Document Detail

Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency.
MedLine Citation:
PMID:  23222192     Owner:  NLM     Status:  Publisher    
OBJECTIVE: Many clinicians believe that exercise-associated muscle cramps (EAMC) occur because of dehydration. Experimental research supporting this theory is lacking. Mild hypohydration (3% body mass loss) does not alter threshold frequency (TF), a measure of cramp susceptibility, when fatigue and exercise intensity are controlled. No experimental research has examined TF following significant (3-5% body mass loss) or serious hypohydration (>5% body mass loss). Determine if significant or serious hypohydration, with moderate electrolyte losses, decreases TF. DESIGN: A prepost experimental design was used. Dominant limb flexor hallucis brevis cramp TF, cramp electromyography (EMG) amplitude and cramp intensity were measured in 10 euhydrated, unacclimated men (age=24±4 years, height=184.2±4.8 cm, mass=84.8±11.4 kg). Subjects alternated exercising with their non-dominant limb or upper body on a cycle ergometer every 15 min at a moderate intensity until 5% body mass loss or volitional exhaustion (3.8±0.8 h; 39.1±1.5°C; humidity 18.4±3%). Cramp variables were reassessed posthypohydration. RESULTS: Subjects were well hydrated at the study's onset (urine specific gravity=1.005±0.002). They lost 4.7±0.5% of their body mass (3.9±0.5 litres of fluid), 4.0±1.5 g of Na(+) and 0.6±0.1 g K(+) via exercise-induced sweating. Significant (n=5) or serious hypohydration (n=5) did not alter cramp TF (euhydrated=15±5 Hz, hypohydrated=13±6 Hz; F(1,9)=3.0, p=0.12), cramp intensity (euhydrated= 94.2±41%, hypohydrated=115.9±73%; F(1,9)=1.9, p=0.2) or cramp EMG amplitude (euhydrated=0.18±0.06 µV, hypohydrated= 0.18±0.09 µV; F(1,9)=0.1, p=0.79). CONCLUSIONS: Significant and serious hypohydration with moderate electrolyte losses does not alter cramp susceptibility when fatigue and exercise intensity are controlled. Neuromuscular control may be more important in the onset of muscle cramps than dehydration or electrolyte losses.
Kyle W Braulick; Kevin C Miller; Jay M Albrecht; Jared M Tucker; James E Deal
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-6
Journal Detail:
Title:  British journal of sports medicine     Volume:  -     ISSN:  1473-0480     ISO Abbreviation:  Br J Sports Med     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-10     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:  -    
Departments of Health, Nutrition, and Exercise Sciences, North Dakota State University, Fargo, North Dakota, USA.
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