Lower-Limb Muscle Mass and Balance Performance

This study will employ a cross-sectional observational design to investigate the relationship between lower-limb muscle mass and balance performance in moderately physically active young men. The primary focus will be to determine whether normalized muscle mass indicators, particularly the ratio of lower-limb muscle mass to body weight (LMM/BW), demonstrate greater sensitivity in explaining balance-performance differences than absolute muscle mass measures.

A cohort of healthy male participants aged 20-30 years will be recruited. All participants will be moderately physically active and free from musculoskeletal injuries, neurological disorders, or medical conditions that could affect balance performance. After providing written informed consent, participants will undergo standardized anthropometric and body composition assessments using bioelectrical impedance analysis to obtain appendicular skeletal muscle mass, leg muscle mass, total muscle mass, body fat percentage, and LMM/BW.

Balance performance will be evaluated using a center-of-pressure-based static balance test performed on a stabilometric platform. Participants will complete a 30-second quiet standing task, during which sway path length and sway area will be recorded as primary balance outcomes. These parameters will be used to classify participants into balance-performance-based groups in order to examine the discriminative capacity of different balance metrics with respect to muscle mass variables.

Between-group comparisons of muscle mass indicators will be conducted to identify differences associated with balance performance classifications. In addition, correlation analyses will be performed across the entire sample to assess the strength and direction of associations between muscle mass variables and balance outcomes. Effect size estimates will be calculated to support the interpretation of observed differences.

The study is expected to clarify whether relative lower-limb muscular capacity provides a more functionally meaningful explanation of balance performance than absolute muscle mass in young, physically active populations. The findings may contribute to improved methodological approaches in balance assessment and support the use of normalized muscle mass indicators in sports science, exercise physiology, and preventive health contexts.

Inclusion criteria

Inclusion criteria

required that participants (i) were between 20 and 30 years of age; (ii) had no lower-limb injuries that could affect test performance; (iii) were moderately physically active; and (iv) had not used ergogenic aids or stimulant substances for at least six months prior to the study.

Exclusion criteria

• Exclusion criteria included the presence of back, neck, leg, foot, or upper-limb pain within the previous six months, as well as a history of major orthopedic surgery involving the lower extremities or trunk.