Cross-Sectional Association of Time Spent Outdoors With Serum Testosterone: Results From the National Health and Nutrition Examination Survey.

Plain-language summary

This study looked at whether time spent outdoors is linked to testosterone in men. It analyzed 2,205 men in the US National Health and Nutrition Examination Survey, tracking daily outdoor time against morning testosterone while accounting for age, education, income, weight, activity, diabetes, vitamin D and diet. Each extra hour spent outside each day was tied to higher testosterone and to lower odds of low testosterone, even after adjusting for all of those, which suggests outdoor time has a connection to testosterone beyond the exercise and vitamin D that usually come with it. The same research group published a companion analysis in this library using wrist-worn light readings instead of reported outdoor time, so the two are one team measuring one question two ways rather than two independent findings.

Key findings

• Each additional hour spent outdoors daily was linked to 9.25 ng/dL higher testosterone.
• More outdoor time was tied to 14% lower odds of having low testosterone (<300 ng/dL).
• The link held after adjusting for age, weight, activity, diabetes, vitamin D, and diet.