Participants will complete an 8-week supervised progressive resistance training (PRT) program performed twice weekly. Each ~45-minute session includes a warm-up, whole-body resistance exercises (with emphasis on lower limbs), and a cool-down. Exercises include squat variations, hip hinge movements, unilateral lower-limb exercises, upper-body pushing/pulling, and core stabilization.

Training intensity is guided by a youth-specific RPE scale (5-8), with progressive overload based on individual technique. Sessions are delivered in small groups under qualified supervision to ensure safety and adherence.

The program consists of three phases: familiarisation (weeks 1-2), progressive overload (weeks 3-5), and strength-oriented training (weeks 6-8). Outcomes are assessed pre- and post-intervention.

An 8-week supervised progressive resistance training (PRT) program performed twice weekly in children aged 10-14 years. Each ~45-minute session includes a warm-up, whole-body resistance exercises (with emphasis on lower-limb musculature), and a cool-down. Exercises include squat variations, hip hinge movements, unilateral lower-limb exercises, upper-body pushing and pulling, and core stabilization.

Training intensity is prescribed using a youth-specific rating of perceived exertion (RPE 5-8), with progressive overload applied individually based on proper technique. The program is divided into three phases: familiarisation (weeks 1-2), progressive overload (weeks 3-5), and strength-oriented training (weeks 6-8). Sessions are delivered in small groups under qualified supervision to ensure safety and adherence.

Ultrasound-derived echo intensity (EI) of the quadriceps femoris (QF) muscle assessed as an indicator of skeletal muscle quality. EI will be derived from longitudinal scans of each QF head and the cross-sectional area (CSAQF) from panoramic mid-thigh images

Maximum voluntary contraction (MVC) of knee extensors measured using an isokinetic dynamometer.

Feasibility assessed by recruitment rate, retention rate, and adherence to the training program (percentage of sessions attended and proportion of participants attending ≥80% of sessions).

Safety evaluated by the number, type, and severity of adverse events recorded during training sessions, and the proportion of participants experiencing at least one adverse event.

Functional lower-body performance assessed using the 30-second sit-to-stand test (30STS).

Body composition assessed using dual-energy X-ray absorptiometry (DXA), including lean mass and fat mass parameters.