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Amino Acid Leucine Also Boosts Muscle Recovery After Exercise, Researchers Find

Aug. 19, 2011 -- Eating or drinking protein after exercise can help muscle recovery and growth, experts agree. What's still debated is which proteins work best.

Whey protein appears to be better than casein protein, according to new research that looked at exercisers doing resistance training.

"A whey protein shake would probably be better than a caseinprotein shake," says researcher Daniel W.D. West, a PhD student at McMaster University in Hamilton, Ontario.

And a separate study shows that protein that includes a higher concentration of the amino acid leucine works better than protein with lower concentrations. It looked exercisers who did aerobic workouts.

"It appears more leucine is beneficial in the context of muscle recovery," says researcher Stefan M. Pasiakos, PhD, a research physiologist with the U.S. Army Research Institute of Environmental Medicine.

Both studies are published in the American Journal of Clinical Nutrition.

Why Protein After Exercise?

As you exercise, muscles undergo a cycle of breakdown during the workout followed by remodeling and growth afterward.

Recently, high-protein drinks have become more popular. They are used during and after exercise to get the best muscle growth and recovery.

Researchers have been studying which combination of proteins is most helpful.

Protein After Resistance Exercise

West and his colleagues wanted to see if one large dose of whey protein taken right after a workout would be better than several smaller doses, spaced out over time.

The smaller doses of whey taken over a longer time period made the protein behave more like another protein, casein, he says. Both whey are casein are found in milk.

''Casein is digested slowly," West tells WebMD, "whereas whey is digested very rapidly."

They used the smaller doses of whey to mimic the casein. So the one-time dose of whey was compared to several doses of whey.

The researchers gave both the one-time dose and the repeated doses to eight men, average age 22, during two different workouts. The men took the protein after doing eight sets of eight to 10 repetitions on a leg extension machine.

''What we did in this study is compare whey -- 25 grams -- like [what is in] a typical protein shake -- and compare it to 25 grams of whey, but ingested in little 2.5 gram shots.''

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