Autoregulated Heavy Slow Resistance Training Combined with Radial Shockwave Therapy for Plantar Heel Pain: Protocol for a Mixed Methods Pilot Randomised Controlled Trial

Background: Plantar heel pain (PHP) is considered a tendinopathy and it affects up to 10% of the population. Both heavy slow resistance training (HSRT) and extracorporeal shockwave therapy (ESWT) have shown effectiveness for treating PHP in isolation. However more comprehensive exercise protocols and progression methods are needed due to poor long-term outcomes, and better standardization of ESWT protocols are required. Autoregulation of resistance training involves self-selecting exercise dosage based on individual factors. Although autoregulation has proven effective for strength gains in athletes, it has not been investigated in tendinopathy. It is recommended that PHP not be treated by one treatment in isolation, with there being a need to investigate feasibility and effectiveness of combined treatments in PHP. Currently, no studies have investigated autoregulated HSRT combined with ESWT, despite their individual efficacy. The optimal treatment protocol for PHP is unknown, and there is a need to ascertain whether the addition of ESWT to autoregulated HSRT leads to better outcomes compared to either alone. Methods: A three-arm randomised controlled trial (RCT) comparing these groups would be the ideal way to investigate this question, with a pilot RCT testing trial procedures and process evaluation required prior to a definitive RCT. Patients expectations, feasibility and acceptability of combined ESWT and exercise for PHP also remain unknown. Therefore, the addition of qualitative interviews in a mixed methods pilot RCT would help ascertain acceptability and help explain the intervention outcomes.