تاثير ريتم شبانه روزي بر پاسخ كورتيزول و انرژي مصرفي در مردان چاق و لاغر

The Effects of Circadian Rhythm on Cortisol Responses and Energy Expenditure in Obese Versus Lean Men

The purpose of this study was to investigate the effects of circadian rhythm on Cortisol responses and energy expenditure in obese versus lean men. 12 sedentary college students divided in 2 groups; six obese (age 22.83±1.9 yr; Vo2max 35.45± 3.9 ml/min/kg; BMI 31.08±1.8kg/m2) and six lean (age 21.17±1 yr; Vo2max 45.86± 3 ml/min/kg; BMI 18.2±1.3kg/m2) subjects. Studentʹs t-test for compare variables in obese and lean group, and one-way ANOVA with repeated measure was used to evaluate Cortisol, EE, Vo2 and RER between groups during baseline and different times after exercise (P<0.05). After 8h fasting, subjects run on treadmill 30 min with intensity 65% maximal oxygen consumption, beginning at 8-AM and 6-PM. Our results show that during baseline, there were no differences between lean and obese groups for salivary Cortisol in morning and evening. In contrast, immediately, 15-min and 30-min after exercise obese group had significantly higher Cortisol concentration than lean group in morning and evening (p<0.05). There were no significant differences between Cortisol responses to 30-min exercise in lean and obese group. Mean EE and oxygen consumption (V02) during 30-min exercise in evening were significantly higher than morning (p<0.05). It can be concluded that obese men had higher and Cortisol level after 30-min exercise than lean men, Also time of day can affect on metabolic condition, and mean EE and VO2 during 30-min exercise in obese and lean men were significantly higher at 8-AM than 6-PM, thus it can be attention in weight programme purposes.