Active Voice: Metabolic Syndrome and Walking — From Kids to Young Adultse

By Andrew W. Gardner, Ph.D.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.

Dr. Gardner is a professor who holds the Donald W. Reynolds Chair of Aging Research in the Department of Geriatric Medicine at the University of Oklahoma Health Sciences Center in Oklahoma City. His training is in clinical exercise physiology, emphasizing the cardiovascular benefits of exercise and physical activity in vascular disease and at-risk populations. Dr. Gardner’s primary research program centers on exercise rehabilitation of peripheral artery disease (PAD) patients, exercise physiology issues as they relate to both PAD and healthy aging, and the roles of community-based daily ambulatory activity and body composition on vascular function in youth.

This commentary presents Dr. Gardner’s views associated with a related research report that he and his colleagues presented in the January 2013 issue of ACSM’s
Medicine and Science in Sports and Exercise® (MSSE).

Metabolic syndrome links insulin resistance, dyslipidemia, hyperglycemia, and hypertension, and is clinically significant because it increases the risk of developing diabetes and cardiovascular disease. Studying metabolic syndrome in children and adolescents is a relatively new phenomenon, primarily due to the explosive rise of obesity in the United States in the general population, particularly in youth. The International Diabetes Federation recently recommended definitions for each component of metabolic syndrome in children and adolescents, consisting of having abdominal obesity plus at least two of the other four components. Since abdominal obesity is the hallmark measure of metabolic syndrome, increased physical activity is a cost-efficient, practical method to reduce visceral fat.

Our study, as recently reported in MSSE, compared the daily ambulatory activity in children, adolescents, and young adults with and without metabolic syndrome, and we assessed which metabolic syndrome components, demographic measures, and body composition measures were associated with daily ambulatory activity. Two-hundred fifty subjects between the ages of 10 and 30 years participated, and 45 (18%) had metabolic syndrome. Our primary finding was that ambulatory cadences (i.e., rates of walking) of continuous durations ranging from one minute to one hour were slower in children, adolescents, and young adults with metabolic syndrome than those without metabolic syndrome. Additionally, they took fewer ambulatory strides each day while spending similar time ambulating than those without metabolic syndrome. Simply put, youth with metabolic syndrome ambulate less vigorously for a similar amount of time each day as those without metabolic syndrome.

Another key finding was that body fat percentage and body fat mass were the most important correlates of daily ambulatory activity in youth, particularly with the cadence of ambulation. Thus, youth with high levels of body fat ambulate at a slower pace than those with less body fat, and this primarily explains why youth with metabolic syndrome ambulate more slowly than those without metabolic syndrome. A final important finding was that the prevalence of metabolic syndrome in youth in this study was 18%, which was much higher than previously reported in children and adolescents (3-4%) and in adults (6.7%). Our results indicate that the obesity pandemic in the United States is now increasing the prevalence of cardiovascular risk factors in youth, thereby initiating the process of atherosclerosis at progressively earlier ages.

We concluded that children, adolescents, and young adults with metabolic syndrome ambulate more slowly and take fewer strides throughout the day than those without metabolic syndrome - even though the total amount of time spent ambulating was not different. Furthermore, the detrimental influence of metabolic syndrome on ambulatory cadence was primarily a function of body fatness. The clinical significance is that youth with metabolic syndrome should be encouraged to ambulate at cadences slightly faster than their preferred pace and for at least 30 additional minutes throughout the course of a day as a simple means to potentially reduce body fatness and improve glucose, triglyceride, and HDL cholesterol profiles.