Apparently, the best way for men to improve their sex lives is by hitting the gym. Medical studies show that there is a direct correlation between men who work out and maintaining a healthy and active sex life. Not only can burning calories boost a man's physical health, but it can also enhance stamina, confidence and testosterone levels.

"Physical fitness absolutely affects the physical intensity and quality of sex," said Dr. Sara Nasserzadeh, co-author of "The Orgasm Answer Guide," according to Fitbie.com.

According to Dr. Jorge Chavarro of the Harvard School of Public Health, exercise can lower the risk of erectile dysfunction in men. "Exercise that helps open the arteries to benefit your heart will also increase blood flow to the penis," Chavarro said, according to FMT News.

Because exercise increases the flexibility of your arteries, it becomes easier for them to expand and get blood coursing through your veins. As a result, men who have better blood flow will have a stronger erection.

Men who excercise may also have fewer symptoms of an enlarged prostate, a common condition called benign prostatic hyperplasia (BPH). Furthermore, men with BPH often have to urinate frequently, or have a weak stream. Men with more severe BPH symptoms may also have a low libido, trouble keeping an erection, and enjoy sex less.

A recent study published in the British Journal of Sports Medicine suggests that men who worked out at a moderate to vigorous intensity for at least 15 hours a week had higher sperm counts than inactive men.

Physically fit men also have an advantage when it comes to the muscular aspect of sex—men in top shape find sex easier and less painful than men who don't exercise much. "If you don't exercise regularly, and especially if you never do crunches, you will feel soreness in your lower abdominals and your hip flexors after sex," said Neal Pire, a fitness consultant to pro athletes. 

Exercise can also help you feel more confident and energized both in and out of the bedroom, which can improve sex. "When you feel good about yourself, and about how your partner sees you physically, you're going to be more relaxed and less distracted," said Pire.

A Baylor University study found that pumping iron can also help pump up your levels of the sex hormone testosterone; men's testosterone levels were highest during the 48 hours after they lifted weights.