This study will examine whether light physical activity after meals can improve 24-hour glucose responses in adults with metabolic syndrome and prediabetes.

Participants will complete three experimental conditions in a randomized crossover order: prolonged sitting, 15 minutes of postprandial walking, and brief resistance exercise snacks consisting of squats and calf raises performed every 20 minutes during the postprandial period. Continuous glucose monitoring will be used to assess 24-hour glucose responses, and heart rate variability will be measured during the 2-hour postprandial period to evaluate acute autonomic responses.

The main outcome is 24-hour mean glucose derived from continuous glucose monitoring.

Metabolic syndrome and prediabetes are associated with impaired glucose regulation and increased cardiometabolic risk. Light physical activity after meals may help reduce postprandial glucose excursions and improve overall daily glucose control. However, it remains unclear whether brief resistance exercise snacks can provide glucose benefits comparable to postprandial walking under standardized meal conditions.

This study is a randomized crossover trial in adults aged 40 to 65 years with metabolic syndrome and prediabetes. Each participant will complete three experimental conditions in a randomized order: prolonged sitting, 15 minutes of walking after a standardized meal, and brief resistance exercise snacks performed every 20 minutes during the postprandial period. The resistance exercise snacks will consist of simple body-weight exercises, including squats and calf raises.

Glucose responses will be assessed using continuous glucose monitoring. The primary outcome will be 24-hour mean glucose after each experimental condition. Key secondary glycemic outcomes will include 2-hour postprandial glucose incremental area under the curve, 2-hour mean glucose, peak glucose, time to peak glucose, nocturnal mean glucose, and glycemic variability indices. Heart rate variability will be assessed during the 2-hour postprandial period using RR interval data collected with a chest strap heart rate monitor to evaluate acute autonomic responses to each condition.

The purpose of this study is to determine whether brief resistance exercise snacks can improve 24-hour glucose regulation and postprandial glucose responses compared with uninterrupted sitting, and whether these responses are comparable to postprandial walking.

Inclusion Criteria:

• Inclusion Criteria:
• Adults aged 40 to 65 years
• Presence of metabolic syndrome
• Fasting glucose of 100 mg/dL or higher or HbA1c of 5.7% or higher
• Not regularly engaged in structured exercise training, defined as less than 150 minutes per week during the past year
• Able to consume the standardized study meals
• Able to wear a continuous glucose monitor and a chest strap heart rate monitor
• Able to provide written informed consent

Exclusion Criteria:

• History of major cardiovascular, cerebrovascular, respiratory, renal, hepatic, neurological, or other severe medical conditions that may affect study participation.
• Uncontrolled hypertension, defined as systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥100 mmHg.
• Current use of medications associated with a high risk of hypoglycemia, such as insulin or sulfonylureas.
• Initiation or dose change of insulin or oral glucose-lowering medications within the past 3 months.
• Initiation or dose change of medications for hypertension, dyslipidemia, or diabetes within the past 3 months.
• Musculoskeletal, neurological, or orthopedic conditions that limit safe participation in walking or body-weight resistance exercise, including severe knee, hip, back, or ankle pain.
• Regular participation in moderate-to-vigorous exercise of 150 minutes or more per week during the past year.
• Difficulty consuming the standardized study meals, including food allergy, dietary restrictions, or severe gastrointestinal symptoms.
• Difficulty wearing a continuous glucose monitor or history of severe skin irritation or allergy to adhesive sensors.
• Difficulty wearing a chest strap heart rate monitor or skin problems at the chest strap site.
• Pregnancy or planned pregnancy.
• Acute illness, infection, surgery, or hospitalization within the past month.
• Current participation in another interventional study.
• Any condition judged by the investigator to make participation unsafe or inappropriate.

Exclusion Criteria:

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Masking is not feasible because participants and investigators will be aware of the assigned exercise condition.