The prostate is a small walnut-sized gland that is involved in the production of semen. It is located below a man's bladder. It also produces a protein called prostate-specific antigen, or PSA, small amounts of which normally circulate in a man's blood. A PSA test measures the amount of the antigen in the blood, and an elevated PSA can indicate prostate cancer or simply an inflamed or enlarged prostate. Exercise, including bicycle riding, may influence the PSA level in certain cases.
A study reported in the July 1996 "Journal of Urology" found no significant difference in PSA in most of 260 volunteers following a four-day 250-mile bike ride. However, the four men who already had elevated PSA did have a large increase after the ride. The authors recommended further study. A study appearing in the January-February 2005 issue of the "International Journal of Sports Medicine" found that PSAs did not differ between 69 professional cyclists, 31 cross-country skiers and 43 healthy but sedentary men. These authors hypothesized that heavy and regular exercise that involved the prostate region of the body -- such as cycling or skiing -- did not affect PSA.
BPH, Prostatitis and PSA
BPH, or benign prostatic hypertrophy, refers to an enlarged prostate gland. Most men will have prostate enlargement as they age and may experience urinary system effects. BPH often increases PSA levels. Bacteria, arising from any number of sources causes prostatitis, an infection of the prostate gland, which can cause PSA levels to fluctuate. Neither an enlarged prostate nor prostatitis leads to cancer. In 2011, a study reported in "Urologe A" found that 21 men with BPH had significant elevation of PSA after either one hour of cycling or one hour on a treadmill. The study concluded that men should not exercise, especially on a bicycle, for several days or at least 24 hours before a PSA test.
Prostate Cancer and PSA
Prostate cancer also increases PSA levels. Like BPH and prostatitis, the risk of prostate cancer increases as a man ages. The PSA test screens for cancer and can detect it in early stages, when treatment would be most effective. However, an elevated PSA is not diagnostic for cancer by itself. A doctor also performs a digital rectal exam to check for prostate pain and lumps, growths or hard areas on the prostate, but even that is not diagnostic. Only a biopsy can definitively diagnose prostate cancer. In men diagnosed with prostate cancer, follow-up PSA tests can detect cancer recurrence. In this case, it is important to refrain from activity that may falsely elevate the PSA, such as riding a bicycle.
A Controversial Test
Several activities can cause a false-positive PSA test. Activities that disturb the prostate area, such as bicycle or motorcycle riding, can result in elevated PSA levels. Digital rectal exams and prostate biopsies also increase PSA. Even experiencing an orgasm in the 24 hours before a test can elevate the PSA in the blood. In addition, though some prostate cancers progress rapidly, most grow slowly over time. Most cases occur in men over 65 years of age. Controversy comes because the cancer may not ever become a medical problem for a man that age, but the surgery and radiation therapy used to treat it can cause erectile dysfunction, urinary incontinence, bowel problems and even death.