Source: runningmagazine.ca
Author: Paul Baswick

Maintaining high levels of cardiorespiratory fitness in young adulthood can help men lower their risk of developing nine different forms of cancer later in life, according to research released this week.

In a study published in the British Journal of Sports Medicine, researchers analyzed the rates of cancer in a cohort of more than a million men in Sweden over an average period of 33 years, beginning at age 18. Using the results from fitness tests that were used to gauge the men’s suitability for military service—assessments that were formerly mandatory in Sweden—researchers divided the participants into low, moderate and high levels of cardiorespiratory fitness, and compared cancer rates among men in these groups in later life.

The researchers found the men who showed the highest levels of fitness in young adulthood had a 20 per cent lower risk of kidney cancer and a 19 per cent lower risk of head and neck cancer compared to men in the low-fitness category.

The study also suggests high cardiorespiratory fitness can play a major role in reducing the risk of gastrointestinal cancers. Participants in the high-fitness category saw their risk of cancer of the liver, the bile ducts, the esophagus and the gallbladder slashed by nearly 40 per cent, and their risk of stomach and colon cancer reduced by 20 per cent.

The greatest difference was seen in rates of lung cancer. The study shows men in the high-fitness category cut their risk of lung cancer by 42 per cent compared to the low-fitness group. However, the researchers attributed this wide gap to smoking habits rather than cardiorespiratory fitness on its own.

The study also identified two forms of cancer that members of the high-fitness cohort were more likely to be diagnosed with, compared to men in the low-fitness group. Diagnoses of skin and prostate cancers were slightly higher in the high-fitness group. The researchers attributed the difference to physically fit men being more likely to spend more time in the sun, and to undergo screening for prostate cancer.

The study adds to a growing body of research linking cardiorespiratory fitness to reduced cancer risks in men. A separate study published by the Swedish School of Sport and Health Sciences in June also showed lower rates of colon and lung cancer in men with high cardiorespiratory fitness. However, that study, unlike the research published this week, linked high fitness levels to a lower risk of prostate cancer.

Although both the above studies looked specifically at cancer risks in men, other research has shown that cardiorespiratory fitness in early adulthood can also lead to reduced cancer risks for women later in life.