Women tend to be more physically flexible than men in the hip region because women have a shallower pelvis than men. This difference allows women to have a greater range of motion in the hip joints.
The differences in flexibility become even greater when a woman is pregnant and as childbirth nears. Hormones produced during pregnancy, such as estrogen, progesterone and relaxin, loosen the connective tissues in muscles. In addition, the extra weight of pregnancy shifts a woman's center of gravity and stretches the lower back.
Both men and women can increase flexibility through proprioceptive neuromuscular facilitation. PNF includes exercises in which a person extends muscles and then tries to contract them from a lengthened position. Research suggests that these types of exercises are more effective than passive stretching. These exercises trigger a muscular reflex that deepens the stretch and increases range of motion.
Many people stretch before a workout, but it is actually more effective to stretch at the end of a workout. Stretching prior to working out can actually make the workout less effective because protein filaments in the muscles expand. This temporarily weakens muscles for about 10 to 15 minutes, making it better to stretch after a workout when muscles are more flexible.