Plasma triglyceride (TG) and high density lipoprotein-cholesterol (HDL-C) concentrations typically improve following a single bout of aerobic exercise of sufficient energy expenditure, however the response to multiple exercise bouts is not well documented, especially in women. Non-smoking, moderately active, young (M±SD; 24.6±7.9 yrs) women (n=11) who were not taking oral contraceptives volunteered to participate in this investigation. The participants had the following characteristics: mass=65.8±11.6 kg, height=161.5±5.9 cm, percent fat=28.3±6.4%, VO2peak=32.1±6.4 ml/kg/min. Menstrual cycle patterns were recorded for three months prior to beginning any experimental procedures. All participants performed a resting control (REST) and exercise (EX) trial in random order. The EX trial consisted of three treadmill exercise sessions at 65%VO2peak expending 500 kcal on non-consecutive days such that exercise was performed at 0 h, 48 h and 96 h. The REST trial required participants to sit for 45 minutes on three non-consecutive days separated by 48 hours. The EX and REST trials began during the early follicular phase of the menstrual cycle. During REST and EX trials, blood was collected following a 12-hour fast immediately prior to the first exercise and resting trial (0 h). Additionally, fasting blood samples were collected 24 h, 48 h, 96 h, and 144 h following the 0 h sample during both trials. Dietary consumption, recorded each day during the EX and REST trials, was not different between the two trials. A 2x5 (trial x time) repeated measures ANOVA was employed to determine significant differences (p£0.05) between groups using a Bonferonni correction. There were no changes in lipid or lipoprotein concentrations during the first 48 h of EX and REST. There was a significant trial x time interaction at 96 h for HDL-C (EX=53.3±9.6 mg/dl; REST=47.1±11.0 mg/dl); however, the EX HDL-C at 96 h was not different than EX HDL-C at 0 h (EX=51.3±9.4 mg/dl). This interaction appeared to be a result of a non-significant elevation (p=0.073) of HDL3-C at 96 h. There was a significant effect of time on TG at 144 h (EX=83±45 mg/dl; REST=72±36 mg/dl) as compared to 0 h (EX=103±61 mg/dl; REST=110±61 mg/dl), but there was no difference between TG during EX and REST at 144 h. No other significant differences in lipid and lipoprotein concentrations were detected. It was concluded that three non-consecutive days of exercise expending 500 kcal have only minimal effects on plasma triglyceride and lipoprotein-cholesterol concentrations in moderately active women.Keyword(s): research