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Love That Leucine

Of the essential amino acids leucine is perhaps the single most important for us exercising folk. Why? Well, as they say on the hit TV series “CSI,” just follow the data. Three recent studies published this year prove the value of leucine.

In the first study, scientists determined whether a practical leucine-and-protein, high-carbohydrate postexercise feeding regimen could improve recovery, as measured by subsequent cycling performance compared to a control feeding. For you endurance nuts out there, the eggheads discovered that getting a leucine-protein supplement along with other high-carbohydrate food following intense training on consecutive days improved endurance performance and may also lessen muscle damage in well-trained male cyclists.1

Another study looked at the effect of leucine supplementation on muscle damage following eccentric-based resistance exercise; that is, negatives. Twenty-seven untrained males were randomly divided into three groups: leucine, placebo and control. The leucine and placebo groups performed 100 depth jumps from 60 centimeters and six sets of 10 repetitions of negative-only leg presses. That’ll tear up your muscles! The subjects took in either leucine or a placebo 30 minutes before, during and immediately after exercise and on the morning of each recovery day following exercise. The researchers found that high-dose leucine may help maintain muscular strength following exercise-induced muscle damage.2 Wow, the stuff is amazing.

In the third study, scientists looked at whether daily oral L-leucine doses affected strength, bone-mineral-free lean-tissue mass and fat mass during a 12-week resistance-training program. Twenty-six initially untrained men took either four grams per day of L-leucine or a corresponding amount of lactose. All participants performed a prescribed resistance-training program under supervision twice per week using eight standard exercise machines. Testing took place at baseline and at the end of the supplementation period. Strength on each exercise was assessed by five-repetition maximum, and body composition was assessed by dual energy X-ray absorptiometry. The leucine group had significantly higher gains in total five-rep-max strength and individual-exercise five-rep-max strength in five out of the eight exercises. The total five-rep-max strength gains were 40.8 percent and 31.0 percent, respectively, for the leucine and placebo groups.3

Bottom line: I’d suggest adding four grams of leucine to your postworkout protein shake for maximum performance and anabolic benefits.

Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (; also check out his site


1 Thomson, J.S., et al. (2011). Leucine-protein supplemented recovery feeding enhances subsequent cycling performance in well-trained men. Appl Physiol Nutr Metab. 36(2):242-253.

2 Kirby, T.J., et al. (2011). Effect of leucine supplementation on indices of muscle damage following drop jumps and resistance exercise. Amino Acids. In press.

3 Ispoglou, T., et al. (2011). Daily L-leucine supplementation in novice trainees during a 12-week weight-training program. Int J Sports Physiol Perform. 6(1):38-50.


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