Co-ingestion of carbohydrate and whey protein increases fasted rates of muscle protein synthesis immediately after resistance exercise in rats.

The objective of the study was to investigate whether co-ingestion of carbohydrate and protein as compared with protein alone augments muscle protein synthesis (MPS) during early exercise recovery. Two months old rats performed 10 repetitions of ladder climbing with 75% of body weight attached to their tails. Placebo (PLA), whey protein (WP), or whey protein plus carbohydrate (CP) was then given to rats by gavage. An additional group of sedentary rats (SED) was used as controls. Blood samples were collected immediately and at either 1 or 2 h after exercise. The flexor hallucis longus muscle was excised at 1 or 2 h post exercise for analysis of MPS and related signaling proteins. MPS was significantly increased by CP compared with PLA (p<0.05), and approached significance compared with WP at 1 h post exercise (p = 0.08). CP yielded a greater phosphorylation of mTOR compared with SED and PLA at 1 h post exercise and SED and WP at 2 h post exercise. CP also increased phosphorylation of p70S6K compared with SED at 1 and 2 h post exercise. 4E-BP1 phosphorylation was inhibited by PLA at 1 h but elevated by WP and CP at 2 h post exercise relative to SED. The phosphorylation of AMPK was elevated by exercise at 1 h post exercise, and this elevated level was sustained only in the WP group at 2 h. The phosphorylation of Akt, GSK3, and eIF2Bε were unchanged by treatments. Plasma insulin was transiently increased by CP at 1 h post exercise. In conclusion, post-exercise CP supplementation increases MPS post exercise relative to PLA and possibly WP, which may have been mediated by greater activation of the mTOR signaling pathway.

Effects of high-intensity exercise training on body composition, abdominal fat loss, and cardiorespiratory fitness in middle-aged Korean females.

The primary purpose of this study was to investigate the effects of high-intensity exercise training under relatively equal energy expenditure on whole body fat and abdominal fat loss, and cardiorespiratory fitness. Twenty-two untrained middle-aged Korean females were randomized into one of the following groups: control, low-intensity training group (LI), and high-intensity training group (HI). Subjects completed 14 weeks of training at 50% maximal oxygen consumption (LI) or 70% maximal oxygen consumption (HI) with the volume of exercise equated relative to kilograms of body weight. Weekly exercise volumes were 13.5 METs⋅h/week for the first 4 weeks, 18 METs⋅h/week for next 5 weeks, and 22.5 METs⋅h/week for the final 5 weeks. Data were analyzed using 2-way repeated measures ANOVA with post hoc test, using Bonferroni's correction. HI showed significant reductions in fat mass (p < 0.05), total abdominal fat (p < 0.01), and subcutaneous abdominal fat (p < 0.01). LI reduced total abdominal fat (p < 0.05), but there were no other significant changes found in the control or LI groups. Maximal oxygen consumption was enhanced in both HI and LI with no significant group difference. High-density lipoprotein cholesterol increased significantly in HI (p < 0.05). IL-6, C-reactive protein, TNF-α, and other blood lipids were unaltered following training. Results indicate that high-intensity exercise training is more beneficial in whole body and abdominal fat loss; however, cardiorespiratory enhancement shows a dose-response relationship with weekly exercise volume. It is suggested that 14 weeks of aerobic exercise training at either high- or low-intensity is not sufficient enough to induce changes in levels of inflammatory proteins.

Effects of aerobic exercise training on C1q tumor necrosis factor α-related protein isoform 5 (myonectin): association with insulin resistance and mitochondrial DNA density in women.

CONTEXT: The C1q TNFα-related protein (C1QTNF) families exhibit a C-terminal complement factor C1q globular domain similar to that of TNF. However, their clinical implications are largely unknown. We recently found that the C1q TNFα-related protein isoform 5 (C1QTNF5 or myonectin) level was increased in insulin-resistant rodents and mitochondrial DNA (mtDNA)-depleted myocytes. OBJECTIVE: We aimed to determine the effects of aerobic exercise training on C1QTNF5 level and its association with insulin resistance and mtDNA density in young and old healthy women. DESIGN AND SETTING: Fourteen healthy young women aged 22.5 ± 2.7 yr and 14 healthy older women aged 60.3 ± 5.2 yr performed aerobic exercise at 60-80% of maximal oxygen consumption (VO(2)max) over three 1-h sessions per week for 10 wk. Insulin resistance was assessed by homeostasis model assessment of insulin resistance and adiponectin concentration. Serum C1QTNF5 level was estimated by immunoblotting. The mtDNA/28S rRNA ratio was used to determine mtDNA density. RESULTS: VO(2)max increased significantly after the exercise training from 33.1 ± 6.2 to 35.3 ± 5.3 ml/kg · min in younger women and from 23.2 ± 3.1 to 27.2 ± 4.8 ml/kg · min in older women (P < 0.05). The C1QTNF5 level and homeostasis model assessment of insulin resistance decreased significantly after exercise training and were correlated positively (r = 0.462; P < 0.01). There were negative correlations between the changes in C1QTNF5 level and the changes in VO(2)max, mtDNA density, and adiponectin level (r = -0.495, -0.672, and -0.569, respectively; all P < 0.01). CONCLUSION: These findings suggest a physiological function for C1QTNF5 (myonectin) in linking insulin resistance with quantitative changes in mtDNA. Further research exploring the role of C1QTNF5 in the development of insulin resistance is warranted.