Dr. Dwyer and colleagues now drew the records for the more than 90,000 men and women who had worn the trackers, skipping anyone with a known history of heart disease when they participated in the study. They divided them into four groups based on how many minutes in total they moved each week and how much of that activity was moderate, such as exercise. B. Walking, or relatively vigorous, such as jogging, as confirmed by their trackers.
Eventually, the researchers collected hospital data and death certificates on who among the 90,000 volunteers developed heart disease in the years after joining the study, and began reviewing their diagnoses based on their activity habits.
Not surprisingly, being active was a protection against heart disease. People in the least active group who rarely ran around or exercised formally were now more than twice as likely to have heart disease as the most active men and women. Switching from the least active to the less inactive group alone reduced the risk of heart disease by nearly 30 percent, even when researchers controlled body composition, smoking, socioeconomic status, and other factors.
The researchers also didn't find a cap on the benefits. The men and women who did the most physical exercise walked up to 1,100 minutes a week or more than two hours a day (totaling both their actual physical activity and everyday activities such as grocery shopping or housework), while also often exercising intensely for 50 minutes or longer per week, showed no increased risk of heart problems. Instead, this group saw the greatest risk reductions, with both men and women showing roughly the same benefits.
The results "provide even stronger evidence than previously available" that "physical activity, including vigorous physical activity, is important in reducing the risk of cardiovascular disease," says Dr. Dwyer. The benefits were "about twice as high as most self-report studies".
However, this study is associative and shows that active people happen to be people with healthy hearts too. It does not prove that walks and other activities directly strengthen people's hearts, just that the two are connected. Dr. Dwyer also points out that the number of people in the study who completed an extremely high amount of intense activity was small. Therefore, it is conceivable that long-term, intense exercise will eventually no longer be good for the heart. That possibility requires more control, he says.
But for most of us, he says, increasing our exercise "to a much higher or more vigorous level" should significantly reduce our chances of developing heart disease later