| Summary: | The presence of an increased accumulation of intraabdominal fat (IAF) has been
linked to dyslipidemia, hyperinsulinemia, and hyperglycemia, which precede the
development of type 2 diabetes and coronary artery disease (CAD). It has been shown
that IAF begins depostition during childhood. Human studies suggest that regular
endurance exercise, that does not necessarily produce an increase in aerobic capacity,
can effectively reduce IAF accumulation during these early years. In contrast to human
research, studies using animal models of human disease typically employ extremely large
volumes of exercise with the intent to maximize aerobic capacity. The present study
examined whether half the amount of endurance training, that was previously reported to
induce cardiac hypertrophy and approximately double the aerobic capacity of skeletal
muscle in rats, would reduce the growth-related accumulation of IAF in growing female
rats. Twenty-two 4-week-old female Sprague-Dawley rats were randomly assigned to a
running experimental or a non-running control group. The runners exercised on a treadmill
5 days/week for 60 min/day at a speed of 27m/min and up a 15% grade for 10 weeks.
After 10 weeks, the parametrial, omental and mesenteric IAF depots and the heart were
excised and weighed. Compared with non-runners, the runners had a significantly lower
mean parametrial fat mass (2.22 g vs. 3.13 g, p=0.05) and a higher mean heart weight
(0.97 g vs. 0.90 g, p=0.05) at the end of 10 weeks. In addition, the lower mean
parametrial fat mass in the runners vs. the non-runners (2.19 g vs. 3.19 g, p=0.02)
remained significant even after adjusting for the greater heart weights of the runners. One-half
the amount of exercise, that was previously reported to induce cardiac hypertrophy
and approximately double the aerobic capacity of skeletal muscle in rats, yielded an 8%
greater heart weight and a 29% lower parametrial IAF mass, on average, in growing female
rats. In addition, the effects of treadmill running on reducing parametrial fat accumulation
were independent of the effects of running on increasing heart weight. Thus, future
studies examining the effects of exercise on IAF and other health-related metabolic
outcomes in rats may consider using lower-dose endurance training protocols that are not
designed to maximize improvements in aerobic capacity. === Graduation date: 2002
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