Glace Beth W, Murphy Christine A, McHugh Malachy P
Nicholas Institute of Sports Medicine and Athletic Trauma, New York, New York 10021, USA.
J Am Coll Nutr. 2002 Dec;21(6):553-9. doi: 10.1080/07315724.2002.10719254.
To relate changes in laboratory indices to dietary intake during extremely prolonged running and to determine if dietary intake influences the ability of runners to finish an 160 km trail race.
We monitored intake and serum chemistries of 26 runners competing in an 160 km foot race in temperatures which peaked at 38 degrees C. Blood was drawn pre-, mid- and post-race. Dietary intake and incidence of gastrointestinal distress or changes in mental status were determined by interview with runners approximately every 13 km. Twenty-three runners completed at least 88 kms and, of these 23 runners, 13 finished 160 km in a mean time of 26.2 +/- 3.6 hours.
Finishers ingested nearly 30,000 J, 19.4 +/- 8.1 L of fluid and 16.4 +/- 9.5 g of sodium (Na). Sodium and fluid intake per hour was estimated to be 0.6 g/hour and 0.7 L/hour, respectively. Electrolyte intake during the first half of the race was similar between those that finished the race and those that did not. Finishers ingested fluid at a greater rate than non-finishers (p = 0.01) and tended to meet their caloric needs more closely than did non-finishers (p = 0.09). Body weight was unchanged over time (ANOVA, p = 0.52). Serum Na concentration tended to fall from 143 to 140 mEq/L during the race (p = 0.06), and was inversely correlated with weight loss (p = 0.009). Serum Na concentration was lower mid-race in runners experiencing changes in mental status than in runners without changes (p = 0.04). Fluid intake was inversely correlated with serum Na concentrations (p = 0.04). Most of the runners experienced nausea or vomiting; these symptoms were not related to serum sodium concentration. Hyponatremia (<135 mEq/L) was seen in one runner at 88 kms, but resolved by 160 km. Urinary sodium excretion decreased (p = 0.002) as serum aldosterone concentration increased pre- to post-race (p < 0.001). From start to finish of the race plasma volume increased by 12%.
Food and fluid was ingested at a greater rate than described previously. Runners consumed adequate fluid to maintain body weight although dietary sodium fell far short of the recommended 1 g/hour. The rate of fluid intake was greater in finishers than in non-finishers, and finishers tended to more nearly meet their energy needs. Maintenance of body mass despite large exercise energy expenditures in extreme heat is consistent with fluid overload during a running event lasting more than 24 hours in hot and humid conditions.
研究在极长时间跑步过程中实验室指标变化与饮食摄入的关系，并确定饮食摄入是否会影响跑步者完成160公里越野赛的能力。
我们监测了26名参加160公里赛跑的跑步者的摄入量和血清化学指标，比赛期间温度最高达38摄氏度。在赛前、赛中和赛后采集血液。大约每13公里通过与跑步者访谈来确定饮食摄入量以及胃肠道不适的发生率或精神状态变化。23名跑步者至少完成了88公里，在这23名跑步者中，13人完成了160公里赛程，平均用时26.2±3.6小时。
完赛者摄入了近30000焦耳能量、19.4±8.1升液体和16.4±9.5克钠（Na）。每小时钠和液体摄入量估计分别为0.6克/小时和0.7升/小时。完赛者和未完赛者在比赛前半程的电解质摄入量相似。完赛者摄入液体的速度高于未完赛者（p = 0.01），并且比未完赛者更接近满足其热量需求（p = 0.09）。体重随时间无变化（方差分析，p = 0.52）。比赛期间血清钠浓度倾向于从143毫当量/升降至140毫当量/升（p = 0.06），并且与体重减轻呈负相关（p = 0.009）。精神状态有变化的跑步者在比赛中途的血清钠浓度低于无变化的跑步者（p = 0.04）。液体摄入量与血清钠浓度呈负相关（p = 0.04）。大多数跑步者经历过恶心或呕吐；这些症状与血清钠浓度无关。一名跑步者在88公里处出现低钠血症（<135毫当量/升），但在160公里时恢复。随着比赛前到赛后血清醛固酮浓度升高（p < 0.001），尿钠排泄减少（p = 0.002）。从比赛开始到结束，血浆量增加了12%。
食物和液体的摄入量比之前描述的要高。跑步者摄入了足够的液体以维持体重，尽管饮食中的钠摄入量远低于推荐的1克/小时。完赛者的液体摄入速度高于未完赛者，并且完赛者更接近满足其能量需求。在炎热潮湿条件下持续超过24小时的跑步赛事中，尽管运动能量消耗巨大，但体重得以维持，这与液体过载是一致的。
