Abstract
The extent and duration of changes on lymphocyte function and serum immunoglobulin (Ig) levels were examined in 12 women who walked 45 min at 60% V̇O2 max in a laboratory setting. A 2-factor, 2×6 design with repeated measures on both factors was utilized. The first factor was condition (exercise and rest), and the second factor was time (six times of measurement over a 24-h period), with treatment order counterbalanced. The 45-min walk, in comparison to rest in a seated position, was not associated with significant changes in circulating numbers of interleukin-2-activated T cells (CD5 and CD25) or on spontaneous or concanavalin-A-stimulated lymphocyte proliferation. A trend for decreased phytohemagglutinin-stimulated lymphocyte proliferation in comparison to the rest condition, however, was seen 1.5 h following the exercise bout (p = 0.047). The patterns of change for serum IgG, IgA, and IgM were significantly different (p = 0.001, p < 0.001, p = 0.010, respectively) between conditions. IgG rose 7.2% immediately following exercise, and then returned to baseline 1.5 h later, which contrasted signficantly with changes in the rest condition. These same patterns of change occurred also with IgA and IgM, but increases immediately following exercise were not significant, although a trend was seen for IgA (p = 0.03). The 45-min walk had no effect on plasma Cortisol and epinephrine levels relative to the rest condition, but was associated with a significant 89% increase in norepinephrine. These data suggest that moderate exercise leads to a transient increase in serum immunoglobulin levels by way of contribution from extravascular pools and/or nonspecific stimulation of memory B cells. Antigen-dependent mechanisms do not appear to play a major role.
Key words
Walking - immune system - lymphocytes - lymphocyte function - catecholamines - cortisol
