ISSN Updates Position Stand on HMB: Key Takeaways and Insights

On December 19, 2024, The International Society of Sports Nutrition (ISSN) released an updated position stand on β-Hydroxy-β-Methylbutyrate (HMB), shedding new light on its efficacy and applications in sports nutrition.^[1]

ISSN Updates Its HMB Position Stand

ISSN’s updated position stand on HMB reinforces its role in muscle health and performance. Key findings show it’s safe, effective for muscle growth and recovery, and works best when timed around training. Best part? Benefits seen across all ages and fitness levels!

The International Society of Sports Nutrition (ISSN) has recently updated its position stand on β-Hydroxy-β-Methylbutyrate (HMB),^[1] a widely studied supplement in the realm of sports nutrition. Their comprehensive review provides valuable insights into HMB’s safety, delivery formats, mechanisms of action, and its effects on muscle performance, recovery, and overall body composition.

What is HMB?

HMB is a metabolite of the essential amino acid leucine. Leucine is naturally found in high-protein foods like meats, and HMB is produced in the human body and also found in certain foods. HMB has garnered attention for its potential to enhance muscle growth, reduce muscle breakdown, and improve recovery — making it a popular supplement among athletes and fitness enthusiasts.

Forms of myHMB from TSI Group

Sold as myHMB by TSI Group, there are two primary forms of HMB used in supplementation:

1. Calcium HMB (HMB-Ca): The original form studied extensively over the past decades.
2. Free Acid HMB (HMB-FA): A newer form that may lead to higher plasma HMB levels compared to HMB-Ca, though recent studies show mixed results.

This article details the key findings from the updated ISSN Position Stand. Before going further, be sure to sign up for our myHMB and TSI Group news alerts:

Key Findings from the ISSN Position Stand

The ISSN’s updated position stand encompasses 12 critical points regarding HMB’s efficacy and application:

1. Natural Occurrence and Forms

   • HMB is a naturally occurring compound in humans and animals.
   • HMB-FA may increase HMB levels in the bloodstream more effectively than HMB-Ca, but recent evidence is inconclusive.

   HMB is produced naturally in the human body during the metabolism of the essential amino acid leucine, which is abundant in high-protein foods like meat, fish, and dairy products. This means HMB is not foreign to our system but is a compound our bodies are already familiar with, contributing to its safe profile as a supplement.^[1]

   There are two primary supplemental forms of HMB: Calcium HMB (HMB-Ca) and Free Acid HMB (HMB-FA). Some research suggests that HMB-FA may be absorbed more efficiently, leading to higher plasma HMB levels compared to HMB-Ca. However, recent evidence is inconclusive, and the ISSN notes that more studies are needed to determine if one form offers significant advantages over the other in terms of absorption and efficacy.

2. Safety Profile

   • Chronic consumption of both HMB-Ca and HMB-FA is considered safe for humans, with studies supporting use for at least one year without adverse effects.

   Extensive research has demonstrated that both HMB-Ca and HMB-FA are safe for human consumption, even with long-term use. Studies spanning up to a year have shown no adverse effects on liver and kidney function, blood parameters, or overall health markers. This strong safety profile supports HMB’s use as a supplement for individuals aiming to enhance muscle health and performance without compromising their well-being.^[1]

3. Glucose Metabolism

   • No negative impacts on glucose tolerance or insulin sensitivity have been observed in humans.
   • Potential improvements in glucose metabolism may occur in younger adults.

   

   Studies indicate that HMB supplementation does not negatively impact glucose tolerance or insulin sensitivity in humans. In some cases, particularly among younger adults, HMB may even improve aspects of glucose metabolism. It could potentially contribute to more efficient energy utilization during exercise and recovery by enhancing insulin sensitivity and facilitating better glucose uptake by muscle cells. However, further research is needed to fully understand these effects across different populations.^[1]

4. Mechanism of Action

   • HMB enhances muscle protein synthesis and suppresses muscle protein breakdown.
   • Activates the mTORC1 pathway independently of the leucine-sensing mechanism (Sestrin2-GATOR2 complex).

   HMB promotes muscle growth by enhancing muscle protein synthesis and inhibiting muscle protein breakdown. It activates the mTORC1 pathway, a crucial regulator of cell growth and muscle mass, independently of the leucine-sensing mechanism involving the Sestrin2-GATOR2 complex.^[1]

   This means HMB can stimulate muscle-building processes even when leucine levels are sufficient. Additionally, HMB suppresses muscle degradation pathways, such as the ubiquitin-proteasome system, reducing muscle protein breakdown and preserving muscle mass.

5. Muscle Damage and Recovery

   • HMB may reduce muscle damage and promote recovery, aiding in muscle growth and repair.
   • Exhibits anti-inflammatory properties that could contribute to decreased muscle soreness.
   

   Don’t call it a comeback – HMB is here to prevent muscle breakdown

   HMB supplementation has been shown to reduce markers of muscle damage following intense or prolonged exercise.^[1] By decreasing muscle protein breakdown and supporting muscle cell integrity, HMB aids in quicker recovery between workouts. Its anti-inflammatory properties may also help reduce delayed onset muscle soreness (DOMS), allowing athletes to train more frequently with less discomfort. This combination of effects contributes to improved muscle repair and growth over time.

6. Timing of Consumption

   • Consuming HMB close to exercise bouts may enhance muscle protein synthesis and reduce inflammatory responses.
   • Beneficial effects are noted with both acute and chronic consumption.

   The timing of HMB intake can influence its effectiveness. Consuming HMB close to exercise sessions, particularly within an hour before training, may maximize its ability to enhance muscle protein synthesis and mitigate inflammatory responses induced by exercise. Both acute (short-term) and chronic (long-term) supplementation strategies have demonstrated benefits, suggesting that consistent intake of HMB around workout times can support optimal training adaptations.^[1]

7. Body Composition

   • Daily supplementation at approximately 38 mg/kg body weight may improve body composition by increasing lean mass and/or decreasing fat mass.
   • Benefits are observed across various ages, sexes, and training statuses.
   • Most pronounced effects seen in studies with rigorous resistance training and dietary control.
   

   Come to the next ISSN Conference!

   Supplementing daily with approximately 38 milligrams of HMB per kilogram of body weight has been associated with improvements in body composition, including increased lean muscle mass and reduced fat mass. This equates to roughly 3 grams of HMB per day for a 175 pound person.^[1]

   These benefits have been observed across various populations, regardless of age, sex, or initial fitness level. The most significant effects are seen in individuals participating in rigorous resistance training programs with controlled diets, highlighting the importance of combining HMB supplementation with appropriate exercise and nutrition strategies.

8. Strength and Power Performance

   • HMB may improve strength and power in untrained individuals.
   • In trained athletes, performance benefits are mixed but tend to increase with longer supplementation periods (over six weeks).
   • Enhanced recovery is a significant contributor to performance improvements.

   HMB may enhance strength and power output, especially in untrained individuals beginning a new exercise regimen. In trained athletes, the results are mixed; however, studies suggest that longer supplementation periods exceeding six weeks may yield more noticeable performance improvements.^[1]

   The primary mechanism appears to be HMB’s ability to reduce muscle damage and accelerate recovery, enabling athletes to train harder and more frequently, which over time can lead to greater gains in strength and power.



About 5% of leucine breaks down into HMB. Below, we’ll discuss HMB vs. Leucine — and how 5% from most diets simply isn’t optimal, so we can supplement more!

9. Aerobic Performance

   • Potential positive impact on aerobic performance, especially in trained athletes.
   • The exact mechanisms remain unclear and warrant further research.

   Emerging evidence indicates that HMB might positively impact aerobic performance, particularly in trained athletes engaged in endurance sports. While the exact mechanisms remain unclear, it’s hypothesized that HMB’s role in reducing muscle protein breakdown and enhancing recovery contributes to improved endurance by delaying fatigue and maintaining muscle function during prolonged exercise. Additional research is necessary to fully understand how HMB influences aerobic capacity and endurance performance.^[1]

10. Applications in Aging Populations

    • HMB supplementation may improve muscle strength, functionality, and quality in sedentary and aging individuals.
    • When combined with exercise, it may benefit the treatment of age-related muscle loss (sarcopenia) under specific conditions.

    In sedentary and aging individuals, HMB supplementation has been shown to improve muscle strength, functionality, and quality of life. Age-related muscle loss, known as sarcopenia, poses significant health risks, including reduced mobility and increased frailty. When combined with exercise, HMB may help counteract sarcopenia by stimulating muscle protein synthesis and inhibiting breakdown, thereby preserving or increasing muscle mass and strength under specific conditions.^[1]



Read the full story in PricePlow’s main HMB Supplements article.

11. Counteracting Muscle Atrophy

    • May be effective in preventing muscle loss during periods of inactivity due to illness or injury.
    • Influences mitochondrial dynamics and lipid metabolism, contributing to muscle preservation.

    HMB may be effective in preventing muscle loss during periods of inactivity, such as bed rest due to illness or injury. It influences mitochondrial dynamics and lipid metabolism, which are critical for maintaining muscle health.^[1]

    By promoting anabolic processes and suppressing catabolic pathways, HMB helps preserve muscle mass and function even when physical activity is limited, aiding in faster recovery and rehabilitation once activity is resumed.

12. Synergistic Effects with Other Nutrients

    • The efficacy of HMB can be enhanced when combined with certain nutrients under select conditions.
    • Co-supplementation with amino acids like arginine, glutamine, and others may amplify benefits.

    The benefits of HMB can be enhanced when combined with other nutrients. Co-supplementation with amino acids like arginine and glutamine has been shown to amplify HMB’s effects on muscle growth and recovery. Additionally, pairing HMB with other supplements such as creatine or ATP (sold as Peak ATP) may offer additive benefits, potentially leading to greater improvements in muscle strength, endurance, and overall performance. Vitamin D status is also critically important to the success of HMB.

    These synergistic interactions highlight the potential of HMB as part of a comprehensive nutritional strategy under select conditions.

Shawn Baier joins PricePlow Podcast Episode #093 to talk HMB.

Practical Implications of HMB

• For Athletes and Fitness Enthusiasts

  • Supplementation Dosage: Approximately 3 grams per day is commonly used in studies.
  • Timing: Consuming HMB close to training sessions may maximize benefits.
  • Training Status: Untrained individuals may experience more immediate benefits, while trained athletes might require longer supplementation periods to notice performance enhancements.

• For Aging Populations

  • HMB may serve as a nutritional strategy to combat age-related muscle decline.
  • Can improve muscle function and quality, potentially enhancing quality of life.

• Combining with Other Nutrients

  • Protein: HMB may work synergistically with high-quality protein sources to promote muscle growth.
  • Other Supplements: Combining HMB with creatine or vitamin D (or simply better UV light exposure) may offer additional benefits, though individual responses can vary. Peak ATP may also be a synergistic supplement to support muscle building, blood flow, and overall energy production.

Conclusion: As Good As It Ever Was

The ISSN’s updated position stand reaffirms HMB’s safety and potential benefits in muscle health, performance, and recovery. While individual results may vary based on factors like age, training status, and diet, HMB remains a promising supplement for those seeking to enhance their fitness and overall muscle function.

Further Reading and Listening

For those looking to delve deeper into HMB, consider reading our article titled “HMB (β-hydroxy β-methylbutyrate): Performance-Driven Muscle Supplement” and listening to PricePlow Podcast Episode #093 featuring Shawn Baier: “HMB – Everything You Need to Know”:

• Article: “HMB (β-hydroxy β-methylbutyrate): Performance-Driven Muscle Supplement“
• PricePlow Podcast: Episode #093 with Shawn Baier: HMB – Everything You Need to Know