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Cancer Prevention through Exercise

     One of the most important benefits of exercise is how it reduces our risk of developing a number of types of cancer—especially colorectal cancer, which according to some estimates is the malignancy most influenced by physical activity, but how workouts guard against colon cancer remains largely unknown. Physical activity speeds the movement of waste through the intestines, as anyone who has had to hunt for a bathroom during a workout knows. But this does not seem to fully account for the protective effects of exercise. Instead, s small study published in February in the Journal of Physiology suggests we should also look to changes in our bloodstream after exercise.

     The new study began with scientists at the University of Queensland in Brisbane, Australia. and other institutions recruiting 20 men who had survived colon cancer. (Women were excluded because menstruation may have affected results.)

     The scientists asked 10 of the men to start working out strenuously three times a week: pedaling a stationary bicycle hard for four minutes, resting for three, and repeating that sequence three more times. They trained for a month and then, a few days after completing the program, rested quietly while researchers drew blood. The other ten men completed the same 4 x 4 interval session, but only once. The researchers drew their blood before, immediately following and an additional two hours after that lone workout.

     The scientists then carefully added a tiny amount of fluid from the men’s blood to petri dishes containing human  colon-cancer tumor cells often used to study cancer growth. At several points during the subsequent 72 hours, the researchers counted the number of cells in each dish. They soon saw substantial differences.

     In the dishes containing fluid taken from the men immediately after a single workout, the scientists counted far fewer cancer cells than in those awash with fluid drawn two hours after exercise. There was no similar decline in the dishes from the men who had trained for a month. In effect, something about the blood drawn immediately after the workout was slowing the growth of the cancer cells.

     The researchers think they may have identified that something in subsequent analysis of the men’s blood. They found a large increase in molecules involved in inflammation immediately after exercise. Inflammation can slow cell growth and cell reproduction. So a transitory increase in inflammatory markers after exercise might be helping to stop the proliferation of tumour cells, says Tina Skinner, a physiologist who was the senior author of the study.

     The implications of these results are both good and bad. The changes in exercisers” blood were potent but transient. So activities would have to be repeated to provide any continuing protection, and the study was unclear about how intense or prolonged that exercise would need to be, or if the effects extended equally to fighting other types of cancer.

  In any case, it seems to me that if you had cancer in the past you should exercise regularly to prevent a recurrence. And if you never had cancer, then exercise regularly to help prevent it. So no matter what your state, it’s time to tie up those laces and get some regular physical workouts.

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