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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
Shore S., Shinkai S., Rhind S., Shephard R. J.
Graduate Programme in Exercise Sciences and Faculty of Physical Education & Health, University of Toronto, Canada; Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada; Health Studies Programme, Brock University, St. Catharines, Ontario, Canada;
School of Public Health, Ehime University, Japan
Background. If the volume of training undertaken is sufficient to induce a negative energy balance, the anticipated benefit of an enhanced immune response may be reduced or lost.
Methods. 33 sedentary but healthy male volunteers aged 19-29 years, recruited from the university community. A peak oxygen intake measurement (cycle ergometer) and a 60-min exercise challenge at 60% of aerobic power were performed before and after 12 wk of treatment. Total leukocytes, subsets, CD3+, CD4+, CD8+, CD16+, CD19+, and CD25+ counts (FACScan), cytolytic activity (51Cr release) and cell proliferation (PHA and PWM) were measured, with subjects assigned arbitrarily to one of three groups: light training (18 subjects, aerobic exercise at 70-85% HRmax 3 times/wk), moderate training (9 subjects, similar programme 4-5 times/wk) and control (6 subjects).
Results. Groups were initially well-matched in physical and physiological terms. Training increased aerobic power (8%, light, 21% moderate training), with a loss of body mass and fat in the moderate training group. Controls showed no changes. Resting CD16+ counts increased by 27% (light training) and CD16+ CD56+ counts by 21% (moderate training), with less post-exercise suppression of counts than at recruitment. Light training also decreased CD3+ and CD4+ counts without changing the CD4+/CD8+ ratio. Moderate training decreased resting CD19+ count.
Conclusions. From the viewpoint of immune function, the optimal training regimen is of low volume. Moderate training sufficient to induce a negative energy balance yields a smaller increase in numbers of non-MHC-restricted cytotoxic cells, and carries the negative consequence of diminished B cell counts.