Whether age-related changes in muscle components differ between the quadriceps femoris and hamstrings has remained unclear. This study aimed to compare the muscle volume and echo intensity-estimated intramuscular adipose tissue content of the vastus lateralis (VL) and long head of biceps femoris (BF) muscles between young and older adults. Thirty young adults (n = 15; mean age, 21 years) and older adults (n = 15; mean age, 71 years) participated in this study. Magnetic resonance imaging was performed to determine muscle volumes of the VL and BF, and muscle volume normalized to body weight (muscle volume/weight). Mean gray-scale echo intensity was calculated as the intramuscular adipose tissue index. Muscle volume/weight and echo intensity were normalized using Z-scores in young and older adults. Muscle volume/weight was lower in older adults than in young adults, and lower in overall women than in men for VL (both p < 0.001) and BF (p < 0.01 and p < 0.05). Echo intensity was higher in older adults than in young adults for VL and BF (both p < 0.001), but did not differ between men and women. Z-score of muscle volume/weight was lower in older adults than in young adults for VL (-2.41 ± 1.22; p < 0.05), and Z-score of echo intensity was higher in older adults than in young adults for BF (2.00 ± 0.68; p < 0.05). These results suggest that muscle volume of quadriceps femoris was lower in older adults than in young adults, whereas intramuscular adipose tissue content of hamstrings was greater in older adults than in young adults.

中文翻译：

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股四头肌和腿筋的肌肉体积和肌内脂肪含量的年龄相关变化。

股四头肌和腿筋之间的年龄相关的肌肉成分变化是否不同尚不清楚。这项研究旨在比较年轻人和老年人之间股外侧肌（VL）和股二头肌（BF）长头的肌肉体积和回声强度估计的肌肉内脂肪组织含量。30名年轻成年人（n = 15；平均年龄21岁）和老年人（n = 15；平均年龄71岁）参加了这项研究。进行磁共振成像以确定VL和BF的肌肉体积，并将肌肉体积标准化为体重（肌肉体积/体重）。计算平均灰度回波强度作为肌内脂肪组织指数。在年轻人和老年人中，使用Z评分将肌肉体积/重量和回声强度标准化。对于VL（p <0.001）和BF（p <0.01和p <0.05），老年人的肌肉体积/重量低于年轻人，而整体女性的肌肉体积/重量低于男性。对于VL和BF，老年人的回声强度高于年轻人（均为p <0.001），但男女之间无差异。VL的老年人的肌肉体积/重量的Z评分低于年轻人（-2.41±1.22; p <0.05），而BF的老年人的回声强度Z评分高于年轻人（2.00 ±0.68; p <0.05）。这些结果表明，老年人股四头肌的肌肉体积比年轻人低，而老年人的腿筋肌内脂肪组织含量比年轻人大。01和p <0.05）。对于VL和BF，老年人的回声强度高于年轻人（均为p <0.001），但男女之间无差异。VL的老年人的肌肉体积/重量的Z评分低于年轻人（-2.41±1.22; p <0.05），而BF的老年人的回声强度Z评分高于年轻人（2.00 ±0.68; p <0.05）。这些结果表明，老年人股四头肌的肌肉体积比年轻人低，而老年人的腿筋肌内脂肪组织含量比年轻人大。01和p <0.05）。对于VL和BF，老年人的回声强度高于年轻人（均为p <0.001），但男女之间无差异。VL的老年人的肌肉体积/重量的Z评分低于年轻人（-2.41±1.22; p <0.05），而BF的老年人的回声强度Z评分高于年轻人（2.00 ±0.68; p <0.05）。这些结果表明，老年人股四头肌的肌肉体积比年轻人低，而老年人的腿筋肌内脂肪组织含量比年轻人大。41±1.22；p <0.05），高龄人群的回声强度的Z值高于年轻人（2.00±0.68； p <0.05）。这些结果表明，老年人股四头肌的肌肉体积比年轻人低，而老年人的腿筋肌内脂肪组织含量比年轻人大。41±1.22；p <0.05），高龄人群的回声强度的Z值高于年轻人（2.00±0.68； p <0.05）。这些结果表明，老年人股四头肌的肌肉体积比年轻人低，而老年人的腿筋肌内脂肪组织含量比年轻人大。