Q. I workout using weight machines at a local fitness club and have noticed that often there is not a lot of difference in the amount of weight men and women lift, particularly with the leg machines. A. Studies indicate that in overall strength men are generally about 30 percent stronger than women. However, most of this difference is in the upper body. The leg strength of both sexes is often very close, particularly when body weight and body fat are factored out. The greater strength of men is due primarily to hormonal levels.
Men produce more testosterone, which has a strong muscle-building effect.
Although, men have more muscle mass and overall strength, there is no inherent sex difference in muscle quality. Muscle physiology is the same in both males and females. Women can generate the same force per muscle fiber as men, and they can make the same relative strength improvements with training.