Document Detail

Neuromuscular responses to hydration in moderate to warm ambient conditions during self-paced high-intensity exercise.
MedLine Citation:
PMID:  19329441     Owner:  NLM     Status:  Publisher    
Objective To examine the neuromuscular responses to 60 minutes of self-paced high-intensity exercise punctuated with 6 x 1-minute "all-out" sprints at 10-minute intervals in moderate (19.8 degrees C, SEM 0.3) and warm (33.2, SEM 0.1), humid ( approximately 64% relative humidity) conditions with either complete hydration (CH) or without hydration (NF). Design Seven subjects (mean age 20.6 years (SE 1.1), mass 73.8 kg (SE 4.5), peak power 288 W (SE 11.3)) performed the time trial on four separate occasions, which were differentiated by ambient temperature and fluid ingestion. For each sprint interval, distance, power output and electromyographic (EMG) data from the rectus femoris and vastus lateralis muscles were recorded. Results The NF trials resulted in a reduction in body mass for the moderate and warm conditions of 1.7% and 2.1%, respectively. Final rectal temperatures were not different among conditions ( approximately 38.7 degrees C). Total body sweating was higher in the warm condition (19.1-21.3 ml/kg per hour) compared with the moderate condition (16.1-16.5 ml/kg per hour; p<0.05). Neither fluid ingestion nor ambient temperature altered total distance cycled for any of the trials (range 30.1-32.6 km). The normalised integrated EMG (as percentage of maximal voluntary contraction) when compared with the first sprint increased from sprint three for the rectus femoris muscle in both no and complete hydration but decreased for the vastus lateralis muscle. The mean percentile frequency shift increased for both the vastus lateralis and rectus femoris muscles in both no and complete hydration. Conclusions These results suggest that the integrity of the neuromuscular system is adjusted according to hydration status and ambient temperatures during intense self-paced cycling.
F E Marino; J Cannon; D Kay
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2010-4-22
Journal Detail:
Title:  British journal of sports medicine     Volume:  -     ISSN:  1473-0480     ISO Abbreviation:  -     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-4-23     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0432520     Medline TA:  Br J Sports Med     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Exercise and Sports Science Laboratories, School of Human Movement Studies, Charles Sturt University, Bathurst, NSW, Australia.
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