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HMB (a metabolite of our much-loved mTOR boosting friend Leucine) is one of those supplements that's been around for a long time in the bodybuilding world. Some say it works, some say it doesn't. That argument's been blowing around forever on the basis of conflicting studies, a lack of real-world test conditions, and very short-term usage protocols.
However in recent years some better designed studies have repeatedly demonstrated that even in trained athletes, daily doses of HMB of as little as 3 x 1g over a period of several months can significantly improve aerobic performance and reduce fat mass, and moderately increase muscle mass. There are also signs that it may improve peak anaerobic power, something that all strength-training athletes would be interested in.
Those are the findings of this new paper due out soon:
J Strength Cond Res. 2016 Feb 2. [Epub ahead of print]
[h=1]The Effect Of Hmb On Aerobic Capacity And Body Composition In Trained Athletes.[/h]Durkalec-Michalski K1, Jeszka J.
[h=3]Author information[/h]
[h=3]Abstract[/h][h=4]PURPOSE:[/h]The aim of this study was to investigate whether supplementation with β-hydroxy-β-methylbutyrate (HMB) affects body composition, aerobic capacity, or intramuscular enzymes activity, as well as in anabolic/catabolic hormones and lactate concentrations.
[h=4]METHODS:[/h]A cohort of 58 highly-trained males was subjected to 12 weeks supplementation with HMB(3x1gHMB·day) and a placebo (PLA) in randomised, placebo controlled, double-blind crossover trials, with a 10 days washout period. Body composition and aerobic capacity were recorded, while the levels of creatine kinase, lactate dehydrogenase, testosterone, cortisol, and lactate, as well as the T/C ratio, in blood samples were measured.
[h=4]RESULTS:[/h]Following HMB supplementation fat-free mass increased (+0.2 kgHMB vs. -1.0 kgPLA, P = 0.021), with a simultaneous reduction of fat mass (-0.8 kgHMB vs. +0.8 kgPLA, P < 0.001). In turn, after HMB supplementation, in comparison to placebo: maximal oxygen uptake (V[Combining Dot Above]O2max: +0.102 L·minHMB vs. -0.063 L·minPLA, P = 0.013), time to reach VT (TVT: +1.0 minHMB vs. -0.4 minPLA, P < 0.0001), threshold load at VT (WVT: +20 WHMB vs. -7 WPLA, P = 0.001), and the threshold HR at VT (HRVT: +8 bpmHMB vs. -1 bpmPLA, P < 0.0001) increased significantly. Analysis of the tested biochemical markers show significant differences only in relation to the initial concentration. In HMB group testosterone levels increased (P = 0.047) and in both groups (HMB: P = 0.008; PLA: P = 0.008) higher cortisol levels were observed.
[h=4]CONCLUSION:[/h]The results indicate that supplying HMB promotes advantageous changes in body composition and stimulates an increase in aerobic capacity, while seeming not to significantly affect the levels of the analyzed blood markers.
As of yet, nobody really understands the mechanism via which HMB works. But for a nicely written interpretation of this paper (and more importantly graphs!), as ever check out this handy summary written by the guys over at Ergolog.
In bodybuilders who train (and more importantly eat) specifically to gain mass, it's probable that the increases in LBM caused by HMB would be more significant. Nevertheless the loss in bodyfat is very welcome and makes HMB a worthwhile addition to your nutrition on top of any Leucine you may already take.
If anyone's interested in reading further on the subject, I suggest starting with further papers from Jeszka and Durkalec-Michalski, such as this one from last year on elite rowers (which points to anaerobic benefits).
However in recent years some better designed studies have repeatedly demonstrated that even in trained athletes, daily doses of HMB of as little as 3 x 1g over a period of several months can significantly improve aerobic performance and reduce fat mass, and moderately increase muscle mass. There are also signs that it may improve peak anaerobic power, something that all strength-training athletes would be interested in.
Those are the findings of this new paper due out soon:
J Strength Cond Res. 2016 Feb 2. [Epub ahead of print]
[h=1]The Effect Of Hmb On Aerobic Capacity And Body Composition In Trained Athletes.[/h]Durkalec-Michalski K1, Jeszka J.
[h=3]Author information[/h]
[h=3]Abstract[/h][h=4]PURPOSE:[/h]The aim of this study was to investigate whether supplementation with β-hydroxy-β-methylbutyrate (HMB) affects body composition, aerobic capacity, or intramuscular enzymes activity, as well as in anabolic/catabolic hormones and lactate concentrations.
[h=4]METHODS:[/h]A cohort of 58 highly-trained males was subjected to 12 weeks supplementation with HMB(3x1gHMB·day) and a placebo (PLA) in randomised, placebo controlled, double-blind crossover trials, with a 10 days washout period. Body composition and aerobic capacity were recorded, while the levels of creatine kinase, lactate dehydrogenase, testosterone, cortisol, and lactate, as well as the T/C ratio, in blood samples were measured.
[h=4]RESULTS:[/h]Following HMB supplementation fat-free mass increased (+0.2 kgHMB vs. -1.0 kgPLA, P = 0.021), with a simultaneous reduction of fat mass (-0.8 kgHMB vs. +0.8 kgPLA, P < 0.001). In turn, after HMB supplementation, in comparison to placebo: maximal oxygen uptake (V[Combining Dot Above]O2max: +0.102 L·minHMB vs. -0.063 L·minPLA, P = 0.013), time to reach VT (TVT: +1.0 minHMB vs. -0.4 minPLA, P < 0.0001), threshold load at VT (WVT: +20 WHMB vs. -7 WPLA, P = 0.001), and the threshold HR at VT (HRVT: +8 bpmHMB vs. -1 bpmPLA, P < 0.0001) increased significantly. Analysis of the tested biochemical markers show significant differences only in relation to the initial concentration. In HMB group testosterone levels increased (P = 0.047) and in both groups (HMB: P = 0.008; PLA: P = 0.008) higher cortisol levels were observed.
[h=4]CONCLUSION:[/h]The results indicate that supplying HMB promotes advantageous changes in body composition and stimulates an increase in aerobic capacity, while seeming not to significantly affect the levels of the analyzed blood markers.
As of yet, nobody really understands the mechanism via which HMB works. But for a nicely written interpretation of this paper (and more importantly graphs!), as ever check out this handy summary written by the guys over at Ergolog.
In bodybuilders who train (and more importantly eat) specifically to gain mass, it's probable that the increases in LBM caused by HMB would be more significant. Nevertheless the loss in bodyfat is very welcome and makes HMB a worthwhile addition to your nutrition on top of any Leucine you may already take.
If anyone's interested in reading further on the subject, I suggest starting with further papers from Jeszka and Durkalec-Michalski, such as this one from last year on elite rowers (which points to anaerobic benefits).