Taking HMB-free acid supplements raises levels of HMB in the blood of older men, but this does not lead to greater improvements in muscle building, gene activity, or physical function than resistance training by itself.

In older men doing strength training, taking HMB-free acid may temporarily boost muscle protein synthesis in the first two weeks, but this effect disappears after that and is not different from taking a placebo.

For older men doing strength training, taking HMB-free acid supplements does not lead to greater increases in muscle strength, muscle size, or maximum force production than taking a placebo over six weeks.

Taking HMB-free acid supplements raised levels of HMB in the blood of older men, showing the body absorbed it, but this did not lead to meaningful health improvements except for a minor gain in thigh muscle mass.

In older men doing strength training, taking HMB-free acid caused a short-term rise in muscle protein synthesis during the first two weeks, but this effect disappeared after that and was not different from taking a placebo. Any muscle growth from this supplement is not due to a lasting increase in protein synthesis.

In older men doing strength training, taking HMB-free acid supplements for six weeks did not lead to measurable improvements in strength, muscle size, or maximum force production compared to a placebo, even if there was a slight increase in lean mass.