Achilles Tendon Loading During Heel-Raising and -Lowering Exercises.

CONTEXT: Achilles tendinopathies are common injuries during sport participation, although men are more prone to Achilles tendon injuries than women. Heel-raising and -lowering exercises are typically suggested for Achilles tendon rehabilitation.

OBJECTIVE: To compare the estimated Achilles tendon loading variables and the ankle range of motion (ROM) using a musculoskeletal model during commonly performed heel-raising and -lowering exercises.

DESIGN: Controlled laboratory study.

SETTING: University biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS: Twenty-one healthy men (age = 21.59 ± 1.92 years, height = 178.22 ± 8.02 cm, mass = 75.81 ± 11.24 kg).

INTERVENTION(S): Each participant completed 4 exercises: seated heel raising and lowering, bilateral standing heel raising and lowering, bilateral heel raising and unilateral lowering, and unilateral heel raising and lowering.

MAIN OUTCOME MEASURE(S): A repeated-measures multivariate analysis of variance (α = .05) was used to compare Achilles tendon stress, force, and strain and ankle ROM for each exercise. Kinematic data were recorded at 180 Hz with 15 motion-analysis cameras synchronized with kinetic data collected from a force platform sampled at 1800 Hz. These data were then entered in a musculoskeletal model to estimate force in the triceps surae. For each participant, we determined Achilles tendon stress by measuring cross-sectional images using ultrasound.

RESULTS: Peak Achilles tendon loading was lowest when performing the seated heel-raising and -lowering exercise and highest when performing the unilateral heel-raising and -lowering exercise. Loading was greater for the unilateral exercise or portions of the exercise that were performed unilaterally.

CONCLUSIONS: Bilateral and seated exercises with less weight-bearing force resulted in less Achilles tendon loading. These exercises may serve as progressions during the rehabilitation process before full-body weight-bearing, unilateral exercises are allowed. Ankle ROM did not follow the same order as loading and may need additional monitoring or instruction during rehabilitation.