How Does Leucine Work?
The maintenance of lean muscle mass is the underlying secret to managing weight, improving performance and sustaining health and wellness. Being able to facilitate greater muscle protein synthesis allows the body to recover from exercise, perform better and counteract the negative effects of aging.
Leucine has a key role in a variety of functions including hormone control, stabilising blood glucose levels, preventing muscle protein breakdown AND facilitating muscle protein synthesis (MPS).
The predominant function of leucine is in the latter of the two benefits mentioned above; namely being a building block for muscle protein development and facilitating the appropriate signals to facilitate growth. Remember more protein synthesis, means more skeletal muscle development.
The Science Behind Leucine
In order to understand how leucine benefits muscle protein synthesis it is important to understand some of the biology which underlies muscle protein development. Protein synthesis is not growth of current muscle, instead it is the construction of new proteins:Read The Science Behind Leucine.
Once covered, we can move onto the benefits of Leucine on a range of factors!
Leucine | Effects On Muscle Mass
Another added benefit of leucine goes beyond its benefit on augmenting MPS.
Leucines role in regulating the activity of various proteins which assist skeletal muscle translation lead it to be examined also as an anti-wasting agent.
 
At higher concentrations than required for muscle protein synthesis, even if MPS rates begin to plateau, if leucine concentration remains sufficient, a muscle preserving effect can be seen in atrophic conditions (19).
This means that in circumstances where muscle wasting (atrophy) is expected, high concentrations of leucine are able to protect the lean muscle mass of the person consuming the supplement in a dose dependent manner (20). In fact this has been seen in cancer (21,22); as well as during blood poisoning or traumatic injuries such as burns (23).
Can Leucine Prevent Muscle Breakdown?
Similar studies also showed that disuse atrophy (as seen during injury or with bed rest) can also be attenuated by leucine supplementation (24-25); as could age related muscle loss (sarcopenia) (26-29).
It is postulated that sufficient concentrations of leucine in normal circumstances may saturate the centres of proteidegradation in the muscle cells to slow down muscle wasting (30-31).
Leucine | Performance Benefits
One particular study examined the effect of 6 weeks of leucine supplementation on a number of physical and performance characteristics in canoeists (Crowe).
This randomised, double blind trial examined the influence of 45mg of leucine per kg of bodyweight (vs 45mg/kg of corn flour placebo) on VO2 max, upper body anaerobic power and time to exhaustion in a 70-75% maximal intensity row. The researchers also ensured that both the normal training regimes of the participants, and their dietary intakes were sufficiently similar throughout the trial.