NATURAL KILLER CELL ACTIVITY IN PRE-AND POST-MENOPAUSAL WOMEN CONSEQUENT TO INTENSE RESISTANCE EXERCISE

Abstract

The purpose of this study was to compare the influence of high-intensity resistance exercise (RE) on natural killer cell activity (NKCA) in pre-and post-menopausal women. Ten women (age 24 ± 3 yr) (YNG) completed two experimental trials (one exercise trial - EX, one resting trial - REST). In a separate experiment 35 women (age 72 ± 6.2 yr) were assigned to one of 3 groups: no estrogen replacement (NHR), estrogen replacement (HRT), or control (no estrogen replacement, CON). NHR and HRT groups performed an exercise trial. The CON did not exercise, but sat quietly in the lab (REST). Subjects were acclimated to RE prior to the first trial. YNG-EX, HRT, and NHR performed 3 sets of 10 resistance exercises at 80% of their 1 repetition maximum (1RM) (EX). Blood samples were collected pre-exercise (PR), immediately post-exercise (PO), and two hours (2H) post-exercise, or at the same time points during the REST trial. Phenotypic differentiation was based on cell surface antigens via immunofluorescence flow cytometry: Th - CD3+/CD4+; Tc - CD3+/CD8+, monocytes - CD14+/CD45+; NK cells - CD3−/CD16+/CD56+. NKCA was determined via a whole blood chromium (51 Cr) release method.TableSignificant group and time effects were observed for NKCA when YNG (EX) was compared to NHR, HRT, and CON, such that NKCA was greater for YNG than the other groups (p ≤ 0.05), and PO and 2H were greater than PR (p ≤ 0.01). RE appears to influence NKCA, leukocyte number, and proportion of circulating NK cells in both young and elderly women. The increase in NKCA across time observed during both the YNG and CON REST trails may have obfuscated the exercise effect and prevented the post-exercise reduction in NKCA observed in young males.