MedicalResearch.com Interview with:
Xuemei Sui, MD, MPH, PhD
Assistant Professor Department of Exercise Science
Graduate Director Division of Health Aspects of Physical Activity
Arnold School of Public Health University of South Carolina
Columbia, SC 29208
Medical Research: What is the background for this study?
Dr. Sui: Previous studies have established that low levels of cardiorespiratory fitness (CRF), an indicator of regular physical activity, and body compositions with higher fat mass serve as risk factors for cardiovascular disease and predictors of deaths related to cardiovascular disease. These studies have examined long-term trends of fatness (i.e., body fat) and cardiorespiratory fitness in children, adolescents and men, but few have looked at these factors in female populations. Therefore, the aim of this study was to investigate secular change of cardiorespiratory fitness and body composition during 35 years in a large sample of women enrolled in the Aerobics Center Longitudinal Study.
13 037 women aged 20 to 64 were enrolled in our study from January first, 1970, through December 31st, 2004. We divided our participants into 2 age groups, and divided 35 years into 7 time groups. Cardiorespiratory fitness was assessed by maximal treadmill testing using a modified Balke protocol, and the percentage of body fat was assessed by hydrostatic weighing or the sum of 7 skinfold measures, following standardized protocols. According to percent body fat, we divided body composition into fat mass and fat free mass.
Medical Research: What are the main findings?
Dr. Sui: The data showed that body mass index (BMI) increased over the 35-year period even though cardiorespiratory fitness levels rose as well. By looking at the body composition of the participants along with their BMIs, the researchers were able to observe that their body fat did not increase. This finding suggests that the weight gains that led to higher BMIs over time were not necessarily comprised of body fat. Participants may have been putting on muscle mass due to their increased physical activity, as indicated by their higher cardiorespiratory fitness.
Another interesting finding was that when leisure-time physical activity (LTPA) reaches 668.5 MET min/wk, cardiorespiratory fitness stays at a higher level. So in order to improve cardiorespiratory fitness for physically inactive women, we should encourage them to meet this level. The drift downward in cardiorespiratory fitness among women indicates the need for continuing efforts to promote their physical activity and fitness.
Medical Research: What should clinicians and patients take away from your report?
Dr. Sui: Regardless of the pervasiveness of chronic diseases, high cardiorespiratory fitness levels suggest that women are trending toward engaging in more physical activity, which has shown to have a number of health benefits. Although cardiorespiratory fitness levels increased by a significant 20 percent overall during the study’s time period, a slight dip in this trend occurred towards the end. This decline, however small, demonstrates the need for continuing efforts to promote physical activity and fitness.
Therefore, clinicians should encourage women to increase their cardiorespiratory fitness levels through promoting physical activity. Women should consider focusing more on body fat percentages and cardiorespiratory fitness levels than simple BMI calculations when setting their fitness goals.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Sui: The increasing prevalence of chronic diseases in our study is disturbing, and future studies are warranted to examine how changes in chronic diseases affect the secular change in fitness and fatness.
MedicalResearch.com Interview with:, & Xuemei Sui, MD, MPH, PhD (2015). Cardiorespiratory Fitness Linked To Body Composition in Women. MedicalResearch.com