How HMB Can Add Muscle Mass and Strength
by: Robbie Durand
β-Hydroxy-β-methylbutyrate (HMB), a leucine-derived metabolite has been demonstrated to augment strength and lean muscle gains when supplemented in conjunction with resistance training. HMB is known to increase muscle protein synthesis through mTOR signaling pathways while concurrently reducing proteolytic processes. Recently, an 18% increase in strength gain was demonstrated following 12 weeks of HMB ingestion compared to placebo in experienced resistance trained men. Two new studies were recently published this year which suggest that HMB maybe a supplement that you want to include in your cabinet for fat loss.
Study 1: HMB Reduces Body Fat in Older Men
The effects of 12-weeks of HMB ingestion and resistance training (RT) on abdominal adiposity were examined in 48 men (66–78 years). All participants were randomly assigned to 1 of 4 groups: no-training placebo, HMB only, resistance training with placebo, or HMB with resistance training. DEXA scans were used to estimate abdominal fat mass. At the end of the study, HMB supplementation with resistance exercise significantly reduced abdominal body fat in older men. These data suggested that HMB in combination with 12 weeks of RT decreased abdominal fat mass in elderly men.
Study 2: HMB Increases GH/IGF-1
The second study, examined the endocrine response to a bout of heavy resistance exercise following acute β-hydroxy-β-methylbutyrate free acid (HMB-FA) ingestion. Twenty resistance-trained men were randomized and consumed either 1 g of HMB-FA or placebo 30 minutes prior to performing an acute heavy resistance exercise protocol. Blood was obtained before, immediately after, and 30 minutes after exercise. Circulating concentrations of testosterone, growth hormone (GH), insulin-like growth factor (IGF-1), and insulin were assayed. The resistance exercise protocol resulted in significant elevations in testosterone, GH, and insulin immediately post-exercise, with GH and insulin remaining elevated 30 minutes post exercise.
A significant interaction was noted between groups in the plasma GH response immediately post-exercise, which was significantly higher following HMB-FA compared to placebo. Elevations in GH and IGF-1 were significantly higher in the HMB-FA group compared to the placebo group. The researchers concluded that HMB-FA prior to resistance exercise increases the GH response to high volume resistance exercise compared to placebo. These findings provide further support for the potential anabolic benefits associated with HMB supplementation.
In summary, these results appear to be the first examination suggesting that one-gram of HMB-FA can promote a significantly greater post exercise increase in GH and IGF-1 compared to placebo.
Study 3: HMB Reduces Body Fat in Elite Rowers
Sixteen elite male rowers were administered a 12-week HMB supplementation (1 gram of HMB, three times a day) and placebo administration following the model of a randomized, placebo controlled, double-blind crossover study with a 10 day washout period. The athletes were told not to change their dietary intake during the 12-week study. Following HMB supplementation, maximal oxygen capacity increased in comparison to its reduction after placebo. As mentioned in the methodological part, dietary recordings were performed every second week, during the whole study, which proved that athletes did not change their dietary habits during the HMB supplementation and placebo period. After HMB supplementation, fat mass decreased (−0.9 kg with HMB vs. +0.8 kg in the placebo). So the HMB group lost fat mass, while the placebo group gained a small amount of body fat. The results indicate that HMB intake in endurance training has an advantageous effect on the increase in aerobic capacity and the reduction of fat mass. It may also stimulate an increase in peak anaerobic power.
HMB may not only be good for increasing performance and increasing lean muscle mass, and reducing catabolism but based on new studies, it seems that HMB can also enhance fat loss.
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