Exercise Physiology Laboratory at Toledo, University of Castilla-La Mancha, Avda. Carlos III, s/n. 45071, Toledo, Spain.
Eur J Appl Physiol. 2011 Nov;111(11):2873-81. doi: 10.1007/s00421-011-1911-6. Epub 2011 Mar 24.
The purpose of this study was to determine whether sweat sodium concentration (Na(+)) during exercise in the heat differs between aerobically trained and untrained individuals. On three occasions, ten endurance-trained (Tr) and ten untrained (UTr) subjects (VO2peak = 4.0 ± 0.8 vs. 3.4 ± 0.7 L min(-1), respectively; P < 0.05) cycled in a hot-ventilated environment (36 ± 1°C; 25 ± 2% humidity, airflow 2.5 m s(-1)) at three workloads (i.e., 40, 60, and 80% VO2peak). Whole-body (SR(WB)) and back sweat rates (SR(BACK)) were measured. At the conclusion of the study, Na(+) in sweat and blood samples was analyzed to calculate Na(+) secretion and reabsorption rates. SR(WB) and SR(BACK) were highly correlated in Tr and UTr (r = 0.74 and 0.79, respectively; P < 0.0001). In both groups, SR(BACK) increased with the increases in exercise intensity (P < 0.05). Likewise, Na(+) increased with the exercise intensity in both groups (P < 0.05) and it tended to be higher in Tr than in UTr at 60 and 80% VO2peak (~22 mmol L(-1) higher; P = 0.06). However, when normalized for SR(BACK), Na(+) was not different between groups. In both groups, Na(+) secretion and reabsorption rates increased with the increases in SR(BACK) (P < 0.05). However, Na(+) reabsorption rate was lower in the Tr than in the UTr (mean slope = 48 vs. 82 ηmol cm(-2) min(-1); P = 0.03). In conclusion, using a cross-sectional study design, our data suggest that aerobic fitness level does not reduce sweat Na(+) secretion or enhance Na(+) reabsorption during prolonged exercise in the heat that induced high sweat rates.
这项研究的目的是确定在热环境下运动时，有氧训练和未训练个体的汗液钠浓度(Na+)是否不同。在三种情况下，十名耐力训练者（Tr）和十名未训练者（UTr）（VO2peak 分别为 4.0 ± 0.8 和 3.4 ± 0.7 L min(-1)；P < 0.05）在热通风环境（36 ± 1°C；25 ± 2%湿度，气流 2.5 m s(-1))下以三种工作量（即 40%、60%和 80% VO2peak）进行自行车运动。全身（SR(WB)）和背部汗液率（SR(BACK)）被测量。在研究结束时，分析汗液和血液样本中的 Na+，以计算 Na+分泌和重吸收速率。Tr 和 UTr 中 SR(WB)和 SR(BACK)高度相关（r = 0.74 和 0.79，分别；P < 0.0001）。在两组中，SR(BACK)随运动强度的增加而增加（P < 0.05）。同样，Na+随两组运动强度的增加而增加（P < 0.05），在 60%和 80% VO2peak 时，Tr 中的Na+倾向于高于 UTr（高约 22 mmol L(-1)；P = 0.06）。然而，当按 SR(BACK)标准化时，两组之间的Na+没有差异。在两组中，Na+分泌和重吸收速率随 SR(BACK)的增加而增加（P < 0.05）。然而，Tr 中的 Na+重吸收速率低于 UTr（平均斜率= 48 与 82 ηmol cm(-2) min(-1)；P = 0.03）。总之，使用横截面研究设计，我们的数据表明，在热环境下进行长时间运动导致高汗液率时，有氧健身水平不会降低汗液 Na+分泌或增强 Na+重吸收。
