Effects of Exercise at Different Times of Day on 72-hour Eating Behaviours and Physical Activity in Physically Inactive Adults

Eligibility and Consent Confirmation Prior to the one-week preliminary test, participants underwent eligibility screening, including measurements of height, weight, and body composition. After the researchers provided a detailed explanation of the experimental procedures, participants decided whether to participate in the study. Eligible participants then completed a 10-minute treadmill walking session (6.4 km/h for males and 6.0 km/h for females) to familiarize themselves with the exercise intensity. Subsequently, the researchers explained the use of pedometers and distributed dietary record forms.

During a one-week preliminary test, participants were instructed to record their physical activity levels measured in steps, sleep duration including wake-up and sleep times, and dietary behaviours through photographs taken (2 weekdays and 1 weekend day) over a period of 7 consecutive days. Participants were allowed to take part in this study, once they met the inclusion criteria: 1) an average daily step count of less than 7,500 over the course of the week and 2) a wake-up time no later than 11:00 AM).

Exercise intervention During the main trials, two main trials, separated by at least one week, were conducted - exercise in the morning (08:00 to 11:00 AM) or exercise in the evening (18:00 to 21:00 PM).

In both trials, participants completed the first Visual Analogue Scale (VAS) for subjective appetite upon waking, wore a pedometer and an accelerometer, and recorded energy intake and physical activity over a 3-day period (the day before exercise intervention, the exercise day and the day after exercise intervention). Upon arrival at the laboratory, participants completed the second VAS, followed by a 15-minute waiting period before commencing the exercise. Participants then performed a 45-minute treadmill brisk walk (6.4 km/h for males, 6.0 km/h for females), followed by a 15-minute rest period, after which they completed the third VAS.

Heart rate and Rating of Perceived Exertion (RPE) were measured every 15 minutes during exercise. Energy balance (e.g., energy intake and spontaneous physical activity) was assessed using a food diary, Actigraph wGT3x-BT accelerometer (Actigraph Co., Ltd., Pensacola, FL, USA), and pedometer (Realalt, Goldhat Ltd., UK), which were worn starting from the night two days before the experiment and removed after waking up two days post-experiment.