Is glucose/amino acid supplementation after exercise an aid to strength training?

Abstract

Background-The precise timing of carbohydrate and amino acid ingestion relative to a bout of resistance exercise may modulate the training eVect of the resistance exercise. Objective-To assess whether regular glucose/amino acid supplementation immediately after resistance exercise could enhance the gain in muscle strength brought about by resistance training. Methods-Seven untrained participants with a median age of 23 years and mean (SD) body mass 68.9 (13.5) kg resistance trained on a leg extension machine for five days a week for 10 weeks, using four sets of 10 repetitions. Alternate legs were trained on successive days, one leg each day. Subjects ingested either a supplement including 0.8 g glucose/kg and 0.2 g amino acids/ kg, or placebo, on alternate training days immediately after training. Therefore the supplement was always ingested after training the same leg (supplement leg). Isometric, isokinetic, and 1 repetition maximum (RM) strength were measured before, during, and after training. Blood samples were analysed to determine the acute responses of insulin and glucose to resistance exercise and supplementation or placebo. Results-Serum insulin concentration peaked 20 minutes after supplement ingestion at ninefold the placebo level, and remained significantly elevated for at least 80 minutes (p<0.01). Isometric, isokinetic, and 1 RM strength improved on both supplement and placebo legs (p<0.05). There were no significant diVerences in the gain in strength between the supplement leg and the placebo leg (p>0.05). Conclusion-Regular glucose/amino acid supplementation immediately after resistance exercise is unlikely to enhance the gain in muscle strength brought about by resistance training. (Br J Sports Med 2001;35:109-113)

Effects of resistance exercise volume and nutritional supplementation on anabolic and catabolic hormones

“…The release of cortisol in response to a single bout of resistance exercise was attenuated by carbohydrate supplementation, and the degree of attenuation was directly and strongly related to the extent of muscle growth achieved. In contrast, Williams et al (2001) have recently shown no significant effect of post-exercise carbohydrate-protein supplementation on the gain in muscle strength achieved during 10 weeks of resistance training using leg extension exercise only. Given the potential role of cortisol in inhibiting training-induced muscle growth (Tarpenning et al 1998), it would be useful to observe whether post-exercise concentrations of cortisol are reduced by carbohydrate-protein supplementation.…”

“…Given the potential role of cortisol in inhibiting training-induced muscle growth (Tarpenning et al 1998), it would be useful to observe whether post-exercise concentrations of cortisol are reduced by carbohydrate-protein supplementation. If cortisol levels are not reduced by postexercise carbohydrate-protein supplementation, this may partly account for the differing conclusions of the two training studies cited (Tarpenning et al 1998;Williams et al 2001). Similarly, it would be useful to observe whether the volume of resistance exercise conducted exerts any influence on the effect of post-exercise supplementation on cortisol levels.…”

Efeitos da Suplementação de Leucina Associada ao Treinamento Resistido Sobre a Força Muscular em Sujeitos Jovens

“…Ao término do treinamento, os autores observaram um aumento da força muscular em todos os grupos, porém nenhum efeito adicional da leucina foi observado. Tais resultados não são surpreendentes considerando prévios estudos, que examinaram os efeitos da suplementação crônica (4-10 semanas) de leucina combinada a outros nutrientes (EAAs, creatina, proteína de soro de leite e/ou carboidrato) sobre a força muscular [11][12][13][14] . Os achados destes estudos não demonstraram efeitos adicionais da suplementação de leucina sobre os ganhos de força muscular.…”

“…No entanto, prévios estudos que examinaram os efeitos da suplementação crônica (4-10 semanas) de leucina combinada a outros nutrientes (EAAs, creatina, proteína de soro de leite e/ou carboidrato), não relataram efeitos benéficos sobre a força muscular [11][12][13][14] . Além disso, nenhum estudo até o momento investigou os possíveis efeitos da suplementação isolada de leucina associada ao TR sobre a força muscular em sujeitos jovens.…”

Co-ingestion of carbohydrate and pea protein does not enhance muscle recovery after strenuous exercise

“…It should be noted that CHO+PRO group received a 4:1 ratio of carbohydrate to protein supplementation as it has already been tested in other studies 1,7,11,12,14,20,22,31,32 . However, more recent studies have tested the 3:1 ratio, i.e., a larger amount of PRO in relation to CHO 18,19,33,34 .…”