No Difference Observed in Sedentary Time per Week between NCAA DIII Distance Runners and Recreationally Active College Students

Sedentary behavior, defined as activities with an energy cost below 1.6 metabolic equivalents (METs), is associated with chronic health risks and mortality even in active individuals. Time spent at sedentary MET levels by Messiah College collegiate distance runners and recreationally active students was documented and analyzed to determine whether competitive athletes accrue more sedentary time than recreationally active students. In this descriptive cross-sectional study, 22 competitive distance runners and 26 recreationally active students wore SenseWear TM armbands (SWA; BodyMedia, Inc.) continuously for seven days of free-living activity. Male (n = 10) and female (n = 12) distance runners were Messiah College track athletes in distance events (800m through 10000m) and who reported running more than 30 miles weekly. The recreationally active group consisted of male (n = 14) and female (n = 12) full-time Messiah College students who reported running at least six but less than 30 miles weekly, or equivalent physical activity and no participation in NCAA intercollegiate sports. The SWA recorded the subjects' total time at sedentary MET levels for seven days. The difference in mean sedentary time for the week between the two groups was analyzed using 2x2 factorial ANOVA for independent samples with standard weighted-means analysis (VassarStats, www.vassarstats.net). No significant difference in mean sedentary time was found between the groups (P = 0.73). NCAA DIII collegiate distance runners do not accrue more time at sedentary MET levels then recreationally active college students. More research is needed to assess the health implications of time spent sedentary by both groups. Comparison of Sedentary Time 2 No Difference Observed in Sedentary Time per Week between NCAA DIII Distance Runners and Recreationally Active College Students Recent studies investigating the impact of sedentary behavior on health form a growing body of literature that links lifestyles marked by sedentary behavior to numerous health problems. Sedentary behavior includes activities that require minimal exertion above resting energy expenditure such as lying down, sitting, and screen time (1). Sedentary behavior is associated with greater waist circumference, increased blood insulin and glucose, lower HDL cholesterol, metabolic syndrome, reduced physical and psychosocial health and increased BMI in adolescents, increased cardiovascular disease risk independent from moderate to vigorous physical activity in youth and adults, unfavorable levels of adiposity-associated inflammation, and decreased mental well-being (2-9). According to findings from the ongoing Harvard Alumni Health Study, bouts of moderate to vigorous physical activity (one to two sessions per week) that were interspersed with longer periods of sedentary behavior instead of physical activity most days of the week were less protective from cardiovascular disease risk than more frequent bouts of exercise even if the total energy expenditure from both activity patterns was equivalent (10). A large prospective study of U.S. adults by Patel et al. concluded that time spent sitting was independently associated with total mortality regardless of physical activity level (11). In contrast, some studies have suggested that the interaction between sedentary behavior and cardiometabolic risk factors (pertaining to both heart disease and metabolic diseases such as diabetes) is not completely independent from moderate to vigorous physical activity levels (1214). However, these studies still acknowledge that sedentary behavior has adverse effects and suggest further investigation of the interaction between sedentary time, physical activity, and disease. The studies mentioned above focused on screen time-related sedentary behavior by adolescents or sedentary behavior by older adults and individuals with existing diseases rather than sedentary time in healthy young adults or athletes. Few studies have investigated the effects of sedentary behavior on healthy young adults. Analysis by Thyfault and Krogh-Madsen of studies involving reduced ambulatory activity in rats and young, healthy men found that reduced physical activity led to increased central adiposity and insulin resistance (15). When the activity of the healthy young men was reduced from greater than 10,000 steps per day to less than 1,500 steps per day for 14 days with no change in dietary habits, insulin response decreased and central adiposity increased despite significant reduction in body weight. Thyfault and Krogh-Madsen suggested that although the acute response to sedentary behavior cannot be directly linked to development of chronic disease, the acute changes tended in a pathological direction. If the detrimental effects extend to periods shorter than 14 days, even individuals who are otherwise active but engage in extended periods of sedentary behavior may risk acute responses that produce negative cardiometabolic changes. Sedentary time has not been quantified in the general population and guidelines for sedentary time have not been developed for adults. However, analysis of physical activity behavior in the US implies that sedentary behavior is prevalent. Data obtained from the 20032004 National Health and Nutritional Examination Survey (NHANES) suggests that less than 5% of adults meet the latest US Department of Health and Human Services Physical Activity Guidelines for Americans (PAGA) of at least 150 minutes of moderate exercise weekly (16,17). Separate studies conducted by Troiano et al. and Metzger et al. both analyzed seven days of accelerometer data from the 2003-2004 NHANES and found that a large portion of the US Comparison of Sedentary Time 3 population engages in less physical activity than recommended by the PAGA and related guidelines (18-20). This trend has been verified among the college student population. Dinger and Behrens observed physical activity of free-living college students via accelerometer data and concluded that most of the study's subjects were not meeting recommendations with regard to physical activity bouts of at least 10 consecutive minutes (21). Exercise in sessions of at least 10 minutes are recommended by the American College of Sports Medicine and American Heart Association physical activity recommendations and incorporated into the PAGA (17,19). As noted earlier, research in the area of sedentary behavior in athletes has been limited. Previous studies have investigated energy efficiency and conservation in amenorrheic female endurance athletes (22-24) but not sedentary time specifically. Sedentary behavior seems to be unexplored entirely for male athletes. Possible contributing factors to this include the assumption that athletes do not engage in significant sedentary behavior and the relatively recent emergence of research on the health risks of sedentary behavior independent of activity level. The premise of this study was that the intense activity required of endurance athletes for competition at the NCAA level may actually increase their risk for engaging in sedentary behavior when not engaged in training activities. The purpose of this study was to determine whether NCAA Division III distance runners compensate for the time and energy required by their training by accumulating more minutes at a sedentary activity level than recreationally active college students. If collegiate distance runners do accrue more sedentary time than their recreationally active peers, changes in training practices may be warranted to avoid the health risks associated with increased levels of sedentary behavior.