Health benefits of training can persist for years
Make healthy choices now, enjoy the benefits indefinitely
Lifestyle interventions can greatly improve cardiometabolic health. But how long do the health benefits persist over time? The legacy effect refers to sustained benefit long after a medical treatment, in this case a lifestyle intervention, ends. Researchers at Duke University conducted an eight-month intervention of supervised physical training between 1999 and 2003. Previously sedentary or overweight men and women participants aged 40 to 65 years were randomized into one of four groups. They included: 1) an inactive control, 2) low amount of moderate-intensity exercise, 3) low amount of vigorous-intensity exercise, and 4) high amount of vigorous exercise. At the end of the study, researchers collected data from the participants.
Ten years later, the participants were contacted to enroll in a Reunion Study to determine the extent to which cardiometabolic conditions at the end of the eight-week intervention persisted over the ensuring decade. Of the original 161 participants, 104 enrolled in the Reunion study. Unsurprisingly, cardiorespiratory fitness, measured as peak oxygen consumption, declined for members of all four groups over 10 years. But the exercisers showed significantly lower decline (4.7 percent) than the control group (9.6 percent). Vigorous exercisers showed even lower decline (3.0 percent). Average waist circumference increased significantly more for the control group (2 inches) than the exercisers (less than one-half inch). Mean arterial blood pressure dropped for all participant groups over 10 years. Curiously, blood pressure for the low moderate exercisers declined the most (5 mm Hg) relative to the control group. Fasting insulin levels decreased significantly (in a healthy direction) for the lower moderate exercisers compared to the control group. Blood glucose increased for all groups over 10 years with no significant differences between the groups. This lack of differences may have reflected the fact that about half of the participants were taking medications that could affect blood sugar levels.
The Reunion study showed that the eight-month period of physical activity training led to positive cardiometabolic changes that persisted for a decade. The reasons for the observed legacy effect were unclear. Perhaps healthy choices begun during the intervention continued over the long term. Relative to the high costs of chronic cardiometabolic illnesses, such as type 2 diabetes, the cost of the training intervention likely paid for itself over the long term. If we are willing to make healthy lifestyle choices part of our everyday life, we can eliminate or postpone type 2 diabetes and other chronic illnesses.