Incidence of Achilles tendinopathy and associated risk factors in recreational runners: A large prospective cohort study.

OBJECTIVES: To determine the incidence of Achilles tendinopathy in a large group of recreational runners and to determine risk factors for developing AT.

DESIGN: Observational cohort study.

METHODS: Runners registering for running events (5-42 km) in the Netherlands were eligible for inclusion. Main inclusion criteria were: age ≥18 years, and registration ≥2 months before the running event. The digital baseline questionnaire obtained at registration consisted of demographics, training characteristics, previous participation in events, lifestyle and previous running-related injuries. All participants received 3 follow-up questionnaires up to 1 month after the running event with self-reported AT as primary outcome measure. To study the relationship between baseline variables and AT onset, multivariable logistic regression analyses were performed.

RESULTS: In total, 2378 runners were included, of which 1929 completed ≥1 follow-up questionnaire, and 100 (5.2%, 95%CI [4.2;6.2]) developed AT. Runners registered for a marathon (7.4%) had the highest incidence of AT. Risk factors for developing AT were use of a training schedule (odds ratio (OR) = 1.8 (95%Confidence Interval(CI)[1.1;3.0])), use of sport compression socks ((OR = 1.7, 95%CI[1.0;2.8]) and AT in the previous 12 months (OR = 6.3, 95%CI[3.9;10.0]). None of the demographic, lifestyle or training-related factors were associated with the onset of AT.

CONCLUSION: One in twenty recreational runners develop AT. AT in the preceding 12 months is the strongest risk factor for having AT symptoms. Using a training schedule or sport compression socks increases the risk of developing AT and this should be discouraged in a comparable running population.

TRIAL REGISTRATION NUMBER: The Netherlands Trial Register (ID number: NL5843).