For the first time, it has been shown that an intensively active lifestyle can “completely prevent” bad diets from impairing sexual function, says a Johns Hopkins University urology fellow.

Put another way, a recent rat study offers strong evidence that erectile dysfunction (ED) is more than just a bedroom bother. It may be one’s own natural biomarker for coronary artery disease.

And vigorous exercise can eliminate it all— at least in the (literal) short run.

“There have been a few previous cross-sectional studies that show that men who are physically active throughout their lives tend to develop ED at lower rates than those who are not,” says Justin La Favor, lead author of the recent American Journal of Physiology: Regulatory, Integrative, and Comparative Physiology study. “However, I think we can safely say that this is the first study to demonstrate that exercise can completely prevent the harmful effects of a bad diet on sexual function.”

Obesity, a worldwide plague, is often caused by the “Western (aka junk food) diet” of saturated fat, omega-6 polyunsaturated fatty acids and added sugar. Science has long known the Western diet can cause both ED and heart disease. Science has also long known exercise can stave off Western diet-induced heart disease.

Could it also stave off Western diet-induced ED?

To test the notion on behalf of unhappy overweight men everywhere, senior author and East Carolina University associate professor Christopher Wingard put rodents on the rat equivalent of the Western diet. Daily, for three months, they were given the rat equivalent of one McDonald’s meal (burger, fries, large soda), regular full-fat dairy products, a pre-prepared or frozen meal, and a snack of potato chips and a can of soda— with a few fruits and vegetables thrown in, says La Favor.

A second group received healthy balanced (rat) meals.

Half of the animals in each group led the lives of rat couch potatoes. The other half actively exercised. “The exercise protocol consisted of four four-minute, high-intensity phases, separated by three-minute recovery phases, walking uphill on a treadmill. I always told my participants that the high-intensity phase is a brisk walk uphill, where at the end of the four minutes they should feel like they need to slow down for a while,” says La Favor. “The recovery is more of a normal walking pace, but still uphill. Put more simply, they did approximately 30 minutes of high-intensity interval uphill walking, three days per week.”

After three months, the animals were anaesthetized. Their erectile function was assessed by electrically stimulating the cavernosal nerve, which prompts an increase in penile blood flow and produces erections. The researchers also examined the rats' coronary arteries to see if their ability to dilate and ease blood flow to the heart was impaired-- a state predicting coronary artery disease and heart attacks.

The (human) team found that exercise effectively staved off both ED and coronary artery dysfunction in the exercising (rat) team. The couch potato (rat) team developed both ED and poorly dilating coronary arteries.

The study indicates that “an intensely active lifestyle” may ward off the debilitating effects of the Western diet in both heart and … hearth … as long as Men Eating Badly stay active while doing so. Whether exercise would still reverse vascular problems after a lifetime of bad eating is unclear.

"The finding that exercise prevents Western diet-associated erectile dysfunction and coronary artery disease progression translates to an intensively active lifestyle throughout the duration of the 'junk food' diet," the authors reported. "It remains to be seen if a moderately active lifestyle, or an active lifestyle initiated after a prolonged duration of a sedentary lifestyle combined with a 'junk food' diet is effective at reversing functional impairment."

Also unclear: whether exercise’s happy effects on rat nether regions were solely the result of healthy hearts, or if the magic of exercise worked its wonders in many ways.

“It's hard to say if exercise has other, separate effects on ED issues,” says La Favor. “I would speculate that it probably does, but I can't say that with certainty at this time. When looking at potential mechanistic causes of the two diseases, we found there were some common features, but some that differed. We do know that exercise prevented the development of both diseases, but it is likely that exercise provided adaptations that commonly protected both organs, and others that protected the two organs separately.”