Glucocorticoid Receptor Expression on Human B-Cells in Response to Acute Heavy Resistance Exercise

Abstract

PURPOSE: In an effort to further understand the physiological role of circulating cortisol during physical stress, we examined glucocorticoid receptor (GCR) expression on B-lymphocytes in response to an acute bout of heavy resistance exercise. METHODS: Using a within subject design, resistance trained women (mean ± SD (n = 7) age: 22.13 ± 3.09 y; height: 1.69 ± 0.084 m; body mass: 65.60 ± 10.01 kg; body mass index: 22.63 ± 2.03 kg/m2) and men (mean ± SD (n = 8) age: 23.28 ± 4.26 y; height: 1.73 ± 0.086 m; body mass: 73.93 ± 12.71 kg; body mass index: 24.51 ± 2.61 kg/m2) performed an acute resistance exercise protocol (6 sets of 5 RM heavy squats) and a control test (i.e., sitting quietly under identical conditions) in a balanced, randomized order. Blood samples were obtained immediately before (pre), at the mid-point (mid), and immediately after the test (post), and at 1, 6, and 24-hrs into recovery. Glucocorticoid (GCR) receptors on circulating B lymphocytes were evaluated with flow cytometry and circulating cortisol was assayed. RESULTS: Resting GCR expression on B lymphocytes was similar between resistance trained, healthy men and women. GCR expression was elevated in anticipation of the exercise protocol (p = 0.047), decreased during the exercise protocol (p = 0.049), and increased during recovery (p = 0.05 and p = 0.03 at 1- and 6- hrs into recovery, respectively). Statistical trends for gender differences were apparent at pre, mid, and 6-hr (p = 0.039, p = 0.063, and p = 0.053, respectively). Significant gender differences in circulating cortisol responses to the exercise protocol were also observed where men had significantly higher values at mid (p = 0.002) and post (p = 0.094) compared to pre-exercise. In women however, circulating cortisol concentrations did not significantly increase in response to the squat exercise protocol. CONCLUSIONS: These findings indicate a differential relationship with circulating adrenal cortical responses to high intensity short term exercise stress but also with GCR expression. Such data provide insights into the temporal interactions between the endocrine and the immune systems in response to the physiological stress of acute heavy resistance exercise in men and women. Practical Applications: Because heavy resistance exercise training is important to sports conditioning, understanding the biological mechanism of the body's response to such training and the differences in that reaction between genders is useful in designing training protocols that would enhance athletic performance.