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Immune response to changes in training intensity and volume in runners
J S Kajiura1, J D MacDougall, P B Ernst
1Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.
High-intensity running transiently decreases CD4+ lymphocytes and the CD4/CD8 ratio in runners. Training intensity, not volume, appears to drive this reduction, with training order influencing responses.
Area of Science:
- Exercise immunology
- Sports science
- Human physiology
Background:
- Training volume and intensity significantly impact athlete physiology.
- Understanding immune responses to exercise is crucial for performance and health.
- Lymphocyte subsets and immunoglobulin levels are key indicators of immune function.
Purpose of the Study:
- To investigate the acute and chronic effects of varying training volume and intensity on blood lymphocyte percentages and immunoglobulin levels in runners.
- To determine if training order influences immune responses to high-intensity exercise.
Main Methods:
- Twelve runners underwent four 10-day training phases: low volume/low intensity (LV/LI), high volume/low intensity (HV/LI), and high volume/high intensity (HV/HI).
- Blood samples were collected at rest and post-exercise.
- Lymphocyte subsets (CD3+, CD4+, CD8+, HLA-DR+) were analyzed using flow cytometry.
- Immunoglobulin (IgG, IgM) levels were measured via ELISA.
Main Results:
- Immunoglobulin, CD8+, HLA-DR+ levels, and pre-exercise cortisol were unaffected by training alterations.
- A transient decrease in CD4+ cells and the CD4/CD8 ratio was observed post-exercise during HV/LI and HV/HI phases (P < 0.05).
- The magnitude of immune response appeared dependent on training intensity and the order of exposure to high-intensity stimuli.
Conclusions:
- Exercise-induced reductions in lymphocyte subsets are transient.
- Training intensity, rather than volume, is the primary driver of these transient immune changes.
- The sequence of training exposure may modulate the immune system's response to high-intensity exercise.
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