Young adults who exercise may have a lower risk of cardiovascular disease and higher survival odds decades later than their peers who aren't as active early in life, a US study suggests.
Fitness has long been linked to a reduced risk of heart disease in older adults. The new study, however, offers fresh evidence that workout routines started years before cardiovascular problems are generally encountered may help keep them from developing in the first place.
"Each additional minute a person could exercise on a treadmill in early adulthood was associated with substantially lower likelihood of risk of dying or developing cardiovascular diseases over 25 years later," lead study author Dr. Ravi Shah of Harvard Medical School and Beth Israel Deaconess Medical Center in Boston said by email.
The study included about 4,900 adults aged 18 to 30 who performed treadmill tests in 1985 and 1986, with roughly half of them repeating the exercise assessments again seven years later. The tests consisted of as many as nine two-minute stages of gradually increasing difficulty.
Over the next several decades, the researchers monitored participants for obesity, hardening in the coronary arteries, heart muscle weakness, and incidents related to cardiovascular disease such as heart attacks or strokes. Half the subjects were followed for at least 27 years.
Overall, 273 people died, though just 73 of these fatalities were related to cardiovascular disease, the researchers report in JAMA Internal Medicine.
In addition, 193 people survived events such as heart attacks or strokes.
Each extra minute participants lasted during the treadmill test as young adults was linked to a 12 per cent lower risk of cardiovascular disease and 15 per cent lower odds of death by the end of the study period.
Every one-minute increase in treadmill time was also linked to less strain on the heart muscle, but exercise test duration wasn't tied to changes in hardening of the coronary arteries.
Among the subset of participants who did the second treadmill test seven years after the initial assessment, each one minute reduction in exercise tolerance was linked with a 20 per cent increase in cardiovascular events and 21 per cent greater odds of death.
The increased risks persisted after the researchers accounted for individuals' age, race, gender, obesity, and other cardiovascular disease risk factors such as smoking, diabetes, elevated blood pressure and high cholesterol.
The fact that even obesity didn't change the outcome highlights the need to think about exercise as more than merely a tool for weight management, noted study co-author Dr. Venkatesh Murthy of the University of Michigan in Ann Arbor.
"Being fit and maintaining fitness over time are very important to your heart and overall health for everyone - especially starting in early adulthood - and not only for people who are trying to lose or to maintain weight," Murthy said by email.
It's possible that some of the association between fitness and heart health may be explained by improved diet, the authors concede. A different measure of cardiorespiratory fitness, known as a peak aerobic capacity test, might also get different results than the treadmill assessments.
Even so, the findings offer a substantive confirmation of the importance of physical activity and cardiorespiratory fitness in the prevention of cardiovascular disease, Dr. David Chiriboga and Dr. Ira Ockene of the University of Massachusetts Medical School in Worcester wrote in an accompanying editorial.
Beyond fitness and exercise, patients should also understand the importance of limiting sedentary time, Ockene said by email. Many daily habits that contribute to inactivity - whether it's channel surfing, using drive-through windows at the bank or the fast food restaurant, or emailing co-workers instead of walking down the hall to talk - all contribute to decreased fitness and increased weight.
"I spend a lot of time talking to folks not just about literal exercise but also about the extraordinary value of day-to-day activity," Ockene said.