Unfortunately, the research didn't pan out so well and individuals realized it didn't do much for their muscles either.
While there were supportive studies available, these were primarily in older individuals who were prone to muscle wasting, not well-trained athletes, who are the ones likely to use the product.
While it's still sold in a number of products, its hype has since died. However, a recent research study shows that supplementation with HMB and another supplement æ-ketoisocaproic acid (KIC) may actually have some benefit.
International Journal Of Sports Nutrition & Exercise Metabolism,
2005, 15, 413-424
Evidence has suggested that HMB may attenuate the normal "damage" response to weight training, which means suppressing some of the markers of muscle damage, such as creatine kinase.
Scientists are not 100% clear as to how HMB exerts its effects; it is thought that HMB may be a structural component within the cell and some research has attributed its role to increasing cell membrane integrity and reducing proteolysis (protein breakdown).
The purpose of this 14-day study was to measure the signs and symptoms of eccentric muscle damage with HMB and KIC supplementation.
This small study included eight males, who were approximately 23 years of age, and who had not performed any resistance training in the previous 12 months.
This was a double blind, placebo controlled, counterbalanced, crossover study. Look back to previous articles of mine if those terms are confusing.
The HMB/KIC treatment group received 3g HMB with 0.3 g KIC/day and the placebo group received 3 grams of corn flour, made to look identical to the other capsules. These were all taken in three divided doses throughout the day, after meals.
Subjects supplemented with their respective products for 14 days. They then underwent an exercise protocol specifically designed to induce muscle damage. This particular protocol consisted of 3 sets of 10 repetitions of single arm biceps curls (Ex- Shown With Two Arms) at 70% of a predetermined 1 RM.
|ONE REP MAX CALCULATOR|
The concentric part of the lift was performed normally, whereas the eccentric part of the lift was performed over a 10 second time period, ensuring sufficient muscle damage.
Keep in mind that eccentric training induces more muscle damage that concentric training, so the technique utilized in this study is fairly common in training studies trying to cause muscle damage.
Plasma creatine kinase was measured prior to and after the exercise protocol. In addition, a rating of perceived muscle soreness was used, where subjects subjectively assessed their level of soreness (ranging from 1, meaning no pain, to 7, meaning unbearably painful).
Finally, range of motion was measured using a tool called a goniometer. This was done to determine if the muscle damage and, subsequently, pain impacted the range of motion of the arm.
| What Is A Goniometer?
A goniometer is an instrument that either measures angles or allows an object to be rotated to a precise angular position. There are many types, each specialised for its particular application.
Goniometers are used in crystallography for measuring angles between crystal faces. They are also used in X-ray diffraction to rotate the samples. Other versions range from devices which measure human joint movement to ones which determine the angle of contact between a liquid droplet and a flat substrate.
I'm sure you've all had arm workouts where the next day or two you would rather run repeatedly head first into a wall because that would be more comfortable than straightening your arm.
The first time my brother and I ever did a set of biceps curls with a 45 lb plate on each end, I considered cutting off my arms at the shoulder because my arms were in such pain the next day (you know, that crease right where your elbow bends).
OK, that thought didn't cross my mind... but it was pretty unbearable. Maybe I needed some HMB and KIC? Let's see the results to determine if that could have helped me.
Results were presented on only 6 subjects because one had elevated baseline creatine kinase levels and another didn't complete the second exercise session.
As expected, there was a significant change in 1 RM over 72 hours because of the muscle soreness. This significant change was a decrease in the overall weight lifted, but this change was attenuated in the subjects who took the HMB/KIC supplement vs. those who took a placebo.
There was also a significant change in the creatine kinase response between treatments, whereas it increased to a mean of 315.2 IU/L in the placebo group and only to a mean of 154.5.0 IU/L in the HMB/KIC group.
Those values probably mean very little too many of you, but notice the difference in numbers between the two groups. Normal values for men range from 38 to 174 IU/L, so the HMB/KIC supplement was able to keep creatine kinase within normal limits, although towards the upper end of the range.
Remember that creatine kinase is a measure of muscle damage, so when the number is elevated, that means there is a greater amount of muscle damage somewhere within the body (in this case, the biceps).
This study found that 3 g HMB/0.3g KIC was effective at attenuating the normal rise in creatine kinase, the normal decrease in 1 RM, and the range of motion when compared to a placebo supplement. One study that was conducted earlier used HMB and showed no effect of the supplement because it did not include KIC. In addition this earlier study was only 6 days in duration vs. this one which was 14.
My concern with this study is that while there did appear to be a benefit from the supplement, it was not conducted with trained individuals, which was a limitation in the previous research studies.
Trained and untrained individuals respond much differently to training; protein needs are higher in "newbie's" as muscle damage may also be higher, etc. Therefore, to show that HMB/KIC positively affects untrained individuals doesn't necessarily carry over to those of us who are trained and regularly train.
In addition, although the study was longer than the other popularized studies on HMB, it was still only 2 weeks long. It would be interesting to see if these same results were apparent when training for a longer duration, and the individuals were more accustomed to training.
HMB is a metabolite of the amino acid leucine. My recommendation would be to instead focus supplementation on something that we know works - a post-workout supplement that combines some fast acting carbs and fast acting protein (2 or 3:1 ratio seems to be ideal). This protein will provide additional leucine that could offer the same thing as HMB itself.