Relationship Between Perceived Exercise Intensity And Natural Killer Cell Mobilization After Exercise

Abstract

The mobilization of lymphocyte subsets into and out of peripheral blood after dynamic exercise is well-characterized. While the magnitude of this effect has been shown to relate to objective measures of exercise intensity, the role of perceived intensity of the exercise bout is less understood. PURPOSE: Determine if the change in frequency of peripheral blood lymphocytes following acute dynamic exercise is associated with ratings of perceived exertion (RPE). METHODS: 18 physically active adults (8 women, aged 27.7 ± 4.4 years) cycled on a stationary bicycle 30 min at a power sufficient to elicit 80% of their age predicted maximum heart rate (HR). Heart rate and RPE (Borg 6-20 scale) was recorded each minute. Venous blood sampled pre- and post-exercise was analyzed by flow cytometry, and the relative change in lymphocyte subset frequency was calculated post-exercise relative to pre-exercise. The relationship between change in lymphocyte subset frequency with RPE in the final minute of exercise (RPE-end), or HR in final minute of exercise (HR-end), was assessed by linear regression. RESULTS: RPE-end significantly predicted the change in NK-cell frequency post-exercise, where RPE-end was higher in those displaying a greater mobilization (b = 40.41, SE = 17.28, p = .034, R2 = .267). Likewise, RPE-end predicted the increase in cytotoxic CD56dim NK-cells (b = 43.81, SE = 18.73, p = .034, R2 = .267). Analyzing subsets of CD56dim NK-cells differentiated by expression of inhibitory NKG2A and killer cell immunoglobulin-like receptor CD158b revealed RPE-end predicted the change in low- (b = 37.26, SE = 15.77, p = .032, R2 = .271), medium- (b = 43.03, SE = 18.41, p = .034, R2 = .267), and high-differentiated (b = 52.08, SE = 21.78, p = .030, R2 = .276) subsets. RPE-end did not significantly predict change in CD4 or CD8 T-cell subsets. HR-end did not significantly predict change in frequency of any lymphocyte subset. CONCLUSIONS: End of exercise RPE, but not HR, significantly predicted changes in the frequency of NK-cells in peripheral blood post-exercise. Although the current results are limited by the small sample, they suggest a role for the perception of exercise intensity in predicting immune responses to exercise.