Does Distance Matter? Metabolic and Muscular Challenges of a Non-Stop Ultramarathon with Sub-Analysis Depending on Running Distance.

Participants experienced a substantial mean energy deficit across all race distances.

• Mean energy deficit was 6797 kcal with a range of 417–18,364 kcal.
• Carbohydrate-dominant fueling was observed, with carbohydrates accounting for 79% of energy intake.
• The study included 43 ultra runners (16 women, 27 men), of whom 39 finished the race.
• Participants were drawn from three race distances: 100 km (19 finishers), 160.9 km (8 finishers), and 230 km (16 finishers).

Significant reductions in anabolic/satiety hormones leptin and insulin were observed post-race.

• Both leptin and insulin showed significant decreases from pre- to post-race assessments.
• These reductions indicate disrupted energy homeostasis during ultramarathon running.
• The 230 km subgroup showed the greatest changes in these biomarkers.
• Blood and saliva samples were collected at pre- and post-race time points as part of the prospective observational design.

Hunger and counter-regulatory hormones ghrelin and glucagon increased significantly post-race.

• Both ghrelin and glucagon showed significant increases from pre- to post-race.
• These changes indicate disrupted energy homeostasis consistent with severe caloric deficit.
• The 230 km subgroup demonstrated the greatest increases in these hormones.
• These findings align with the substantial mean energy deficit of 6797 kcal observed across participants.

Muscle damage biomarkers creatine kinase muscle type (CKM) and lactate dehydrogenase (LDH) increased significantly post-race.

• Both CKM and LDH showed significant increases from pre- to post-race, indicating muscle damage.
• The 230 km subgroup showed the greatest increases in these markers.
• Elevated CKM and LDH indicate disrupted structural integrity consistent with extreme endurance exercise.
• Musculoskeletal symptoms increased post-race, aligning with these biomarker patterns.

Gastrointestinal and musculoskeletal symptoms increased post-race across all distance groups.

• Symptom assessment was conducted using the validated General Assessment of Side Effects (GASE) questionnaire.
• Both gastrointestinal and musculoskeletal symptom scores increased post-race.
• Symptom patterns aligned with the observed biomarker changes including elevated CKM and LDH.
• Symptom increases were observed regardless of race distance (100 km, 160.9 km, or 230 km).

The 230 km subgroup experienced the greatest metabolic and muscular disturbances compared to shorter distance groups.

• The 230 km group (16 finishers) showed the greatest changes across all measured biomarkers including leptin, insulin, ghrelin, glucagon, CKM, and LDH.
• Despite greater magnitude of changes in the longest distance group, significant disturbances were observed across all three distances (100 km, 160.9 km, 230 km).
• The authors concluded that profound disturbances in metabolic and structural integrity occur 'regardless of race distance.'
• Sub-analysis by running distance was a primary analytical approach of the study.

Continuous glucose monitoring (CGM) was employed alongside blood and saliva biomarker assessments to characterize metabolic responses.

• CGM was used throughout the race as part of the prospective observational design.
• Additional measurements included body composition via bioimpedance analysis (BIA) at pre- and post-race time points.
• Energy intake and expenditure were assessed as part of pre- and post-race evaluations.
• The study involved 43 participants from the 2024 TorTour de Ruhr® event across three distance categories.