No matter how much your partner pleads, you can't substitute time in the sack for time on the treadmill. However, certain sex positions do work a woman's. No. 43 - Ride the slow train, We countdown 69 of the best sex positions around! See how many sex positions you can try. MH- sex - position christopherrconfections.com 1/6 Thinkstock. Having sex uses a lot of muscles you don't normally use during the course of the day.