HMB: Uses, Benefits, Side Effects, and Dosage

As endurance athletes, we are constantly beating our bodies up through training and racing. The thousands of footsteps and pedal strokes we take creates significant damage to muscle tissue that necessitates proper rest and recovery strategies that ultimately lead to greater adaptations to exercise.

Besides taking easy or off days and slamming protein to help muscles recover, there is also one supplement that might facilitate the recovery process while also improving aerobic and anaerobic capabilities. This supplement is beta-hydroxy beta-methylbutyrate, or HMB for short.

In this article we will discuss what HMB is, what HMB does, the benefits of HMB, the research on HMB, when and how much HMB to take, and if HMB has any side effects.

What Is HMB? What Does HMB Stand For?

HMB is a performance-enhancing aid that has been demonstrated in over 50 human studies to enhance strength, power, lean mass, and improve recovery. HMB, short for beta-hydroxy beta-methylbutyrate, is a metabolite of the amino acid leucine that has both anabolic and anti-catabolic properties. This means HMB reduces muscle protein breakdown while also stimulating MPS (muscle protein synthesis).

A recent position stand by the ISSN has validated HMB’s ergogenic claims. They concluded that HMB ameliorates muscle recovery by reducing muscle damage; HMB enhances muscle size, strength, and power in a variety of populations when an appropriate exercise protocol is applied; HMB works in the young and the elderly, and HMB is safe for consumption.

What Does HMB Do?

HMB’s primary physiological functions are its ability to stabilize the cell membrane of muscles, stimulate MPS, and decrease protein breakdown. The mechanism is related to HMB’s role as an alternate substrate for cholesterol creation.

The obstruction of cholesterol synthesis results in decreased muscle functions increased damage to muscles, and finally, muscular death. To help maintain membrane integrity, muscle cells count on cholesterol synthesis. Increased intramuscular HMB can provide an available substrate for the creation of cholesterol needed to form and stabilize the cell membrane of the muscle.

HMB has been demonstrated to stimulate muscle protein synthesis via activation of the mTOR pathway and to decrease muscle breakdown by influencing the UPD pathways of protein breakdown. In non-geek speak, HMB shifts the balance of protein synthesis, tipping the scale in muscle’s favor. When protein synthesis is equal to protein breakdown, there is no net gain of muscle protein. This is important in maintaining/increasing strength and promoting recovery.

HMB Benefits

The benefits of HMB as demonstrated by the research are:

  • Stimulates muscle protein synthesis.
  • Reduces muscle protein breakdown.
  • Improves recovery.
  • Decreases muscle damage.
  • May increase power output.
  • Decreases fat mass.
  • Improves aerobic and anaerobic running capacity.

Research On HMB

HMB has been very well studied in athletes, by itself and in combination with other supplements like creatine.

50 plus human clinical studies, 20 reviewed articles, and 2 meta-analyses published in peer-reviewed journals have shown HMB’s effectiveness in increasing lean body mass and strength, decreasing muscle damage, and minimizing muscle soreness.

HMB’s benefits have been demonstrated in both trained and untrained populations, both sexes, and in the young and elderly. Let’s take a look at a few studies examining HMB’s performance-enhancing effects.

HMB supplementation ameliorates strength, power, and body composition

  • A 1996 study by Nissen et al. found that strength training in combo with HMB supplementation for four weeks resulted in greater upper body strength and greater increases in lean body mass in both men and women when compared to placebo.
  • A 2016 study conducted by Wilson et al. researched the effects of twelve weeks of HMB and ATP supplementation on lean body mass, strength, and power in trained subjects. A three-phase double-blind, placebo, and diet-controlled study was conducted. Phases consisted of an eight week periodized resistance-training program (phase 1), followed by a 2-week overreaching cycle (phase 2), and a 2-week taper (phase 3).

Lean body mass was increased with a combination of HMB/ATP by 12.7%. Strength gains after training were increased in HMB/ATP-supplemented subjects by 23.5%. Vertical jump and Wingate power also increased by 21.5% and 23.7%. During the overreaching cycle, strength and power decreased in the placebo group whereas supplementation with HMB/ATP resulted in continued strength gains. In summary, HMB and ATP in combination with strength training improved lean body mass and muscular power and strength.

  • A 2011 study run by Muller set out to determine whether HMB supplementation would increase lean body mass and muscle power output in men who resistance trained recreationally, after a combination of strength training, consuming a balanced set diet and, supplementation with HMB for eight weeks.

Two near identical groups of 20 males were tested for initial strength capabilities and body composition. For eight weeks, the subjects strength trained 3 times a week and followed a balanced diet. Markers of muscle damage (creatine kinase) decreased with HMB supplementation. Gains in power output were greater in the experimental group compared to placebo, and decreases in body fat were observed with HMB supplementation.

HMB supplementation decreases muscle damage and improves recovery

  • A 2013 study run by Wilson et al. examined the effects of short-term supplementation with HMB on markers of muscle damage, muscle protein breakdown, recovery, and hormone status following a high-volume strength training protocol with athletes. 20 strength-trained men participated in a high-volume resistance training session that focused on full squats, bench presses, and deadlifts.

Subjects randomly received either 3 grams of HMB or placebo. Before the exercise session and 48 hours post-workout, creatine kinase (CK), 3-MH, testosterone, and cortisol measurements were taken. The results showed that CK increased to a greater extent in the placebo than in the HMB group.

HMB supplementation enhances aerobic capacity

  • A 2016 double-blinded, placebo-controlled, crossover design study conducted by Jeszka et al. discovered subjects who supplemented HMB improved aerobic metabolism, VO2 max, time to ventilatory threshold, and power at ventilatory threshold compared to placebo.
  • A 2015 double-blind, placebo-controlled, crossover study conducted by Michalski et al. discovered 16 elite rowers who supplemented with HMB for 12 weeks were able to increase VO2 max, time to ventilatory threshold, threshold load, and threshold heart rate.
  • A 2001 double-blind switchback study conducted by Vukovich et al. conducted by Vukovich et al. demonstrated that HMB supplementation increased endurance as measured by VO2 peak and lactate threshold in trained cyclists.

When/How To Take HMB

The recommended dosage of HMB is one to three grams per day for average-size individuals. If you want to “customize” your dosage, research has shown that 38 mg per kg or 17 mg per pound of body weight each day is optimal.

It is recommended to take HMB one hour before exercise to help minimize muscle damage. If you can’t take HMB before exercise, then take a dose immediately after your workout.

HMB Side Effects

HMB supplementation up to 3g daily appears to be very well tolerated, and it is assumed that higher doses are safe as well. Overall, there should be no safety concerns when supplementing with beta-hydroxy beta-methylbutyrate (HMB).

The Bottom Line On HMB

For endurance athletes, HMB appears to be a safe and effective supplement that can improve aerobic and anaerobic running capacity and enhance recovery. When taken as a supplement, HMB should be dosed at 1-3 grams daily and ideally be taken before bed. This dose can also be split into 2 equal doses and taken 2 times a day.

HMB also stacks well with creatine with multiple studies demonstrating greater results when both are taken together.

About The Author Matt Mosman - Spearfish, South Dakota

Matthew Mosman South Dakota

Matt Mosman (MS, CISSN, CSCS) is a research scientist, endurance athlete, and the founder and Chief Endurance Officer at EndurElite. Matt holds his B.S. in Exercise Science from Creighton University and his M.S. in Exercise Physiology from the University of California. Matt and his family reside in Spearfish South Dakota where they enjoy running, mountain biking, camping, and all the outdoor adventures Spearfish has to offer.


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