Longitudinal Changes in Achilles Tendon and Medial Gastrocnemius Muscle Architecture During a 156-km Ultradistance Trail Running Event

Longitudinal Changes in Achilles Tendon and Medial Gastrocnemius Muscle Architecture During a 156-km Ultradistance Trail Running Event

This study aimed to assess the longitudinal changes in triceps surae muscle-tendon architecture to an ultra distance trail running. Experienced trail runners (N=55, 78% men, age: 45.2 [13.5] years) participated in a 156-km trail run (6000m climbing) consisting in six 26-km laps. The resting architectural properties of triceps surae muscle-tendon were measured using ultrasound imaging for Achille tendon cross-sectional area (AT CSA), medial gastrocnemius muscle pennation angle, thickness, length and fiber length. Measurements were performed the day before the race (Baseline), at 52-km (T1), at 104-km (T2), at 156-km (T3) and 12 hours after the race (H12).

Inclusion criteria

• Experienced runners voluntarily participating in the Trail Scientifique de Clécy (156 km/6000 D+)
• Participants who had already completed 2 ultratrail races (+160 km and -160 km), at least one of them in the past 24 months; the participants had to justify their events and rankings
• Participants affiliated with a social security system or those who were a beneficiary of such a system
• Participants who could speak and read the French language
• Participants with the ability to physically participate in the ultraendurance race
• Participants with the ability to provide written consent for participation in the study

Exclusion criteria

• Participants with cardiac or extracardiac contraindications to intense physical activity
• Participants who had run a mountain ultramarathon (160 km) after September 2, 2021
• Pregnant or breastfeeding women
• Minor participants
• Participants included in another biomedical research protocol during this study
• Participants with recent muscular and orthopedic injuries, limiting running for <15 days
• Participants with a history of ankle joint surgery (eg, arthrodesis)
• Participants with a history of foot or ankle surgery
• Participants with lower-limb pathology or trauma