From Ergo Log
Runners have less chance of an enlarged prostate, the more kilometres per week they run and the faster the speed. An epidemiologist at the Ernest Orlando Lawrence Berkeley National Laboratory in California discovered this when he analysed data from nearly thirty thousand runners.
In the body of the average Western male the prostate is a ticking time bomb. The organ increases in size as men age. Benign Prostatic Hyperplasia is the scientific term. An enlarged prostate is in itself harmless, although doctors believe that an enlarged prostate increases the risk of prostate cancer. But because an enlarged prostate makes urination more difficult it is a problem for men.
Studies have shown that a moderate amount of physical exercise protects against prostate enlargement. Studies on the effects of vigorous physical exercise are less clear, however. Some conclude that men who pursue physical exercise fanatically are less likely to develop enlarged prostates, others that they are more likely. This confusion prompted the American study.
Between 1992 and 1993, the researchers approached nearly thirty thousand athletes through a magazine for long-distance runners, all of whom were healthy and did not have an enlarged prostate. The researchers then looked at which athletes had developed prostate problems between 1999 and 2002: there were two thousand of them. Then the researchers looked to see if they could find a relationship between the training times and performances of the runners on the one hand and the likelihood of prostate enlargement on the other.
The chart below shows the relationship between the times of the runners for a ten-kilometer run and the risk.
The men who ran faster than 4.5 meters per second had a 32 percent less risk of an enlarged prostate than the men who ran less than 3 meters per second.
The risk of prostate problems increases the more fat you carry. Perhaps faster runners are lighter you might think. But this reasoning does not hold: the relationship was still found to hold when the researchers corrected for BMI. The number of hours training that the runners did is also not an explanatory factor – although the number of hours that men train does also lower the risk of prostate enlargement.
The data in the figure above are corrected for age and weekly intakes of meat, fish, fruit, and alcohol. The men in the group who trained the longest had a 33 percent less risk of an enlarged prostate than the men who trained the least number of hours.
Unlike interval training, endurance training has been found to lower androgen levels in some studies. The researchers do not think that this reduction plays a role here, however. They suspect rather that the better runners in their study manufactured less stress hormones. Some earlier studies have shown a relationship between prostate problems and adrenalin and other stimulant hormones.
This study shows not only that long-distance running is healthy. It also throws more light on the protective effects of physical activity. We are told that we should have at least half an hour of physical activity every day. This study shows what happens if we up the amount. “Our results add to the accumulating evidence that important health benefits accrue at greater exercise doses and greater exercise intensities than currently recommended”, the researchers write.
Med Sci Sports Exerc. 2008 Oct;40(10):1733-9.