Bourgois Gil, Colosio Alessandro L, Caen Kevin, Bourgois Jan G, Mucci Patrick, Boone Jan
Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium.
Univ. Lille, Univ. Artois, Univ. Littoral Côte d'Opale, ULR 7369-URePSSS-Unité de Recherche Pluridisciplinaire Sport Santé Société, F-59000, Lille, France.
Eur J Appl Physiol. 2023 Apr;123(4):847-856. doi: 10.1007/s00421-022-05106-y. Epub 2022 Dec 12.
The aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities.
Eleven physically active male participants performed four incremental exercise tests, two RAMP (30 W·min) and two STEP (40 W·3 min), both in 18 °C (TEMP) and 36 °C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LT) and fixed value lactate concentrations (LT).
A decrease in mean power output (PO) was observed in HOT at LT (-6.2 ± 1.9%), more specific LT (-5.4 ± 1.4%) and LT (-7.5 ± 2.4%), compared to TEMP, however not at RT (-1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from -53 W to +26 W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8 bpm).
This study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes.
本研究旨在探讨在两种最常用的递增运动测试方案（斜坡式和阶梯式）中，急性热暴露如何影响呼吸阈值（RT）和乳酸阈值（LT），这两种方案用于有氧适能的功能评估、运动处方制定及训练强度监测。
11名身体活跃的男性参与者进行了四项递增运动测试，两项斜坡式测试（30瓦·分钟）和两项阶梯式测试（40瓦·3分钟），测试均在18°C（常温）和36°C（高温）、相对湿度40%的环境下进行，分别测定2个呼吸阈值和16个乳酸阈值。在乳酸阈值中进行区分时，考虑了个体乳酸动力学（LT）和固定值乳酸浓度（LT）。
与常温相比，高温环境下乳酸阈值时的平均功率输出（PO）下降（-6.2±1.9%），更具体的乳酸阈值（-5.4±1.4%）和乳酸阈值（-7.5±2.4%）也是如此，但呼吸阈值时未下降（-1.0±2.7%）。在所有阈值方法中，高温与常温相比的个体功率输出差异范围为-53瓦至+26瓦。乳酸阈值时平均心率（HR）无差异，而高温环境下呼吸阈值时平均心率增加（+10±8次/分钟）。
本研究表明，环境空气温度升高时运动阈值会受到影响。然而，发现不同阈值概念对急性热暴露的敏感性存在相当大的变异性，并且存在较大的个体差异。在解释运动测试结果时应考虑测试设计和程序。
