The Effect of a Heel Insert Intervention on Achilles Tendon Loading during Running in Soccer

Abstract

The use of heel inserts has been shown to reduce the risk of sustaining Achilles Tendon (AT) injury in soccer. Likewise, heel lifts have been positively used in the treatment of Achilles tendon injury. Despite this evidence however, the mechanism behind such findings is still unclear. Consequently, this study recruited nine amateur male soccer players (83.4 kg (±5.8), 23 years (±3.7), Achilles tendon radius 19.13 cm (±2.3), ankle width 0.072 cm (±0.005), forefoot width 0.10 cm (±0.005), size 10 feet) to collect kinetic and kinematic data during 10 running trials. Trials were performed on a third generation artificial turf whilst wearing a soccer boot with and without a 10 mm heel insert placed inside. From the data obtained, measures of Achilles tendon load and rate of loading were estimated. Paired t-tests with the combined participant data indicated that there were no overall effect of the heel-insert on peak Achilles tendon force (p=0.25), peak plantar flexion moment (p=0.68) or their corresponding loading rates (p=0.92) and p=0.97 respectively). Individual participant data did however show that for some the heel lift significantly reduced Achilles tendon loading, whilst others it was significantly increased. These findings therefore suggest that the response is highly individual. As such the application of heel lifts should be used with caution and the routine use of the inserts is not recommended.