Personalized Activity Intelligence (PAI) for Prevention of Cardiovascular Disease

To derive and validate a single metric of activity tracking that associates with lower risk of cardiovascular disease mortality.

We derived an algorithm, Personalized Activity Intelligence (PAI), using the HUNT Fitness Study (n = 4631), and validated it in the general HUNT population (n = 39,298) aged 20-74 years. The PAI was divided into three sex-specific groups (≤50, 51-99, and ≥100), and the inactive group (0 PAI) was used as the referent. Hazard ratios for all-cause and cardiovascular disease mortality were estimated using Cox proportional hazard regressions.

After >1 million person-years of observations during a mean follow-up time of 26.2 (SD 5.9) years, there were 10,062 deaths, including 3867 deaths (2207 men and 1660 women) from cardiovascular disease. Men and women with a PAI level ≥100 had 17% (95% confidence interval [CI], 7%-27%) and 23% (95% CI, 4%-38%) reduced risk of cardiovascular disease mortality, respectively, compared with the inactive groups. Obtaining ≥100 PAI was associated with significantly lower risk for cardiovascular disease mortality in all prespecified age groups, and in participants with known cardiovascular disease risk factors (all P-trends <.01). Participants who did not obtain ≥100 PAI had increased risk of dying regardless of meeting the physical activity recommendations.

PAI may have a huge potential to motivate people to become and stay physically active, as it is an easily understandable and scientifically proven metric that could inform potential users of how much physical activity is needed to reduce the risk of premature cardiovascular disease death.

Low levels of physical activity have reached pandemic proportions, contributing to >5 million deaths each year worldwide.1, 2 Inadequate physical activity not only results in increased individual health burden,3 but also contributes to tremendous health care expenditures for the society.4, 5 Therefore, promotion of physical activity is needed throughout the health care system.6, 7

Current recommendations of physical activity suggest that adults should engage in at least 150 minutes of moderate-intensity activity or 75 minutes of vigorous-intensity activity per week, or any combination of activity that approximates the same total energy expenditure.8, 9, 10 Recent studies have also shown significant benefits at activity levels as low as half of the recommended quantity.11, 12

Evolving evidence suggests that cardiorespiratory fitness outperforms physical activity as a predictor of future health.13, 14, 15 Moreover, several studies suggest that people with established cardiovascular disease risk factors, such as high body mass index (BMI), hypertension, or diabetes, but with high cardiorespiratory fitness, have highly attenuated risk of cardiovascular disease and premature mortality.13, 14, 16

A major challenge in activity counseling and promotion of physical activity is to provide clear feedback to individuals with personalized and meaningful information that motivate individuals to increase or sustain physical activity.17, 18 Goals such as “10,000 steps per day” or “30 minutes of activity per day” tend to be vague and misleading, as they do not reflect the body’s response to each activity. The most personalized, accurate way to track and measure the body’s response to activity is through monitoring a person’s heart rate.9 Unlike all other physical activity metrics, such as distance walked, number of steps, frequency or duration of activity, heart rate changes reflect the body’s response to physical activity regardless of the type of activity performed. However, there has never been a simple way to convert heart rate changes during physical activity into a meaningful metric for understanding how much activity or exercise is necessary, and what intensity level is needed to achieve optimal health results.

Therefore, the aim of the current study was to develop a new single metric (Personalized Activity Intelligence [PAI]) that can be integrated in self-assessment heart rate devices, and defines a weekly beneficial heart rate pattern during physical activity. Further, we aimed to assess whether PAI could translate into reduced long-term risk of premature cardiovascular disease and all-cause mortality.