Availability of MRI and MRS for talent identification in terms of muscle properties.

为了提高日本体育的国际竞争力，有必要有效地、恰当地发掘具有优秀体育能力的人才。骨骼肌方面的人才鉴定尤其重要，因为肌肉性能影响运动性能。本研究通过对志愿者骨骼肌进行磁共振成像（MRI）、磷（~ 3 <31>P）-和碳（~ 3C<13>）-磁共振波谱（MRS）和生化分析，探讨了MRI和MRS在评价骨骼肌运动能力中的作用。磷酸肌酸（PC）/三磷酸腺苷（ATP）、（PCr +无机磷酸盐（Pi））/ATP、横向弛豫时间（T2）与肌纤维类型组成呈显著相关。在对比短跑运动<31>员和耐力运动员的MRI和~ 1H-MRS数据的实验中，前者的PCr/ATP、（PCr+Pi）/ATP、细胞内pH值均显著高于后者，而T_2则显著低于后者。我们证明了<13>使用普通1.5特斯拉临床扫描仪的~ 13 C-MRS能够无创地测量肌糖原浓度。此外，我们发现了一个最佳的条件，以评估骨骼肌的扩散能力，这区分了肌肉有一个独特的扩散性质。为了研究肌肉能量在运动过程中，我们进行了13 <31>P-MRS和近红外光谱，并证明具有较高的氧化能力的肌肉表现出优越的上级氧利用率。这些发现表明，MRI和MRS可以无创地评估纤维类型的组成，能量底物浓度、微循环和人体骨骼肌的氧化能力。

It is necessary to identify effectually and properly individuals who are endowed with outstanding sports capabilities in order to improve Japan's international competitiveness in sports. Talent identification in terms of skeletal muscle is especially important because the muscle performance affects sports performance. This study investigated the availability of magnetic resonance imaging(MRI) and magnetic resonance spectroscopy(MRS) for evaluation of muscle properties in order to identify individuals with a talent for sports.We performed MRI, phosphorus (^<31>P)- and carbon (^<13>C)-MRS, and biochemical assay of the skeletal muscle in volunteers. There were significant correlations between phosphocreatine (PC) / adenosine triphosphate (ATP), (PCr + inorganic phosphate (Pi) ) /ATP, transverse relaxation time (T2) and muscle fiber type composition. In the experiment comparing MRI and ^<31>P-MRS data between sprinters and endurance runners, the former showed significantly higher PCr/ATP, (PCr+Pi)/ATP, intracellular pH and lower T2 than the latter. We demonstrated that ^<13>C-MRS using normal 1.5-tesla clinical scanner enables noninvasive measurement of the muscle glycogen concentration. Moreover, we found an optimal condition for evaluating the diffusion capacity of skeletal muscle, which distinguished muscles that have a distinct diffusion property.To investigate muscle energetics during exercise, we performed ^<31>P-MRS and near infrared spectroscopy simultaneously and demonstrated that muscles possessing higher oxidative capacity show superior oxygen availability.These findings suggest that MRI and MRS can noninvasively evaluate the fiber type composition, concentration of energy substrates, microcirculation and oxidative capacity in human skeletal muscle.