The Impact of Various Exercise Intensities on Energy Expenditure Metabolism

An Observational Study on the Relationship Between Different Exercise Intensities and Energy Expenditure Metabolism

The goal of this observational study is to learn about the effects of physical activity in adult on metabolic response. The main question it aims to answer is:

• if physical activity is unlimited to increase the total energy expenditure (TEE)?

Participants will engage in the following measurements:

• Record their daily physical activity by GT3X.
• Measure TEE by doubly-labeled water (DLW) method
• Measure basal energy expenditure(BEE) and thermic effect of food(TEF) by respiratory chamber

The purpose of this study is to explore the effect of various physical activities on metabolic and behavior response. Energy expenditure, body composition, and metabolism will be measured by the following measurements:

• TEE:

TEE will be measured using the DLW method. Urine samples from all participants in the DLW subset will be stored at -20℃ and shipped on dry ice for analysis in the laboratory of Prof. John Speakman at the Shenzhen Institutes of Advanced Technology, Chinese academy of sciences. Isotopes will be measured in benchtop near-infrared isotope gas analyzer, and mean CO2 production will be calculated from isotope ratios using the recently derived equation. TEE will then be calculated using mean CO2 production.

• REE and TEF:

REE and TEF will be measured by indirect calorimetry while participants are resting supine in a respiratory chamber with thermoneutral conditions. Oxygen consumption and CO2 production will be measured to calculate energy expenditure. REE will be consistently measured throughout sleeping at night and in the morning after overnight fasting, and TEF will be measured after breakfast.

• Physical activity：

Physical activity of the participants will be recorded using GT3X accelerometer worn near the hip for a consecutive period of 14 days. The monitor should not be worn while bathing or swimming. The first day is discarded along with any day with less than 12 hours of wear. For a valid measure the goal is to get 2 weekday and 2 weekend days.

• VO2max test:

Participants need to warm up with simple stretching or light aerobic exercise before the test. The test will be conducted on a treadmill. A comfortable running speed acceptable to the participants will be set. The treadmill's incline will be increased by 10% every two minutes until the individual reaches their physical limit and can no longer continue. During this test, a respiratory mask and gas analyzer will be used to measure the concentration of oxygen (O2) and carbon dioxide (CO2) in the breath to calculate VO2max.

• Food intake

Photographic and food weighing methods to record food intake for two random days throughout the period of DLW measurement.

• Blood glucose

Fasting and post-prandial glucose will be recorded by a continuous glucose monitoring system.

• Body composition：

Fat mass will be measured by Magnetic Resonance Imaging (MRI, Shanghai united imaging, uMR 790 ).

Bioimpedance Analysis will measure fat-free mass (Tanita, MC-980). Bone mass will be measured by Dual Energy X-ray Absorptiometry (DXA, Horizon Wi, HOLOGIC).

• Body weight:

At visit 1, fasting body weight will be measured using a calibrated seca at the beginning of the visit. Fasting weight will be measured at visit 2 and, if applicable.

• Height:

Height (to +0.1 cm) will be measured by seca 217 stable without wearing shoes.

• Waist circumference:

Hip and waist circumference (to +0.3 cm) will be measured using a whole body laser scanner.

• Blood pressure:

Systolic and diastolic blood pressure will be measured using an Omron digital sphygmomanometer.

Inclusion Criteria:

• BMI ≥ 18.5 kg/m2

Exclusion Criteria:

• Individuals who have undergone major surgery in the past 6 months (excluding tooth extraction);
• Individuals with severe metabolic and cardiovascular diseases such as diabetes, hypoglycemia, and hypertension;
• Individuals with exercise-related injuries, including joint diseases and fractures;
• Individuals diagnosed with infectious diseases such as HIV, tuberculosis, malaria, etc.;
• Individuals with mental and neurological disorders including anorexia nervosa;
• Individuals who have attempted weight loss or gain through various methods in the past three months;
• Individuals in preconception, pregnancy, and lactation periods;
• Individuals with autism and those with metal implants in their bodies.