Effects of Regular Activity on Physiology Between Recreational Athletes of Different Body Fatness

The popularity of marathons and endurance events has increased over the last few decades and, interestingly, the demographics of participants have also changed. From 1980 to 2002 the average race time to complete the marathon lengthened from \~3.5 hours to \~4.5 hours. Likewise, many endurance races include "Clydesdale" and "Athena" divisions for heavier weight male and female runners, respectively. As such, there has been an increase of overweight and obese participants in these races. For example, one study consisting of 250 runners determined, according to BMI, that approximately 15% and 31% of the female and male participants, respectively, were classified as overweight, with 31% and 33% classified as obese. Therefore, many recreational endurance athletes are overweight despite their high level of activity. On one hand, these data are positive as regular exercise reduces cardiovascular disease and all-cause mortality in overweight and obese populations. Yet, it is well documented in sedentary obese individuals that excess adiposity can lead to disturbances in adipocyte lipolysis and altered substrate utilization at rest and during exercise, and can decrease muscle quality. However, it is unknown if overweight individuals that exercise regularly have disrupted fat metabolism, circulating hormones, or muscle quality. No study has directly determined if differences exist in fat metabolism, circulating hormones, and muscle quality between overweight recreational female athletes and their lean counterparts when training status is equivalent. Therefore, the purpose of this investigation is to determine if differences in pre and post-exercise fat metabolism, circulating insulin and growth hormone, and muscle quality exist between active overweight individuals compared to active lean individuals with similar training history and who have regularly trained for and participated in endurance events within the last few years.