While a high fitness level is already known to have a positive impact on conditions like heart disease, a new study suggests that adults who are more fit have the lowest risk of developing lung and colorectal cancer compared with those who have low fitness levels.For the study, the research team examined 49,143 adults who underwent exercise stress testing from 1991-2009 and followed them for a median of 7.7 years. Those in the highest fitness category had a 77 per cent decreased risk of developing lung cancer and 61 per cent decreased risk of developing colorectal cancer, the results showed.The study, published in the journal Cancer, showed that among individuals who developed lung cancer, those with the highest fitness had a 44 per cent decreased risk of dying during follow-up, and among adults who developed colorectal cancer, those with the highest fitness had an 89 per cent decreased risk."Our findings are one of the first, largest, and most diverse cohorts to look at the impact of fitness on cancer outcomes," said Catherine Handy Marshall, Assistant Professor at Johns Hopkins University in the US. "Fitness testing is commonly done today for many people in conjunction with their doctors. Many people might already have these results and can be informed about the association of fitness with cancer risk in addition to what fitness levels mean for other conditions, like heart disease," Marshall added.