Influence of Temperature and Performance Level on Pacing a 161 km Trail Ultramarathon

ArticleinInternational journal of sports physiology and performance 6(2):243-51 · June 2011with16 Reads
DOI: 10.1123/ijspp.6.2.243 · Source: PubMed
Even pacing has been recommended for optimal performances in running distances up to 100 km. Trail ultramarathons traverse varied terrain, which does not allow for even pacing. This study examined differences in how runners of various abilities paced their efforts in the Western States Endurance Run (WSER), a 161 km trail ultramarathon in North America, under hot vs cooler temperatures. Temperatures in 2006 (hot) and 2007 (cooler) ranged from 7-38°C and 2-30°C, respectively. Arrival times at 13 checkpoints were recorded for 50 runners who finished the race in both years. After stratification into three groups based on finish time in 2007 (<22, 22-24, 24-30 h), paired t tests were used to compare the difference in pace across checkpoints between the years within each group. The χ2 test was used to compare differences between the groups on the number of segments run slower in the hot vs cooler years. For all groups, mean pace across the entire 161 km race was slower in 2006 than in 2007 (9:23 ± 1:13 min/km vs 8:42 ± 1:15 min/km, P < .001) and the pace was slower from the start of the race when temperatures were still relatively cool. Overall, the <22 h cohort ran slower in 2006 than 2007 over 12 of the 14 segments examined, the 22-24 h cohort was slower across 10 of the segments, and the >24 h cohort was slower across only 6 of the segments χ(2)2 = 6.00, P = .050). Comparable pacing between the 2 y corresponded with onset of nighttime and cooling temperatures. Extreme heat impairs all runners' ability to perform in 161 km ultramarathons, but faster runners are at a greater disadvantage compared with slower competitors because they complete a greater proportion of the race in the hotter conditions.
    • "The run then follows trails used by the gold and silver miners of the 1850s, with 5500 m of cumulative climb and 7000 m of cumulative descent before reaching the finish in Auburn 161.3 km from the start. Ambient temperatures peak for most runners during the middle half of the race, and much of the last 40–50 km is completed in darkness and cooler temperatures by most race participants (Parise & Hoffman, 2011). During the 2014 WSER, nearby weather station ambient temperatures ranged from a low of 0°C just after the start to a high of 31.7°C in the afternoon, which was near the historical median high temperature for this event. "
    [Show abstract] [Hide abstract] ABSTRACT: This work examines whether nausea or vomiting during an ultramarathon are due to a fluid or electrolyte imbalance, and if these symptoms can be reduced through the use of buffered sodium supplements. Starters (n = 376) of a 161.3-km ultramarathon underwent body weight measurements, 74.5% completed a post-race questionnaire, and 53.0% also underwent a post-race blood draw. The incidence of nausea or vomiting progressively increased during the race, and affected 60% of runners overall. Weight change and rate of sodium intake in supplements or in buffered sodium supplements did not differ between those with and without nausea or vomiting. Post-race serum sodium concentration also did not differ between those with and without symptoms in the last race segment. We conclude that weight change, the rate of sodium intake in supplements or in buffered sodium supplements, and serum sodium concentration are not related to symptoms of nausea or vomiting during a 161-km ultramarathon.
    Article · Mar 2016
    • "The course has 5500 m of cumulative climb and 7000 m of cumulative descent. Other details of the race have been provided previously [4,141516 . Nearby weather station ambient temperatures during the race ranged from a low 0 °C shortly after the start to a high 31.7 °C in the afternoon, which was close to the historical median high temperature for this event. "
    [Show abstract] [Hide abstract] ABSTRACT: Background: Ultramarathon runners commonly believe that sodium replacement is important for prevention of muscle cramping, dehydration, hyponatremia, and nausea during prolonged continuous exercise. The purpose of this study was to measure total sodium intake to determine if these beliefs are supported. Methods: Participants of a 161-km ultramarathon (air temperature reaching 39 °C) provided full dietary information during the race, underwent body weight measurements before and after the race, completed a post-race questionnaire about muscle cramping and nausea or vomiting during the race, and had post-race plasma sodium concentration measured. Results: Among 20 finishers providing dietary data, mean (±SD) total sodium intake was 13,651 ± 8444 mg (range 2541-38,338 mg), and sodium in food and drink accounted for 66 % of the sodium when averaged across subjects (range 34-100 %). Sodium intake rates were similar when comparing the 10 % of subjects who were hyponatremic with those who were not hyponatremic, the 39 % with muscle cramping or near cramping with those without cramping, and the 57 % who reported having symptoms of nausea or vomiting with those without these symptoms. Weight change between race start and finish was significantly related to rate of sodium intake (r = 0.49, p = 0.030) and total sodium intake (r = 0.53, p = 0.016), but the maximum weight loss among those taking the least total sodium (<4400 mg total sodium during the race) was 4-5 % below the weight measured immediately pre-race. Conclusions: Exercise-associated muscle cramping, dehydration, hyponatremia, and nausea or vomiting during exercise up to 30 h in hot environments are unrelated to total sodium intake, despite a common belief among ultramarathon runners that sodium is important for the prevention of these problems.
    Full-text · Article · Dec 2015
    • "Some of these races are taking place under extreme conditions such as extraordinary heat such as the 'Marathon des Sables' held in the desert of Morocco [8]. A problem of races held in the heat is the fact that performance will be im- paired [9,10], thus, heat acclimation is recommended to help preventing exertional heat illnesses and optimizing performance [11]. "
    [Show abstract] [Hide abstract] ABSTRACT: An ultra-marathon can be defined as any running performance lasting for longer than six hours and/or longer than the classical marathon distance of 42.195 km. An ultra-marathon can be held as a single stage race in distance- and time-limited races and as a multi-stage race. The longest ultra-marathons cover several thousands of kilometres and can endure for up to two months. Ultra-marathoners are generally married and well-educated men at the age of ~45 years. Female ultra-marathoners account for ~20%. Ultra-marathoners differ from marathoners regarding anthropometry and training. Ultra-marathoners complete more running kilometres in training than marathoners do, but they run more slowly during training than marathoners. Previous experience is the most important predictor variable for a successful ultra-marathon performance apart from specific anthropometric characteristics (i.e. low body mass index and low body fat) and training characteristics (i.e. high volume and speed during running training). Women compete slower than men in ultra-marathon running; however, they were able to reduce the sex gap in recent years. The fastest ultra-marathon race times are generally achieved at 35-45 years for both women and men.
    Article · Nov 2015 · Sports Medicine - Open
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