title: Modulation of immune responses by treadmill exercise in Sprague-Dawley rats.
abstract: OBJECTIVE
  The duration-dependence of the effect of forced treadmill exercise on the immune system is a subject of ongoing research. In this study, the effect of forced treadmill exercise on immune responses was investigated by evaluating the lymphocyte subset fractions in the peripheral blood and spleen of Sprague-Dawley rats.
  
  
  METHODS
  
  
  
  METHODS
  Comparative investigation over 8 weeks.
  
  
  METHODS
  Experimental animal laboratory.
  
  
  METHODS
  Male Sprague-Dawley rats 5 weeks of age, weighing 150+/-10 g.
  
  
  METHODS
  Animals were randomly assigned to one of the 4 following groups: the control group, the 1-week-exercise group, the 4-week-exercise group, and the 8-week-exercise group.
  
  
  METHODS
  Lymphocyte subset fractions, including those for T, B, CD4+, and CD8+ cells and the T/B and CD4+/CD8+ ratios in the peripheral blood and spleen were measured via flow cytometric analysis after treadmill exercise.
  
  
  RESULTS
  The T cell and CD4+ cell fractions in both the peripheral blood and spleen were increased significantly after 8 weeks of treadmill exercise, but the B cell and CD8+ cell fractions did not change significantly.
  
  
  CONCLUSIONS
  From the results of the present study, it is suggested that a period of one week is insufficient to eliminate the effects of exercise-induced stress, that 4 weeks are needed to return to the control state, and that at least 8 weeks are needed in order for exercise of moderate intensity to have a positive effect on the immune system.
authors.affiliation: Research Institute of Sports Science, Korea University, Seoul, Korea.
authors.forename: H
authors.initials: H
authors.lastname: Kim
authors.forename: M-S
authors.initials: MS
authors.lastname: Shin
authors.forename: S-S
authors.initials: SS
authors.lastname: Kim
authors.forename: B-V
authors.initials: BV
authors.lastname: Lim
authors.forename: H B
authors.initials: HB
authors.lastname: Kim
authors.forename: Y-P
authors.initials: YP
authors.lastname: Kim
authors.forename: J-H
authors.initials: JH
authors.lastname: Chung
authors.forename: E-H
authors.initials: EH
authors.lastname: Kim
authors.forename: C-J
authors.initials: CJ
authors.lastname: Kim
mesh_terms: D000222:Adaptation, Physiological / Q000276:immunology; D000818:Animals; D005080:Exercise Test; D005434:Flow Cytometry; D018655:Lymphocyte Count; D008297:Male; D010805:Physical Conditioning, Animal / Q000379:methods*; D010807:Physical Endurance / Q000276:immunology*; D051381:Rats; D013154:Spleen / Q000276:immunology; D013995:Time