低。因此，患有高血压和 2 型糖尿病的老年工人在高温下长时间运动时可能会出现更大的细胞应激，从而更容易受到热诱导的细胞损伤。
