한국 성인 남성의 단일 근섬유 유형별 수축 특성과 하지 근력과의 상관관계

PURPOSE: This study investigated the muscle fiber type-related contractile properties and examined the relationship between whole limb muscle strengths and single muscle fiber contractile properties in Korean men. METHODS: Six Korean men (29.8±1.49 yr) were recruited and participated in the study. Samples were obtained from vastus lateralis muscles. CSA, Po, SF, Vo of single fiber segments were measured using an isometric force transducer and a high-speed motor. Silver staining was performed to identify MHC isoform composition of single muscle fiber segments. Multiple regression was tested to identify the relationship between single muscle fiber contractile properties and whole muscle strength. RESULTS: MHC isoforms were distributed in different proportion (Type I: 57.3%, IIa: 34.2%, IIa/IIx: 4.3%, IIx: 4.3%). CSA of type IIx were smaller compared to type I (-50%) and type IIa (-57.5%). Po in type IIa was 12.9% higher compared to type I (p<.05). While SF in type IIa were 7.7% higher than type I, type IIx were higher than type I, IIa, IIa/IIx (31.4%, 25.7%, 30.9%). Vo increased in the order type Ithigh strength: r2=.248, Po vs. thigh power: r2=.058, Vo vs. thigh power: r2=.095). CONCLUSIONS: These results suggest that single muscle fiber contractile properties were exclusively dependent on fiber type isoforms, ruling out a possibility of race-induced difference in fiber type-matched contractile properties.