The goal of this randomized trial is to find out if an 8-week korfball-based training program can improve lower-body strength and jumping ability in children aged 10-12 years. Korfball is a mixed-gender sport that promotes teamwork and equal participation.

The study will test two main questions:

Does korfball training increase explosive leg power measured by the Margaria-Kalamen Stair Climb Test? Does korfball training improve performance in the Standing Long Jump Test?

Children are randomly assigned to one of two groups:

Korfball Training Group: Participants take part in supervised korfball-based exercise sessions 3 times per week for 8 weeks, in addition to their normal school activities.

Control Group: Participants continue with standard school physical education classes only.

All participants complete both the Margaria-Kalamen Stair Climb Test and the Standing Long Jump Test before and after the 8-week period.

This study will show whether korfball training is an effective and inclusive way to improve explosive leg power and motor skills in school-aged children.

Korfball is a mixed-gender team sport that emphasizes cooperation, spatial awareness, and technical ball skills. Its unique format prohibits gender-based physical contact and requires players to coordinate offensive and defensive movements in a cooperative way. These characteristics make korfball not only a socially inclusive activity but also a potential tool for motor development in children. However, there is limited experimental evidence examining the physical benefits of korfball training in youth populations.

This randomized controlled trial was designed to investigate whether an 8-week korfball-based training program can improve explosive lower-body performance in children aged 10-12 years. A total of 30 participants were randomly assigned to either a korfball training group or a control group. The training group completed three 90-minute sessions per week for eight weeks, in addition to their regular school physical education classes. The control group continued with their standard school-based activities only.

The intervention program included structured korfball drills such as passing, shooting, lay-up techniques, and defensive footwork. Sessions were organized progressively from basic skills to more complex game-like movements. All training sessions were supervised by a certified physical education teacher to ensure safety and protocol fidelity.

Two validated physical performance tests were used to assess outcomes:

Margaria-Kalamen Stair Climb Test (MK): to evaluate anaerobic power by measuring the time taken to ascend stairs with predetermined step intervals.

Standing Long Jump Test (SLJ): to assess horizontal explosive power of the lower limbs.

Tests were conducted before and after the 8-week intervention under standardized conditions. Trained evaluators blinded to group assignments recorded all measurements. The primary outcome was change in Margaria-Kalamen test performance, while the secondary outcome was change in Standing Long Jump distance.

The study hypothesis was that participants in the korfball training group would demonstrate significantly greater improvements in both MK and SLJ performance compared to the control group, regardless of gender. By testing this hypothesis, the trial aims to provide evidence for korfball as a safe, inclusive, and effective training method for improving lower-limb explosive strength in school-aged children.

If positive, the findings could inform physical education curricula and youth sports programming, supporting the use of korfball-based activities as a practical approach to enhance motor development while promoting gender equality in sport participation.

Inclusion Criteria:

• Healthy children aged 10-12 years
• Regular participation in school-based physical activity or physical education classes
• Ability to attend training sessions and testing procedures for the full 8-week - period
• Written informed consent obtained from parents/guardians

Exclusion Criteria:

• Presence of chronic or acute illnesses (e.g., cardiovascular, respiratory, or metabolic diseases)
• Orthopedic or musculoskeletal injuries/disorders that may limit safe participation
• Neurological disorders affecting motor performance
• Lack of regular participation in physical activities prior to study enrollment
• Failure to obtain parental/guardian consent

Individual participant data (IPD) underlying the results (e.g., test scores from Margaria-Kalamen and Standing Long Jump) will be available upon reasonable request from the corresponding author. De-identified datasets may be shared for academic research purposes only, following approval by the principal investigator and in compliance with data protection regulations.

De-identified individual participant data (IPD) and supporting documents will be available beginning 6 months after publication of the study results and will remain accessible for 5 years thereafter.

De-identified individual participant data (IPD), including test results from the Margaria-Kalamen Stair Climb Test and the Standing Long Jump Test, as well as supporting documents (Study Protocol, Statistical Analysis Plan, Informed Consent Form), will be available to qualified academic researchers. Data will be shared solely for non-commercial, academic research purposes upon reasonable request to the corresponding author. Requests will be reviewed by the principal investigator to ensure compliance with ethical standards and data protection regulations. Access will be granted through secure data transfer after approval.

The investigators conducting the outcome measurements were blinded to group assignments and study hypotheses to reduce bias.