Beta-Hydroxy Beta-Methylbutyrate (HMB) as a Supplement for Athletes: A Scientific Review

Hey Peak Performer's,

Have you ever heard of HMB? It's been a common supplement over the past two decades and added to many multi-ingredient supplements. Beta-Hydroxy Beta-Methylbutyrate (HMB) is a metabolite of the essential amino acid leucine. It has garnered attention in the athletic community for its potential to enhance muscle mass, improve strength, and aid in recovery. Overall, while HMB might be a valuable supplement for specific populations, its benefits may be less pronounced in highly trained athletes. Below, this review aims to summarize the biochemical role of HMB, its effects on athletes, and the scientific evidence supporting or refuting its use as a dietary supplement. 

What is HMB?

HMB is produced in the body during the metabolism of leucine, a branched-chain amino acid (BCAA). Approximately 5% of dietary leucine is converted to HMB. The primary interest in HMB stems from its role in protein metabolism, particularly in reducing muscle protein breakdown and promoting muscle protein synthesis.

Mechanisms of Action

1. Anti-Catabolic Effects: HMB has been shown to reduce muscle protein breakdown by inhibiting the ubiquitin-proteasome pathway. This pathway is responsible for the degradation of damaged or unnecessary proteins within the muscle cells.

2. Anabolic Effects: By activating the mTOR pathway, HMB promotes muscle protein synthesis, aiding in muscle repair and growth. This dual action makes HMB a potent supplement for both preventing muscle loss and enhancing muscle gain.

3. Cell Membrane Stabilization: HMB may stabilize muscle cell membranes, which can reduce damage during intense exercise and improve recovery.

4. Anti-Inflammatory Properties: HMB also exhibits anti-inflammatory effects, which can help reduce muscle damage and inflammation following injury or surgery. This was highlighted in a study published in Nutrition Research, where HMB supplementation reduced markers of muscle damage and inflammation in athletes.

Effects on Athletes

The potential benefits of HMB supplementation for athletes include increased muscle mass, enhanced strength, improved recovery, and reduced muscle damage:

1. Muscle Mass and Strength: Studies have shown that HMB supplementation can lead to gains in muscle mass and strength, particularly in untrained individuals or those beginning a resistance training program. For example, Nissen et al. (1996) found that HMB supplementation in combination with resistance training resulted in greater increases in lean body mass and strength compared to a placebo group. However, muscle mass should expect to be increased in untrained athletes who being a resistance training program.

2. Recovery and Muscle Damage: HMB has been reported to reduce markers of muscle damage following intense exercise. A study by Wilson et al. (2008) indicated that athletes taking HMB had lower levels of creatine kinase (CK) and lactate dehydrogenase (LDH), enzymes associated with muscle damage, compared to a placebo group .

3. Performance in Trained Athletes: While the benefits of HMB are well-documented in novice athletes, the evidence for its effectiveness in well-trained athletes is mixed. Some studies suggest minimal to no significant improvements in performance metrics such as strength and endurance in highly trained individuals .

HMB in Athletic Injury Recovery

In athletes, muscle injuries can lead to significant downtime and loss of muscle mass and strength. HMB supplementation has been shown to mitigate these effects by preserving muscle mass and enhancing recovery. A study published in the Journal of Applied Physiology demonstrated that HMB supplementation in athletes undergoing resistance training resulted in increased muscle mass and strength compared to a placebo group . This suggests that HMB can be particularly beneficial in maintaining muscle integrity during periods of inactivity following an injury.

HMB and Post-Surgical Recovery

Post-surgical recovery, particularly following orthopedic surgeries, involves similar challenges as athletic injuries—muscle atrophy, decreased strength, and prolonged rehabilitation periods. HMB's ability to preserve muscle mass and promote protein synthesis is particularly valuable in this context. A randomized controlled trial published in Clinical Nutrition found that elderly patients undergoing hip fracture surgery who received HMB supplementation exhibited less muscle loss and improved physical function compared to those who did not receive HMB .

Practical Applications

For athletes recovering from injury, incorporating HMB supplementation can aid in preserving muscle mass and accelerating the return to training. A typical dosage of HMB is around 3 grams per day, which has been shown to be effective and safe in numerous studies .

In the context of post-surgical recovery, HMB can be particularly beneficial for elderly patients or those undergoing major orthopedic surgeries. The improved muscle retention and reduced recovery time can significantly enhance rehabilitation outcomes and overall quality of life.

Scientific Evidence Supporting HMB

1. Nissen et al., 1996: This landmark study demonstrated that HMB supplementation (3 grams per day) in conjunction with resistance training significantly increased muscle mass and strength in untrained males .

2. Wilson et al., 2013: This comprehensive review concluded that HMB supplementation can reduce muscle damage, improve recovery, and enhance gains in muscle mass and strength, particularly in untrained or moderately trained individuals .

3. Rowlands and Thomson, 2009: This study found that HMB supplementation reduced markers of muscle damage and accelerated recovery in trained athletes, though the improvements in performance were modest .

Scientific Evidence Refuting HMB

1. Kreider et al., 1999: This study involving well-trained collegiate athletes found no significant differences in body composition or strength gains between the HMB and placebo groups .

2. Slater et al., 2001: This research reported no significant benefits of HMB supplementation on performance or body composition in highly trained athletes, suggesting a potential ceiling effect where the benefits of HMB diminish as training status increases .

Conclusion

HMB supplementation appears to offer some benefits for muscle mass, strength, and recovery, particularly in untrained or moderately trained individuals. The evidence for its efficacy in well-trained athletes is less convincing, with mixed results reported. Overall, while HMB might be a valuable supplement for specific populations, its benefits may be less pronounced in highly trained athletes. Further research is needed to clarify its role and optimize dosing strategies for different athletic populations. 

My opinion would be to save your money on this supplement and focus on nutrient dense food and supplement with more scientific evidence unless used for special cases like injury recovery.

Your Sports Dietitian, 

Jordan