Glucose-Level During Endurance Exercise (GLEE)

Glucose-Level During Endurance Exercise (GLEE Study): Influencing Factors and Mechanisms

As part of the mandatory annual assessment of physical fitness, soldiers are required to complete a standardized military march. A total of 100 healthy volunteer participants will be recruited from soldiers serving at the Bundeswehr Hospital Ulm. During this march, physiological and metabolic parameters will be assessed.

At baseline, anthropometric data and information on medical history, lifestyle, and fitness status will be collected, including a validated questionnaire on physical activity. Blood and urine samples will be obtained to determine routine laboratory and metabolic parameters, and body composition will be assessed using bioelectrical impedance analysis. In addition, selected sensors will be applied to continuously record physiological data.

Participants will then complete a 6 km march carrying 15 kg of equipment. After completion of the march, sensors will be removed and additional blood and urine samples will be collected to evaluate metabolic responses to physical exertion, including catecholamine levels.

Study Overview

• Status: Recruiting
• Conditions: Glucose Metabolism
• Intervention / Treatment: Other: Standardized military march

Detailed Description

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.

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

• Study Contact: Name: Martin Heni, MD; Phone Number: +4973150044505; Email: martin.heni@uniklinik-ulm.de
• Study Contact Backup: Name: Sabrina Wanglelr; Phone Number: +4973150044782; Email: sabrina.wangler@uniklinik-ulm.de

Study Locations

• Germany
  • Ulm, Germany, 89081
    • Recruiting
    • Bundeswehr Hospital Ulm
    • Contact: Birgit Richter, MD; Phone Number: +49 731/1710-0; Email: birgit1richter@bundeswehr.org
    • Contact: Sabrina Wangler; Phone Number: +4973150044505; Email: sabrina.wangler@uniklinik-ulm.de

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

healthy volunteer participants recruited from soldiers serving at the Bundeswehr Hospital Ulm

Description

Inclusion Criteria:

• BMI between 18.5 and 30 kg/m^2

Exclusion Criteria:

• Pregnancy or lactation
• cardiovascular disease
• vegan diet
• drug or alcohol abuse
• Drug therapy that raises or lowers blood sugar, e.g. steroids, antidiabetics, insulin or influences the autonomic nervous system
• No consent to be informed about incidentally discovered pathological findings
• Any other (clinical) condition that would endanger participants safety or question scientific success according to the physicians opinion.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Soldiers; healthy volunteer participants recruited from soldiers serving at the Bundeswehr Hospital Ulm	Other: Standardized military march; 6 km march carrying 15 kg of equipment. The march will be conducted in uniform in accordance with central military regulations. Participants will be equipped with a continuous glucose monitor an electrocardiography wearable during the march. Before and after the march blood and urine samples will be obtained.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glucose dynamics during exercise	Interstitial glucose responses during the standardized endurance exercise (6 kilometer march with 15 kilogram load) measured via continuous glucose monitoring.	1 hour
Sympathetic nervous system activation (catecholamines)	Activation of the sympathetic nervous system during a standardized endurance exercise measured via changes in catecholamine levels.	Baseline, immediately after the march (approximately 1 hour after baseline)
Correlation between sympathetic activation (catecholamines) and glucose dynamics during endurance exercise	Correlation between sympathetic nervous system activation measured via catecholamine levels and glucose responses during a standardized endurance exercise (6 kilometer march with 15 kilogram load).	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Heart rate variability	Heat rate variability during a standardized endurance exercise measured via electrocardiography.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Correlation between heart rate variability and glucose dynamics during endurance exercise	Correlation between heart rate variability and glucose responses during a standardized endurance exercise (6 kilometer march with 15 kilogram load).	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Training status	Individual fitness level assessed via the Movement and Sport Activity questionnaire (sport and physical activity based on reported frequency and duration of activities and provides estimates of activity in minutes per week or MET-hours per week)	Baseline
Correlation between training status and glucose dynamics during endurance exercise	Correlation between training status and glucose responses during the standardized endurance exercise.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Body composition	Muscle mass in kilogram assessed by bioelectrical impedance analysis.	Baseline.
Correlation between body composition and glucose dynamics during exercise.	Correlation between muscle mass and glucose responses during the standardized endurance exercise.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Biomarkers of inflammatory response	Inflammatory markers measured in blood samples.	Baseline and immediately after the march (approximately 1 hour after baseline)
Correlation between inflammatory markers with glucose dynamics during exercise.	Correlation between inflammatory markers and glucose responses to endurance exercise.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Cortisol levels	Cortisol levels measured from blood samples.	Baseline and immediately after the march (approximately 1 hour after baseline)
Correlation between cortisol levels and glucose dynamics during exercise.	Correlation between changes in cortisol levels and glucose responses during the standardized endurance exercise	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Biomarkers of lipolysis	Biomarkers of lipolysis measured from blood samples.	Baseline, immediately after the march (approximately 1 hour after baseline)
Correlation between lipolysis and glucose dynamics during endurance exercise	Correlation between changes in biomarkers of lipolysis and with glucose dynamics during endurance exercise.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sex differences in correlation between sympathetic activation (catecholamines) and glucose dynamics during endurance exercise	Comparison of sympathetic activation measured via catecholamines and glucose dynamics during endurance exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences in the correlation between heart rate variability and glucose dynamics during endurance exercise	Comparison of the correlation between heart rate variability and glucose responses during a standardized endurance exercise (6 kilometer march with 15 kilogram load) between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences in the correlation of training status with glucose dynamics during endurance exercise	Comparison of correlation of individual fitness level and glucose responses during the standardized endurance exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences in the influence of body composition on glucose dynamics during exercise	Comparison of the influence of body composition on glucose dynamics during exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences Inflammatory response and its correlation with glucose dynamics during exercise	Comparison of the correlation between inflammatory markers and glucose responses to endurance exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences in the correlation of cortisol levels and glucose dynamics during exercise.	Comparison of the correlation between cortisol levels and glucose responses during the standardized endurance exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)
Sex differences in the correlation between lipolysis and glucose dynamics during endurance exercise	Comparison of the correlation between lipolysis and glucose dynamics during endurance exercise between sexes.	Baseline, during the 1 hour-march, immediately after the march (approximately 1 hour after baseline)

Collaborators and Investigators

• Sponsor: University of Ulm
• Investigators: Principal Investigator: Martin Heni, MD, University of Ulm

Study record dates

Study Major Dates

• Study Start (Actual): May 5, 2026
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): June 1, 2028

Study Registration Dates

• First Submitted: March 16, 2026
• First Submitted That Met QC Criteria: April 14, 2026
• First Posted (Actual): April 22, 2026

Study Record Updates

• Last Update Posted (Actual): May 11, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: continuous glucose monitoring; endurance exercise; glucose levels
• Other Study ID Numbers: 276/25

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No