Profiling measures of muscle strength and power throughout a 156 km ultra-trail running event

Markov, A ORCID: 0000-0002-1855-5552, Edwards, BJ ORCID: 0000-0001-8913-0941, Goutorbe, A, Gilli, S ORCID: 0009-0009-4485-3690, Lemire, M ORCID: 0000-0002-8023-0329, Nguyen, AP ORCID: 0000-0002-6473-1780 and Mauvieux, B ORCID: 0000-0003-4862-6531 (2026) Profiling measures of muscle strength and power throughout a 156 km ultra-trail running event. Frontiers in Sports and Active Living, 7. ISSN 2624-9367

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Abstract

Purpose: Ultra-endurance performance involves complex neuromuscular demands, yet continuous in-race assessment of strength and power development is lacking. This study examined the first-ever continuous profile of neuromuscular fatigue throughout an entire ultra-trail race to understand fatigue mechanisms and inform training and pacing strategies. Methods: Fifty-five participants (43 men, 12 women; 45.2 ± 13.6 years) attempted six identical 26 km laps with 1,000 m elevation gain and loss per lap, 14 did not complete the course. Maximum knee-extensor and handgrip strength, peak-power output, and jump-height were measured pre-race, after each lap, and 12 h post-race using standardized protocols and linear mixed models. Results: Knee-extensor strength decreased by ∼41% from pre-race to finish (p <.001), with substantial recovery (Δ26%–27%) at 12 h post-race. Handgrip strength showed minimal overall decline (Δ∼2%–5%), suggesting fatigue localized to the lower limbs. Peak-power and jump-height declined gradually (Δ6%–7% from early laps; p <.001). Critically, no significant relationship existed between the magnitude of strength loss and final ranking (early and late finishers showed no differences in strength profiles). However, participants who withdrew at lap 5 displayed substantially lower baseline strength (Δ27%; p =.004) and progressive strength declines compared to finishers, suggesting baseline neuromuscular capacity may influence completion likelihood. Conclusion: Continuous in-race profiling reveals that ultra-trail running induces substantial and predominantly peripheral neuromuscular fatigue in the lower limbs, with limited systemic effects. While strength loss magnitude does not predict race placement among finishers, lower baseline strength may increase non-completion risk. These findings underscore the importance of targeted strength training and metabolite-clearance strategies (e.g., glycogen replenishment, hydration, recovery) in ultra-endurance preparation.

Item Type:	Article
Uncontrolled Keywords:	fatigue; finisher; non-finisher; trail-running; ultra-endurance; 42 Health Sciences; 4207 Sports Science and Exercise; Rehabilitation; Neurosciences; 4207 Sports science and exercise
Subjects:	Q Science > QP Physiology G Geography. Anthropology. Recreation > GV Recreation Leisure > GV561 Sports
Divisions:	Sport and Exercise Sciences
Publisher:	Frontiers Media SA
Date of acceptance:	8 December 2025
Date of first compliant Open Access:	6 February 2026
Date Deposited:	06 Feb 2026 09:57
Last Modified:	06 Feb 2026 09:57
DOI or ID number:	10.3389/fspor.2025.1734785
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28064

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