Dose-Response Relationship
The 2008 Physical Activity Guidelines for Americans state that ‘For most health outcomes, additional benefits occur as the amount of physical activity increases through higher intensity, greater frequency, and/or longer duration’[24]. A 2010 systematic review critically examined whether this dose-response relationship exists for the primary prevention of hypertension[25]. A total of 12 articles were identified, with all studies demonstrating a positive effect of physical activity on the risk for hypertension. Of the 12 studies, seven (58%) reported a graded relationship between incident hypertension and physical activity. Five (42%) of the studies showed variable results as the dose-response relationship differed by gender and/or ethnicity. Investigators concluded that current evidence supports the protective effects of physical activity in the prevention of hypertension, however the dose-response relationship is still unclear.
Two large studies in 2013 have further explored the dose-response relationship between physical activity and incident hypertension. In the Australian Longitudinal Study on Women, Pavey and colleagues showed that the risk for incident hypertension decreased with increasing total volume of physical activity[26]. The decreasing risk of hypertension was similar among women who engaged in only moderate physical activity and women who engaged in both moderate and vigorous physical activity at all volumes of MET equivalent physical activity with the exception of the highest volume of physical activity (>2000 MET minutes/week; 4 times greater than physical activity guidelines). Investigators concluded that a dose-response relationship for total volume of physical activity and incident hypertension exists, but that the addition of vigorous physical activity does not provide additional benefits in the prevention of hypertension above those from moderate intensity activity, except at very high volumes of physical activity.