Tendon Structure Quantified using Ultrasound Imaging Differs Based on Location and Training Type

Abstract

Achilles tendinopathy is ten-times more common amongst running athletes compared to age-matched peers. Load induced tendon remodeling and its progression in an at-risk population of developing symptomatic tendinopathy is not well understood. The purpose of this study was to prospectively characterize Achilles and patellar tendon structure in competitive collegiate distance runners over different competitive seasons using quantitative ultrasound imaging. Twenty-two collegiate cross country runners and eleven controls were examined for this study. Longitudinal and cross-sectional ultrasound images of bilateral Achilles and patellar tendons were obtained at the one week prior to start of formal collegiate cross country practices, one week after the conclusion of cross country season, and one week prior to outdoor track and field championships. Collagen organization, mean echogenicity, tendon thickness, and neovascularity were determined using well established image processing techniques. We found that Achilles and patellar tendons respond differently to high-volume running and transitions from one sport season to another, suggesting that tendon structure is sensitive to differences in tendon loading biomechanics. Our findings indicate that Achilles tendon structure in trained runners differ structurally to control tendons but is stable throughout training while patellar tendon structure changes in response to the transition in training volume between cross country and track seasons. These findings expand upon prior reports that some degree of tendon remodeling may act as a protective adaptation for sport specific loading.\n\nNews and NoteworthyIn this study we prospectively examined the Achilles and patellar tendon structure of distance runners to determine if continued training through multiple seasons elicits tendon remodeling or pathology. We found that Achilles and patellar tendons respond uniquely to the changing loads required during each season. Achilles tendon collagen alignment is mostly stable throughout the competitive cycle, but the patellar tendon undergoes structural changes following the transition from cross-country to track season.