Verde, T. J., Thomas, S. G., Moore, R. W., Shek, P., & Shephard, R. J. (1992). Immune responses and increased training of the elite athlete. Journal of Applied Physiology, 73, 1494-1499.

Elite male runners (N = 10) increased training schedules by an average of 38% for three weeks.

Resting heart rate and VO2max were unchanged but HR in acute exercise was decreased. Under normal training loads, phytohemaglutinin-stimulated lymphocyte proliferation was steady. After 3-wk of increased training, the same exercise bout caused an 18% suppression of proliferation.

The immune system of endurance trained athletes at rest seemed to tolerate the stress of increased training but superimposition of a bout of acute exercise on the chronic stress of heavy training resulted in immunosuppression, which was transient and most likely not of clinical significance.

Implication. Under tolerable training loads, suppression of immune response capabilities is not severe. When training levels are raised extensively, immune response suppression is heightened noticeably when a standard test intensity is experienced. When training is excessive, the likelihood of athletes becoming ill due to infections is increased.

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