Enhancing Exercise Adherence Among Patients With Lateral Hip Pain

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.

All participants are recruited through the Sport and Exercise Medicine clinic at University Hospitals of Leicester NHS Trust and receive the same hip-strengthening exercise programme prescribed by their NHS healthcare provider as part of standard clinical care. The exercise programme itself is not an experimental variable; the intervention under investigation concerns exclusively the timing guidance and reminder components layered onto standard care.

Intervention Arms:

Group A - ASAP with Reminders: Participants receive a written information leaflet explaining the theoretical basis for early-morning exercise completion and its anticipated benefit for adherence. In addition, participants receive weekly digital reminders (delivered via a messaging platform) throughout the 28-day primary intervention period. These reminders reinforce the ASAP timing message and prompt participants to prioritise morning exercise completion.

Group B - ASAP without Reminders: Participants receive the same information leaflet as Group A but do not receive any digital reminders. This arm isolates the effect of the written psychoeducational component from the reminder-augmented condition.

Group C - Usual Care Control: Participants proceed with their prescribed hip exercise programme without receiving any additional timing guidance, written information relating to exercise timing, or digital reminders. This arm reflects current standard practice and serves as the comparator condition.

Feasibility Objectives: As a feasibility trial, the primary aim is to evaluate the practicability and preparatory requirements for a future definitive full-scale RCT. Specific feasibility criteria include:

Recruitment rate: The rate at which eligible participants are identified, approached, and successfully enrolled over the recruitment period.

Retention rate: The proportion of enrolled participants who complete follow-up assessments at each pre-specified time point, including the primary endpoint at Day 28.

Questionnaire completion rate: The proportion of completed data fields across all outcome measure timepoints, including the daily adherence survey.

Participant acceptability: Qualitative and quantitative assessment of participants' experiences of the intervention, study procedures, and perceived burden.

These parameters will inform sample size calculations, outcome selection, and procedural refinements for the design of a future definitive trial.

Data Collection and Assessment Schedule: All data collection is conducted online via a secure digital platform. Participants complete a standardised battery of validated outcome measures at five timepoints: baseline (Day 1), Day 14, Day 28, Day 42, and Day 84. This schedule is designed to capture short-term adherence behaviour and early symptomatic response (Day 14 and Day 28), medium-term outcomes following the active intervention period (Day 42), and longer-term maintenance of effect (Day 84).

In addition, participants complete a brief daily adherence survey for the first 28 days of the intervention period. This survey is estimated to take 1-2 minutes per day and captures self-reported exercise timing and completion, as well as any relevant contextual factors affecting adherence on that day.

Qualitative Component: Following completion of the quantitative phase, a purposively sampled subset of participants across all three arms will be invited to participate in online focus group discussions. These discussions will be conducted using a semi-structured topic guide and will explore participants' subjective experiences of the intervention, perceived barriers and facilitators to morning exercise timing, the acceptability of the study procedures and digital components, and suggestions for intervention refinement. Focus groups will be audio-recorded, transcribed verbatim, and analysed using an appropriate qualitative framework methodology. Qualitative findings will be integrated with quantitative feasibility data to provide a comprehensive basis for informing a future definitive trial.

Clinical Setting: Initial participant identification and recruitment takes place at the Sport and Exercise Medicine clinic at University Hospitals of Leicester NHS Trust. Following enrolment, the study is conducted entirely online, enabling participation from any location with internet access and supporting engagement from participants who may have mobility limitations or scheduling constraints associated with their GTPS diagnosis.

• The Exercise Adherence Scale (EXAS) [Time frame: Daily from Baseline (Day 1) up to Day 28]
• The Exercise Adherence Rating Scale (EARS)- Section B [Time frame: Day 7, Day 28, Day 42, and Day 84 (up to 12 weeks)]
• Morningness-Eveningness Questionnaire (MEQ) [Time frame: Day 1 (Baseline)]
• Victorian Institute of Sport Assessment - Gluteal Tendinopathy (VISA-G) [Time frame: Baseline (Day 1), Day 28, Day 42, and Day 84 (up to 12 weeks)]
• Non-Arthritic Hip Score (NAHS) [Time frame: Baseline (Day 1), Day 28, Day 42, and Day 84 (up to 12 weeks)]
• Musculoskeletal Health Questionnaire (MSK-HQ) [Time frame: Baseline (Day 1), Day 28, Day 42, and Day 84 (up to 12 weeks)]
• Pain Numerical Rating Scale (NRS) [Time frame: Baseline (Day 1), Day 28, Day 42, and Day 84 (up to 12 weeks)]
• The Tampa Scale for Kinesiophobia (TSK) [Time frame: Baseline (Day 1), Day 28, Day 42, and Day 84 (up to 12 weeks)]
• Theoretical Framework of Acceptability Questionnaire (TFA-Q) [Time frame: Day 84 (up to 12 weeks)]