The 'As Soon As Possible (ASAP)' Intervention for Enhancing Therapeutic Exercise Adherence Among Patients With Greater Trochanteric Pain Syndrome (GTPS): A Feasibility Trial

Background and Rationale: Greater Trochanteric Pain Syndrome (GTPS) is a common musculoskeletal condition affecting the lateral hip, with an estimated prevalence of 10-25% in the general population and a disproportionately higher incidence among middle-aged women. The condition is characterised by pain and tenderness localised to the greater trochanter, most commonly attributed to gluteal tendinopathy (particularly of the gluteus medius and minimus tendons) and trochanteric bursitis. GTPS can significantly impair functional capacity, quality of life, and participation in daily activities.

Current evidence supports therapeutic exercise, including progressive hip-strengthening programmes, as a first-line treatment for GTPS. Despite this, the clinical effectiveness of exercise-based rehabilitation is substantially undermined by poor patient adherence to prescribed programmes. Non-adherence is a persistent and well-documented challenge across musculoskeletal rehabilitation settings, contributing to suboptimal outcomes, prolonged symptom duration, and increased healthcare utilisation. Scalable, low-resource strategies to support adherence in this population are lacking.

Theoretical Framework: The ASAP (As Soon As Possible) intervention is grounded in established behavioural science theory on motivational resource depletion and self-regulatory capacity throughout the day. Research in ego depletion and time-of-day effects on self-control suggests that motivational resources and executive function are relatively stronger in the early waking hours and decline progressively as cognitive and decisional demands accumulate throughout the day. Consequently, health-related behaviours that require deliberate effort or involve discomfort, such as adherence to a therapeutic exercise programme, are more vulnerable to avoidance or abandonment when deferred to later in the day.

The ASAP intervention operationalises this framework by encouraging participants to complete their prescribed exercises as early as possible each day, ideally immediately or shortly after waking. The rationale is that performing exercises during a window of higher motivational resources reduces the likelihood that competing demands will displace the exercise behaviour. This approach is designed to be pragmatic, requiring no specialised equipment, additional clinical contact, or complex behaviour change techniques beyond the provision of psychoeducational information and, in one arm, periodic digital reinforcement.

Study Design: This is a three-arm, parallel-group feasibility randomised controlled trial (RCT) with an embedded qualitative component. Participants are allocated in a 1:1:1 ratio to one of three groups using computer-generated block randomisation (block size of six) administered via Sealed Envelope, an established online randomisation platform. The three-arm structure enables simultaneous evaluation of (1) the ASAP timing concept relative to usual care, and (2) the incremental value of digital reminders as an adherence-support adjunct.