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NCT Number: NCT07512570

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

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).

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Key information

Conditions

Muscle Architecture Ultrasonic Diagnosis

Age range

10 year–14 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Physical Education and Sport Charles University

Prague, Czech Republic, 16200, Czechia

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Progressive Resistance Training Program

Behavioral

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.

Primary outcomes

  1. Muscle Quality (Echo Intensity)

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

    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

  2. Muscle Strength (Knee Extensor Strength)

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

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

  3. Feasibility of the Intervention

    Time frame: Throughout the 8-week 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).

  4. Safety of the Intervention

    Time frame: Throughout the 8-week 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.

Secondary outcomes

  1. Functional Performance

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

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

  2. Body Composition

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

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

Study contacts

Contact information is provided by the study sponsor or research team.

Michal Steffl, PhD

CONTACT

[email protected]

+420778701882

Sponsors and collaborators

Lead sponsor

Charles University, Czech Republic

Other

Registry information

Official study title

Feasibility and Preliminary Effects of a Structured Resistance Training Programme in Children Aged 10-14 Years: A Randomised Controlled Pilot Study

Important dates

Study start
2026
Primary completion
2027
Study completion
2028
First posted
Apr 6, 2026
Registry last updated
Apr 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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