Ingesting protein and amino acid supplements after working out does not boost musclemass and strength, researchers report this week.
"At least for the average person, protein and amino acid supplements would probably notproduce the effects often claimed," according to study lead author Dr. A. G. Williams of Staffordshire University in Stoke-on-Trent, UK.
Williams and his colleagues explored the effect of an oral supplement designed to manipulate the balance of protein breakdown and buildup that occurs when muscles are subject to the stress of weight-training.
The researchers followed 12 university students for 10 weeks, during which some followed a leg-training regimen and the rest did not.
In addition, the participants took either a supplement including amino acids and glucose (sugar) or an inactive placebo.
The investigators found that the supplement did increase blood levels of glucose and the glucose-regulating hormone insulin for a short period.
However, they had no effect on the students' muscle strength.
In addition, Williams and his colleagues found that body fat and body mass percentages did not change for any of the students - regardless of whether they trained or had taken the supplement.
"Protein and amino acid supplements are often sold with claims of increasing muscle size and strength...
[but] a rational look at the science behind this shows that there is very little evidence supporting these claims," Williams told Reuters Health.
"As long as people doingstrength training eat a well-balanced diet, they are likely to be getting all the protein they need to support muscle growth."
Williams acknowledged, however, that the benefit of supplements cannot be totally dismissed.
He noted that some serious athletes may find that, when coupled with an intensive training program, such protein supplements help.
"Perhaps supplementation has more effect on the gain in muscle strength in well-trained athletes," he said.
"Only more research will answer this question."
Full findings are published in the April issue of the British Journal of Sports Medicine.
Source: Reuters Health and the British Journal of Sports Medicine 2001;35:109-113.