Effects of passive ankle dorsiflexion stiffness on ankle mechanics during drop landings

• Published in: Journal of science and medicine in sport 2012-09, Vol.15 (5), p.468-473
• Main Authors: Whitting, J.W, Steele, J.R, McGhee, D.E, Munro, B.J
• Format: Article
• Language: English
• Subjects: Achilles Tendon - injuries; Achilles Tendon - physiology; Adult; Ankle; Ankle Injuries - physiopathology; Ankle Joint - physiopathology; Biomechanical Phenomena; Biomechanics; Compliance; Cross-Sectional Studies; Flexibility; Humans; Male; Mechanics; Muscular system; Physical Medicine and Rehabilitation; Range of Motion, Articular; Sports injuries; Sports Medicine; Tendinopathy; Triceps surae; Weight-Bearing; Young Adult
• ISSN: 1440-2440; 1878-1861
• DOI: 10.1016/j.jsams.2012.03.004

Abstract Objectives Vertical landing tasks strain the Achilles tendon and plantar-flexors, increasing acute and overuse strain injury risk. This study aimed to determine how passive ankle dorsiflexion stiffness affected ankle mechanics during single limb drop landings at different vertical descent velocities. Design Cross-sectional study. Methods Passive ankle dorsiflexion stiffness and passive weight-bearing dorsiflexion range of motion (DROM) were quantified for 42 men. Participants were then grouped as having low (LPS: 0.94 ± 0.15 Nm °−1 ; n = 16) or high (HPS: 2.05 ± 0.36 Nm °−1 ; n = 16; p < 0.001) passive ankle dorsiflexion stiffness. Three-dimensional ankle joint kinematics was quantified while participants performed drop landings onto a force platform at two vertical descent velocities (slow: 2.25 ± 0.16 m s−1 ; fast: 3.21 ± 0.17 m s−1 ). Results Although affected by landing velocity, there were no significant effects of passive ankle dorsiflexion stiffness, nor any significant ankle dorsiflexion stiffness × vertical descent velocity interactions on any outcome variables characterising ankle mechanics during drop landings. Furthermore, there was no significant difference between the groups for passive weight-bearing DROM (LPS: 43.9 ± 4.1°; HPS: 42.5 ± 5.7°), indicating that the results were not confounded by between-group differences in ankle range of motion. Conclusions Neither high nor low passive ankle dorsiflexion stiffness was found to influence ankle biomechanics during drop landings at different descent velocities. Landing strategies were moderated more by the demands of the task than by passive ankle dorsiflexion stiffness, indicating that passive ankle dorsiflexion stiffness may not affect plantar-flexor strain during a drop landing.