The successful regeneration of muscle tissue is dependent upon the infiltration of phagocytic CD14++CD16- monocytes that support the proliferation and differentiation of myogenic precursor cells. Physiologically, the magnitude of the cellular response following resistance exercise is dictated by the level of receptor expression on the plasma membrane of the monocyte, as well as the secretion of their cognate ligands from tissue resident cells. However, it remains unclear whether the innate pro-inflammatory immune response varies with different resistance training protocols, and how it may impact recovery and the muscle remodeling process. Therefore, the purpose of this investigation was to examine temporal changes in the expression of chemotactic and adhesion receptors following an acute bout of high-volume, moderate-intensity (VOL) versus high-intensity, low-volume (HVY) lower-body resistance exercise in experienced, resistance trained men. Changes in receptor expression were assessed in conjunction with plasma concentrations of MCP-1, TNF?, and cortisol. Ten resistance-trained men (90.1 ± 11.3 kg; 176.0 ± 4.9 cm; 24.7 ± 3.4 yrs; 14.1 ± 6.1% body fat) performed each resistance exercise protocol in a random, counterbalanced order. Blood samples were obtained at baseline (BL), immediately (IP), 30 minutes (30P), 1 hour (1H), 2 hours (2H), and 5 hours (5H) post-exercise. Analysis of target receptor expression on CD14++CD16- monocytes was completed at BL, IP, 1H, 2H and 5H time points via flow cytometric analysis. Plasma concentrations of myoglobin, and LDH AUC were significantly greater following HVY compared to VOL (p = 0.003 and p = 0.010 respectively). Changes in plasma TNF?, MCP-1, and expression of CCR2, CD11b, and GCR on CD14++CD16- monocytes were similar following HVY and VOL. When collapsed across groups, TNF? was significantly increased at IP, 30P, 1H and 2H post-exercise (p = 0.001 – 0.004), while MCP-1 was significantly elevated at all post-exercise time points (p = 0.002 – 0.033). CCR2 expression was significantly lower at IP, 1H, 2H and 5H post-exercise (p = 0.020 – 0.040). In contrast, CD11b receptor expression was significantly greater at 1H relative to BL (p = 0.001), while GCR expression was not significantly different from baseline at any time point. As expected, plasma cortisol concentrations were significantly higher following VOL compared to HVY (p = 0.001), although this did not appear to be related to changes in receptor expression. Plasma testosterone concentrations and TNFr1 receptor expression did not appear to be affected by resistance exercise. Our results do not support a role for cortisol in the modulation of CCR2 receptors in vivo, while the degree of muscle damage does not appear to influence plasma concentrations of TNF?, or MCP-1. It is therefore likely that both HVY and VOL protocols constitute an exercise stimulus that is sufficient enough to promote a robust pro-inflammatory response, which is similar in timing and magnitude.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-2191 |
| Date | 01 January 2015 |
| Creators | Wells, Adam |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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