1. Comparison between the Effect of Six Weeks Morning or Evening Aerobic Exercise on Appetite and Anthropometric Indices
Zahra Alizadeh, MD Assistant Professor of Sports and Exercise Medicine Tehran University of Medical Sciences

2. Introduction
In recent decades, obesity has become a major health problem. So far, several studies have showed that exercise is related to creating negative energy balance and changes in appetite directly. However, few of the studies examined the effect of exercise time during the day on these factors.

3. Objectives
The aim of the present study was demonstrating the effect of 6 weeks morning or evening aerobic exercise on appetite and anthropometric indices

4. Methods

5. Methods Inclusion criteria:
20-45-year-old sedentary overweight female subjects;
not suffering from cardiovascular, pulmonary, metabolic diseases or musculoskeletal problems ;
not taking any medication affecting heart rate, blood pressure, exercise capacity or appetite suppressors ;
and not being pregnant.

6. Methods
Exclusion criteria: pregnancy during the intervention; musculoskeletal problem during the exercise sessions; and refusal to participation in the study.

7. Forty-eight overweight females were recruited in this clinical trial
Methods
Forty-eight overweight females
were recruited in this clinical trial

8. Methods After inclusion in the three visits,
Informed consent were completed;
Healthy nutrition were educated;
Anthropometric measurements including height, waist circumferences, abdominal and suprailiac skin fold thicknesses were determined.

9. Methods After inclusion in the three visit,
Weight, PBF and SLM were calculated using Body Impedance Analyzer (AVIS33 body composition analyzer, Jawon Medical Co. Ltd, South Korea);

10. Methods After inclusion in the three visit,
Exercise test for determination of the maximal heart rate and ventilatory threshold (VT) were done by the gas analysis device (Quark CPET, COSMED, Italy).

11. Methods
By the time of exercise, the participants were divided randomly into two groups (morning 8-10 AM or evening 2-4 PM) and performed 6 weeks supervised aerobic exercise on treadmill in the obesity clinic (30 minute/session) with the target heart rate on the ventilatory threshold.

12. Methods
In three time points (at baseline and in the third and the sixth week of the trial),
24 hours food consumption was recorded before and after exercise session,

13. Methods
In three time points (at baseline and in the third and the sixth week of the trial),
The appetite visual analogue scale was completed before the exercise session and 15 minutes after that in order to estimate the level of prospective food consumption, fullness, hunger, satiety and the desire to eat savory, sweet, salty and fatty foods.

15. Methods
All of the variables (Appetite changes, calorie intake, and anthropometric indices) were compared between two groups and within groups at baseline, in the third and sixth week.

16. Results

17. Exercise Test and primary measurements, n = 48
Recruitment
n = 48
Exercise Test and primary measurements, n = 48
Morning exercise, n = 25
Starting supervised morning exercise , n = 25
Mid trial measurements
n = 23, 2 = dropped out
End trial measurements
n = 21, 2 = dropped out
Evening exercise, n = 23
Starting supervised evening exercise
n = 20, 3 = dropped out
n = 19, 1 = dropped out
n = 16, 3 = dropped out

18. Results
Significant differences were not seen in the parameters evaluated at baseline between two groups.

19. Assessment time points
Anthropometric outcomes over time in the morning and evening exercise groups
Variables
Assessment time points
P-value
Baseline
Week 3
Week 6
Weight, kg
0.04
Morning exercise group*
71.71 (1.32)
70.72 (1.32)
70.16 (1.38)
Evening exercise group
71.77 (1.62)
71.49 (1.68)
71.49 (1.69)
BMI, kg/m2
27.29 (0.31)
26.91 (0.31)
26.69 (0.33)
27.57 (0.32)
27.46 (0.34)
27.47 (0.38)

20. Assessment time points
Anthropometric outcomes over time in the morning and evening exercise groups
Variables
Assessment time points
P-value
Baseline
Week 3
Week 6
Body fat, %
0.26
Morning exercise group *
35.71 (0.38)
35.08 (0.39)
34.60 (0.43)
Evening exercise group *
35.71 (0.53)
35.27 (0.55)
35.12 (0.57)
Lean body mass, %
0.27
64.29 (0.38)
64.92 (0.39)
65.40 (0.42)
64.28 (0.53)
64.73 (0.55)
64.88 (0.57)
Soft lean mass, %
0.25
58.64 (0.38)
59.25 (0.39)
59.75 (0.42)
58.65 (0.52)
59.10 (0.54)
59.24 (0.56)

21. Assessment time points
Anthropometric outcomes over time in the morning and evening exercise groups
Variables
Assessment time points P
Baseline
Week 3
Week 6
Abdominal circumference, cm
0.60
Morning exercise group *
95.40 (1.00)
94.73 (1.06)
93.90 (1.03)
Evening exercise group
96.47 (1.64)
96.49 (1.77)
95.80 (1.81)
Abdominal skinfold thickness, mm
0.21
36.92 (1.81)
35.23 (1.46)
33.66 (1.04)
33.61 (1.16)
32.99 (1.27)
33.36 (1.12)
Supra-iliac skinfold thickness, mm
0.13
Morning exercise group
33.48 (1.59)
33.06 (1.50)
31.44 (1.52)
35.26 (2.23)
33.05 (1.65)
32.84 (1.70)

22. Results
Consistent changes in the appetite scores were not found along the 6 weeks (P > 0.05)

23. Results
Calorie consumption of the morning group decreased along the 6 weeks significantly greater than that of the evening group (P= 0.02).

24. Assessment time points
Summary of 24-hour food records over time in the morning and evening exercise groups
Variables
Assessment time points
P-value
Baseline
Week 3
Week 6
Total energy intake, kcal
0.02
Morning exercise group*
(115.58)
(79.87)
(128.07)
Evening exercise group
(93.49)
(84.29)
(147.89)

25. Discussion

26. Discussion: Anthropometric outcomes
A large body of studies have demonstrated the effect of exercise on weight and PBF reduction.
But there is no evidence to compare the effect of time of exercise during the day on body composition.

27. Discussion: Anthropometric outcomes
However, in the present study, the time of exercise during the day could induce some different effects on weight and body composition of the subjects.

28. Discussion: Appetite and desire scores for specific food types
To the best of our knowledge Maraki et al. experience is the only study to investigate the effects of morning versus evening exercise on appetite indices.
They analyzed the effect of single exercise trial on 12 normal weight women in two different times of the day.

29. Discussion: Appetite and desire scores for specific food types
They showed that exercise, regardless of the time, could decrease satiety and fullness significantly. But prospective food consumption (PFC) and hunger enhanced in both groups, without significant differences between the two.

30. Discussion: Appetite and desire scores for specific food types
However, the results of the Maraki study were inconsistent with the previous studies many of which have showed that exercise, apart from exercise time during the day, has no effect on appetite indices or food consumption after exercise.

31. Discussion: Appetite and desire scores for specific food types
This contradiction could be explained by the exercise program and the assessment time of appetite in the participants.

32. Discussion: Appetite and desire scores for specific food types
Neither did we find consistent changes in the appetite scores along the 6 weeks.
Moreover, the transient changes in appetite indices were not significant between the two groups.

33. Discussion: Outcomes of 24-hour food records
There are plenty of studies that have investigated the effect of high or moderate intensity aerobic exercise on calorie intake in short time.

34. Discussion: Outcomes of 24-hour food records
According to the existing evidence, energy intake after exercise does not increase remarkably, so absolute energy intake decreases.
However, some studies reported significant increase or decrease in calorie intake after physical activity. These differences could be concluded due to exercise intensity or duration of the trials.

35. Discussion: Outcomes of 24-hour food records
In sum, according to the present study, moderate to high intensity aerobic exercise leads to negative energy balance with further effect of morning time in comparison to evening. Further studies are needed to prove the effect of exercise time on calorie intake and probable mechanisms such as increasing control on intake and post exercise oxygen consumption, etc. in morning time exercise.

36. Conclusions
It seems that moderate to high intensity aerobic exercise in the morning along 6 weeks could be considered as a more effective program than evening exercise on appetite control, calorie intake, and weight loss in overweight female subjects

37. E-mail: z_alizadeh@tums.ac.ir
Thank you for your attention