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Heat Stress Degrades Hiking Performance

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This study investigated the effect of environmental heat stress on physiological and performance measures during a ~4 mi time trial (TT) mountain hike in the Phoenix metropolitan area. Participants (n = 12; 7M/5F; age 21.6 ± 2.47 [SD]) climbed ‘A’ mountain (~1 mi) four times on a hot day (HOT;…

This study investigated the effect of environmental heat stress on physiological and performance measures during a ~4 mi time trial (TT) mountain hike in the Phoenix metropolitan area. Participants (n = 12; 7M/5F; age 21.6 ± 2.47 [SD]) climbed ‘A’ mountain (~1 mi) four times on a hot day (HOT; wet bulb globe temperature [WBGT] = 31.6°C) and again on a moderate day (MOD; WBGT = 19.0°C). Physiological and performance measures were made before and throughout the course of each hike. Mean pre-hike hydration status (urine specific gravity [USG]) indicated that participants began both HOT and MOD trials in a euhydrated state (1.016 ± 0.010 and 1.010 ± 0.008, respectively) and means did not differ significantly between trials (p = .085). Time trial performance was impaired by -11% (11.1 minutes) in the HOT trial (105 ± 21.7 min), compared to MOD (93.9 ± 13.1 min) (p = .013). Peak core temperatures were significantly higher in HOT (38.5 ± 0.36°C) versus MOD (38.0 ± 0.30°C) with progressively increasing differences between trials over time (p < .001). Peak ratings of perceived exertion were significantly higher in HOT (14.2 ± 2.38) compared to MOD (11.9 ± 2.02) (p = .007). Relative intensity (percent of age-predicted maximal heart rate [HR]), estimated absolute intensity (metabolic equivalents [METs]), and estimated energy expenditure (MET-h) were all increased in HOT, but not significantly so. The HOT condition reduced predicted maximal aerobic capacity (CRFp) by 6% (p = .026). Sweat rates differed significantly between HOT (1.38 ± 0.53 L/h) and MOD (0.84 ± 0.27 L/h) (p = .01). Percent body mass loss (PBML) did not differ significantly between HOT (1.06 ± 0.95%) and MOD (0.98 ± 0.84%) (p = .869). All repeated measures variables showed significant between-subjects effects (p < .05), indicating individual differences in response to test conditions. Heat stress was shown to negatively affect physiological and performance measures in recreational mountain hikers. However, considerable variation exists between individuals, and the degree of physiological and performance impairment is probably due, in part, to differences in aerobic fitness and acclimatization status rather than pre- or during-performance hydration status.
ContributorsLinsell, Joshua (Author) / Wardenaar, Floris (Thesis advisor) / Berger, Christopher (Committee member) / Forzani, Erica (Committee member) / Hondula, David M. (Committee member) / Arizona State University (Publisher)
Created2019
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Female Collegiate Gymnast's Nutritional Knowledge and Health

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Forty collegiate gymnasts were recruited for a nutrition and health study. Participants must have been at least eighteen years old at Arizona State University (ASU) in the club or team gymnastics program. The Institutional Review Board (IRB) reviewed and accepted my survey in order to hand out to the gymnasts.…

Forty collegiate gymnasts were recruited for a nutrition and health study. Participants must have been at least eighteen years old at Arizona State University (ASU) in the club or team gymnastics program. The Institutional Review Board (IRB) reviewed and accepted my survey in order to hand out to the gymnasts. The ASU club and team coach and the ASU study team also approved my survey. As soon as the survey was approved, it was emailed to all of the gymnasts. ASU gymnasts were surveyed on nutritional knowledge and personal health. Subjects answered a quiz on nutrient needs and serving sizes. Personal questions consisted of height, weight, injuries, body image, and typical meal plans. Gymnasts were given a $10 compensation to increase the participation. We found that only 16% of gymnasts surveyed scored a 70% or higher on their nutritional knowledge. Although these gymnasts do not have adequate knowledge, the majority consume a healthy diet. Diets included fruits, vegetables, protein-rich foods, and few high fat and sugary foods. Four of the gymnasts had one or fewer injuries in the past two years, although, four gymnasts also had three or more injuries. No correlation was found between diet and injuries. There was also no correlation between the gymnast's nutritional knowledge and their health.
ContributorsKugler, Natalie K. (Author) / Levinson, Simin (Thesis director) / Berger, Christopher (Committee member) / School of Nutrition and Health Promotion (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12