Abstract
Background
This study aimed to explore the relationship between running biomechanics on two flat surfaces—athletic track and trail—and strength deficit (SDef) at various percentages of one-repetition maximum (1 RM) in the half-squat (HSQ). Additionally, it sought to examine whether SDef at these loads is influenced by patellar tendon morphology in highly trained trail runners.
Methods
Fifteen trail runners performed an HSQ 1 RM test following a velocity-based approach and two running time trials (9 and 3 min) on two different surfaces. Mean propulsive velocity and peak force were recorded using a linear position transducer and used to calculate SDef from 30 to 90% of 1 RM. The Stryd power meter (Stryd Next Gen, Boulder, CO, USA) was used to assess leg stiffness, speed, ground contact time, and cadence during the four running bouts. Patellar tendon thickness and cross-sectional area were also measured with a high-definition ultrasound device.
Results
Large negative associations were found between SDef at 40–70% 1 RM and shorter ground contact time and higher leg stiffness, particularly in the 3‑min trial on trail terrain. Furthermore, patellar tendon thickness was also negatively associated with SDef at low-to-moderate loads (40–60% 1 RM).
Conclusion
These findings suggest that runners with greater SDef compensate via enhanced musculotendinous elastic properties, highlighting the functional role of patellar tendon thickness. Assessment of SDef provides a valuable basis for individualized training prescription in trail runners, guiding practitioners to focus either on increasing the rate of force development at low-to-moderate loads to reduce SDef or on plyometric training to maximize elastic efficiency.
Description
The study examines strength and biomechanics in trail runners.