Dietary supplements are purported to do everything from enhance recovery, boost strength, reduce body composition or increase energy. One supplement that popped up in the mid-1990's as one to enhance muscular strength and improve body composition is b-Hydroxy b-Methylbutyrate, AKA, HMB.
HMB is a byproduct of the essential amino acid luecine. An essential amino acid is one that cannot be produced by the body but must instead be consumed in the diet. Since we all consume protein through the foods we eat, we subsequently ingest luecine as a component of this protein.
On average, it has been estimated that a 150 lb human would produce approximately 0.2-0.4 g of HMB each day, but of course this is dependent on overall luecine intake.
It is hypothesized that HMB may be beneficial because it may increase collagen synthesis and connective tissues. Moreover, it may regulate specific enzymes responsible for muscle tissue. In return, this would shorten recovery and lessen the risk of overtraining.
So let's take a look at a study that measured the effects of HMB to see if it actually works in "real life."
The objective of this study was to evaluate the effects of HMB on muscular strength and body composition. This study was a randomized, double-blind crossover, placebo design. There were 35 subjects in the study, in which 16 were assigned to a placebo group and 19 to the HMB group.
Subjects were supplemented with either 3 g of HMB per day or the placebo. One benefit of this study was the way it was designed. It was called a "crossover" study because the subjects initially received either HMB or placebo for 4 weeks.
Then, there was a one week washout period, in which subjects did consume any of the dietary supplements. Then, the subjects switched groups and were given the other supplement for the remaining 4-weeks.
This design is set up like this to ensure that no subjects had what is called a "placebo effect" which I've described in previous articles. All subjects ultimately get the supplement being tested so the results can truly be compared among individuals.
Also keep in mind that three grams is the dose typically recommended to achieve the desired results.
The subjects were NCAA Division I football players. This is one benefit because many times these studies are conducted using non-trained individuals. Therefore, the only difference of the study would be the supplement, rather than the training program, which could affect the results and make something look like it works when it really does not.
Subjects participated in training sessions that lasted approximately 4 hours per day, 4 days per week. So, if there was ever a need for something to decrease the possibility of overtraining, this is it. Not many individuals have the ability or desire to train for so long each day.
Both strength and endurance exercises were performed during the sessions. Strength exercises were performed at 10 exercises per session, with 8-12 sets per exercise and 2-10 reps/set.
The endurance drills consisted of speed and tempo exercises, with 26-30 seconds of recovery time between repetitions and full recovery between sets.
Without getting into specifics, a number of strength and endurance tests were conducted to determine the effectiveness of HMB. After all the data was collected and analyzed, it was determined that there were no significant differences between groups for muscular strength (using bench press, power cleans and squats as the measures). There were also no significant differences among individuals for body composition or body weight.
There may be differences in other groups of individuals (elderly or untrained individuals), but not in those who are already trained. Anyhow, the use of HMB at the doses recommended is a bit pricey, making it cost-prohibitive for many.
The Journal of Strength and Conditioning Research, Vol 17(1), 34-39.
Ransone et al.