Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA; Air Force Institute of Technology, Wright-Patterson Air Force Base, OH, 45433, USA.
Human Cardiovascular Physiology Laboratory, Department of Health and Exercise Science, Colorado State University, Fort Collins, CO, 80521, USA.
J Therm Biol. 2021 Aug;100:103026. doi: 10.1016/j.jtherbio.2021.103026. Epub 2021 Jun 9.
To determine if electrolyte or carbohydrate supplementation vs. water would limit the magnitude of dehydration and decline in cognitive function in humans following long-duration hyperthermic-exercise.
24 subjects performed 3 visits of 2 h walking (3mph/7% grade) in an environmental chamber (33 °C/10% relative humidity). In random order, subjects consumed water (W), electrolytes (Gatorade Zero; E), or electrolytes+carbohydrates (Gatorade; E+C). Throughout exercise (EX), subjects carried a 23 kg pack and drank ad-libitum. Pre-and post-EX, body mass (BM) and plasma osmolality (pOsm) were measured. Physiological Strain Index (PSI) and core temperature (T) were recorded every 15 min. Plasma glucose (GLU) was measured every 30 min. Cognitive processing (SCWT) was measured post-EX and compared to baseline (BL). A subset of 8 subjects performed a normothermic (N) protocol (21 °C/ambient humidity) to ascertain how the exercise stimulus influenced hydration status and cognition without heat.
There were no significant differences between fluid conditions (W, E, E+C) for BM loss (Δ2.5 ± 0.2, 2.5 ± 0.2, 2.3 ± 0.2 kg), fluid consumption (1.9 ± 0.2, 1.9 ± 0.2, 1.8 ± 0.2L), pOsm (Δ1.5 ± 2.7, 2.2 ± 2.4, 2.0 ± 1.5 mmol/L), peak-PSI (7.5 ± 0.4, 7.0 ± 0.6, 7.9 ± 0.5), and peak-T (38.7 ± 0.1, 38.6 ± 0.2, 38.8 ± 0.2 °C). GLU decreased significantly in W and E, whereas it increased above BL in E+C at 60, 90, and 120 min (P < 0.05). Compared to BL values (43.6 ± 26 ms), SCWT performance significantly decreased in all conditions (463 ± 93, 422 ± 83, 140 ± 52 ms, P < 0.05). Importantly, compared to W and E, the impairment in SCWT was significantly attenuated in E+C (P < 0.05). As expected, when compared to the heat-stress protocol (W, E, E+C), N resulted in lower BM loss, fluid consumption, and peak-PSI (1.1 ± 0.1 kg, 1.2 ± 0.7L, 4.8, respectively), and improved SCWT performance.
These data are the first to suggest that, independent of supplementation variety, cognitive processing significantly decreases immediately following long-duration exercise in the heat in healthy humans. Compared to water and fluids supplemented with only electrolytes, fluids supplemented with carbohydrates significantly blunts this decrease in cognitive function.
为了确定在长时间高热运动后，电解质或碳水化合物补充剂与水相比是否会限制脱水程度和认知功能下降。
24 名受试者在环境室（33°C/10%相对湿度）中进行了 3 次 2 小时的步行（3 英里/小时/7%坡度）。随机顺序，受试者分别饮用水（W）、电解质（佳得乐零；E）或电解质+碳水化合物（佳得乐；E+C）。在整个运动（EX）过程中，受试者携带 23 公斤的背包并自由饮水。在 EX 前后测量体重（BM）和血浆渗透压（pOsm）。每 15 分钟记录一次生理应激指数（PSI）和核心温度（T）。每 30 分钟测量一次血浆葡萄糖（GLU）。在 EX 后测量认知处理（SCWT），并与基线（BL）进行比较。8 名受试者的一部分进行了常温（N）协议（21°C/环境湿度），以确定运动刺激如何在没有热量的情况下影响水合状态和认知。
在体重损失（Δ2.5±0.2、2.5±0.2、2.3±0.2 公斤）、液体消耗（1.9±0.2、1.9±0.2、1.8±0.2 升）、渗透压（Δ1.5±2.7、2.2±2.4、2.0±1.5 毫摩尔/升）、峰值 PSI（7.5±0.4、7.0±0.6、7.9±0.5）和峰值 T（38.7±0.1、38.6±0.2、38.8±0.2°C）方面，W、E 和 E+C 之间没有显著差异。W 和 E 中的 GLU 显著下降，而 E+C 在 60、90 和 120 分钟时 GLU 高于 BL（P<0.05）。与 BL 值（43.6±26 毫秒）相比，所有条件下的 SCWT 表现均显著下降（463±93、422±83、140±52 毫秒，P<0.05）。重要的是，与 W 和 E 相比，E+C 显著减轻了 SCWT 的损伤（P<0.05）。如预期的那样，与热应激方案（W、E、E+C）相比，N 导致体重损失、液体消耗和峰值 PSI 降低（分别为 1.1±0.1 公斤、1.2±0.7 升和 4.8），并改善了 SCWT 表现。
这些数据首次表明，在健康人群中，长时间高热运动后，认知处理会立即显著下降，而与补充剂种类无关。与水和仅补充电解质的液体相比，补充碳水化合物的液体可显著减轻认知功能下降。
