improves insulin resistance. However, the effect of training sessions a day is not

clear in this regard. The aim of this study was to investigate the effect of one or

two sessions a day of exercise training, with equal intensity and duration, on

insulin resistance in sedentary middle-aged men. Materials & Methods: 30

sedentary middle-aged male volunteers (age=43.6±6.5 yr, weight=80.4±13.6kg,

height=174.1±5.5cm,BMI=26.5±3.6kg/m2،VO2max=35.46±6ml/kg) randomized to

the control (n=10), one session a day (n=10)and two sessions a day training

group( n=10). Exercise program consisted of 16 weeks, five days a week, tread

mill running which was implemented as one (30 minutes) or two sessions (2×15

minutes) a day. Training intensity was 40-50% of HRmax at first week and

reached to 70-80% at 16th week of the training. Measurements of fasting blood

samples (insulin, glucose and adiponectin), insulin resistance, cardiorespiratory

fitness, abdominal obesity and BMI were obtained at baseline and post

exercise. Paired t test and analysis of Variance were used to analyze the data.

Results: After 16 weeks of training, compared with the control group, a

significant reduction in blood glucose, abdominal obesity and BMI, and a

significant increase in cardiorespiratory fitness were observed in the both

experimental groups; whereas insulin resistance remained unchanged, and

adiponectin was significantly increased only in the one session a day training

group. Conclusion: based on the findings it seems that, dividing the physical

activity session in two shorter parts can improve glucose profile, cardiorespiratory

fitness and obesity indicators the same as a continuous exercise session. But in

terms of increased adiponectin and decreased abdominal obesity, continuous

exercise session is more effective.