Achilles Tendon Load is Progressively Increased with Reductions in Walking Speed.

Introduction: Achilles tendon rehabilitation protocols commonly recommend a gradual increase in walking speed to progressively intensify tendon loading. This study used transmission-mode ultrasound to evaluate the influence of walking speed on loading of the human Achilles tendon in vivo. Methods: Axial transmission speed of ultrasound was measured in the right Achilles tendon of 33 adults (mean +/- SD; age, 29 +/- 3 years; height, 1.725 +/- 0.069 m; weight, 71.4 +/- 19.9 kg) during unshod, steady-state treadmill walking at three speeds (slow, 0.85 +/- 0.12ms; preferred, 1.10 +/- 0.13m/s; fast, 1.35 +/- 0.20 m/s). Ankle kinematics, spatiotemporal gait parameters and vertical ground reaction force were simultaneously recorded. Statistical comparisons were made using repeated measure ANOVA models. Results: Increasing walking speed was associated with higher cadence, longer step length, shorter stance duration, greater ankle plantarflexion, higher vertical ground reaction force peaks and a greater loading rate (P <.05 maximum p and minimum ultrasound transmission velocities in the achilles tendon were significantly lower m during stance but not swing phase of gait with each increase walking speed. conclusions: despite higher vertical ground reaction forces greater ankle plantarflexion increasing speed resulted a reduction axial velocity indicating speed-dependent tensile load within triceps surae muscle-tendon unit walking. these findings question rationale for current progressive loading protocols involving which reduced speeds are advocated early course treatment to loads. american college sports medicine>

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