Several mechanisms have been proposed for such effects;
- enhanced immune function from increases circulation of immune cells or cells responsible for body defence; clearing of bacterial load in tissue and blood; those may have accessed,
- decreased inflammation, through inhalation of oxygen rich fresh air of outdoor, where exercise is usually taken up.,
- reduced insulin levels through use/entry to muscle tissue, where demand increases to produce more energy from glucose metabolism,
- decreased insulin resistance through physical activity, and
- higher vitamin D levels, which may be acquired from sunny outdoor.
As a summary the study concludes that physical activity may reduce the risk of colon polyps by 15% and may provide a substantially larger reduction in risk of large and advanced polyps. Risk reductions were similar for men and women.
Physical activity and high fibre in diet may go hand in hand to be cheap mode of preventing the cancer colon and to reap many more advantages.