As Henry VIII would tell you (if he were not already dead for nearly four and a half centuries) infertility is not just a woman's problem. All told, 15 percent of couples cannot conceive, with the blame being distributed equally among the man, the woman, and, as some historians speculate was the case with that famous Tudor monarch and his many wives, a reproductive incompatibility between the man and the woman.

It wouldn't have helped King Henry, but researchers think many men today can boost the quality of their sperm by exercising three to five times a week. Run or jog for around 45 minutes a day and your sperm will enjoy an increase in both its motility as well as its concentration, according to a study released by Urmia University in Iran.

The researchers recruited 261 men aged 25 to 40 with self-described sedentary lifestyles and split them into three groups. The first engaged in moderate intensity continuous training – defined here as walking for jogging for 25 to 0 minutes a day, three or four times per week. The second was tasked with running three times per week for40 to 50 minutes, with ten-minute high-intensity bursts. The third group exercised in full-on high intensity training, and the fourth group did not exercise at all. 

The results showed that men who exercised had improved sperm at the end of the training, regardless of which group they were in, but the best return on exercise investment coming to the men who engaged in moderate intensity workouts.

The authors summarized: "The present study adds to this body of evidence and shows seminal markers of inflammation and oxidative stress improved significantly after 24 weeks [of exercise], and these changes correspond with favorable improvements in semen quality parameters and sperm DNA integrity.

"These observations suggest that the intensity, duration and type of exercise training could be taken into consideration when investigating reproductive responses to exercise training in men."

The study reinforces what fertility experts have long understood, that a sedentary lifestyle is anathema to starting a family. It also adds a new layer of granularity to the type of steps men may take to goose their odds. Other steps men may take include eating a healthy diet, ceasing smoking, cutting down on alcohol and wearing loose underwear. 

The results of the study were published in the journal Reproduction.