Skeletal muscle ¹H MRSI before and after prolonged exercise. I. muscle specific depletion of intramyocellular lipids

Abstract

Aim of the study was to determine distribution and depletion patterns of intramyocellular lipids (IMCL) in leg muscles before and after two types of standardized endurance exercise. ¹H-magnetic resonance spectroscopic imaging was performed (1) in the thigh of eight-trained cyclists after exercising on an ergometer for 3 h at 52 ± 8% of maximal speed and (2) in the lower leg of eight-trained runners after exercising on a treadmill for 3 h at 49 ± 3% of maximal workload. Pre-exercise IMCL contents were reduced postexercise in 11 out of 13 investigated upper and lower leg muscles (P < 0.015 for all). A strong linear correlation with a slope of ∼0.5 between pre-exercise IMCL content and IMCL depletion was found. IMCL depletion differed strongly between muscles. Absolute and also relative IMCL reduction was significantly higher in muscles with predominantly slow fibers compared to those with fast fibers. Creatine levels and fiber orientation were stable and unchanged after exercise, while trimethyl-ammonium groups increased. This is presented in the accompanying paper. In conclusion, a systematic comparison of metabolic changes in cross sections of the upper and lower leg was performed. The results imply that pre-exercise IMCL levels determine the degree of IMCL depletion after exercise.

The effect of diet and exercise on lipid droplet dynamics in human muscle tissue

“…After acute exercise at moderate intensity, most studies report not only a decrease in IMCL in healthy and sedentary subjects (Bucher et al, 2014;Decombaz et al, 2001;Egger et al, 2013;SchrauwenHinderling et al, 2003a;White et al, 2003) but also in endurancetrained athletes (Brechtel et al, 2001b;De Bock et al, 2007;Decombaz et al, 2001;Johnson et al, 2003;Krssak et al, 2000;Rico-Sanz et al, 2000;van Loon et al, 2003a;van Loon et al, 2003b;Vermathen et al, 2012;Zehnder et al, 2005). Importantly, the utilization of IMCL during exercise depends upon the duration and intensity of exercise and the training status of the participant.…”

“…Furthermore, it was shown that a HFD increased net IMCL degradation during exercise, an effect that was not altered by an exercise training program (Van Proeyen et al, 2011), again possibly owing to increased basal IMCL values. Indeed, several studies indicate that it may be basal IMCL values that are the determinant of IMCL usage during exercise (Steffensen et al, 2002;Vermathen et al, 2012;Zehnder et al, 2006), so higher IMCL levels at the onset of exercise may result in higher IMCL utilization. For example, athletes given 1.5 days of lipid supplementation before an acute cycling exercise showed increased pre-exercise IMCL levels; the IMCL depletion during exercise was strongly correlated with these preexercise IMCL levels (Zehnder et al, 2006).…”

Increased intramyocellular lipid/impaired insulin sensitivity is associated with altered lipid metabolic genes in muscle of high responders to a high-fat diet

“…Vermathen et al (46) investigated IMCL levels in 13 different muscles, including VL, SOL, and TA, before and after aerobic exercise. They found that baseline IMCL levels for different subjects were strongly correlated between the muscle (average correlation coefficient between all muscle was r ϭ 0.83).…”

High-Resolution Echo-Planar Spectroscopic Imaging of the Human Calf

“…The reduction of IMCL contamination was achieved by using smaller voxel sizes and by a post-acquisition selection of voxels with acceptable separation of IMCL CH2 line from EMCL CH2 . Conventional STEAM, PRESS or slice selective 2D MRSI techniques reached nominal voxel sizes 5×5×10 mm 3 using spatial matrices 32×32 or 36×36 [11]–[15]. Acquisition time was 20–35 minutes.…”