This observational study aims to investigate the effect of heel lift insole on kinematics and kinetics of the lower limb and lumbar spine among healthy individuals.

This clinical trial will be conducted among physiotherapy students at Misr University for Science and Technology. Participants will be recruited based on predefined inclusion criteria, and informed consent will be obtained prior to their involvement. Once enrolled, each participant will complete a standardized demographic questionnaire and undergo height and weight measurements to calculate their Body Mass Index (BMI). Those with BMI values outside the normal range, as defined by Shrestha et al. (2023), will be excluded to reduce confounding factors.

Before testing begins, participants will be familiarized with all equipment and procedures. Electromyographic (EMG) data will then be collected to measure maximum muscle activity in the bilateral erector spinae, rectus femoris, and both medial and lateral gastrocnemius muscles. EMG measurements will be taken under two conditions: first, while standing in standardized flat shoes, and second, while wearing a standardized heel lift insole inside the same shoes. Three trials will be performed in each condition, and the mean amplitude will be used for analysis.

In addition to EMG, kinematic data will be assessed using Kinovea software. Photographs will be captured from anterior and lateral views to evaluate each participant's Q angle and lumbosacral angle. As with EMG, these measurements will be repeated under both footwear conditions (flat shoes alone and flat shoes with heel lift insoles), and the results will be compared.

All procedures will follow standardized protocols to ensure consistency and reliability. The primary outcome measure is muscle activity (maximum EMG amplitude), while secondary outcomes include changes in the Q-angle and lumbosacral angle. The study aims to evaluate the impact of heel lift insoles on lower limb muscle activity and postural alignment in healthy individuals.

Inclusion Criteria:

• Adult non-athletic individuals with age range between (18: 25) years old (Joshi et al., 2024).
• Height between (160 - 180 cm).
• Body mass index between (18.5:24.99) Kg/ m² (Joshi et al., 2024).
• Foot length between (23,3 - 28.0 cm).
• Never used heel lift insole.
• Participants must have a normal and pain-free range of motion in the lower limbs and spine (Hapsari et al., 2016).
• Participants must demonstrate stable balance and coordination in weight-bearing activities (Hapsari et al., 2016).

Exclusion Criteria:

• Traumatic conditions of the lower limb (Joshi et al., 2024).
• Pelvis and lower limb musculoskeletal disorders (Joshi et al., 2024).
• Previous orthopedic disorders or neurological deficit of the lower limb (Joshi et al., 2024).
• Previous surgery of the lower limbs (Lindenberg et al., 2019).
• Any sensory problems.
• Neuromuscular diseases such as multiple sclerosis, intervertebral disc disorders…etc (Joshi et al., 2024).
• Pregnancy.
• Cancer Patients.
• Immunodeficiency diseases.
• Psychological disorders (depression - anxiety).
• Chronic diseases as (diabetes - hypertension).
• Participants with lower limbs deformity (Joshi et al., 2024).
• Participants with specific lower limb muscles weakness.
• Low back pain in the past 30 days (Colonna et al., 2024).

Healthy Individuals