Immune responses to training: how critical is training volume?

Area of Science:

• Exercise immunology
• Sports science
• Human physiology

Background:

• High-volume exercise can induce negative energy balance, potentially negating immune benefits.
• Understanding the impact of training volume on immune function is crucial for optimizing health outcomes.

Purpose of the Study:

• To investigate the effects of different training volumes on immune cell profiles in sedentary males.
• To determine the optimal exercise regimen for enhancing immune function without adverse effects.

Main Methods:

• 33 healthy sedentary males (19-29 years) underwent 12 weeks of light or moderate aerobic training, or served as controls.
• Immune cell subsets (leukocytes, CD3+, CD4+, CD8+, CD16+, CD19+, CD25+), cytolytic activity, and cell proliferation were measured.
• Peak oxygen intake and exercise challenge responses were assessed before and after the intervention.

Main Results:

• Moderate training increased aerobic power and reduced body fat, while light training showed less physiological change.
• Both training groups exhibited increased CD16+ and CD16+CD56+ natural killer cell counts and reduced post-exercise suppression.
• Light training decreased CD3+ and CD4+ T-cell counts, while moderate training reduced B cell (CD19+) counts.

Conclusions:

• Low-volume training appears optimal for enhancing specific immune cell populations, particularly cytotoxic cells.
• Moderate training, sufficient to cause negative energy balance, resulted in diminished B cell counts.
• Exercise regimens should be carefully considered to maximize immune benefits and avoid potential negative consequences on immune cell subsets.