The effectiveness of customised 3D-printed insoles on perceived pain, comfort, and completion time among frequent Park Runners: Study protocol for a pragmatic randomised controlled trial (The ZOLES RCT)

Background: Running, a popular recreational activity, often leads to the experience of pain and discomfort among participants impacting performance and participation longevity. The ZOLES trial evaluates customised 3D-printed insoles for reducing pain in frequent parkrunners aged 35 and over. An innovative process of foot-scanning and responses to questions relating to size, pain, discomfort, and previous medical conditions are combined leading to the production of personalised 3D-printed orthotics.

Methods: The ZOLES trial is a pragmatic, outcome assessor blinded, randomised, controlled, superiority trial involving 200 recreational runners, randomised to receive either customised 3D-printed insoles (ZOLES) or to a "do-as-usual" control group. The study follows a robust protocol, ensuring adherence to established guidelines for clinical trials, and is based at St Mary's University, Twickenham, London. The primary outcome is change in running-related pain over a 10-week period, assessed using an 11-point Numeric Rating Scale. Secondary outcomes include overall pain and discomfort, running-related comfort, 5k-completion time, time-loss due to injuries, running exposure, and adherence to the intervention. A balanced-block randomisation process is stratified by sex and parkrun location, and an intention-to-treat analyses will be employed on all outcomes in the primary trial report. The trial includes a 52-week post-market surveillance to assess long-term effects of the customised insoles.

Discussion: The ZOLES trial aims to provide insights into real-world applicability and effectiveness of customised 3D-printed insoles in reducing running-related pain and enhancing overall running experience. Despite the limitation of a subjective primary outcome measure without participant blinding, the methodological rigor, including external outcome assessment and data handling, we anticipate results that are academically credible and applicable in real-world settings The results of this trial may have important implications for runners, clinicians, and the sports footwear industry, as evidence for the use of individualised insoles to improve running experience and prevention of pain may become evident.

Trial registration: The trial was pre-registered at ClinicalTrials.gov with the trial identifier NCT06034210 on September 4, 2023, and publicly posted on September 13, 2023 (https://clinicaltrials.gov/study/NCT06034210).

Protocol version: Version 1, September 27, 2023.