Glucose-Level During Endurance Exercise

In this study, physiological data from healthy volunteers will be investigated. A total of 100 healthy volunteer participants will be recruited from soldiers serving at the Bundeswehr Hospital Ulm. As part of the mandatory annual assessment of physical fitness required by their employer, these individuals must complete a standardized military march. During this march, metabolic parameters will be assessed.

At the beginning of the study, anthropometric data as well as general information regarding medical history, lifestyle, and fitness status will be collected using a baseline questionnaire developed by the Section of Endocrinology and Diabetology. In addition, a validated questionnaire on physical activity (BSA questionnaire) will be administered. The information obtained will support the interpretation of physiological parameters, as individual fitness levels may influence heart rate and glucose dynamics.

Blood samples (maximum 60 mL) and urine samples will be collected to determine routine laboratory parameters as well as metabolic markers. Participants will undergo bioelectrical impedance analysis to assess body composition. To collect physiological data, selected sensors and devices will be attached to the participants (continuous glucose monitoring, electrocardiography).

After the sensors have been applied and calibrated, participants will complete a 6 km march carrying 15 kg of equipment. The march will be conducted in uniform in accordance with central military regulations, with standardized marching equipment and a fixed route consisting of two laps around the grounds of the Bundeswehr Hospital Ulm.

At the end of the march, the sensors will be removed by the study physicians. Subsequently, an additional blood sample (maximum 60 mL) will be collected to assess metabolic parameters following physical exertion, and a urine sample will be obtained for the analysis of catecholamines.

Restricting participation to soldiers provides optimal conditions for investigating glucose dynamics and their influencing factors during endurance exercise in healthy individuals. Soldiers undergo regular comprehensive health check-ups every three years, including medical questionnaires, physical examinations, laboratory diagnostics, and additional specialist evaluations when indicated. Conditions such as prediabetes or arterial hypertension are therefore detected and treated at an early stage, resulting in a medically well-screened cohort of healthy individuals.

Scientific data on glucose dynamics during physical exercise are already available for individuals with diabetes and for professional athletes. However, data in healthy individuals remain limited. The pre-screened cohort of soldiers is therefore particularly suitable for addressing this research question. Compared with other potential study populations, such as participants recruited from university recreational sports programs, this cohort offers several advantages, including a broader range of fitness levels, a wider age distribution (up to 65 years), and substantial experience with the specific exercise task. The annually performed 6 km march with load is conducted under standardized conditions and is familiar to the participants, thereby minimizing stress-related metabolic effects. Standardized clothing and equipment further reduce potential external confounding factors.

• Training status [Time frame: Baseline]
• Correlation between training status and glucose dynamics during endurance exercise [Time frame: Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)]
• Body composition [Time frame: Baseline.]
• Correlation between body composition and glucose dynamics during exercise. [Time frame: Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)]
• Biomarkers of inflammatory response [Time frame: Baseline and immediately after the march (approximately 1 hour after baseline)]
• Correlation between inflammatory markers with glucose dynamics during exercise. [Time frame: Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)]
• Cortisol levels [Time frame: Baseline and immediately after the march (approximately 1 hour after baseline)]
• Correlation between cortisol levels and glucose dynamics during exercise. [Time frame: Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)]
• Biomarkers of lipolysis [Time frame: Baseline, immediately after the march (approximately 1 hour after baseline)]
• Correlation between lipolysis and glucose dynamics during endurance exercise [Time frame: Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)]