Effects of previous carbohydrate supplementation on muscular fatigue: double-blind, randomized, placebo-controlled crossover study

Abstract AIMS The aim of this study was to examine the effects of previous carbohydrate supplementation on high-volume resistance exercise performance METHODS Twenty males physically independent adults aged ≥18 years participated in a double-blind randomized placebo-controlled crossover study. Sixty minutes before the experimental protocol, each participant ingested 0,6 g.kg of body mass-1 of carbohydrate supplementation or placebo. Maximum voluntary isometric contraction tests were performed before and after the dynamic fatigue induction protocol consisting of 10 sets of 8 repetitions of right leg knee extensors at 120º s-1. RESULTS Lower decrement of the isometric peak torque (p<0,001) and of the rate of torque development (p<0,001) was observed in carbohydrate supplementation after the dynamic protocol. Both concentric and eccentric peak torque differed significantly (p<0,001) between carbohydrate supplementation and placebo treatments from the second set, although the slope of the force-repetitions curve was not different between them. Additionally, the carbohydrate supplementation resulted in a lower session rating of perceived exertion (p<0,05). CONCLUSIONS Previous carbohydrate supplementation attenuates muscle fatigue and internal load exercise in a high-volume isokinetic leg protocol

Metabolic and hormonal responses to different resistance training systems in elderly men

Objective: To compare acute and sub-acute responses in hormonal profile and metabolic parameters in elderly people who participated in two methods of strength training (ST) with equalized loads.Methods and materials: A total of 12 elder individuals (653years) were randomly assigned to two training methods: constant intensity (CI, 3 sets of 10 repetitions with 75% of 1RM) and variable intensity (VI, 1st set: 12 repetitions at 67% of 1RM>2nd set: 10 repetitions at 75% of 1RM and 3rd set: 8 repetitions at 80% of 1RM). Both methods included the following exercises: leg press, knee extension, and squat with 1min rest intervals between sets. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. Blood samples were analyzed included glucose, testosterone (T), cortisol (C), T/C rate, growth hormone (GH), and lactate at 2 and 24h post intervention.Results: There were no observed differences in glucose, testosterone, GH, and lactate concentrations both at 2 and 24h after the execution of the two training methods. However, significant increases in the levels of T/C rate and decrease on cortisol were observed immediately post exercise for both protocols.Conclusions: Although no significant differences were observed between the two interventions in relation to the hormonal and metabolic parameters analyzed, both training methods promoted a favorable response, with a slight superiority noted for the CI method relative to the hormonal profile.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Sao Judas Tadeu Univ USJT, Post Grad Program Phys Educ & Aging Sci, Translat Physiol Lab, Sao Paulo, BrazilNove de Julho Univ UNINOVE, Dept Phys Educ & Biophoton, Sao Paulo, BrazilFed Univ Sao Paulo UNIFESP, Obes Study Grp GEO, Interdisciplinary Lab Metab Dis, Santos, BrazilPraia Grande Coll FPG, Fac Phys Educ, Praia Grande, BrazilUniv West Scotland, Inst Clin Exercise & Hlth Sci, Hamilton, EnglandCUNY, Dept Hlth Sci, Bronx, NY USAFed Univ Sao Paulo UNIFESP, Obes Study Grp GEO, Interdisciplinary Lab Metab Dis, Santos, BrazilWeb of Scienc