Body Composition, Fitness, and Thermoregulation in Young Boys With Type I Diabetes vs. Healthy Soccer Players

Thermal images of the lower limbs will be taken using a thermal camera (Flir SC 640, manufactured in the USA) before, during, and after exercise (during recovery). The assessment will be performed in degrees Celsius (°C).

Core temperature will be measured using the eCelsius Performance system (BodyCap, France).

Athletes with type 1 diabetes (study group) and healthy individuals (control group) will also have a continuous glucose monitoring (CGM) sensor (Dexcom, Dexcom, Inc., San Diego, CA, USA or FreeStyle Libre, Abbott Diabetes Care, Abbott Laboratories, Abbott Park, IL, USA, or an equivalent CGM system) placed on the back of one arm (according to the manufacturer's instructions). The sensors will be applied one week before the exercise test and will remain active for 14 days. Glucose levels will be measured in milligrams per deciliter (mg/dL).

Body weight (kg) will be measured using a digital stadiometer (SECA 285, SECA, Hamburg, Germany).

Body height (cm) will be measured using a digital stadiometer (SECA 285, SECA, Hamburg, Germany).

Bone Mineral Density (BMD) will be measured using dual-energy X-ray absorptiometry (DXA) with the Lunar Prodigy Pro DXA device (GE Healthcare, Madison, WI, USA) and enCORE v. 16 SP1 software. BMD is expressed in grams per square centimeter (g/cm²) and indicates the density of minerals, such as calcium, in bones. All DXA scans will be performed and analyzed by the same trained technician according to the manufacturer's protocols to ensure consistency and accuracy. The procedure involves the participant lying on a table while a low-dose X-ray scans their body. The process is non-invasive and generally considered safe, with minimal exposure to radiation, comparable to the amount received during a cross-country flight.

Fat Mass will be assessed using the DXA method with the Lunar Prodigy Pro DXA device and enCORE v. 16 SP1 software. This parameter is measured in kilograms (kg) or as a percentage of total body weight (%), representing the total mass of fat in the body.All DXA scans will be performed and analyzed by the same trained technician according to the manufacturer's protocols to ensure consistency and accuracy. The procedure involves the participant lying on a table while a low-dose X-ray scans their body. The process is non-invasive and generally considered safe, with minimal exposure to radiation, comparable to the amount received during a cross-country flight.

Lean Mass will also be measured using the DXA method. This includes the weight of muscles, organs, and other non-fat tissues, expressed in kilograms (kg). All DXA scans will be performed and analyzed by the same trained technician according to the manufacturer's protocols to ensure consistency and accuracy. The procedure involves the participant lying on a table while a low-dose X-ray scans their body. The process is non-invasive and generally considered safe, with minimal exposure to radiation, comparable to the amount received during a cross-country flight.

Ventilation will be measured using an ergospirometer (Cortex Metamax 3B R2, Leipzig, Germany) and analyzed with MetasoftStudio v. 5.1.0 software (Cortex-Metamax 3B R2; Cortex Biophysik, Leipzig, Germany). The ventilation parameter will be expressed in liters per minute (L/min), which allows for the assessment of the volume of air inhaled and exhaled by the participant per minute.

Oxygen consumption (VO2) will be measured using an ergospirometer (Cortex Metamax 3B R2, Leipzig, Germany) and analyzed with MetasoftStudio v. 5.1.0 software (Cortex-Metamax 3B R2; Cortex Biophysik, Leipzig, Germany). The VO2 parameter will be expressed in milliliters per kilogram per minute (mL/kg/min), which allows for the assessment of the amount of oxygen consumed by the body per unit of body weight per minute.

A Polar Bluetooth Smart HR H6 heart rate monitor (Polar Electro Oy, Kempele, Finland) will be used to monitor heart rate (HR), measured in beats per minute (bpm).

The Rating of Perceived Exertion (RPE) scale will be used to monitor fatigue levels during exercise. The RPE will be measured on a scale from 6 to 20.

Level 6 on the RPE scale indicates no exertion. This is the lowest level, suggesting that the exercise requires no physical effort.

Level 20 on the RPE scale indicates maximum exertion. This is the highest level, suggesting that the exercise is performed with the maximum possible effort, at the limit of endurance.

To measure lactate accumulation, a Biosen C-line (EKF Diagnostics, Barleben, Germany) will be used. In brief, 20 µL of whole blood will be drawn into a prefilled micro test tube using a capillary. The L-lactate contained in the sample will be enzymatically converted to pyruvate and hydrogen peroxide, which will be detected by the electrode. The lactate concentration will be measured in mmol/L.

To measure glucose levels, a glucose meter (e.g., Accu-Chek, Roche Diagnostics, Mannheim, Germany) will be used. In brief, a small drop of blood will be obtained from the fingertip using a lancet. The blood sample will then be placed on a test strip inserted into the glucose meter. The glucose in the sample will react with the chemicals on the strip, producing an electrical signal that will be measured by the meter. The glucose concentration will be displayed in mg/dL.