Testicular pain during or after running usually comes from repetitive mechanical bouncing, inadequate support, or overactive muscles around the spermatic cord, though a handful of less obvious causes range from vascular congestion to referred nerve pain from the hip and pelvis. The discomfort is common enough that most male runners experience it at some point, yet the possible explanations span a surprisingly wide spectrum. Understanding which one applies to you depends on when the pain starts, where exactly you feel it, and what makes it worse or better.
The Bouncing Problem and the Cremaster Muscle
The most straightforward explanation is purely mechanical. Each running stride produces vertical forces that the scrotum absorbs, and without firm support the testes bounce repeatedly against surrounding tissue. Over a long run, that low-grade trauma adds up. Compression shorts and athletic supporters exist precisely for this reason, though scientific data on their protective value beyond comfort remain limited.1Taylor & Francis Online (The Physician and Sportsmedicine). Athletic Supporters: Comfort and Safety
Wrapped around the spermatic cord is the cremaster muscle, a thin layer of tissue that raises and lowers the testicle in response to temperature, touch, and exertion. During running, repeated contraction of the cremaster can fatigue or strain this muscle, causing a dull ache that lingers well after you stop. One case study documented a man whose chronic testicular pain began during high school cross-country training and persisted for 16 years; his pain, rated five to eight out of ten, was aggravated by physical activity and even prolonged sitting.2JOSPT Cases. Return to Running After Manual Therapy for Chronic 16-year Cremaster Muscle Strain: A Case Study That case resolved with targeted manual therapy, suggesting the cremaster itself was the culprit all along.
Some men have a measurably thicker cremaster muscle, which predisposes them to a hyperactive cremaster reflex. In these individuals the testicle retracts forcefully into the groin during exertion, causing sharp pain. Research comparing men with this condition to controls found the average cremaster thickness was roughly four times greater in affected men.3PubMed Central. Cremaster muscle thickening: the anatomic difference in men with testicular retraction due to hyperactive cremaster muscle reflex A characteristic clue is whether you ever have to manually push the testicle back down from the groin during or after exercise. When conservative treatment fails, a microsurgical release of the cremaster has shown promising results, with complete pain resolution in over 90 percent of treated cases in one series.4PubMed Central. Microsurgical subinguinal cremaster muscle release for chronic orchialgia secondary to hyperactive cremaster muscle reflex in adults
Varicoceles and Vascular Congestion
A varicocele is an enlargement of the veins inside the scrotum, somewhat like a varicose vein in the leg. They are extremely common and usually painless, but running can change that. A study measuring spermatic vein diameter before and after exercise found that acute physical activity increased both the vein diameter and the duration of backward blood flow in men who already had varicoceles.5PubMed. Effects of acute exercise on the diameter of the spermatic vein, and duration of reflux in patients with varicocele In other words, running makes a varicocele temporarily worse. The pain is typically a heavy, dragging sensation on one side, most often the left, and it tends to worsen the longer you are upright and active. If lying down relieves the ache fairly quickly, a varicocele is a strong possibility.
A related but rarer vascular issue involves compression of the left renal vein between two major blood vessels in the abdomen. This can increase pressure in the gonadal veins and contribute to pelvic congestion, producing pain that worsens with standing and prolonged physical activity.6Verlag Hans Huber. Pelvic congestion syndrome and left renal compression syndrome – clinical features and therapeutic approaches This condition is diagnosed more often in women, but it occurs in men too and is worth considering when testicular pain accompanies flank discomfort or blood in the urine.
Musculoskeletal and Groin-Related Causes
Your testicles share nerve pathways with the muscles and connective tissue of the lower abdomen, hip, and pelvis. Pain that seems to originate in the testicle can actually be referred from somewhere else entirely. One of the most common musculoskeletal culprits in runners is groin-related strain, sometimes called athletic pubalgia or “sports hernia.” Despite the name, there is no actual hernia; instead, the injury involves the tendons and muscles anchoring to the pubic bone.7RadioGraphics. Athletic pubalgia and “sports hernia”: optimal MR imaging technique and findings These injuries account for roughly five to twenty percent of groin problems in male athletes.8PubMed Central. Inguinal-Related Groin Pain and/or Disruption in Athletes: Current Understanding, Assessment and Management Strategies
The inguinal canal, the passageway through which the spermatic cord travels from the abdomen to the scrotum, is surrounded by the very muscles that absorb force during running. When the external oblique, internal oblique, or transversus abdominis muscles develop trigger points from overuse, they can project pain directly into the testicle. A study of men with chronic pelvic pain found that simply pressing on the external oblique muscle triggered testicular and groin pain in at least 80 percent of patients.9PubMed. Painful myofascial trigger points and pain sites in men with chronic prostatitis/chronic pelvic pain syndrome If your pain is accompanied by lower-abdominal tenderness or worsens when you cough or twist your torso, a musculoskeletal origin is worth investigating.
Dysfunction in the thoracolumbar spine, hip, or pelvic floor can also feed into testicular pain through shared nerve networks. Physical therapy targeting these areas has resolved chronic testicular pain even when standard urological evaluations came back normal.10Topics in Geriatric Rehabilitation. Physical Therapy Management of Chronic Testicular Pain Impacting Sexual Function: A Case Report The takeaway for runners is that testicular pain with no obvious scrotal cause often turns out to be a hip or core problem in disguise.
Nerve Irritation and Referred Pain
Two nerves in particular, the ilioinguinal and the genitofemoral, run through the inguinal region and serve the testicle. Running involves repetitive hip flexion that can compress or irritate these nerves along their path through the abdominal wall. The pain is usually burning or electric in quality rather than the dull ache of a varicocele, and it can radiate into the inner thigh. Because these same nerves are shared by the ureter, the tube connecting the kidney to the bladder, kidney stones lodged in the lower ureter can mimic exercise-related testicular pain.11PubMed Central. Distal Ureteric Stone Presenting Solely As Testicular Pain: Diagnostic Lessons From a Primary-Care Setting If your testicular pain came on suddenly and is not clearly related to impact or exertion, a ureteric stone is one of the diagnoses a doctor will want to rule out.
Chronic nerve irritation in this area can become self-sustaining: the nerve stays sensitized even between runs, producing pain with sitting, driving, or any position that increases pressure on the inguinal canal. In severe cases, targeted nerve stimulation has been used to break the pain cycle, with one reported case showing a drop from a nine-out-of-ten pain rating to two out of ten after treatment.12PubMed Central. Successful treatment of testicular pain with peripheral nerve stimulation of the cutaneous branch of the ilioinguinal and genital branch of the genitofemoral nerves Most runners will never reach that point, but knowing that nerve irritation can underlie exercise-related testicular pain helps explain cases where the scrotum itself looks perfectly normal on imaging.
Intermittent Testicular Torsion
Testicular torsion, where the testicle twists on its spermatic cord and cuts off blood supply, is rightly feared as a surgical emergency. What is less well known is that torsion can happen in a partial or intermittent form. The testicle twists partway, causes intense pain, then untwists on its own. Running can trigger an episode because of the combination of mechanical jostling and cremaster contraction. The pain is sudden, severe, and may come with nausea, but it resolves within minutes to hours without treatment, so many men dismiss it as a cramp.
This is not a condition to brush off. A study of adults with intermittent torsion found that those who underwent surgical fixation had pain resolution or significant improvement in about 95 percent of cases, compared to roughly half of those managed conservatively. Among the men treated without surgery, over half reported no improvement at all.13PubMed Central. Intermittent Testicular Torsion in Adults: An Overlooked Clinical Condition If you have episodes of sudden, severe testicular pain that resolve spontaneously, especially if the testicle appears to sit at an unusual angle, a urologist should evaluate you for intermittent torsion.
When to See a Doctor
Most post-run testicular soreness is benign and resolves on its own, but certain patterns demand prompt medical attention. The four most common causes of acute scrotal pain in active men are trauma, testicular torsion, torsion of a testicular appendage, and epididymitis. While they can look similar, a physician’s evaluation and sometimes imaging or surgery is needed to distinguish them and prevent loss of the testicle.14Europe PMC. Initial evaluation and management of acute scrotal pain
Seek care the same day if you experience any of the following:
- Sudden, severe pain: especially if the testicle appears swollen, high-riding, or rotated. This pattern suggests torsion, where hours matter.
- Fever or painful urination: these suggest infection, such as epididymitis, which requires antibiotics.
- Swelling that does not resolve: persistent scrotal swelling after a run warrants an ultrasound to rule out fluid collections or masses.
- Pain with a firm lump: testicular cancer is painless more often than not, but occasionally presents as discomfort alongside a hard, fixed mass.
Pain that is purely dull, related to prolonged effort, and improves once you lie down is far less alarming but still worth mentioning at a regular checkup if it keeps happening. A scrotal ultrasound is quick, painless, and can identify varicoceles, cysts, or structural abnormalities that might be contributing.
Practical Steps to Reduce the Pain
If you have ruled out anything requiring medical treatment, several straightforward changes can help. The single most effective intervention is better support. Compression shorts that hold the scrotum snugly against the body minimize bouncing, reduce cremaster fatigue, and keep the testes from swinging into positions that kink veins or irritate nerves. Some runners layer a traditional jockstrap under compression shorts for maximum stability on long runs. The evidence is largely anecdotal, but the rationale aligns with the biomechanics of every mechanism discussed above.
Strengthening the core and hip stabilizers can address the musculoskeletal component. Weak lower abdominals and tight hip flexors are common in runners and put extra strain on the structures around the inguinal canal. Targeted exercises for the transversus abdominis, hip adductors, and pelvic floor can reduce referred pain over time. If trigger points in the oblique muscles are contributing, a physical therapist trained in pelvic or sports rehabilitation can release them manually.
Pay attention to hydration and running surface as well. Dehydration concentrates urine and increases the risk of kidney stone formation, which can masquerade as testicular pain. Hard surfaces amplify impact forces through the whole body, including the pelvis. Transitioning some runs to softer terrain like trails or tracks may help if pavement runs consistently provoke symptoms.
Anabolic Steroids and Supplement Use
Runners who use performance-enhancing substances face an additional risk factor. Anabolic-androgenic steroids are the leading cause of drug-related andrological problems in both competitive and recreational athletes.15PubMed. Andrological aspects of physical exercise and sport medicine Exogenous testosterone causes the body to stop producing its own, which leads to testicular shrinkage and can produce aching or tenderness. In extreme cases, the thickened blood that results from steroid-induced polycythemia has been linked to testicular infarction, where part of the testicle loses blood supply and tissue dies.16Corewell Health Scholarly Works and Archives. Acute Segmental Testicular Infarction Resulting From Illicit Anabolic Steroid Use If you are using testosterone, prohormones, or selective androgen receptor modulators, testicular pain during or after running should not be attributed to the exercise alone.
Why External Testes Are Vulnerable in the First Place
It might seem like a design flaw that the testes hang outside the body where they are exposed to impact during physical activity. One evolutionary hypothesis suggests that the exteriorization of the testes is actually an adaptation to the high intra-abdominal pressures generated by running and jumping. Animals that gallop or leap tend to have external testes, while animals like elephants, which move without rapid vertical forces, keep theirs internal. The idea is that the scrotum protects sperm production not only by providing a cooler environment but also by isolating the testes from the pressure spikes of vigorous locomotion.17PubMed Central. Reappraising the exteriorization of the mammalian testes through evolutionary physiology The irony is obvious: the very anatomy that evolved to handle high-impact movement is also what leaves the testes vulnerable to the bouncing and torsional forces that cause pain during a run. The evolutionary tradeoff favored fertility over comfort, which is cold comfort on mile eight of a long run.