Medicine & Science in Sports & Exercise:
May 2006 - Volume 38 - Issue 5 - p S482
Friday Afternoon Poster Presentations: Posters displayed from 1:00-6:00 p.m.: One-hour author presentation times are staggered from 2:00-3:00 p.m., 3:00-4:00 p.m., and 4:00-5:00 p.m.: F-27 Free Communication/Poster - Diet or Exercise and Chronic Disease Risk: FRIDAY, JUNE 2, 2006 2:00 PM - 5:00 PM: ROOM: Hall B
Exercise-induced changes in high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG) are thought to occur at different levels of caloric expenditure depending on an individual's level of cardiorespiratory fitness. The caloric expenditure threshold for young, high-fit males is thought to occur at approximately 800 kcals; whereas, 350 kcals of exercise caloric expenditure has been shown to increase HDL-C and lower TG in older sedentary males. At present, blood lipid changes in young males of high- and moderate-fitness after aerobic exercise of moderate-intensity and duration has not been directly compared.
PURPOSE: The purpose of this investigation was to compare blood lipid responses after aerobic exercise of moderate intensity and duration in young, apparently healthy males of different fitness status.
METHODS: Ten high-fit males (29 ± 6 yrs of age, BMI = 24.9 ± 1.9 kg/m2, waist circumference = 81 ± 7 cm, body fat = 13 ± 5%, VO2max = 53.9 ± 7.0 ml/kg/min) and eleven moderate-fit males (33 ± 8 yrs of age, BMI = 28.4 ± 3.4 kg/m2, waist circumference = 90 ± 11 cm, body fat = 22 ± 5%, VO2max = 36.0 ± 5.0 ml/kg/min) expended 500 kcals of energy by treadmill jogging at 70% VO2peak. Fasting blood samples were obtained 24 hours before and again 24, 72 and 120 hours after exercise and were analyzed for HDL-C, HDL2&3-C subfractions and TG. All blood lipid concentrations were adjusted for plasma volume shifts that occurred with exercise and were analyzed using a 2 (group) × 4 (time) ANOVA repeated for time.
RESULTS: HDL-C and HDL3-C were significantly greater in the high-fit group (p < 0.05); however, 500 kcals of exercise caloric expenditure elicited no significant changes in any of the measured blood lipid variables (p > 0.05 for all).
CONCLUSION: These data indicate that 500 kcals of exercise energy expenditure is not sufficient to induce blood lipid changes in young healthy males of at least average fitness.