Document Detail

Exercise in hot and cold environments: differential effects on leukocyte number and NK cell activity.
MedLine Citation:
PMID:  14692464     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: Exercise and environmental temperature have been reported to affect the immune system, but few studies have examined the combined effects of very hot or cold temperatures during exercise in the same group of subjects. Therefore, the purpose was to examine the immune responses following exercise combined with exposure to hot and cold environments. METHODS: There were 10 men who completed 2 60-min cycle ergometry (60% VO2peak) trials: hot (HT: 38 degrees C, 45% RH) and cold (CD: 8 degrees C, 50% RH). Rectal core temperatures (Tc), average skin temperatures (Tsk), and HR were recorded every 15 min of exercise. Venous blood was collected before (PRE), immediately after (POST), 2 h after (2 h), and 24 h after exercise (24 h). Physiologic strain index (PSI) was calculated. Total and differential leukocytes were determined by manual counting (adjusted for plasma volume shifts). Natural killer cell activity (NKCA) was determined by a whole blood 51Cr-release assay. RESULTS: Tsk, Tc, and PSI were significantly lower in the CD than HT trial (p < 0.05). Total leukocyte count was greater POST (40%) and 2 h (74%) than PRE and 24 h in both conditions (p < 0.05). Neutrophil count was greater POST (49%) and 2 h (132%) than PRE and 24 h in both conditions (p < 0.05). Lymphocyte count was greater POST (24%) in HT than CD (p < 0.05). NKCA was greater POST (38%) than PRE, 2 h, and 24 h in both conditions (p < 0.05). HT caused significant increases for Tc and Tsk above those observed for CD (p < 0.05). PSI was greater in HT (9.92 +/- 0.93) than CD (4.24 +/- 0.56) (p < 0.05). DISCUSSION: Exercise in HT produced more physiological stress than CD; however, this difference was not manifested in the immune system response. Heat and cold stress in combination with exercise produce similar disturbances in immunity during recovery from exercise.
Brian K McFarlin; Joel B Mitchell
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  74     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-12-24     Completed Date:  2004-03-16     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1231-6     Citation Subset:  IM; S    
Department of Kinesiology, Texas Christian University, Fort Worth, TX 76129, USA.
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MeSH Terms
Body Temperature
Body Temperature Regulation / physiology*
Cold Temperature*
Exercise / physiology*
Exercise Test
Hot Temperature*
Killer Cells, Natural / physiology*
Leukocyte Count

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