ABSTRACT
The objective of this study was to compare the effects of 8 weeks of aerobic exercise with low and intermediate intensity on appetite, body weight, exercise energy expenditure, and plasma ghrelin level in women. Sixteen relatively obese [BMI>28] and 14 relatively thin [BMI<22] volunteer female-subjects were divided randomly into four groups, including obese with low intensity exercise [age=45.75 +/- 6.75 years, BMI=29.21 +/- 0.50 kg/m2]; obese with moderate intensity exercise [age=47.12 +/- 4.12 years, BMI= 29.59 +/- 0.127 kg/m2]; thin with low intensity exercise [age = 8 +/- 4.65 years, BMI = 21.21 +/- 0.53 kg/m2]; and thin with moderate intensity [age = 38.125 +/- 2.53 years, BMI= 21.49 +/- 0.377 kg/m2] exercise. Both the thin and obese groups with low intensity exercise ran 30 minutes per session [3 sessions/wk] for 8 weeks by 50% of the Maximum Heart Rate [MHR]. The intermediate exercise counterparts did the same exercise by 60% of MHR. Body weight at the beginning of each session and the distance run were recorded in each session. The Visual Analog Scale-based appetite questionnaires were filled in the morning of the 1st session of the first and fifth weeks and also in the morning of the day after the final session of the 8th week of the training; in all cases blood samples were taken to measure plasma acylated ghrelin level. The statistical tests used for data analysis included one-way ANOVA, ANOVA for repeated measurements, pair t-test, and partial Pearson correlation at 0.05 significance level. In all groups, feeling of hunger and plasma acylated ghrelin level increased, while body weight and satiety decreased [P<0.05]. There were significant differences in the magnitude of changes in hunger and satiety among the groups between the 4th and 8th weeks of exercise [P<0.05]. The distances run in each group between the 4th to 8th weeks were longer than those run in first 4-week of exercise [P<0.05]. The distances run by the thin groups in both the 1st and 2nd 4-week periods were longer than those run by the obese groups [P<0.05]. The data also showed that both the thin groups' exercise energy expenditures were higher than those of the obese groups between the 4th and 8th weeks of the training [P<0.05]. A statistically significant correlation was observed only in the thin group with low-intensity exercise between the body weight changes and hunger changes by the end of the 8-week period and between the aerobic exercise energy expenditure and the acylated ghrelin level changes between the 4th and 8th weeks [P< 0.05]. Moreover, there was a significant correlation between the distance run and changes in the plasma acylated ghrelin level between the 4th and 8th week of the training only in the thin group with moderate-intensity excercise [P<0.05]. It is unlikely that the aerobic exercise intensity or obesity/thinness would be the only effective factors on appetite in women. It seems moderate-intensity exercise would be preferential in weigh loss programs because of its higher energy expenditure. Additionally, it is expected that moderate-intensity exercise would give better results also in body weigh gain programs due to smaller increases in a feeling of hunger in thin individuals with low-intensity exercise. However, since true energy intake was not measured in this study [and considering lack of evidence in this area], longitudinal studies are needed to throw more light on the subject