This pilot study evaluates whether passive static stretching can improve hip movement in three groups: people who have had hip replacement surgery, individuals with long-term hip pain, and healthy volunteers. Participants will follow a 4-week stretching program, doing exercises three times per week under the supervision of a trained clinician. Hip range of motion will be measured before and after the program using accurate electronic sensors. The goal is to determine if passive static stretching is a safe and effective way to increase hip flexibility and support daily activities. The study involves no new medications or invasive procedures and is considered low risk.

This pilot study investigates the effects of passive static stretching on hip range of motion (ROM) in three populations: patients who have undergone total hip arthroplasty (THA), individuals with chronic non-surgical hip pain, and healthy volunteers. A total of 12 participants will be enrolled, divided equally into three groups.

Participants will follow a four-week stretching program, performing assisted hip flexion and abduction exercises three times per week, with each stretch held for 30 seconds. All sessions are supervised by a trained kinesiologist to ensure proper alignment, submaximal intensity, and participant safety.

Hip ROM will be measured pre- and post-intervention using high-precision triaxial electronic sensors (accelerometers and gyroscopes) under standardized conditions. The study will track changes in hip flexion and abduction, monitor for adverse events, and assess compliance.

The purpose is to explore whether passive static stretching is a safe, feasible, and effective method to enhance hip mobility across different populations, providing preliminary data for future larger studies.

Inclusion Criteria:

• Adults able to participate in a 4-week passive hip stretching protocol
• No contraindications to passive hip stretching
• No neurological or musculoskeletal comorbidities affecting motor control
• Willingness and ability to provide written informed consent

Exclusion Criteria:

• Presence of neurological or musculoskeletal conditions that impair hip movement or motor control
• Contraindications to stretching (e.g., recent surgery not related to hip arthroplasty, acute injuries)
• Inability or unwillingness to complete the full 4-week study protocol

The study included 12 adult participants (7 women, 5 men; mean age 52.5 ± 6.8 years) divided into three groups:

Group A: 4 patients who had undergone total hip arthroplasty (THA) Group B: 4 patients with chronic non-surgical hip pain Group C: 4 healthy individuals with no prior hip or joint pathology

Participants were selected based on their ability to safely perform passive hip stretching, absence of neurological or musculoskeletal comorbidities affecting motor control, and willingness to complete the 4-week intervention protocol. Written informed consent was obtained from all participants.

Individual participant data will not be shared to protect participant privacy and confidentiality. Given the small sample size and sensitive nature of the measurements, sharing raw data could potentially allow identification of participants. Data will be used solely for the purposes of this study.