Do Short Spurts of Physical Activity Benefit Cardiovascular Health? The CARDIA Study

Background: For optimal health benefits moderate to vigorous intensity physical activity (MVPA) is recommended in sustained bouts lasting > 10 minutes. However, short spurts of MVPA lasting < 10 minutes are more common in everyday life. It is unclear whether short spurts of MVPA further protect against the development of hypertension and obesity in middle-aged adults beyond bouted MVPA.

Methods: Objectively measured physical activity was collected in the Coronary Artery Risk Development in Young Adults (CARDIA) study at the 20-year (2005-2006) examination, and blood pressure and BMI were collected at the 20-year and 25-year (2010-2011) examinations. Time spent in MVPA was classified as either bouted MVPA, i.e., > 10 continuous minutes or short spurts of MVPA, i.e., < 10 continuous minutes. To examine the association of short spurts of MVPA with incident hypertension and obesity over five years, we calculated risk ratios (RR) adjusted for bouted MVPA and potential confounders.

Results: Among 1,531 and 1,251 participants without hypertension and obesity, respectively at Year 20 (Age 45.2 +/-3.6, 57.3% Women, BMI 29.0 +/- 7.0), 14.8% and 12.1% developed hypertension and obesity by Year 25. Study participants in the highest tertile of short spurts of MVPA were 31% less likely to develop hypertension 5 years later (RR=0.69 [0.49, 0.96]) compared with those in the lowest tertile. There was no statistically significant association of short spurts of MVPA with incident obesity.

Conclusion: These findings support the notion that accumulating short spurts of MVPA protects against the development of hypertension, but not obesity in middle-aged adults.