Clinical Context

Exercise is commonly valued as a means to help maintain a healthy weight and reduce the risk for cardiovascular disease, and joint recommendations from the American Heart Association and the American College of Sports Medicine validate these goals. The guidelines, which were published in the August 28, 2007, issue of Circulation, state that adults should perform at least 30 minutes of moderate-intensity exercise at least 5 times per week in order to derive the health benefits associated with exercise.

That requirement clearly does not fit everyone. An alternative is completion of vigorous exercise at least 3 times per week for at least 20 minutes per session. The prime example cited that illustrates the difference between moderate and vigorous exercise is walking briskly (moderate) vs jogging (vigorous). Adults can mix and match their exercise patterns to achieve the minimum standard, and exercise sessions as short as 10 minutes can count toward the exercise goal. Although the recommendations stop short of advocating for a particular form of exercise, they do suggest exercise to increase muscular strength and endurance on at least 2 days per week.

One potential benefit of exercise that many adults do not consider is improved sexual function. Previous research has found that exercise can improve erectile function and sexual satisfaction among men. However, the minimum level of exercise required to achieve these goals is unclear, and there are less data on exercise and sexual function among black men. The current study by Simon and colleagues addresses these issues.

Study Synopsis and Perspective

Men who engage in a high level of physical activity report better erectile and sexual function regardless of their race, according to the first study of this association in a racially diverse population.

Results of the cross-sectional study, published online March 20 and in the May issue of the Journal of Sexual Medicine, indicate that the benefit was significant only for those logging at least 18 metabolic equivalent (MET) hours of activity weekly, an amount translating to 2 hours of strenuous exercise such as running or swimming, 3.5 hours of moderate exercise, or 6 hours of light exercise.

"Collectively, our study along with the prior studies provide support that a minimum level of exercise is needed to be associated with better erectile/sexual function and that threshold is around 18 MET hours/week," write the researchers, led by Ross M. Simon, MD, from the Duke Prostate Center, Division of Urology, Department of Surgery and Pathology, Duke University School of Medicine, and the Urology Section, Veterans Affairs Medical Center, Durham, North Carolina.

"These data support future randomized trials to test the use of high levels of exercise (≥18 MET hours/week) to improve erectile and sexual function," they maintain.

Race did not influence the association between physical activity and erectile and sexual function, suggesting that black men and nonblack men derived similar benefit. "[T]hese data suggest that trials focused on exercise as a means to improve erectile/sexual function should include a racially diverse population with significant [erectile dysfunction] risk factors," the researchers recommend.

The team studied 295 healthy male veterans who participated in a study assessing risk factors for prostate cancer. The men had a median age of 62 years, and almost one third were black. The median body mass index was 30.5 kg/m², 39% had type 2 diabetes, and 36% had coronary artery disease.

On the basis of self-reported weekly physical activity, 44% of the men were classified as sedentary (<3 MET hours/week), 17% as mildly active (3 - 8.9 MET hours/week), 13% as moderately active (9 - 17.9 MET hours/week), and 26% as highly active (≥18 MET hours/week).

The median erectile and sexual function score was 53.4 points on a 100-point scale created from the Expanded Prostate Cancer Index Composite sexual assessment, indicating a modest level of function. However, scores increased significantly with physical activity, ranging from 33.4 in the sedentary group to 70.0 in the highly active group.

In a multivariate analysis, highly active men had an erectile and sexual function score that was 17.3 points higher than that of sedentary counterparts, exceeding the cutoff value of 16.5 points for a clinically significant difference. Lower levels of activity conferred smaller, nonsignificant benefit.

The authors note several study limitations, including lack of data on possible confounders, such as socioeconomic status and medications, and a focus on only current physical activity as opposed to cumulative amount across time.

"Although these factors limit the interpretation of our results, the level of exercise associated with better erectile/sexual function is comparable with that of previous population studies examining the association between exercise and [erectile dysfunction]," they note.

The authors have disclosed no relevant financial relationships.

J Sex Med. 2015;12:1202-1210. Abstract

Clinical Implications

• Recommendations from the American Heart Association and the American College of Sports Medicine call for at least 30 minutes of moderate-intensity exercise at least 5 times per week, or vigorous activity for at least 20 minutes during at least 3 sessions per week, in order to derive the health benefits associated with exercise.
• The current study by Simon and colleagues finds that exercise at a level of 18 MET hours/week or more was effective among black and nonblack men in improving erectile and sexual function.

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