Document Detail

Examining the influence of hydration status on physiological responses and running speed during trail running in the heat with controlled exercise intensity.
MedLine Citation:
PMID:  22024610     Owner:  NLM     Status:  In-Data-Review    
Lopez, RM, Casa, DJ, Jensen, KA, DeMartini, JK, Pagnotta, KD, Ruiz, RC, Roti, MW, Stearns, RL, Armstrong, LE, and Maresh, CM. Examining the influence of hydration status on physiological responses and running speed during trail running in the heat with controlled exercise intensity. J Strength Cond Res 25(11): 2944-2954, 2011-The purpose of this study was to determine the effects of dehydration at a controlled relative intensity on physiological responses and trail running speed. Using a randomized, controlled crossover design in a field setting, 14 male and female competitive, endurance runners aged 30 ± 10.4 years completed 2 (hydrated [HY] and dehydrated [DHY]) submaximal trail runs in a warm environment. For each trial, the subjects ran 3 laps (4 km per lap) on trails with 4-minute rests between laps. The DHY were fluid restricted 22 hours before the trial and during the run. The HY arrived euhydrated and were given water during rest breaks. The subjects ran at a moderate pace matched between trials by providing pacing feedback via heart rate (HR) throughout the second trial. Gastrointestinal temperature (TGI), HR, running time, and ratings of perceived exertion (RPE) were monitored. Percent body mass (BM) losses were significantly greater for DHY pretrial (-1.65 ± 1.34%) than for HY (-0.03 ± 1.28%; p < 0.001). Posttrial, DHY BM losses (-3.64 ± 1.33%) were higher than those for HY (-1.38 ± 1.43%; p < 0.001). A significant main effect of TGI (p = 0.009) was found with DHY having higher TGI postrun (DHY: 39.09 ± 0.45°C, HY: 38.71 ± 0.45°C; p = 0.030), 10 minutes post (DHY: 38.85 ± 0.48°C, HY: 38.46 ± 0.46°C; p = 0.009) and 30 minutes post (DHY: 38.18 ± 0.41°C, HY: 37.60 ± 0.25°C; p = 0.000). The DHY had slower run times after lap 2 (p = 0.019) and lap 3 (p = 0.025). The DHY subjects completed the 12-km run 99 seconds slower than the HY (p = 0.027) subjects did. The RPE in DHY was slightly higher than that in HY immediately postrun (p = 0.055). Controlling relative intensity in hypohydrated runners resulted in slower run times, greater perceived effort, and elevated TGI, which is clinically meaningful for athletes using HR as a gauge for exercise effort and performance.
Rebecca M Lopez; Douglas J Casa; Katherine A Jensen; Julie K Demartini; Kelly D Pagnotta; Roberto C Ruiz; Melissa W Roti; Rebecca L Stearns; Lawrence E Armstrong; Carl M Maresh
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of strength and conditioning research / National Strength & Conditioning Association     Volume:  25     ISSN:  1533-4287     ISO Abbreviation:  J Strength Cond Res     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-10-25     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9415084     Medline TA:  J Strength Cond Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2944-54     Citation Subset:  IM    
1Department of Orthopaedics and Sports Medicine, University of South Florida, Tampa, Florida; 2Korey Stringer Institute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut; and 3Movement Science Sport and Leisure Studies, Westfield State University, Westfield, Massachusetts.
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