Changes in Energy Expenditure in Response to Physical Activity in Healthy Adults

This study investigates how short, high-intensity body-weight exercises affect energy use in healthy young adults. The focus is on resting metabolic rate (RMR), total energy expenditure (TEE) and excess post-exercise oxygen consumption (EPOC), measured with a portable indirect calorimetry system (COSMED K5). Participants will be 14 volunteers, seven women and seven men aged 18 to 30 years, recruited from the academic community of the Medical University of Białystok. Each subject will first undergo basic screening, including ECG, blood pressure, and body composition. Measurements will be taken in three phases. In the resting phase, RMR will be recorded after fifteen minutes of quiet sitting. In the exercise phase, participants will perform squats, burpees, or a plank for one minute at maximum effort or sustained position while energy use is continuously monitored. In the recovery phase, EPOC will be measured immediately after exercise to capture short-term changes. Oxygen uptake, ventilation, heart rate, and oxygen saturation will be tracked throughout the session. Environmental conditions such as room temperature and humidity will be standardized, and participants will avoid caffeine, alcohol, and heavy physical activity at least 24 hours before testing. The main aim is to determine whether even one minute of exercise can meaningfully alter EPOC steady state parameters, and to compare the energy cost of different exercise types. The data will be analyzed in relation to anthropometric variables and cardiopulmonary function. Results are expected to improve understanding of short-term energy dynamics and may support more precise recommendations in pulmonary rehabilitation, cardiology, sports medicine, and nutrition. By providing reliable measurements of caloric cost in simple exercises, the study can help design safer and more effective training, rehabilitation, and weight control programs.

Inclusion Criteria: * Age 18-30 years * Healthy volunteers without chronic diseases * Normal resting ECG (regular sinus rhythm, 60-90 bpm) * Normal blood pressure according to ESC guidelines * Ability and willingness to provide written informed consent Exclusion Criteria: * Chronic diseases or musculoskeletal injury within the past 6 months * Use of tobacco or nicotine products within the past 6 months * Blood donation \>20 mL (except diagnostic) within the past 6 months * Use of narcotics, sedatives, or dietary supplements (e.g., creatine) within the past 2 weeks * Active infection, fever, or acute illness at the time of study * Inability to comply with study instructions (dietary restrictions, abstinence from alcohol/caffeine, exercise restrictions)