Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, United States.
Department of Orthopedics, Emory University School of Medicine, Atlanta, Georgia, United States.
J Appl Physiol (1985). 2023 May 1;134(5):1083-1092. doi: 10.1152/japplphysiol.00387.2022. Epub 2023 Feb 9.
The objective of this pilot study was to characterize relationships between skeletal muscle energy metabolism and body composition in healthy adults with varied amounts and distribution of adipose tissue. In vivo muscle energetics were quantified using dynamic P magnetic resonance spectroscopy with knee extension exercise standardized to subject lean body mass. Spearman's correlation analysis examined relationships between muscle metabolism indices and measures of adiposity including body mass index (BMI), total body fat, and quadriceps intermuscular adipose tissue (IMAT). Post hoc partial correlations were examined controlling for additional body composition measures. Kruskal-Wallis tests with Dunn-Sidak post hoc comparisons evaluated group differences in energy metabolism based on body composition profiles (i.e., lean, normal-weight obese, and overweight-obese) and IMAT tertiles. BMI negatively correlated with end-exercise muscle pH after correcting for IMAT and total body fat ( = -0.46, = 0.034). Total adiposity negatively correlated with maximum oxidative capacity after correcting for IMAT ( = -0.54, = 0.013). IMAT positively correlated with muscle proton buffering capacity after correcting for total body fat ( = 0.53, = 0.023). Body composition groups showed differences in end-exercise fall in [PCr] with normalized workload ( = 0.036; post hoc: overweight-obese < lean, = 0.029) and maximum oxidative capacity ( = 0.021; post hoc: normal-weight obese < lean, = 0.016). IMAT tertiles showed differences in end-exercise fall in [PCr] with normalized workload ( = 0.035; post hoc: 3rd < 1st, = 0.047). Taken together, these results support increased adiposity is associated with reduced muscle energetic efficiency with more reliance on glycolysis, and when accompanied with reduced lean mass, is associated with reduced maximum oxidative capacity. Skeletal muscle energy production is influenced by both lean body mass and adipose tissue but the effect of their distribution on energy metabolism is unclear. This study examined variations in quadriceps muscle energy metabolism in healthy adults with varied relative amounts of lean and adipose tissue. Results suggest increased adiposity is associated with reduced muscle energetic efficiency with more reliance on glycolysis, and when accompanied with reduced lean mass, is associated with reduced maximum oxidative capacity.
本初步研究的目的是描述健康成年人中不同脂肪量和分布的骨骼肌肉能量代谢与身体成分之间的关系。通过使用膝关节伸展运动标准化至受试者瘦体重的动态 P 磁共振波谱，定量测量活体肌肉能量代谢。Spearman 相关性分析检验了肌肉代谢指标与肥胖指标（体重指数（BMI）、全身脂肪量和股四头肌肌间脂肪组织（IMAT））之间的关系。采用事后偏相关分析，在控制其他身体成分指标的情况下检验相关性。基于身体成分分布（即瘦、正常体重肥胖和超重肥胖）和 IMAT 三分位数，Kruskal-Wallis 检验结合 Dunn-Sidak 事后比较评估了能量代谢的组间差异。BMI 与校正 IMAT 和全身脂肪量后的运动终末肌肉 pH 值呈负相关（= -0.46，= 0.034）。总脂肪量与校正 IMAT 后的最大氧化能力呈负相关（= -0.54，= 0.013）。校正全身脂肪量后，IMAT 与肌肉质子缓冲能力呈正相关（= 0.53，= 0.023）。身体成分组在标准化工作负荷时运动终末 [PCr] 的下降（= 0.036；事后：超重肥胖<瘦，= 0.029）和最大氧化能力（= 0.021；事后：正常体重肥胖<瘦，= 0.016）方面存在差异。IMAT 三分位数在标准化工作负荷时运动终末 [PCr] 的下降方面存在差异（= 0.035；事后：第 3 分位<第 1 分位，= 0.047）。总的来说，这些结果表明，脂肪量增加与肌肉能量效率降低有关，更多地依赖糖酵解，当伴有瘦体重减少时，与最大氧化能力降低有关。骨骼肌能量产生既受瘦体重又受脂肪组织的影响，但脂肪组织分布对能量代谢的影响尚不清楚。本研究检查了不同相对瘦体重和脂肪量的健康成年人股四头肌能量代谢的变化。结果表明，脂肪量增加与肌肉能量效率降低有关，更多地依赖糖酵解，当伴有瘦体重减少时，与最大氧化能力降低有关。
