Older Bodybuilders May Need More Leucine than Younger Bodybuilders
Older bodybuilders are becoming more and more common these days.  In general, aging is associated with a decrease in protein synthesis which has been termed "anabolic resistance."  This is shown by a decrease sensitivity and responsiveness of protein synthesis in muscle in both rats and humans.  The leucine signal is also observed to be less sensitive in older subjects15. In one study, leucine concentrations 1–2 times greater than in young animals were necessary to observe the same changes in older rats. This suggests that the defect in postprandial muscle protein anabolism in old subjects is related to the alterations of the leucine signaling in muscle. However, the molecular mechanism responsible for the blunted signaling pathways for leucine remains unresolved. Interestingly, a recent study reported that when comparing younger (8 months old) and older rats (22-months-old) protein breakdown rates; the rates of protein breakdown were higher in older rats compared to younger rats, but when older rats are fed a diet which is supplemented with 5% Leucine, there is a rejuvenation of muscle and an inhibition of protein breakdown similar to young rats16.   Based on the research in old rats and humans, high concentrations of leucine appear capable of stimulating muscle protein synthesis to the same degree as physiological concentrations in younger subjects. Thus, aging seems to be associated with a decrease in leucine-induced stimulation of muscle protein synthesis.  The long-term utilization of leucine-rich diets may therefore limit muscle protein wasting during aging.

It seems that taking leucine in large dosages not only increases protein synthesis rates, activates satellite cells, reduced the catabolic actions of cortisol, and reduces bodyfat.  The good news is that leucine is among the most tolerated Amino Acids as no adverse effects of increased leucine intake (usually 3x of the daily requirement) were reported in various human studies9.  Leucine is clearly the most potent anabolic amino acid on the market today. 

Key Points:
• Leucine alone increases protein synthesis independent of insulin
• Leucine had potent fat loss properties
• Leucine has both anabolic and anti-catabolic actions
• Leucine synthesis is decreased with age

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