Weight Training: Men Get Bigger, Women Get Stronger

From Exercise ETC's FitBits:

Men Get Bigger, Women Get Stronger In Response to Strength Training

Adults who begin resistance training often experience vastly different gains in strength and size than counterparts who are on similar programs. The purpose of this study was to document the range of responses in men and women to a progressive resistance program.

Five hundred eighty-five subjects (342 women, 243 men) ranging in age from 18-40 served as subjects. Subjects participated in 12 weeks of progressive resistance training of the non-dominant elbow flexors. Testing consisted of evaluating the isometric and dynamic strength of the elbow flexors, as well as measuring the cross sectional area of the biceps brachii, as determined by MRI.

The results showed that increases in the muscle cross sectional area ranged from 2% to 59%. Isometric strength increases ranged from 32% to 149% and dynamic strength increases ranged from 0% to 250%. Men experienced greater gains in the muscle's cross sectional area than women did, but women had greater gains in relative strength than men.

Results of this study show a wide range of strength and size gains in response to resistance training for men and women, with some participants showing no change and others showing dramatic changes. Men increased slightly more in size than women, but women showed considerably more increase in relative strength than men.

Hubal, Monica. et al. Variability in Muscle Size and Strength Gain after Unilateral Resistance Training. Medicine & Science in Sports & Exercise. 2005, 37(6), 964-972.

The most obvious difference here is in hormone levels. Higher levels of testosterone will result in greater protein synthesis, which results in larger muscles. However, it is interesting that the women showed greater increases in relative strength in the absence of higher T levels.

I'll post updated info whenever it becomes available. There has long been an assumption that women should train exactly as men train, but that may change as we find physiological training differences between the genders.