The immune response to short-duration exercise in trained, eumenorrhoeic women

Few studies have characterised the immune response to exercise of different intensities and durations in women. In those that have, baseline hormone levels and training status were not always adequately controlled for. Here, leucocyte and cytokine profiles of 11 aerobically trained, eumenorrhoeic females (33 ± 5 years) in the early follicular phase of the menstrual cycle were characterised after 30-min exercise at 3 intensities: 90% lactate threshold (LT), LT, and 110% LT. Proposed cytokine response mediators were quantified: plasma lactate and basal oestradiol concentrations. Intensity-dependent increases occurred in total white blood cells and lymphocyte counts (P < 0.001). Elevated plasma IL-6 and IL-1ra concentrations post-exercise [F = 12.38, P < 0.01 and F = 7.65, P < 0.05, respectively] were not intensity-dependent, indicating that cytokine release may be better associated with exercise duration than intensity in trained women. Changes in plasma IL-1ra and basal oestradiol (ρ = -0.893, P < 0.01) were correlated at intensities above LT only. These findings suggest a role for plasma sex hormones in moderating the exercise-induced immune response in women. However, the associations observed did not account for the magnitude of the cytokine response observed, and future studies should explore contributions of other potential mediators following short-duration exercise.