title: Do Short Spurts of Physical Activity Benefit Cardiovascular Health? The CARDIA Study.
abstract: BACKGROUND
  For optimal health benefits, moderate- to vigorous-intensity physical activity (MVPA) is recommended in sustained bouts lasting ≥10 min. However, short spurts of MVPA lasting <10 min 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-age adults beyond bouted MVPA.
  
  
  METHODS
  Objectively measured physical activity was collected in the Coronary Artery Risk Development in Young Adults study at the 20-yr (2005-2006) examination, and blood pressure and BMI were collected at the 20- and 25-yr (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 5 yr, we calculated risk ratios adjusted for bouted MVPA and potential confounders.
  
  
  RESULTS
  Among 1531 and 1251 participants without hypertension and obesity, respectively, at year 20 (age, 45.2 ± 3.6 yr; 57.3% women; body mass index, 29.0 ± 7.0 kg·m(-2)), 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 yr later (risk ratio = 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.
  
  
  CONCLUSIONS
  These findings support the notion that accumulating short spurts of MVPA protects against the development of hypertension but not obesity in middle-age adults.
authors.affiliation: 1Department of Physical Therapy, University of Delaware, Newark, DE; 2Health Science Center at Houston, School of Public Health-Austin Regional Campus, University of Texas, Austin, TX; 3University of Alabama at Birmingham, Birmingham, AL; and 4Division of Research, Kaiser Permanente, Northern California, Oakland, CA.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: White
authors.forename: Kelley Pettee
authors.initials: KP
authors.lastname: Gabriel
authors.forename: Yongin
authors.initials: Y
authors.lastname: Kim
authors.forename: Cora E
authors.initials: CE
authors.lastname: Lewis
authors.forename: Barbara
authors.initials: B
authors.lastname: Sternfeld
mesh_terms: D000328:Adult; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000517:prevention & control*; D011446:Prospective Studies; D012307:Risk Factors