HMB Supplementation Also Works in Trained Subjects

While the positive effect of HMB on body composition and strength in untrained subjects is not controversial, the case doesn’t seem so for trained subjects but not for lack of positive data! 

Written by
Sérgio Fontinhas, CISSN

Key points: 

1. Studies lasting 6 weeks or less are too short to show positive results from HMB in trained subjects. 

2. Studies lasting more than 6 weeks can show positive results. 

3.Positive results also depend of training intensity, volume and supervision.

In short, HMB is an anti-catabolic supplement and a metabolite from the aminoacid leucine. HMB supplementation can increase plasma and intramuscular HMB concentrations compared to leucine, stimulate muscle protein synthesis to a slight lower degree than leucine, and produce decreases in muscle protein breakdown (1).

It has been shown to increase lean body mass, decrease body fat, and improve performance in untrained or sedentary (and old) populations. HMB also speeds recovery, decreases muscle damage and provides a favorable anabolic hormonal environment. 

In trained subjects results are mixed and confounded by study duration, exercise intervention and supervision.

In a few meta-analysis (pooling results from different studies grouped according to specific criteria): 

1. “HMB was found to significantly increase net lean mass gains of 0.28%/wk and strength gains of 1.40%/wk” in both trained and untrained healthy adults” (2). 

2. “Supplementation with HMB during resistance training incurs small but clear overall and leg strength gains in previously untrained men, but effects in trained lifters are trivial. The HMB effect on body composition is inconsequential” (3). 

3. “Beta-hydroxy-beta-methylbutyrate supplementation contributed to preservation of muscle mass in older adults. HMB supplementation may be useful in the prevention of muscle atrophy induced by bed rest or other factors” (4). 

4. The latest meta-analysis found “no effect of HMB supplementation on strength and body composition in trained and competitive athletes" (5).

However, meta-analysis are as good as the studies they include, so let’s take a closer look at the latest one.

The meta-analysis included RCTs that examined the effect of HMB supplementation interventions on modification in bench and leg press strength, body mass, fat-free mass and fat mass. Six studies were selected comprising a total of 193 participants.

"Range duration of intervention was between 0.4 and 12 weeks, the mean was 6.8 ± 3.1”.

They also point out “a large variability of training protocols (i.e. work load, intensity, years of sports experience, etc.), making it difficult to accurately compare the results of these studies." 

There are several problems with this meta-analysis. 

1.  Study duration 

First, the mean study duration was about 6 weeks. This is problem number one. In the Issn position stand on HMB (6) it is stated:

"The majority of studies in trained individuals lasting six weeks or less found little to no significant differences with HMB-Ca compared to a placebo [15,18,19,26]. However, those lasting longer than six weeks generally elicited positive effects in strength, and FFM [7,22,42]. "

Let´s take a closer look at these studies. The first one cited lasted only 28 days and assigned 40 experienced (5.5 years) resistance-trained athletes fortified to a carbohydrate/protein powder containing either 0, 3 or 6 g x d(-1) of calcium HMB. Results indicated that: 28 d of HMB supplementation (3 to 6 g x d(-1)) during resistance-training does not reduce catabolism or affect training-induced changes in body composition and strength in experienced resistance-trained males" (7). 

In addition to only lasting 28 days, training wasn´t supervised and “Subjects maintained their usual individualized training program and recorded all training on training log sheets during the supplementation period.” This will be important later on.

They also suggest that “it is possible that untrained subjects initiating training may obtain greater benefit from HMB supplementation than experienced resistance trained athletes. Second, it is possible that athletes undergoing intense training may need to supplement their diet with larger doses of HMB in order to obtain ergogenic benefit.” (This is already from 1999). 

Another study cited lasted only… 10 days?! Although “cortisol concentrations were significantly decreased from PRE to POST", results suggested that "short duration HMB supplementation does not provide any ergogenic benefit in collegiate football players during pre season training camp" (8).

Another had subjects with a minimum of 2 years of experience who ingested 3 g x day(-1) of HMB or placebo for 6 weeks. In this one, resistance training program were prepared and monitored at each training session, and body composition assessed by DEXA. Results again suggested that "6 weeks of HMB supplementation in either SH or TRH form does not influence changes in strength and body composition in response to resistance training in strength-trained athletes" (9). 

Now, the studies lasting more than 6 weeks: 

One was a 2 part study lasting 7 weeks. In study 1, subjects (n = 41) were randomized among three levels of HMB supplementation (0, 1.5 or 3.0 g HMB/day) and two protein levels (normal, 117 g/day, or high, 175 g/day) and weight lifted for 1.5 h 3 days/wk for 3 wk. In study 2, subjects (n = 28) were fed either 0 or 3.0 g HMB/day and weight lifted for 2–3 h 6 days/wk for 7 wk. 

HMB significantly decreased the exercise-induced rise in muscle proteolysis during the first 2 wk of exercise and plasma creatine phosphokinase, and increased fat-free mass compared with the unsupplemented group at 2 and 4–6 wk of the study.

They concluded: "Supplemention with either 1.5 or 3.0 g HMB/day can partly prevent exercise-induced proteolysis and/or muscle damage and result in larger gains in muscle function associated with resistance training" (10). 

In study 1 subjects trained 3 times per week and performed 3 sets of 3–5 repetitions at 90% of 1 RM. When necessary, weights were adjusted to assure failure on the third to fifth repetitions. Importanty “Weight lifted was increased by HMB supplementation when compared with the unsupplemented subjects during each week of the study (linear increase)”.

In study 2, the exercise regimen consisted of weight training 6 days per week, which included work on all major muscle groups, and lasted from 2 to 3 h/day, with some aerobic training at least three times per week.

The body-composition showed 1–1.8 kg of fat lost over the 3-wk period (first study), and lean tissue gain tended to increase in a dose-responsive manner with HMB supplementation (0.4, 0.8, and 1.2 kg lean gain for 0-, 1.5-, and 3.0-g HMB groups, respectively; P < 0.11, linear). However body composition was measured by total body electrical conductivity. There was no significant effect of protein level on body weight change.

Researchers underlined “The resistance-exercise regimen used in study 1 resulted in marked anabolic response with weight training, although in the second study where the frequency and length of exercise were longer, the net effects of resistance exercise without HMB supplementation appeared to be minimal.” 

In a 9 week study examining the effects of HMB supplementation in trained men, based on skinfolds and BIA estimates “HMB had a decreasing (although inconclusive) influence on fat mass of -9 +/- 14%, but it had a clear, trivial effect on fat-free mass of 0.2 +/- 2.2%.” They concluded: "In previously trained men, supplementation of HMB in conjunction with resistance training provides a substantial benefit to lower-body strength, but has negligible effect on body composition" (11). 

In this study, the weight was increased during the following session to permit progressive adaptation. Although average energy intake and fat intake increased in the HMB group, no differences evident between groups regarding changes in carbohydrate and protein intake throughout the study duration. There was only a small correlation between percent change in fat intake per kilogram of body weight with percent change in leg extension lift in the HMB group.

Importantly they state:

“Although it is possible that our resistance training program was not intense enough to elicit sufficient muscle damage and protein catabolism to allow for an HMB-induced attenuation of protein breakdown or stimulation of protein synthesis, several previous studies using very intensive training programs have also failed to show ergogenic effects of HMB in trained individuals (13,14,27).”

The other studies cited (13,14,27) lasted less than 6 weeks, including the one previously mentioned of 28 days, and another with 4 weeks, both included the latest meta-analysis! 

2. Timing and duration 

Briefly, the HMB anti-catabolic effects could only become apparent in the third week after starting supplementation (10). In the study from 1996 previously mentioned (the 2 part study), CK concentrations (indirect marker of muscle damage) weren’t significantly reduced until the third week of training.

So it makes sense positive results are mostly seen in interventions lasting more than 6 weeks. 

3. Supervised vs unsupervised training 

From the issn position stand again: 

"The most recent study using HMB-Ca was conducted by Thomson and colleagues [22]. These researchers supplemented individuals with reportedly one year or more of resistance training experience with 3 g of HMB-Ca or a placebo while performing a linear (periodized) resistance-training program. Subjects were asked to follow the program for nine weeks; however, they were not monitored. Subject compliance to the training program was on average 84 ± 22%. 

This study was the 9 week study previously mentioned (11).   

They continue:

“First, a 20% lack of compliance lowers overall training frequency, which decreases the probability of optimizing HMB’s effects on recovery rate. Second, research demonstrates that directly supervised, heavy-resistance training results in a greater rate and magnitude of training load increases in resistance-trained individuals [47].”

Indeed “Mean training loads (kg per set) per week were significantly greater in the SUP group than the UNSUP group at weeks 7 through 11 for the squat, and weeks 3 and7 through 12 for the bench press exercises" (12).

They continue “Moreover, supervised training results in greater maximal strength gains compared with unsupervised training [48].” 

Again it is shown that: "Overall the average self-selected intensity for all exercises was approximately 51.4% in PT group and approximately 42.3% in the No PT group. Under the supervision of a personal trainer leads to greater initial 1RM strength values, self-selection of greater workout intensities, and greater ratings of perceived exertion values during resistance exercise” (13). 

More on this from other studies: 

- "Members whose training is directed by well-qualified PTrs administering evidence-based training regimens achieve significantly greater improvements in LBM and other dimensions of fitness than members who direct their own training" (14). 

- "Most individuals can perform a number of repetitions well above the 10repetitions predicted for the self-selected 10RM load" (15). 

- "Results show that subjects do not select a lifting intensity sufficient to induce hypertrophic responses and subsequent strength increases" (16).

The issn position stand continues:

“For this reason it is likely that the training stimulus and frequency in this nine week study (11) did not exploit HMB’s capacity to speed recovery under maximal, and constantly varying training stimuli."

And about yet another study mentioned (17) in the issn position stand, “when the training protocol consisted of very high intensity loads (>80 % 1-RM) which were consistently adjusted as subject tolerance for a given weight increased, the HMB-Ca group showed greater decreases in body fat, increases in bench press strength (7.5 kg vs. 5.2 kg, respectively); and LBM (1.4 kg vs.0.9 kg, respectively). These changes were independent of training experience.” No dietary data was presented.

These positive results were seen despite the short duration of only 4 weeks!  All subjects trained three times per week for 4 wk. Diets weren’t evaluated in this study. Body composition by underwater weighing and skinfolds before the underwater weighing procedures to evaluate any regional changes that may have occurred.

About the training protocol “Eleven exercises were chosen to isolate the major muscle groups of the body and all training sessions and lifts were supervised by trained staff; who would also make the appropriate weight changes. In addition, staff members helped with spotting of weights and ensured adherence to the protocol”
Need supervision? Call this guy:

Back to the meta-analysis: 

“Most studies (4/6) used a resistance-training program as intervention (4,18-20). In the remaining studies, athletes were asked to maintain their regular training schedule focused on their sport discipline" 

Reference 4 is the 9 week study. In that study dietary intake was standardized, “subjects were asked to maintain their normal diets throughout the study” and protein intake before and after the intervention was +3% more for the HMB group and -15% for the placebo group, rendering results as unclear.

Reference 18 is a 6 week study in which it was concluded "no ergogenic effect on muscular strength and endurance, leg power, or anthropometry when taken orally by highly trained male athletes over 6 weeks" (18) even though “All training sessions were fully supervised and loads were individually determined for each subject for every weight session”. No mention of any dietary data in this one.

Reference 19 is the 28 days study with no positive effect. Reference 20 is another 6 week study already mentioned before with no positive results. Total energy and protein intake was not different between groups at baseline or during the period of supplementation, mean energy intake tended to increase, and mean protein intake increased from 1.7g/kg pre to 2.4g/kg post intervention.

The only 12 week study included in elite male rowers concluded “HMB intake in endurance training has an advantageous effect on the increase in aerobic capacity and the reduction of fat mass” (19). Fat mass was decreased by 0.9 kg in the HMB group and increased by 0.8 kg in the placebo group. However fat free mass was decreased in the HMB group by 1 kg, but significantly decreased in the placebo group by 2.1 kg, meaning it helped save FFM. Again, no dietary data was reported.

So 4 out the 6 studies selected for the meta-analysis were equal or shorter than 6 weeks and results indicated no positive effect in body composition and strength?!

The Issn Position Stand concludes the following:

Collectively these findings lead us to suggest the following: HMB supplementation appears to speed recovery in untrained and trained individuals if the exercise stimulus is high intensity, and/or high volume in nature.

For untrained individuals this would likely occur with the introduction of most exercise regimens; however, in a trained population the exercise stimulus will likely need to center on free weights and compound movements.” 

More in trained subjects 

When training was demanding and intense during the intervention (18–22 h/week and consisted of mixed anaerobic and endurance exercise, "HMB (3g/day) led to a significant greater increase in FFM by skinfold thickness in elite, national team level adolescent volleyball players during the first 7 weeks of the training season" (20). HMB supplementation was also associated with greater increases in, muscle strength and anaerobic properties with no effect on aerobic capacity. No dietary data was presented.

However, the effects were not accompanied by hormonal and inflammatory mediator changes, possibly due to lack of tapering of the training intensity, unlike Kraemer et al which also demonstrated HMB beneficial changes in lean body mass, muscle strength, and power  following HMB supplementation for 12 weeks in recreationally active subjects, accompanied by increases in resting and exercise-induced testosterone and resting growth hormone concentrations (21).

In another study, HMB supplementation increased fat-free mass (HMB: +0.8 kg vs. PLA: −0.6 kg), decreased fat mass (HMB:−0.8 kg vs. PLA: +0.7 kg) and stimulated an increase in aerobic and anaerobic capacity in combat sports athletes (22). No dietary data was presented.

Lastly, HMB-FA in combination with HIIT improved aerobic fitness in college age men and women and “There was no significant difference for daily energy or leucine intake (PLA-HIIT, 3.3 ± 1.7 g; HMBFA-HIIT, 3.9 ± 2.1 g) between the two treatment groups" (23).

Final commentary: 

As you can see, there are indeed studies in trained subjects showing positive results in body composition and strength, and even in aerobic performance; the Wilson et al studies are not the only ones! I see a trend nowadays to simply bash HMB in echochambers, disregarding literature such as presented here, of which I have been aware for years.

So I hope, after this, that people will drop the jokes and get back to scrutinizing studies, like this latest meta-analysis, rather than jumping on the horse and scream HMB is useless in trained populations following their favorite fitness expert or guru like fanboys. It all depends on study duration and exercise intervention. 

Laugh all you want, for these reasons (being aware of the relevant variables for positive effects) and more, I have been using HMB on myself and clients I coach for years. It has been part of my arsenal of tools to speed recovery and reach high amounts of volume loads over the  weeks, and increase strength. And this is the point, it allows for improved recovery and higher volume. If you don´t know how to make it work, then don´t use it.
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I have reached more than 140.000 kg per week (quadruple the volume of a normal week at the start of a mesocycle), and others have been up to 50.000-70.000 kg per week (trained women) and 90.000 kg (trained men), with no soreness, fatigue and loss of performance and great strength gains at the end. I have a 43 year old male client who already reached 100.000 kg/w and didn’t even reach the peak of periodization (half-way through it). Such high volumes are not achieved via traditional ways, so don’t venture too much, you might burn yourself (I’m serious), it requires strategic planning and nutrition on point.

And yes, when HMB is taken out the equation recovery is clearly not possible in time. At one time I was recovering from 12-14 sets of chest with 4s second negatives in all reps in just 48h and ready for more. But I also periodize dosages, and use specific training strategies and techniques to elicit a positive effect from HMB. 

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