How Physical Activity Keeps your Heart in Good Shape

Decades of research, including recent studies involving descendants of participants in the Framingham Heart Study, consistently emphasize the positive impact of physical activity on heart health. Dr. Hicham Skali, a cardiologist at Harvard-affiliated Brigham and Women’s Hospital, highlights the crucial role of exercise in promoting a healthier and longer life.

The Framingham Heart Study, initiated in 1948, has been instrumental in uncovering insights into cardiovascular health. The recent studies involving descendants of the original participants delve deeper into understanding how various types and amounts of physical activity contribute to cardiovascular fitness. The overarching message remains clear: regular exercise and reduced sedentary behavior are key components of a heart-healthy lifestyle.

The fastest route to fitness

The studies focused on cardiorespiratory fitness (CRF), a measure of how efficiently the heart and lungs supply oxygen to muscles during physical activity. The first study, published in the European Heart Journal on November 21, 2021, included 2,070 individuals from the Third Generation cohort, many of whom are the grandchildren of the original Framingham participants. Participants underwent exercise tests on stationary bicycles to assess CRF, and they wore fitness trackers for a week to monitor activity levels. Comparisons were made between current values and measurements taken eight years earlier.

The results showed that individuals who engaged in more moderate-to-vigorous exercise, took more steps, and were less sedentary between the two examinations experienced significant improvements in CRF. This trend held true across various factors such as age, sex, weight, risk of heart disease, and baseline activity levels.

Moderate-to-vigorous exercise, including activities like brisk walking, jogging, and cycling, was found to be the most effective in enhancing fitness. Achieving a similar improvement in fitness levels with just one minute of moderate-to-vigorous exercise would require walking for three minutes or reducing sedentary time by approximately 15 minutes.

Interestingly, those with exercise levels or step counts above the norm exhibited higher-than-average CRF, irrespective of sedentary time. This implies that being more active might partially counteract the negative effects of prolonged sitting. Nonetheless, it is still advisable to minimize extended periods of sedentary behavior, according to Dr. Skali.

Walk, jog, run: How fast?

Moderate-intensity walking, as defined by the CDC, falls within a speed range of 2.5 to 4 mph. The specific pace within this range depends on an individual’s fitness level. For those who exercise regularly and are in good shape, a moderate-intensity pace might be closer to 4 mph, equivalent to a 15-minute mile. On the other hand, individuals who are less fit may find moderate intensity closer to the lower end of the range.

A study suggests that a walking pace of approximately 100 steps per minute, which translates to 2.7 mph, qualifies as brisk walking for most adults. To achieve vigorous-intensity activity, a pace of at least 130 steps per minute is needed, which is just over 4 mph and qualifies as jogging. Running is often defined as 6 mph or faster.

Beyond blood vessel benefits

The second study, published on October 29, 2021, in JAMA Network Open, involved 2,962 participants from the Framingham Offspring Study, initiated in 1971. This cohort consists of the sons and daughters of the original Framingham participants and their spouses. Rather than directly measuring cardiorespiratory fitness (CRF), which can be costly and requires specialized equipment, researchers estimated CRF using factors such as age, sex, waist circumference, resting heart rate, and physical activity, starting when participants were in middle age. Unlike the first study, this one included measures of participants’ cardiovascular health, such as tests to assess arterial stiffness and identify early signs of atherosclerosis (plaque buildup inside the arteries).

Over an average follow-up period of 15 years, individuals with higher CRF in midlife were more likely to have healthier blood vessels—more flexible with less plaque buildup—compared to those with lower CRF. More fit individuals were also less likely to develop high blood pressure, diabetes, chronic kidney disease, and cardiovascular disease, and were less likely to die during the follow-up period.

These findings emphasize the significance of maintaining higher fitness levels in midlife. However, Dr. Skali notes that it’s never too late to start exercising, and regardless of age, individuals can improve their cardiovascular health through regular physical activity.