Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Geelong, Victoria, Australia.
J Appl Physiol (1985). 2023 Mar 1;134(3):581-592. doi: 10.1152/japplphysiol.00637.2021. Epub 2023 Jan 19.
Intramuscular lipid (IMCL) utilization during exercise was controversial as numerous studies did not observe a decline in IMCL content post-exercise when assessed in muscle biopsies using biochemical techniques. Contemporary techniques including immunofluorescence microscopy and H-magnetic resonance spectroscopy (H-MRS) offer advantages over biochemical techniques. The primary aim of this systematic review, meta-analysis, and meta-regression was to examine the net degradation of IMCL in response to an acute bout of cycling exercise in humans, as assessed with different analytical approaches. A secondary aim was to explore the factors influencing IMCL degradation including feeding status, exercise variables, and participant characteristics. A total of 44 studies met the inclusion criteria using biochemical, immunofluorescence, and H-MRS techniques. A meta-analysis was completed using a random effects model and percentage change in IMCL content calculated from the standardized mean difference. Cycling exercise resulted in a net degradation of IMCL regardless of technique (total effect -23.7%, 95% CI = -28.7 to -18.7%) and there was no difference when comparing fasted versus fed-state exercise ( > 0.05). IMCL degradation using immunofluorescence techniques detected larger effects in type I fibers compared with whole muscle using biochemical techniques ( = 0.003) and in type I fibers compared with type II fibers ( < 0.001). Although IMCL degradation was associated with exercise duration, V̇o, and BMI, none of these factors independently related to the change in IMCL content. These findings provide strong evidence that the analytical approach can influence the assessment of IMCL degradation in human skeletal muscle in response to exercise.
肌肉内脂质 (IMCL) 在运动中的利用一直存在争议，因为许多研究在使用生化技术进行肌肉活检时，并没有观察到运动后 IMCL 含量下降。包括免疫荧光显微镜和 H 磁共振波谱 (H-MRS) 在内的现代技术具有优于生化技术的优势。本系统评价、荟萃分析和荟萃回归的主要目的是检查使用不同分析方法评估人类急性自行车运动后 IMCL 的净降解情况。次要目的是探讨影响 IMCL 降解的因素，包括喂养状态、运动变量和参与者特征。共有 44 项研究使用生化、免疫荧光和 H-MRS 技术符合纳入标准。使用随机效应模型和标准化均数差值计算的 IMCL 含量百分比变化进行荟萃分析。无论使用何种技术，自行车运动都会导致 IMCL 的净降解（总效应 -23.7%，95%CI=-28.7 至-18.7%），并且在比较禁食与进食状态的运动时没有差异（>0.05）。与使用生化技术检测整块肌肉相比，免疫荧光技术检测到 I 型纤维中 IMCL 降解的影响更大（=0.003），与 II 型纤维相比也是如此（<0.001）。尽管 IMCL 降解与运动持续时间、V̇o 和 BMI 相关，但这些因素均不能独立与 IMCL 含量的变化相关。这些发现有力地证明了分析方法会影响运动后人类骨骼肌中 IMCL 降解的评估。
