Resistance exercise effects on blood glutathione status and plasma protein carbonyls: influence of partial vascular occlusion.

Seven weight-trained males performed both light resistance with partial occlusion (LRO: 30% 1 RM) and moderate resistance (MR: 70% 1 RM) to failure to ascertain whether blood protein carbonyls (PC) and glutathione status was altered compared to partial occlusion (PO) in a counterbalanced fashion. PO was identical in duration to the LRO session and all sessions were on separate days. PC did not differ for the three conditions at PRE (0.05 nM mg protein(-1)). PC significantly increased for PO and MR over time and was greater than the LRO treatment at POST (0.13 nM mg protein(-1)). The GSSG/TGSH ratio at PRE did not differ across treatments (8%) whereas the ratio at POST was significantly elevated for PO and MR treatments (17%). In contrast, no change occurred for the LRO session at any time. These results indicate that MR to failure and PO can significantly increase blood oxidative stress but LRO did not elicit oxidative stress.

Ghrelin and other glucoregulatory hormone responses to eccentric and concentric muscle contractions.

OBJECTIVE: Heavy resistance exercise increases growth hormone (GH) and blood glucose levels. Ghrelin is an endogenous ligand for the GH secretagory receptor that stimulates growth hormone release. Circulating ghrelin levels are suppressed by insulin and glucose. The study was conducted to determine effects of concentric (CON) and eccentric (ECC) muscle actions at the same absolute workload on circulating ghrelin and glucose as well as related glucoregulatory peptides. METHODS: Ten-RM loads for bench press, leg extension, military press, and leg curl were obtained from nine males, mean age 25. +/- 1.2 yr and body fat 17.2 +/- 1.6%. Subjects then completed two experimental trials of either CON or ECC contractions at the same absolute workload. Subjects performed four sets of 12 repetitions for each exercise at 80% of a 10-RM with 90 s rest periods. A pulley system or steel levers were positioned on each machine to raise or lower the weight so only CON or ECC contractions were performed. Pre-, post-, and 15-min post-exercise blood samples were collected. RESULTS: Ghrelin did not increase in response to either muscle action and actually declined during the CON trial. Glucose and insulin increased regardless of the form of muscle action, but amylin and C-peptide did not change. CONCLUSIONS: Data indicate that ghrelin does not contribute to moderate resistance exercise-induced increases in growth hormone, whether from CON or ECC muscle actions. Results suggest that with a moderate loading protocol both CON and ECC muscle actions performed at the same absolute workload elevate glucose and insulin concentrations, but are not related to post-CON exercise ghrelin suppression.