Federal University of Minas Gerais, School of Physical Education, Physiotherapy and Occupational Therapy, Belo Horizonte, Brazil.
Int J Sports Med. 2011 Oct;32(10):749-53. doi: 10.1055/s-0031-1277191. Epub 2011 May 17.
The aim of this study was to compare the maximal lactate steady state (MLSS) and ventilatory threshold (VT) under different environments (TEMP: 22°C; and HOT: 40°C; 50% RH). 8 male subjects (age 23.9±2.4 years, body mass 75.9±7.3 kg and VO2(max) 47.8±4.9 mL·kg(-1)·min(-1)) performed a series of tests to determine the peak workload (W(peak)), VT and MLSS on a cycle ergometer. W(peak) was higher in the TEMP as compared to the HOT condition (225±9 W vs. 195±8 W, respectively; p<0.05). The workload at MLSS was higher at 22°C (180±11 W) than 40°C (148±11 W; p<0.05), as well as VT at 22°C (156±9 W) was higher than 40°C (128±6 W). Likewise, the blood lactate concentration at MLSS was higher at 22°C (5.60±0.26 mM) than 40°C (4.22±0.48 mM; p<0.05). The mean of heart rate (HR) was not statistically different between TEMP (168±3 bpm) and HOT (173±3 bpm) at MLSS, despite being different at trials between the 25(th) and the 30(th) min of exercise. The HR at VT was significantly higher in HOT (153±4 bpm) as compared to the TEMP (145±2 bpm). Our results suggest that environmental conditions may influence the determination of MLSS and VT. Moreover, VT was appropriate for estimation of the workload at MLSS in the HOT.
本研究旨在比较不同环境下（TEMP：22°C；HOT：40°C，50%相对湿度）的最大乳酸稳态（MLSS）和通气阈（VT）。8 名男性受试者（年龄 23.9±2.4 岁，体重 75.9±7.3kg，最大摄氧量 47.8±4.9mL·kg(-1)·min(-1)）在功率自行车上进行了一系列测试，以确定峰值工作负荷（W(peak)）、VT 和 MLSS。与 HOT 相比，TEMP 下的 W(peak)更高（分别为 225±9W 和 195±8W，p<0.05）。22°C 时 MLSS 的工作负荷（180±11W）高于 40°C（148±11W；p<0.05），22°C 时的 VT（156±9W）也高于 40°C（128±6W）。同样，MLSS 时 22°C 的血乳酸浓度（5.60±0.26mM）也高于 40°C（4.22±0.48mM；p<0.05）。尽管在 25 分钟和 30 分钟的运动之间的试验中，TEMP（168±3bpm）和 HOT（173±3bpm）之间的平均心率（HR）没有统计学差异，但在 MLSS 时 HR 在 HOT 中明显更高（153±4bpm）。与 TEMP（145±2bpm）相比，HOT 中的 VT 显著更高。我们的结果表明，环境条件可能会影响 MLSS 和 VT 的确定。此外，在 HOT 中，VT 适合用于估计 MLSS 的工作负荷。
