It also plays a role in body fat, and in muscle size, strength, and function.
The mice show greater than normal muscle size and strength and do not lose it as they age.
But Andrews calls the use of creatine worrisome because it increases muscle size by retaining fluid and causing dehydration.
"High doses of testosterone increase muscle size and strength in healthy men," the authors of the Journal article wrote.
Both substances are believed to be used illicitly now by athletes using conventional methods to increase muscle size and strength.
Then they estimated the amount of metabolic power available for flight, based on muscle size and other factors.
In fact, only now is a study being conducted to see if any of these supplements increase muscle size.
The majority of men and women increased muscle size 15 to 25percentt; and most men improved their muscle strength 40percentt while women increased theirs 65percentt.
Dr. Stedman's group said the findings "raise the intriguing possibility that the decrement in masticatory muscle size removed an evolutionary constraint on encephalization".
"Your muscle size might increase, but your frame stays the same, and I think sometimes, with some of these players, they get too big for their bodies".
Weight training without supplements will increase muscle size, said Toronto General Manager J. P. Ricciardi, "but only to a certain degree".
