Muscle-building supplements or drugs have always been thought of as democratic in their effects. You take them and as long as your training and diet are conducive to the cause, your entire body grows uniformly. Chest, shoulders, back, arms, and legs all increase in size. Small Hulk turns into bigger Hulk and smashes bigger things, incurring crippling insurance liabilities.
Creatine may be an outlier, though. Not only has it been shown in previous studies to increase upper body strength more than lower body strength, but according to new research by T Nation contributor Brad Schoenfeld and his colleagues, it looks like creatine might also produce greater growth in the upper body than the lower body.
What They Did
Schoenfeld's group recruited 43 resistance-trained men in their early twenties to participate in a randomized, double-blind, placebo-controlled study.
All the men received either creatine or placebo over an 8-week study period. The men first went on a creatine-loading phase (7 days, four doses of 0.03 grams per kilogram of bodyweight per day) followed by a maintenance phase (7 weeks, single dose of 0.03 grams per kilogram of bodyweight per day).
While on creatine or placebo, the men lifted weights 4 times a week using a two-way split routine:
- Monday and Thursday: Chest, shoulders, triceps, abs
- Tuesday and Friday: Back, biceps, thighs, and calves
Muscle mass (lean soft tissue) was measured before and after the 8-week period using duel-energy X-ray absorptiometry (DEXA).
What They Found
Both groups (placebo and creatine) showed significant muscle increases in "upper limbs," "lower limbs," and "trunk," but the creatine group did better than the placebo group, as expected.
What perhaps wasn't expected, though, was that the creatine group's upper limbs gained (7.1 + 2.9%) twice as much lean tissue as the lower limbs (3.2 + 2.1%) and over three times as much lean tissue as the trunk (2.1 + 2.2%).
The growth of the placebo group's lean tissue, while considerably less than the creatine group, was nevertheless pretty equal; all body parts grew largely in concert with the others.
The team noted that creatine is preferentially absorbed by fast-twitch muscles and that lower body muscles generally possess fewer fast-twitch muscles. Therefore, it makes sense that upper body muscles grew more than the lower body because it has more creatine-absorbing fast-twitch muscle fibers.
What This Means to You
Schoenfeld and the other researchers are quick to point out that the exercise program they put together provided higher volume for the upper limb muscles than it did for the lower limb muscles.
This wasn't just some bonehead mistake, though. They deliberately designed the exercise program that way because they felt it was consistent with typical bodybuilding-type programs, i.e., they wanted to "preserve ecological validity as opposed to equating volume between body segments."
So sure, it's possible that the lower limbs didn't grow as much as the upper limbs because there simply wasn't enough volume built in to make the lower legs grow. Still, it's hard to ignore the fact that the lower body has fewer creatine-absorbing fast twitch muscles. That fact alone makes sense in explaining the growth discrepancy between upper and lower growth.
Fine, but maybe the real lesson here is that lifters should habitually give their legs more training volume than they typically do. Maybe then the growth rates between upper and lower body would approach parity, regardless of whether they're using creatine or not.
- Nunes JP et al. Creatine supplementation elicits greater muscle hypertrophy in upper than lower limbs and trunk in resistance-trained men. Nutr Health. 2017 Dec;23(4):223-229.