1.
Supplementation with a low-dose of octopamine does not influence endurance cycling performance in recreationally active men.
Beaumont, RE, Cordery, P, James, LJ, Watson, P
Journal of science and medicine in sport. 2017;(10):952-956
Abstract
OBJECTIVES The aim of this study was to examine the influence of octopamine supplementation on endurance performance and exercise metabolism. DESIGN Double-blind cross-over study. METHODS Ten healthy, recreationally active men (Mean±SD; age: 24±2 years; body mass: 78.4±8.7kg; VO2peak: 50.5±6.8 mLkg-1min-1) completed one VO2peak test, one familiarisation trial and two experimental trials. After an overnight fast, participants ingested either a placebo or 150mg of octopamine 60min prior to exercise. Trials consisted of 30min of cycle exercise at 55% peak power output, followed by a 30min performance task whereby participants completed as much work (kJ) as possible. RESULTS Performance was similar between the experimental trials (placebo: 352.8±39kJ; octopamine: 350.9±38.3kJ; Cohen's d effect size=0.05; p=0.380). Substrate oxidation and circulating concentrations of free fatty acids, prolactin and cortisol were similar between trial conditions (all p>0.05). There were also no differences across trials for heart rate or perceived exertion during exercise (both p>0.05). CONCLUSIONS Acute supplementation with a low dose of octopamine did not influence endurance cycle performance, substrate oxidation or circulating hormonal concentrations, which could be due to the low serum octopamine concentrations observed. Future studies should investigate the influence of larger doses of octopamine in recreationally active and well-trained individuals during prolonged exercise in temperate and high ambient conditions.
2.
Protein ingestion increases myofibrillar protein synthesis after concurrent exercise.
Camera, DM, West, DW, Phillips, SM, Rerecich, T, Stellingwerff, T, Hawley, JA, Coffey, VG
Medicine and science in sports and exercise. 2015;(1):82-91
Abstract
PURPOSE We determined the effect of protein supplementation on anabolic signaling and rates of myofibrillar and mitochondrial protein synthesis after a single bout of concurrent training. METHODS Using a randomized crossover design, eight healthy males were assigned to experimental trials consisting of resistance exercise (8 × 5 leg extension, 80% 1RM) followed by cycling (30 min at approximately 70% V˙O2peak) with either postexercise protein (PRO, 25-g whey protein) or placebo (PLA) ingestion. Muscle biopsies were obtained at rest and at 1 and 4 h after exercise. RESULTS Akt and mTOR phosphorylation increased 1 h after exercise with PRO (175%-400%, P < 0.01) and was different from PLA (150%-300%, P < 0.001). Muscle RING finger 1 and atrogin-1 messenger RNA (mRNA) were elevated after exercise but were higher with PLA compared with those in PRO at 1 h (50%-315%, P < 0.05), whereas peroxisome proliferator-activated receptor gamma coactivator 1-alpha mRNA increased 4 h after exercise (620%-730%, P < 0.001), with no difference between treatments. Postexercise rates of myofibrillar protein synthesis increased above rest in both trials (75%-145%, P < 0.05) but were higher with PRO (67%, P < 0.05), whereas mitochondrial protein synthesis did not change from baseline. CONCLUSIONS Our results show that a concurrent training session promotes anabolic adaptive responses and increases metabolic/oxidative mRNA expression in the skeletal muscle. PRO ingestion after combined resistance and endurance exercise enhances myofibrillar protein synthesis and attenuates markers of muscle catabolism and thus is likely an important nutritional strategy to enhance adaptation responses with concurrent training.