Department of Physiology, School of Medical Sciences, University of KwaZulu-Natal, Private Bag 7, Congella 4013, South Africa.
Br J Sports Med. 2010 May;44(6):430-6. doi: 10.1136/bjsm.2008.049551. Epub 2008 Jun 6.
In this study, the hydration status of amateur cyclists who voluntarily adjusted their fluid intake to environmental conditions during a 3-day, 248-km mountain bike (MTB) race was assessed.
Prospective observational field study.
Sani2C MTB Race, KwaZulu-Natal, South Africa, 2006.
18 randomly selected amateur, male MTB cyclists.
Reported usual fluid intake, environmental conditions, voluntary fluid intake, urine voided, changes in body mass, serum osmolality (SO), sodium concentration [Na(+)] and urinary specific gravity (Usg) during each stage (S).
Dry bulb temperature (adjusted for windchill) ranged from 6 degrees to 21.4 degrees C during S1, S2 and S3. While 77.8% (n = 14) of subjects reported a usual intake of >750 ml h(-1) in previous MTB events, mean (SE) fluid intake in this race ranged from 341 (32) ml h(-1) during S1 to 551 (56) ml h(-1) during S3. Changes in mean body mass ranged between -0.99% and -2.02% during the three stages. Mean SO and serum [Na(+)] ranged between 292 (0.73) mOsm kg(-1) and 298 mOsm kg(-1) and 137 (0.35) mEq and 140 (0.42) mEq, respectively, during the 3-day period, while Usg remained <or=1.025.
Ad libitum fluid intake during the 2006 Sani2C MTB Race, which took place in unexpectedly cold environmental conditions, was substantially lower than the usual reported fluid intake of subjects. Changes in body mass, SO, serum [Na(+)] and Usg were not clinically significant, indicating that an adequate hydration status was maintained during the multiday MTB cycle race.
本研究评估了 18 名业余男性山地自行车运动员在参加 3 天 248 公里山地自行车（MTB）比赛期间，根据环境条件自愿调整液体摄入量的水合状态。
前瞻性观察性现场研究。
2006 年南非夸祖鲁-纳塔尔省的 Sani2C MTB 比赛。
18 名随机选择的业余男性 MTB 自行车运动员。
报告的通常液体摄入量、环境条件、自愿液体摄入量、排尿量、每个阶段（S）的体重变化、血清渗透压（SO）、钠浓度[Na(+)]和尿比重（Usg）。
干球温度（风寒调整后）在 S1、S2 和 S3 期间范围为 6 摄氏度至 21.4 摄氏度。虽然 77.8%（n=14）的受试者在之前的 MTB 比赛中报告了 >750ml h(-1)的通常摄入量，但在本次比赛中，平均（SE）液体摄入量在 S1 期间为 341（32）ml h(-1)，在 S3 期间为 551（56）ml h(-1)。三个阶段的平均体重变化范围在-0.99%至-2.02%之间。3 天期间，SO 和血清[Na(+)]的平均值分别在 292（0.73）mOsm kg(-1)和 298 mOsm kg(-1)以及 137（0.35）mEq 和 140（0.42）mEq 之间，而 Usg 保持在<或=1.025。
在环境条件出乎意料地寒冷的 2006 年 Sani2C MTB 比赛中，随意液体摄入量明显低于受试者报告的通常液体摄入量。体重、SO、血清[Na(+)]和 Usg 的变化没有临床意义，表明在多日 MTB 自行车比赛中保持了适当的水合状态。
