The goal of this observational study is to examine the relationship between foot type and dynamic stability (balance while standing on one leg) in judo athletes. Judo requires excellent balance to perform techniques effectively and avoid injuries. However, there is limited scientific knowledge about how foot posture affects balance in judokas.

The main questions this study aims to answer are:

• Does foot type (neutral, pronated, or supinated) affect dynamic stability in judokas?
• Are there differences in balance between male and female judokas?
• Does injury history affect dynamic stability?
• Is there a difference in balance between the dominant and non-dominant foot?

Participants in this study will:

• Have their foot type assessed using the Foot Posture Index (FPI-6), a clinical tool that evaluates foot alignment
• Perform the Y Balance Test, which measures how far they can reach in three directions while standing on one leg
• Complete a questionnaire about their training history, injuries, and demographic information

All assessments will be conducted in the participants' judo training facilities (tatami) during a single session.

Researchers will compare three groups of judokas (those with neutral, pronated, and supinated feet) to see if foot type influences balance performance. This information may help coaches and healthcare professionals better assess athletes, prevent injuries, and improve sports performance in judo.

Judo is a combat sport that places high demands on dynamic postural control due to continuous changes in stance, center of mass, and base of support during throws, defenses, and transitions between standing and ground fighting. Alterations in foot posture (neutral, pronated, or supinated) may modify lower limb biomechanics and could influence dynamic stability and injury risk, but this relationship has not been specifically examined in adult judokas.

This cross-sectional observational study was conducted in federated judokas from clubs in the Galician provinces of A Coruña and Pontevedra (Spain). A total of 45 athletes were classified into three groups according to the Foot Posture Index (FPI-6): pronated, neutral, and supinated feet. Dynamic postural stability was assessed using the Y Balance Test (YBT), normalized to limb length to obtain a composite percentage score for each lower limb. Additional variables included age, sex, training exposure, years practicing judo, dominant (habitual support) foot, and history of neck, spine, hip, or lower limb injuries.

The primary objective is to determine whether dynamic stability differs between foot posture groups. Secondary objectives are to: (1) explore associations between stability and sociodemographic/training variables, (2) examine differences in YBT scores between judokas with and without a history of lower limb or spine injuries, and (3) compare stability between the dominant and non-dominant foot in single-leg techniques. Statistical analyses include descriptive statistics, normality testing, one-way ANOVA with appropriate post-hoc tests for group comparisons, and Student's t-tests for bivariate analyses, with a two-sided significance level of p < 0.05.

The findings are expected to clarify whether specific foot morphologies are associated with reduced dynamic stability in judokas, providing clinically useful information for biomechanical assessment, targeted injury prevention, and performance optimization in this population.

Inclusion Criteria:

• Federated judo athletes between 15 and 40 years of age.
• Minimum of 3 years practicing judo.
• At least 2 judo training sessions per week.
• Ability to understand and follow study instructions.
• Signed informed consent (and parental consent for minors, if applicable).

Exclusion Criteria:

• Presence of any systemic disease that may cause morphological or biomechanical alterations of the lower limbs.
• Current biomechanical limitations of the lower limbs that prevent safe performance of the Y Balance Test.
• History of recent lower limb surgery or spinal surgery that may interfere with balance assessment.
• Refusal to undergo measurements or to have data collected at the time of evaluation.

Federated judo athletes aged 15 to 40 years from judo clubs in the Galician provinces of A Coruña and Pontevedra (Spain), with at least 3 years of practice and regular weekly training.