Research By Focus

Muscle and Strength

β-Hydroxy-β-methylbutyrate and its impact on skeletal muscle mass and physical function in clinical practice: a systematic review and meta-analysis.

A systematic review and meta-analysis of fifteen randomized controlled trials was conducted to investigate the efficacy of HMB alone, or supplements containing HMB on skeletal muscle mass and physical function. After reviewing the evidence the authors concluded that HMB and supplements containing HMB increased muscle mass and strength in a variety of clinical conditions.

HMB supplementation in trained and untrained individuals

In a comprehensive review of HMB studies over the past two decades, the authors examine HMB efficacy. This review also examines why many newer studies, longer in length than some of the original studies and also conducted with HMB in the free acid form, are suggestive of stronger efficacy in both trained and untrained populations. The authors concluded that recent studies utilizing high-intensity training have demonstrated HMB efficacy in maintaining muscle mass and attenuating the inflammatory response. In particular these studies show improved efficacy of HMB free acid in trained athletes.

The Effect of β-Hydroxy-β-Methylbutyrate on Aerobic Capacity and Body Composition in Trained Athletes.

The effects of HMB supplementation in highly-trained combat sport athletes (wrestlers, judokas, and Brazilian jiu-jitsu) was studied.  The athletes maintained their usual daily training and dietary regimens during the placebo-controlled crossover study. HMB supplementation resulted in an increase in lean body mass and decrease in fat mass compared with placebo supplementation.  In addition HMB supplementation resulted in increased aerobic capacity and anaerobic peak power. The authors concluded that for combat sport athletes, HMB promotes advantageous changes in body composition and aerobic and anaerobic capacity.

The addition of beta-hydroxy-beta-methylbutyrate and isomaltulose to whey protein improves recovery from highly demanding resistance exercise.

This study in resistance-trained college-aged men measured recovery from 3 consecutive days of intense resistance training.  The training regimen consisted of heavy resistance raining on day one and metabolic resistance training on days 2 and 3. HMB addition to the whey protein supplemented in the study improved recovery by decreasing creatine kinase levels, decreasing inflammatory IL-6, and decreasing pain assessment during recovery.  Vertical jump power during recovery was also increased compared to those supplemented with whey protein alone. The authors concluded that the addition of HMB to whey protein enhanced the recovery benefits and athletic performance.

Influence of HMB supplementation and resistance training on cytokine responses to resistance exercise.

This 12-week study was conducted in college aged-men undergoing a resistance training program and supplemented with HMB (plus arginine and glutamine).   At baseline, 6, and 12 weeks an acute exercise protocol was administered. Similar to another recent study by Hoffman et al with BetaTOR HMB, HMB supplementation attenuated the inflammatory markers interferon-gamma (IFN-γ), interleukin 10 (IL-10), and interleukin 1β (IL-1β) after the acute exercise protocol.

International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB).

This publication is the International Society of Sports Nutrition position stand on the efficacy of HMB use in sports nutrition and combines a comprehensive review of HMB with the official position of the ISSN on HMB use.  The position statements included in this paper were reviewed and approved by the Research Committee of the ISSN. Based upon this comprehensive review of HMB literature, the primary position statements were that HMB enhances muscle recovery by attenuating muscle damage; HMB increases muscle hypertrophy, strength, and power in trained and untrained populations when the appropriate exercise protocol is applied; HMB efficacy is manifested in young and old; and HMB is safe to consume.

Effect of calcium β-hydroxy-β-methylbutyrate (CaHMB) with and without resistance training in men and women 65+yrs: a randomized, double-blind pilot trial.

Two groups of older men and women (> 65 years of age) were studied for 24 weeks.  One group was sedentary and one group underwent resistance training. Within each group participants were also randomized to either a placebo or HMB treatment. The researchers concluded that resistance training was an effective intervention for improving muscle strength and function in older adults, but may be of limited benefit in the population as a whole because of compliance issues.  The study also showed that HMB improves strength and muscle quality in sedentary older adults. Therefore, HMB may be a nutritional intervention to prevent sarcopenia in older adults.

Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults.

In this study older men and women (average age ~67 years) were randomized to receive either HMB or placebo treatments during 10 days of bed rest.  While the placebo group lost lean body mass due to this period of inactivity, the HMB group maintained lean body mass. In conclusion, during at least a 10 day period of inactivity, HMB preserves lean body mass in healthy older adults.

The effect of HMB supplementation on body composition, fitness, hormonal and inflammatory mediators in elite adolescent volleyball players: a prospective randomized, double-blind, placebo-controlled study.

This randomized, double-blind, placebo-controlled study examined HMB supplementation in young male and female elite volleyball players for 7 wks.  HMB supplementation resulted in improved body composition and significantly increased strength, while also decreasing fat mass percentage. HMB supplementation also increased peak and mean anaerobic power.  No changes in hormones or inflammatory mediators were seen in this study.

Vitamin D status affects strength gains in older adults supplemented with a combination of β-hydroxy-β-methylbutyrate, arginine, and lysine: a cohort study.

This year-long retrospective study in elderly adults demonstrated that a nutrient mixture of HMB, arginine, and lysine alone was effective in improving body composition regardless of vitamin D status, but accompanying strength increases were observed only when participants also had adequate vitamin D status indicating a synergistic effect between the HMB, arginine, and lysine and vitamin D.

Effects of beta-hydroxy-beta-methylbutyrate supplementation during resistance training on strength, body composition, and muscle damage in trained and untrained young men: a meta-analysis.

This recent meta-analysis was conducted on the effects of HMB in younger men participating in resistance-training programs.  The data were broken into trained and untrained subject groups. The authors concluded that HMB supplementation resulted in clear overall increases in strength in men entering a resistance training program, but that the benefit of HMB in trained athletes was smaller.

Effects of nine weeks of beta-hydroxy-beta- methylbutyrate supplementation on strength and body composition in resistance trained men.

In this 9-week, randomized, double-blind, placebo-controlled study, HMB improved body composition and decreased fat mass which resulted in a substantial increase in lower body strength.

Year-long changes in protein metabolism in elderly men and women supplemented with a nutrition cocktail of beta-hydroxy-beta-methylbutyrate (HMB), L-arginine, and L-lysine.

In this year-long, double-blind, placebo-controlled study in the elderly, daily supplementation with HMB, arginine, and lysine resulted in improved body composition and protein turnover.

Effects of amino acids supplement on physiological adaptations to resistance training.

This randomized, double-blind, placebo-controlled study tested the effects of EAS Muscle Armor® (main ingredients HMB, arginine and glutamine) in resistance-training men in a 12 week study.  This study showed that supplementation with Muscle Armor® improved the effects of the training on improving body composition and increasing fat loss compared with placebo supplementation. Muscle Armor® beneficially improved hormonal markers associated with intense resistance exercise and improvement in body composition.  Muscle Armor® also resulted in greater increases in strength, power, thigh circumference, and decreased indicators of muscle damage.

Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review

This independent, peer-reviewed paper discusses the critical details of HMB studies and the variables affecting the results of these studies.  Included is a review of the current research showing how HMB works (metabolic mechanisms). This paper concludes that collectively there is not only clinical data, but also mechanistic data supporting HMB’s effect on improving body composition and increasing muscle strength.

Effects of six weeks of beta-hydroxy-beta-methylbutyrate (HMB) and HMB/creatine supplementation on strength, power, and anthropometry of highly trained athletes.

Subjects’ ethical backgrounds prevented this study from being conducted as a double-blind, placebo-controlled study; however, a placebo treatment was utilized.  Using skin-fold data reported in this paper, results demonstrated a numerical improvement in body composition with HMB supplementation. This calculation was however not reported in the paper.

Beta-hydroxy-beta-methylbutyrate supplementation in critically ill trauma patients.

This placebo-controlled, double-blind clinical study of HMB in critically injured patients suggests that HMB can improve nitrogen balance in severely injured trauma patients.

ß-Hydroxy-ß-methylbutyrate. In J.A. Driskell (Ed.) Sports Nutrition: Fats and Proteins

This chapter in the CRC series of desk references for professional nutritionists and trainers discusses the origins, mechanisms, uses, safety, and results of HMB supplementation in both healthy individuals and those experiencing unwanted muscle loss.

Effect of beta-hydroxy-beta-methylbutyrate, arginine, and lysine supplementation on strength, functionality, body composition, and protein metabolism in elderly women.

In two independent double-blind, randomized, placebo-controlled clinical studies in elderly women, data from both of the studies studies demonstrate that a nutritional mixture of HMB, arginine, and lysine can enhance whole body protein synthesis and improve functionality in elderly women.

The effect of beta-hydroxy beta-methylbutyrate on muscular strength and body composition in collegiate football players.

This study was a double-blind, randomized crossover study in 35 training collegiate football players. This study was performed with highly trained athletes undergoing an intense training program.  Although this study failed to show significant differences, HMB-supplemented subjects showed improved body composition and a decrease in body fat.

Effect of dietary supplements on lean mass and strength gains with resistance exercise: a meta-analysis.

This meta-analysis of dietary supplements used to improve body composition and strength with resistance-exercise training shows that few supplements used as ergogenic aids have two or more peer-reviewed studies.  Only HMB and creatine have been shown to significantly improve body composition and increase strength gains with exercise.

Body composition in 70-year-old adults responds to dietary beta-hydroxy-beta-methylbutyrate similarly to that of young adults.

This paper reports a double-blind, randomized study in elderly men and women participating in a weight training exercise program. In this 8-week study in older adults, HMB tended to increase muscle strength and improve body composition while significantly increasing fat loss.

Creatine and beta-hydroxy-beta-methylbutyrate (HMB) additively increase lean body mass and muscle strength during a weight-training program.

This study reported the effects of HMB and creatine in a double-blind, randomized study in weight-training males. The results showed that HMB combined with creatine supplementation results in even greater strength gains and improvements in body composition than either HMB or creatine supplementation alone.

HMB supplementation during resistance training in trained men

In this double-blind, randomized study in trained male athletes undergoing a weight-training program, HMB supplementation numerically increased strength and improved body composition; however, the gains were not significantly greater than those of the placebo group.

Beta-hydroxy-beta-methylbutyrate ingestion, Part I: effects on strength and fat free mass.

In this double-blind, randomized study with male weightlifters, either three or six grams of HMB were consumed per day. HMB improved body composition, increased peak muscle torques, and decreased plasma CPK after resistance training with no added benefit seen from consuming the higher level.

Nutritional supplementation of the leucine metabolite beta-hydroxy-beta-methylbutyrate (hmb) during resistance training.

Two double-blind randomized studies including males and females and trained and untrained weightlifters. Both studies showed that regardless of gender or prior training, HMB increases strength and minimizes muscle damage when combined with a four-week resistance-training program.

Effects of calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength.

This paper describes a four-week, randomized, placebo-controlled study of 40 experienced resistance-trained males. In this study the trained athletes consumed either three or six grams of HMB per day. While not statistically significant, HMB consumption resulted in improved body composition and numerically greater strength gains.

Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training.

Two double-blind, placebo-controlled, randomized studies were conducted in weight training males. In these separate studies, one for three weeks and one for seven weeks, it was found that supplementing three grams of HMB to exercising humans improved body composition, increased strength, and reduced muscle damage.