Department of Sport and Exercise Sciences, University of Chichester, College Lane, Chichester, West Sussex, PO19 6PE, UK.
Eur J Appl Physiol. 2011 Aug;111(8):1901-8. doi: 10.1007/s00421-010-1822-y. Epub 2011 Jan 14.
Effects of a carbohydrate beverage on the physiological responses to load carriage were examined. Ten fit male participants (age: 28 ± 9 years, body mass: 81.5 ± 10.5 kg, VO(2max): 55.0 ± 5.5 mL kg(-1) min(-1)) completed two test conditions in random order, walking on a treadmill (6.5 km h(-1)) for 120 min, carrying a 25-kg backpack. At 0 and 60 min of exercise participants consumed 250 mL of a placebo (flavoured water) (PLA) or 6.4% carbohydrate (CHO) beverage. There were no differences in VO(2,) respiratory exchange ratio (RER), heart rate or EMG activity of m. rectus femoris, m. vastus lateralis, m. semitendinosus and m. biceps femoris between conditions at minute 5 of exercise. The increase in VO(2) between minutes 5 and 120 was less during CHO than PLA (8 ± 5 vs. 14 ± 6%, P = 0.036). RER decreased during PLA, from 0.96 ± 0.05 at minute 5 to 0.87 ± 0.04 at minute 120 (P < 0.001), but not during CHO (P = 0.056). Heart rate increased between minutes 5 and 120 during PLA (16 ± 10%, P < 0.001) and CHO (12 ± 6%, P < 0.001), with no difference between conditions (P = 0.251). EMG peak RMS did not change between minutes 7 and 107 during PLA or CHO for the leg muscles. However, individual responses in EMG were highly variable (i.e. both increases and decreases in RMS). It was concluded that carbohydrate intake during load carriage reduced the VO(2) drift, which could be partially attributed to higher carbohydrate oxidation rates. Despite muscle fatigue/damage previously being identified as a cause of VO(2) drift, it appears that carbohydrate had no effect on neuromuscular responses during load carriage.
研究了碳水化合物饮料对负重行走生理反应的影响。10 名健康男性参与者（年龄：28±9 岁，体重：81.5±10.5kg，最大摄氧量：55.0±5.5mlkg^(-1)min^(-1)）以随机顺序完成两种测试条件，在跑步机上行走（6.5kmh^(-1)）120 分钟，携带 25kg 背包。在运动的 0 分钟和 60 分钟时，参与者分别饮用 250ml 安慰剂（风味水）（PLA）或 6.4%碳水化合物（CHO）饮料。在运动第 5 分钟时，各条件下的 VO(2)、呼吸交换比（RER）、心率或股直肌、股外侧肌、半腱肌和股二头肌的肌电图活动均无差异。与 PLA 相比，CHO 时 VO(2)在 5 分钟至 120 分钟之间的增加幅度较小（8±5%比 14±6%，P=0.036）。RER 在 PLA 期间下降，从第 5 分钟的 0.96±0.05 降至第 120 分钟的 0.87±0.04（P<0.001），但 CHO 期间无变化（P=0.056）。PLA 和 CHO 期间，心率在第 5 分钟至 120 分钟之间增加（PLA 时为 16±10%，P<0.001；CHO 时为 12±6%，P<0.001），两种条件下无差异（P=0.251）。PLA 或 CHO 期间，股四头肌和股二头肌的 EMG 峰值 RMS 从第 7 分钟到 107 分钟之间没有变化。然而，EMG 的个体反应变化很大（即 RMS 既增加又减少）。结论是，负重行走时摄入碳水化合物可减少 VO(2)漂移，这可能部分归因于较高的碳水化合物氧化率。尽管肌肉疲劳/损伤以前被认为是 VO(2)漂移的原因，但碳水化合物似乎对负重行走时的神经肌肉反应没有影响。
