Eb. Zelazowska et al., LYMPHOCYTE SUBPOPULATION EXPRESSION IN WOMEN - EFFECT OF EXERCISE ANDCIRCADIAN-RHYTHM, Medicine and science in sports and exercise, 29(4), 1997, pp. 467-473
It is well established that exercise affects immune responses in men,
but little information is available for women. whether exercise-induce
d immune responses are affected by circadian rhythm has not been deter
mined. This study examined lymphocyte responses of women to exercise i
n the morning (AM) and evening (PM). Lymphocytes expressing markers fo
r T, B, and natural killer (NK) cells were identified by FACScan in bl
ood samples collected before (baseline), immediately after, and 40 min
after exercise (recovery). Absolute counts of all lymphocyte subpopul
ations increased immediately after exercise, bur at recovery values we
re below baseline counts. Circadian variations were noted in absolute
counts for total T, helper/inducer T cells, and B cells. Although thes
e counts were significantly higher in the PM, the magnitude of the imm
une response to exercise was the same in the AM and PM. In contrast, n
atural killer cells, both the relative counts and the magnitude of imm
une response were higher in the AM. Thus, it appears that despite diff
erences in baseline cell counts the overall exercise-induced response
in most lymphocyte subpopulations is similar in the AM and PM.