Recently, while watching tv, I saw a commercial for Ensure. You know, that nutritional drink for old people. I’ve also been told it helps with hang overs : ). Anyways, they recently released a new forumula of Ensure that contains HMB to help promote the retention of muscle mass in the elderly. I then did some research on pubmed and found that HMB could benefit athletes and bodybuilders as well. That lead to this HMB review.
What is HMB?
HMB is short for beta-hydroxybeta-methylbutyrate and is a metabolite of the branch chain amino acid leucine. After leucine is ingested, it is partly (dependent of dosage) broken down into a-ketoisocaproate (KIC). After leucine is metabolized to KIC, KIC is either metabolized into isovaleryl-CoA in the mitochondria, or into beta-hydroxybeta-methylbutyrate (HMB) in the cytosol.
The majority of KIC is converted into isovaleryl-CoA, while under normal conditions; approximately 5% of leucine is metabolized into HMB. Assuming the average recommended dosage of HMB is 3g, 60g of leucine would need to be consumed under regular conditions to provide 3 g HMB to the body.
Studies have suggested the HMB has anti-catabolic and anabolic effects. These benefits have made HMB a popular supplement for both bodybuilders and powerlifters. However, studies have had conflicting results on the actual benefits seen from supplementing with HMB.
HMB Review For Various Populations
Studies Supporting HMB Supplementation
In 1996, Nissen et al. (1) examined the effects of HMB on muscle metabolism and performance during resistance exercise in two experiments in healthy untrained males. Participants in the first experiment ingested 0g, 1.5g, or 3 g of HMB daily, while weight lifting 3 days per week for 3 weeks. Two dosages of HMB of 0g or 3g were used in the second experiment with weight training occurring 2–3 hours daily for 7 weeks.
Results from the first experiment found that HMB decreased plasma markers of muscle damage degradation in a dose dependent response with a range of 20–60%. Total weight lifted also increased in a dose dependent manner . Finally, lean body mass (LBM) increased with each increment increase in HMB ingestion.
In the second experiment, LBM was significantly increased with the HMB supplemented participants compared to the non-supplemented participants at weeks 2 and 4–6 with no further differences seen during the final week (week 7). Diminished improvements in LBM during the final week of training may be due to accommodation of the participants to the training stimulus. Participants ingesting HMB increased their 1 repetition maximum bench press by an average of 15 pounds, compared
to a 5-pound increase in the non-supplemented group.
In 2001, Jowko et al. (2) investigated whether creatine and HMB act by similar or different mechanisms. Participants resistance trained and consumed creatine, HMB, or combination of both for a total of 3 weeks. Results found that HMB, creatine, and the combination group gained .39, .92, and 1.54 kg of LBM above the placebo. The total amount of weight lifted increased above the placebo on all exercises combined was 37.5, 39.1, and 51.9 kg for HMB, creatine, and the combination group. Both HMB-supplemented conditions showed decreased creatine kinase, urine urea nitrogen (indicating less protein breakdown), and plasma urea, while creatine supplementation alone did not decrease these markers. The apparent additive effects of these supplements indicate that creatine and HMB operate through separate mechanisms and can have a synergistic effect when taken together.
Nissen et al. (3) investigated HMB supplementation on strength and body composition in trained and untrained males coupled with intense resistance training. Greater decreases in body fat and increases in LBM were found with HMB supplementation regardless of training status. There was also an overall 55% greater increase in bench press performance.
Similarly, Panton et al. (4) examined the effects of HMB supplementation during resistance training in 36 women and 39 men, 20 to 40 years of age, with varying levels of training experience for 4 weeks. The HMB group decreased body fat to a greater extent, experienced greater increases in upper body strength. and greater LBM increases than the placebo group, independent of training experience.
HMB supplementation also has benefits for endurance athletes. Vukovich and Adams (5) found that 2 weeks of HMB supplementation in experienced cyclists increased both peak oxygen consumption (VO2 peak) and the time to reach VO2 peak, while supplementation with leucine or a placebo did not change these measurements.
Studies Not Supporting HMB Supplementation
Kreider et al. (6) used 40 experienced resistance trained athletes who averaged 7 hours of training per week for 28 days, while supplementing with 0g, 3g, or 6 g of HMB daily. Participants were not monitored, but were instructed to maintain their normal training programs during the experiment and record their training volume before and after the experiment in a log. No differences were found in training volume performed before and after supplementation with HMB. Kreider found no significant decrease in markers of muscle damage, fat mass, increased LBM or 1 RM performance in any of the lifts measured in the placebo or HMB supplemented groups.
Slater et al. (7) had experienced resistance trained males consume 3g of HMB or a placebo for 6 weeks while performing 2–3 sessions weekly of compound movements, for a total of 24–32 sets, at a training intensity of 4–6 reps. The assigned training significantly increased LBM and total strength gains, but did not increase any of the individual lifts. HMB supplementation had no significant effect on LBM or strength or biochemical markers of muscle damage.
Possible Reasons For Varying Results
There will always be variability among humans both physiologically and participants mental states (i.e. motivation). A way to combat this is to have large sample sizes, however, this is often difficult with these types of studies.
Another possible explanation for conflicting results seen in experienced athletes consists of methodologies which contain a lack of specificity between training and testing conditions. For example Slater and Jenkins suggested that:
“It may be that for highly trained individuals, 4 weeks of HMB supplementation is an inadequate time frame to allow adaptations unique to HMB supplementation to be identified. Studies involving longer periods of supplementation, as used in some of the trials with untrained volunteers, are needed to address this issue.”
Is HMB Worth It?
With the current available research and after writing this HMB review, I would say yes, especially if you are a new trainee where any weight lifting will cause large amounts of muscle damage. For athletes with years of training experience, longer cycles may be necessary to fully benefit from HMB. In a later post, I will focus on the side effects of HMB and the proper dosing protocol.
Which HMB Supplement Do I Recommend?
HMB Review Video
1. Nissen SR, Sharp M, Ray JA, Rathmacher D, Rice JC, Fuller Jr, Connelly AS, Abumrad N: Effect of leucine metabolite beta -hydroxy-beta -methylbutyrate on muscle metabolism during resistance-exercise training. J Appl Physiol 1996,81:2095-2104.
2. Jowko E, Ostaszewski P, Jank M, Sacharuk J, Zieniewicz A, Wilczak J, Nissen S: Creatine and β-hydroxy-β-methylbutyrate (HMB) additively increase lean body mass and muscle strength during a weight-training program. Nutr 2001, 17:558-566.
3. Nissen SL, Panton L, Wilhelm R, Fuller JC: Effect of β-hydroxy-β-methylbutyrate (HMB) supplementation on strength and body composition of trained and untrained males undergoing intense resistance training. FASEB J 1996, 10:287.
4.Panton LB, Rathmacher JA, Baier S, Nissen S: Nutritional supplementation of the leucine metabolite beta-hydroxy-betamethylbutyrate (hmb) during resistance training. Nutr 2000, 16(9):734-9.
5. Vukovich Matthew D, Adams GD: Effect of β-hydroxy β-methylbutyrate (HMB) on vo2peak and maximal lactate in endurance trained cyclists. Medicine & Science in Sports & Exercise 1997, 29(5):252.
6. Kreider RB, Ferreira M, Wilson M, Almada AL: Effects of calcium β-hydroxy-β-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength. Int J Sports Med 1999, 20(8):503-9.
7. Slater G, Jenkins D, Logan P, Lee H, Vukovich M, Rathmacher JA, Hahn AG: Beta-hydroxy-beta-methylbutyrate (HMB) supplementation does not affect changes in strength or body composition during resistance training in trained men. Int J Sport
Nutr Exerc Metab 2001, 11(3):384-96.