Feasibility and Preliminary Effects of a Structured Resistance Training Program in Children Aged 10-14 Years

N/ANot Yet RecruitingNCT07512570

Charles University, Czech Republic31 enrolled

Overview

This study is a randomised controlled pilot trial designed to evaluate the feasibility, safety, and preliminary efficacy of a 12-week resistance training intervention in children aged 10-14 years. The study adheres to the CONSORT extension for randomised pilot and feasibility trials and incorporates key elements of the SPIRIT guidelines for clinical trial protocols. The primary purpose of the study is to assess feasibility-related outcomes and to generate effect size estimates to inform the design of a subsequent fully powered randomised controlled trial (RCT).

Study Type

INTERVENTIONAL

Allocation

Purpose

PREVENTION

Masking

NONE

Enrollment

Conditions

Muscle Architecture Ultrasonic Diagnosis

Interventions

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.

Eligibility

Sex: ALLMin age: 10 YearsMax age: 14 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Children aged 10-14 years * Ability to safely participate in supervised resistance training * Written informed consent from a parent or legal guardian * Assent provided by the child participant * Willingness to comply with all study procedures and attend training sessions Exclusion Criteria: * Acute illness at the time of enrolment * Recent musculoskeletal injury or immobilisation * Chronic cardiovascular, metabolic, or endocrine disorders * Use of medications that may affect muscle composition or function * Any medical or psychological condition that may compromise safety or adherence

Outcomes

Primary Outcomes

Muscle Quality (Echo Intensity)

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

Time frame: Time Frame: Pre-intervention (baseline) and post-intervention (8 weeks)

Muscle Strength (Knee Extensor Strength)

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

Time frame: Time Frame: Pre-intervention and post-intervention (8 weeks)

Feasibility of the Intervention

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).

Time frame: Throughout the 8-week intervention

Safety of the Intervention

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.

Time frame: Throughout the 8-week intervention

Secondary Outcomes

Functional Performance

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

Time frame: Pre-intervention and post-intervention (8 weeks)

Body Composition

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