Achilles tendon thickness reduces immediately after a marathon

BACKGROUND: The purpose of the present investigation was to evaluate the immediate effect of running a marathon on Achilles tendon anteroposterior thickness. METHODS: In 25 runners who took part in the London marathon, ultrasonography was used to measure the Achilles tendon thickness pre- and immediately post-marathon and to identify any structural abnormalities indicating tendinopathy. Pain was recorded using a numerical rating scale at baseline and post-marathon. Twenty-one participants were included in the final analysis. RESULTS: Running a marathon resulted in a significant decrease (− 13%, p < 0.01) in anteroposterior diameter of the Achilles tendon immediately following the marathon. There was no change in the proportion of Achilles tendons with structural abnormalities (34%) or pain (12%) following the marathon (p > 0.05). CONCLUSION: Running a marathon resulted in an immediate reduction in anteroposterior diameter of the Achilles tendon. This finding may have implications for injury prevention and recovery following a marathon.