This cross-sectional study will be conducted at the Lokman Hekim University Muscle and Nerve Diseases Application and Research Center over a 20-month period from May 2024 to December 2025. The study will include a total of 42 children, with three groups of 14 participants each: children diagnosed with Duchenne Muscular Dystrophy (DMD), children diagnosed with Spinal Muscular Atrophy (SMA), and a healthy control group. The study is designed to evaluate key respiratory, functional, and muscular parameters in these groups.

Respiratory parameters will be assessed using spirometry and Structured Light Plethysmography (SLP). Spirometry will involve maximal inspiratory and expiratory maneuvers to measure lung volumes and capacities, conducted under standardized conditions and monitored by a trained technician. SLP will be conducted using the PneumoCare device, a non-invasive system that measures thoracoabdominal movement during tidal breathing. A grid of light will be projected onto the chest to capture three-dimensional movement patterns over a five-minute period with participants in a seated position.

Functional and muscular assessments will include the Six-Minute Walk Test (6MWT), the Six-Peg Board Ring Test (6PBRT), and hand grip strength measurements. The 6MWT will be conducted in a 20-meter corridor, where participants will walk for six minutes at their own pace, with heart rate, blood pressure, and oxygen saturation recorded before and after the test. The 6PBRT will assess upper-limb endurance and strength through the timed movement of rings across a pegboard, with accuracy and task duration recorded. Hand grip strength will be measured using a handheld dynamometer, with participants performing three trials, and the highest value noted for analysis.

Data analysis will be performed using IBM SPSS Statistics version 23.0. Descriptive statistics will summarize the demographic and clinical characteristics of participants. Group comparisons will be conducted using independent samples t-tests, Mann-Whitney U tests for non-normally distributed variables, and one-way ANOVA for multi-group comparisons. Correlations between variables will be assessed using Pearson or Spearman correlation coefficients, depending on the distribution of the data. A significance threshold of p<0.05 will be applied, with Bonferroni corrections for multiple comparisons as needed.

Ethical approval for this study was granted by the Lokman Hekim University Scientific Research Ethics Committee (approval number: 2024114). All participants and their legal guardians will provide informed consent prior to enrollment, and all data will be anonymized and securely stored in compliance with the General Data Protection Regulation (GDPR). The study will follow Good Clinical Practices (GCP) and adhere to the ethical principles of the Declaration of Helsinki.

The primary objective is to evaluate and compare respiratory, functional, and muscular parameters in children with DMD and SMA against those in healthy peers. The study aims to identify distinctive patterns and impairments within the patient groups, which could provide insights for developing targeted therapeutic interventions.