Plant Protein and Strength Training. Impacts on Plasma Leucine Concentrations

Physical exercise, especially strength training, has health benefits, including increased muscle mass. Adequate protein intake was essential to optimise these effects, especially leucine, an essential amino acid. Although proteins of animal origin have been considered superior, plant proteins, when combined, could also be effective. This study aimed to evaluate the effects of a protein supplement derived from immature cowpea pods on plasma leucine concentration in young adults after a strength training session. Ten healthy men took part in the study, performing strength training under four conditions: control, exercise, supplementation and supplementation with exercise. Blood samples were taken to analyse leucine. The supplementation consisted of 150g of mashed cowpea pods, with an estimated protein content of between 15g and 18g. Leucine levels varied significantly between conditions. Exercise alone maintained levels for longer, while supplementation resulted in an earlier but smaller increase. The combination of supplementation and exercise showed a trend of progressive reduction, suggesting that the vegetable protein may not have provided enough leucine to optimise the training response. It was concluded that cowpea protein supplementation did not significantly increase plasma leucine after training, possibly due to slower digestion and a less complete amino acid profile. Additional strategies, such as combining with other amino acids or carbohydrates, may have been necessary to optimise the use of plant proteins in strength training.