The DREW (Dose Response to Exercise) study was proposed in response to an NHLBI Program Announcement (Physical Activity and Cardiopulmonary Health) requesting applications on a variety of issues, including physical activity dose-response studies. Our goal is to investigate the effect of different amounts of exercise training on cardiorespiratory fitness and systolic blood pressure.
It was important to define a key term used throughout this application to describe the specific component of exercise that we evaluated. Exercise dose refers here to the total amount or volume of exercise to be completed during 1 week, specifically defined as the total energy expended in supervised exercise sessions in kcal • kg-1 * week-1 (abbreviated here as KKW).
The randomized controlled trial of 464 sedentary, postmenopausal, overweight or obese women with a body mass index between 25 and 43 and systolic blood pressure between 120 and 159.9 mm Hg was conducted at The Cooper Institute in Dallas, Texas from 2001 to 2006. This study examined the effect of 50%, 100%, and 150% of the recommended physical activity dose on fitness.
Participants were randomly assigned to 1 of 4 groups: non-exercise control, 4 kcal/kg energy expenditure per week, 8 kcal/kg energy expenditure per week, and 12 kcal/kg energy expenditure per week, for a 6-month intervention. Target training intensity was the heart rate associated with 50% of each woman's peak Vo2. The primary outcome was aerobic fitness assessed on a cycle ergometer and quantified as peak absolute oxygen consumption (Vo2abs, L/min).
The mean (SD) baseline Vo2abs values were 1.3 (0.25) L/min. The mean (SD) minutes of exercising per week were 72.2 (12.3), 135.8 (19.5), and191.7 (33.7) for the 4-, 8-, and 12-kcal/kg per week exercise groups, respectively. After adjustment for age, race/ethnicity, weight, and peak heart rate, the exercise groups increased their Vo2abs compared with the control group by 4.2%, 6.0%, and 8.2% in the 4-, 8-, and 12-kcal/kg per week exercise groups, respectively (P<.001 for each vs. control; P for trend <.001). There was no treatment x subgroup interaction for age, body mass index, weight, baseline Vo2abs, race/ethnicity, or baseline hormone therapy use. There were no significant changes in systolic or diastolic blood pressure values from baseline to 6 months in any of the exercise groups vs. the control group.
Previously sedentary, overweight or obese postmenopausal women experienced a graded dose-response change in fitness across levels of exercise training. More information about this study can be referenced at the following:
|Anaya SA, Church TS, Blair SN, Myers JN, and Earnest CP.||Exercise Dose-Response of the V? E/V? CO2 Slope in Postmenopausal Women in the DREW Study. Med. Sci. Sports Exerc., Vol. 41, No. 5, pp. 971-976, 2009.||Read Abstract|
|Church TS, Martin CK, Thompson AM, Earnest CP, Mikus CR, et al. (2009).||Changes in Weight, Waist Circumference and Compensatory Responses with Different Doses of Exercise among Sedentary, Overweight Postmenopausal Women. PLoS ONE 4(2): e4515. doi:10.1371/journal.pone.0004515.||Read Abstract|
|Martin CK, Church TS, Thompson AM, Earnest CP, Blair SN.||Exercise Dose and Quality of Life. Arch Intern Med. 2009;169(3):269-278.||Read Abstract|
|Mikus CR, Earnest CP, Blair SN, Church TS.||Heart Rate and Exercise Intensity During Training: Observations From the DREW Study. Br J Sports Med 2009;43:750-755. doi:10.1136/bjsm.2008.046342.||Read Abstract|
|Sisson SB, Katzmarzyk PT, Earnest CP, Bouchard C, Blair SN, and Church TS.||Volume of Exercise and Fitness Nonresponse in Sedentary, Postmenopausal Women. Med. Sci. Sports Exerc., Vol. 41, No. 3, pp. 539-545, 2009.||Read Abstract|
|Church TS, Earnest CP, Skinner JS, Blair SN.||Effects of Different Doses of Physical Activity on Cardiorespiratory Fitness Among Sedentary, Overweight or Obese Postmenopausal Women With Elevated Blood Pressure. JAMA. 2007;297:2081-2091.||Read Abstract|