Autism spectrum disorder (ASD) is an increasing public health concern, with preschool children often exhibiting persistent deficits in school readiness. However, targeted and developmentally comprehensive interventions remain limited. This randomized controlled trial will evaluate a 12-week Fundamental Movement Skills-CrossFit Training Program (FCTP) in 184 children with ASD aged 3-6 years, compared with a Treatment As Usual (TAU) control group. The program integrates progressive FMS training with CrossFit-style circuit training to improve motor competence, social interaction, and self-regulation. Primary outcomes focus on school readiness assessed by the Strengths and Difficulties Questionnaire (SDQ), while secondary outcomes include motor development, executive function, social responsiveness, and biomarkers. Assessments will be conducted at baseline, mid-intervention (8 weeks), post-intervention (12 weeks), and follow-up (20 weeks).

Autism spectrum disorder (ASD) is a major public health concern, and increasing prevalence underscores the need for evidence-based interventions that improve functional outcomes. While school readiness is a critical developmental milestone, deficits remain pervasive among preschoolers with ASD, yet targeted interventions remain scarce. Exercise interventions grounded in Fundamental Movement Skills (FMS) are promising, but many existing approaches lack systematic progression and do not adequately address the multidimensional nature of school readiness.

This randomized controlled trial will evaluate the effectiveness of a novel Fundamental Movement Skills-CrossFit Training Program (FCTP) in 184 preschool children with ASD aged 3-6 years. Participants will be randomly assigned to the FCTP intervention group or a Treatment As Usual (TAU) control group using a computer-generated randomization. The FCTP is a 12-week structured program integrating FMS development through CrossFit-style circuit training, designed to enhance motor competence, social interaction, and self-regulation skills essential for school readiness. Primary outcomes will include school readiness measures assessed using the Strengths and Difficulties Questionnaire (SDQ). Secondary outcomes will encompass motor development, executive function, social responsiveness, and biomarker analyses. Assessments will be conducted at baseline, 8 weeks (mid-intervention), 12 weeks (end-of-intervention), and 20 weeks (8 weeks post-intervention).

Discussion: This study will address a critical gap in early intervention research by targeting school readiness through a systematic, theory-driven approach combining motor skill development with social learning opportunities. The FCTP will offer several advantages over traditional interventions: systematic FMS progression, group-based social interaction, cost-effectiveness, and high implementation feasibility. By integrating neuroplasticity principles with contextual learning, this intervention will provide a comprehensive approach to preparing children with ASD for successful educational transitions.

Inclusion Criteria:

1. age 3-6 years;
2. confirmed ASD diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria or the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2);
3. written informed consent from parent/caregiver.

Exclusion Criteria:

1. participation in structured exercise programs within the preceding 6 months;
2. comorbid severe neurological disorders (e.g., epilepsy, phenylketonuria, fragile X syndrome, tuberous sclerosis) or major psychiatric conditions (e.g., schizophrenia, bipolar disorder);
3. visual, auditory or intellectual impairments that would interfere with participation;
4. history of significant head trauma or brain injury;
5. medical contraindications to physical activity ;
6. other factors deemed unsuitable for program participation by the research team.

IPD will not be shared due to participant privacy and confidentiality protections. The informed consent did not include provisions for data sharing beyond the research team, and relevant data protection regulations preclude dissemination of identifiable personal health information.