Exercise Intensity and Postprandial Effects of Breaking Sedentary Behavior in Overweight Adults

N/ANot Yet RecruitingNCT07229963

Hacettepe University16 enrolled

Overview

The purpose of this study is twofold: (1) to determine whether breaking up prolonged sitting with aerobic or sprint cycling breaks reduces postprandial blood glucose, insulin, CRP, and blood pressure, which are established risk markers for cardiometabolic diseases; and (2) to assess substrate oxidation during this period in order to identify which exercise condition promotes the greatest increase in fat oxidation.

Sedentary behavior (SED) refers to activities such as sitting, lying down, or reclining that require energy expenditure of ≤1.5 MET during the time spent awake. Prolonged and continuous sedentary behavior leads to adverse effects such as abnormal postprandial metabolic responses, insulin resistance, vascular dysfunction, high blood pressure, increased carbohydrate oxidation, and inflammation. Epidemiological data also show that SED increases the risk of mortality, cardiovascular disease, type 2 diabetes, and certain types of cancer. Experimental studies have shown that 2-5 minutes of low- or moderate-intensity aerobic exercise performed every 20-30 minutes during the postprandial period improves cardiometabolic health by reducing glucose, insulin, and blood pressure during the postprandial period. On the other hand, it is known that short-term sprint interval exercise (SIE) increases insulin sensitivity by rapidly depleting muscle glycogen, improves glucose control, lowers blood pressure, and increases fat oxidation. With these effects, SIE may be a time-efficient method for interrupting SED. Although the cardiometabolic benefits of SIE and aerobic exercise interruptions (AEI) are known, there is a lack of studies comparing the effects of interrupting SED with these two exercise types of different intensities in preventing postprandial cardiometabolic dysfunction. In this context, the aim of the study is to compare the postprandial cardiometabolic effects of interrupting sedentary behavior with AIE and sprint exercise interruptions (SEI) in overweight but otherwise healthy women and men aged 35-45. In this randomized crossover trial, volunteers will participate in three trials: 1) AEI, 2) SEI, and 3) SED. There will be a minimum 3-day washout period between trials. In the SEI and AEI trials, exercise interruptions will be implemented every 30 minutes during the 7-hour sitting period, whereas in the SED trial, participants will remain seated continuously for the entire duration. In all conditions, two meals (breakfast and lunch) will be served 3 hours apart, and the trials will begin, after the breakfast meal is consumed. Venous blood samples taken hourly during the experiment will be used to analyze insulin, glucose, and C-reactive protein (CRP) levels. In addition, blood pressure will be measured hourly, and fat oxidation will be assessed at the baseline, 2nd, 5th, and 7th hours. The effects of the conditions on glucose and insulin will be evaluated using linear mixed models. A Two-Way (Trial x Number of Repeats) Analysis of Variance for Repeated Measures will be used to detect differences between conditions.

Interventions

Aerobic Exercise InterventionOTHER

In the aerobic exercise condition, participants will perform 2 minutes of moderate-intensity continuous cycling.

Sprint Exercise InterventionOTHER

In the sprint condition, participants will complete a 10-second all-out sprint, as determined during the preliminary test.

Sedentary Behaviour InterventionOTHER

Participants will remain seated for a total duration of 7 hours. During this period, they will be instructed to minimize excessive movement and will only be permitted to rise from the chair for voiding purposes.

Eligibility

Sex: ALLMin age: 35 YearsMax age: 45 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria * Being physically inactive (not doing at least 150 minutes/week of structured exercise). * Having a physical activity level of \<5000 steps/day. * Having a BMI between 25 and 29.9 kg/m2. * Having a history of regular menstrual cycles for female participants. * Having medical examination approval. Exclusion Criteria * Taking any acute or chronic medication or supplement that may affect metabolism. * Having an acute or chronic illness that limits exercise (musculoskeletal problems, cardiovascular disorders, respiratory problems, etc.). * Consuming tobacco products. * Meeting 3 or more of the metabolic syndrome criteria (waist circumference of 102 cm or more in men, 88 cm or more in women, triglyceride level of 150 mg/dL or higher, HDL cholesterol level below 40 mg/dL in men and 50 mg/dL in women, blood pressure of 130/85 mmHg or higher, fasting blood glucose level of 100 mg/dL (5.6 mg/L) or higher).

Outcomes

Primary Outcomes

Insulin

Postprandial insulin. Net incremental area under the curve and total area under the curve for each 7 h condition will be calculated for insulin.

Time frame: 7 hour for each experimental condition

Secondary Outcomes

Glucose

Postprandial glucose. Net incremental area under the curve and total area under the curve for each 7 hour condition will be calculated for glucose.

Time frame: 7 hour for each experimental condition

CRP

Postprandial CRP. Net incremental area under the curve and total area under the curve for each 7 h condition will be calculated for CRP.

Time frame: 7 hour

Substrate oxidation

Postprandial substrate oxidation. During each experimental visit, for 7 hours, volunteers' respiratory data will be collected using a direct calorimeter in a seated position for 10 minutes at 0, 2th, 5th, and 7th hours. The volunteers' resting fat and carbohydrate oxidations will be determined from the obtained data.

Time frame: 0, 2th, 5th, 7th hours

Blood pressure

Postprandial arterial blood pressure will be measured hourly for 7 h using an automatic blood pressure monitor with a cuff of appropriate size. The systolic and diastolic BP values measured will be recorded, and the mean arterial pressure will be calculated.