Females in general have lower total muscle mass than males, and also having lower muscle mass in comparison to total body mass;[32] males convert more of their caloric intake into muscle and expendable circulating energy reserves, while females tend to convert more into fat deposits.[33] As a consequence, males are generally physically stronger than females. While individual muscle fibers have similar strength between male and female, males have more fibers as a result of their greater total muscle mass.[34] Males remain stronger than females when adjusting for differences in total body mass, due to the higher male muscle-mass to body-mass ratio.[35] The greater muscle mass is reported to be due to a greater capacity for muscular hypertrophy as a result of higher levels of circulating testosterone in males.[36]
Gross measures of body strength suggest that women are approximately 50-60% as strong as men in the upper body, and 60-70% as strong in the lower body.[37] One study of muscle strength in the elbows and knees—in 45 and older males and females—found the strength of females to range from 42 to 63% of male strength.[38] Another study found men to have significantly higher hand-grip strength than women, even when comparing untrained men with female athletes.[39] Differences in width of arm, thighs and calves also increase during puberty.