Surface properties affect the interplay between fascicles and tendinous tissues during landing

Area of Science:

• Biomechanics
• Human Movement Science
• Sports Medicine

Background:

• Muscle-tendon units buffer impact forces during landing to prevent muscle damage.
• Landing surface properties influence energy dissipation and injury risk.

Purpose of the Study:

• To investigate how three different landing surfaces affect the muscle-tendon interactions of the gastrocnemius medialis (GM) and vastus lateralis (VL) during single- and double-leg landings.
• To determine the influence of surface stiffness on fascicle behavior and muscle activity.

Main Methods:

• Collected ultrasound images, muscle activity, and joint kinematics from 12 participants during landing tasks.
• Characterized the mechanical properties of three distinct landing surfaces.

Main Results:

• Stiffer surfaces led to increased VL fascicle lengthening and velocity, and higher muscle activity during single-leg landings.
• No significant differences in GM fascicle length changes were observed across surfaces.
• Double-leg landings showed similar fascicle and tendon behavior regardless of surface stiffness, despite increased knee flexion on stiffer surfaces.

Conclusions:

• Increased surface stiffness elevates VL fascicle lengthening during single-leg landings due to reduced knee flexion and surface energy absorption.
• The vastus lateralis muscle-tendon unit is primarily affected by surface damping properties, potentially increasing injury risk on stiffer surfaces during single-leg landings.
• Gastrocnemius medialis muscle-tendon interactions are not significantly influenced by landing surface type or landing strategy.