An expert has warned men that intense exercise can cause temporary genital shrinkage, creating a little-known post-workout phenomenon known as gym penis.
Chris Bustamante, an aesthetic nurse practitioner and founder of Lushful Aesthetics, explained that while working out usually leaves muscles looking bigger, stronger and fuller, it can temporarily have the opposite effect below the belt. Speaking to the New York Post, Bustamante said that "many men experience some degree of temporary retraction while working out, but the amount varies dramatically."
According to Bustamante, some men will "barely notice it" while others may feel like they are "turtling," a term used to describe when the penis retracts closer to the body.
Why exercise causes temporary shrinkage
The condition can be triggered by strenuous workouts that activate the body's fight-or-flight reflex. The fight-or-flight response is an automatic physiological reaction to stress or intense physical exertion that causes adrenaline levels to surge. Activities that trigger this reaction include heavy weightlifting and intense cardio exercises such as running.
During these high-intensity activities, the human body prioritises directing blood flow to the muscles performing the work, drawing circulation away from inactive areas such as the penis. Aesthetic nurse practitioners and medical professionals note that blood flow redistribution is a standard physical mechanism during heavy exertion.
Bustamante stressed that the temporary reduction is a normal symptom and usually nothing to worry about. "Once your body cools down, your nervous system settles and blood flow redistributes, the penis typically returns to its usual flaccid appearance," he explained, adding that "for most men, that can happen within minutes to an hour after working out."
However, recovery may take longer if a person is dehydrated or has consumed large amounts of caffeine or pre-workout supplements. Cold temperatures and particularly intense training sessions can also delay genitals returning to their natural size.
Psychological impact and health advice
Despite being temporary and physically harmless, Bustamante warned that gym penis can cause significant psychological distress. He noted that the phenomenon can make men feel anxious about their size and leave them reluctant to use shared changing rooms at gyms or sports facilities.
The warnings come alongside global data regarding male anatomy. According to 2024 statistics, men in Britain have the 68th-biggest penises in the world on average. A Daily Mail interactive map published at the time revealed that the average erect penis size in the UK was 5.17 inches. Ecuador ranked first globally with an average size of 6.93 inches, followed by Cameroon and Bolivia, while the United States also ranked ahead of Britain.
While gym penis itself is generally harmless, Bustamante advised men to pay attention to persistent or unexplained physical changes. He warned that any changes in penis size that do not resolve after exercise, or accompanying symptoms such as erectile dysfunction, pain or numbness, warrant evaluation by a healthcare professional.
