Acute Cardiac Effects of Ultra-Trail Running

Ultra-endurance running has gained increasing popularity, yet its acute cardiovascular effects remain incompletely characterized. Previous studies in endurance athletes have reported transient changes in myocardial function and elevations in cardiac biomarkers after prolonged exercise, but available data in ultra-trail settings remain limited and heterogeneous. Most prior investigations relied on pre- and post-race comparisons, small sample sizes, or incomplete assessment of right ventricular and atrial function, and rarely integrated multimodal echocardiographic imaging with standardized biological analyses.

The ULTRA-ECHO study is a prospective observational physiology study designed to investigate acute and short-term cardiovascular adaptations to ultra-endurance exercise under real-life conditions. Adult runners participating in the "Trail des Échos" ultra-trail race (80 km or 160 km) will undergo standardized transthoracic echocardiography, clinical evaluation, and biological sampling at predefined time points, including baseline screening, pre-effort, during the race, immediately after exercise, and during early recovery approximately one week after the event. Echocardiographic acquisitions will be performed using standardized imaging protocols on identical ultrasound systems, with centralized offline analysis and blinded secondary review in order to ensure reproducibility and minimize operator-related bias.

The primary focus of the study is the assessment of left ventricular global longitudinal strain (GLS), a sensitive marker of subclinical systolic myocardial function that may detect exercise-induced myocardial fatigue even when conventional ejection fraction remains preserved. Secondary evaluations include comprehensive structural and functional echocardiographic parameters of the left ventricle, right ventricle, and left atrium, as well as cardiac and systemic biological responses to prolonged endurance exercise.

This exploratory before-after design does not include a control group, as each participant serves as their own control through repeated within-subject assessments. The study also aims to explore potential modifiers of cardiovascular responses, including race distance, finisher status, training level, performance level, and sex. By integrating sequential imaging, biomarker analysis, and early follow-up evaluation, ULTRA-ECHO seeks to improve understanding of transient cardiac adaptations and recovery dynamics associated with ultra-endurance exercise and to generate physiological insights that may inform future research and cardiovascular monitoring strategies in endurance athletes.

Inclusion criteria

• Adults aged ≥18 years
• Registered participants in the "Trail des Échos" ultra-trail race (80 km or 160 km)
• Valid health clearance according to French Athletics Federation requirements
• Affiliation with a national health insurance system
• Able to understand study procedures and provide written informed consent

Exclusion criteria

• Known or suspected cardiovascular disease at screening, including coronary artery disease, heart failure, clinically significant arrhythmias, moderate-to-severe valvular disease, uncontrolled hypertension, or prior stroke
• Acute infection or unstable chronic medical condition (e.g., uncontrolled diabetes, renal, hepatic, respiratory, thyroid, or inflammatory disease)
• Current treatments that may interfere with cardiovascular or biological assessments (including renin-angiotensin-aldosterone system blockers, chronic diuretics, anticoagulants, or systemic corticosteroids)
• Use of systemic non-steroidal anti-inflammatory drugs within 3 days before the race or planned during the event
• Participation in another ultra-endurance race (≥80 km) within 7 days before or after the study race
• Pregnancy or breastfeeding
• Inability to provide informed consent or legal protection status
• Participation in another interventional clinical study