Dicks N D, Kotarsky C J, Trautman K A, Barry A M, Keith J F, Mitchell S, Byun W, Stastny S N, Hackney K J
Nathan D. Dicks, Concordia College, Department of Nutrition, Dietetics and Exercise Science, 901 8th St. S., Moorhead, MN 56562; 218-299-4440 Email:
J Frailty Aging. 2020;9(1):51-56. doi: 10.14283/jfa.2019.40.
The use of magnetic resonance imaging (MRI) derived functional cross-sectional area (FCSA) and intramuscular adipose tissue (IMAT) to define skeletal muscle quality is of fundamental importance in order to understand aging and inactivity-related loss of muscle mass.
This study examined factors associated with lower-extremity skeletal muscle quality in healthy, younger, and middle-aged adults.
Cross-sectional study.
Ninety-eight participants (53% female) were classified as younger (20-35 years, n=50) or middle-aged (50-65 years, n=48) as well as sedentary (≤1 day per week) or active (≥3 days per week) on self-reported concurrent exercise (aerobic and resistance).
All participants wore an accelerometer for seven days, recorded a three-day food diary, and participated in magnetic resonance imaging (MRI) of the lower limbs. Muscle cross-sectional area (CSA) was determined by tracing the knee extensors (KE) and plantar flexors, while muscle quality was established through the determination of FCSA and IMAT via color thresholding.
One-way analysis of variance and stepwise regression models were performed to predict FCSA and IMAT. KE-IMAT (cm2) was significantly higher among sedentary (3.74 ± 1.93) vs. active (1.85 ± 0.56) and middle-aged (3.14 ± 2.05) vs. younger (2.74 ± 1.25) (p < 0.05). Protein intake (g•kg•day-1) was significantly higher in active (1.63 ± 0.55) vs. sedentary (1.19 ± 0.40) (p < 0.05). Sex, age, concurrent exercise training status, and protein intake were significant predictors of KE FCSA (R2 = 0.71, p < 0.01), while concurrent exercise training status and light physical activity predicted 33% of the variance in KE IMAT (p < 0.01).
Concurrent exercise training, dietary protein intake, and light physical activity are significant determinants of skeletal muscle health and require further investigation to mitigate aging and inactivity-related loss of muscle quality.
利用磁共振成像（MRI）得出的功能性横截面积（FCSA）和肌内脂肪组织（IMAT）来定义骨骼肌质量，对于理解衰老和与缺乏运动相关的肌肉量流失至关重要。
本研究调查了健康的年轻和中年成年人下肢骨骼肌质量的相关因素。
横断面研究。
98名参与者（53%为女性）根据自我报告的同时进行的运动（有氧运动和阻力运动）情况，分为年轻组（20 - 35岁，n = 50）或中年组（50 - 65岁，n = 48），以及久坐组（每周≤1天）或活跃组（每周≥3天）。
所有参与者佩戴加速度计7天，记录3天的饮食日记，并接受下肢的磁共振成像（MRI）检查。通过描绘膝伸肌（KE）和跖屈肌来确定肌肉横截面积（CSA），同时通过颜色阈值法确定FCSA和IMAT来建立肌肉质量。
进行单因素方差分析和逐步回归模型以预测FCSA和IMAT。久坐组（3.74±1.93）的KE - IMAT（cm²）显著高于活跃组（1.85±0.56），中年组（3.14±2.05）显著高于年轻组（2.74±1.25）（p < 0.05）。活跃组（1.63±0.55）的蛋白质摄入量（g•kg•天⁻¹）显著高于久坐组（1.19±0.40）（p < 0.05）。性别、年龄、同时进行的运动训练状态和蛋白质摄入量是KE FCSA的显著预测因素（R² = 0.71，p < 0.01），而同时进行的运动训练状态和轻度身体活动预测了KE IMAT中33%的方差（p < 0.01）。
同时进行的运动训练、饮食蛋白质摄入量和轻度身体活动是骨骼肌健康的重要决定因素，需要进一步研究以减轻与衰老和缺乏运动相关的肌肉质量流失。
