A new Canadian study has shown that it is possible to bulk up selected muscles by consuming creatine supplements immediately after training them. Exercising immediately before creatine ingestion is known to increase the uptake of creatine into muscles which, in turn, is known to stimulate muscle hypertrophy growth). And the researchers were keen to test the theory that muscle groups in need of such growth could be selectively enhanced with creatine supplements.

Thirteen men and 11 women were randomly assigned to creatine supplements with either creatine 0.2g per kg of body weight) or placebo while pursuing a six-week resistance training programme for arms and legs, training each side of the body separately (ie on different days) twice a week. Those on creatine supplements were further randomised to receive creatine supplements only after training of one side of the body and placebo after training the other side. The placebo group received only placebo after exercise.

Before and after the six-week programme, the researchers measured elbow flexor and knee extensor muscle thickness, lean tissue mass, fat and bone mass and single-limb bench and leg press strength.

Their first major finding was that, for both men and women, elbow flexor muscle thickness in the creatine supplements group increased more in the limbs trained with creatine supplements than with placebo supplementation. There was a trend for the same effect in the legs (knee extensors) but this did not reach statistical significance.

‘These results,’ comment the researchers, ‘have practical implications for individuals who may want to preferentially increase size of muscle groups that may have been atrophied due to previous injury or disease ie stroke).’

The second major finding of the study was that creatine supplements during resistance training increased lean tissue mass in males but not in females. The researchers speculate that the greater responsiveness in males may be due to their relatively greater inhibition of muscle catabolism (break down) with creatine supplements.

By contrast, creatine supplements were equally effective in males and females at increasing bench press strength, although not leg press strength.

‘Increases in leg press strength may be more dependent on neural mechanisms than increases in bench press strength,’ the researchers suggest.

Another interesting finding was that while the men in the study increased the bone mineral content mass) of their legs – independently of the effects of creatine supplements – the women did not.

In conclusion, the researchers call for further studies to investigate whether creatine supplements are beneficial for increasing muscle mass in limbs that are atrophied due to disease or disuse.

Med Sci Sports Exerc, vol 36, no 10, pp 1781-1788