Immune status of physically active women during lactation

Purpose: The purpose of this study was to provide baseline data on immune status of exercising and sedentary exclusively lactating women. Dietary intake and body composition were also investigated to determine whether they related to immune function. Methods: Healthy, exclusively breastfeeding women with a body mass index between 20 and 30 kg(.)m(-2) were studied at 3 months postpartum. Participants in the exercise group (EG; N = 27) exercised aerobically at least 30 min(.)d(-1), 3 x wk(-1), and women in the sedentary group (SG; N = 23) exercised once a week or less during the previous 6 wk. Immune status while at test was determined by measuring: 1) a complete blood cell count and differential leukocyte count; 2) percentages and absolute counts of peripheral blood T cells (CD3 +), cytotoxic T cells (CD3+CD8+), helper T cells (CD3+CD4+), B cells (CD]9+), and natural killer cells (CD56+); 3) neutrophil bacterial killing and oxidative burst activity; and 4) in vitro mitogenic responsiveness of lymphocytes. Cardiorespiratory fitness, body composition, and dietary intake were also measured. Results: Participants in the EG had a significantly higher level of mean predicted cardiorespiratory fitness than women in the SG (39.5 +/- 1.1 vs 32.5 +/- 1.0 mL O-2.min(-1.)kg(-1); P < 0.05); however, there were no significant differences in body composition or dietary intake. There were no significant differences in any of the indicators of immune status between groups. In addition, there were no significant relationships between body composition or dietary intake and immune status. Conclusions: The results of this study suggest that women may exercise moderately during lactation and increase their fitness level without impairing their immune function.