High-intensity interval, but not endurance training induces muscle fiber type-specific subsarcolemmal lipid droplet size reduction in type 2 diabetic patients

TY - JOUR

T1 - High-intensity interval, but not endurance training induces muscle fiber type-specific subsarcolemmal lipid droplet size reduction in type 2 diabetic patients

AU - Koh, Han-Chow E

AU - Ørtenblad, Niels

AU - Winding, Kamilla M

AU - Hellsten, Ylva

AU - Mortensen, Stefan P

AU - Nielsen, Joachim

N1 - CURIS 2018 NEXS 377

PY - 2018/11

Y1 - 2018/11

N2 - This study compared the effects of moderate-intensity endurance training and high-intensity interval training on fiber type-specific subcellular volumetric content and morphology of lipid droplets and mitochondria in skeletal muscles of type 2 diabetic patients. Sixteen sedentary type 2 diabetic patients (57 ± 7 yr old) were randomized to complete 11 wk of either 40-min cycling at 50% peak workload (Endurance, n = 8) or 10 1-min cycling intervals at 95% peak workload separated by 1 min of recovery (High-Intensity Interval, n = 8), three times per week. Assessments for cardiorespiratory fitness, body composition, glycemic control, together with muscle biopsies were performed before and after the intervention. Morphometric analyses of lipid droplets and mitochondria were conducted in the subcellular fractions of biopsied muscle fibers using quantitative electron microscopy. The training intervention increased cardiorespiratory fitness, lowered fat mass, and improved nonfasting glycemic control (P < 0.05), with no difference between training modalities. In the subsarcolemmal space, training decreased lipid droplet volume (P < 0.003), and high-intensity interval, but not endurance, training reduced the size of lipid droplets, specifically in type 2 fibers (P < 0.001). No training-induced change in intermyo-fibrillar lipid droplets was observed in both fiber types. Subsarcolemmal mitochondrial volume was increased by high-intensity interval (P = 0.02), but not endurance, training (P = 0.79). Along with improvement in glycemic control, low-volume high-intensity interval training is an alternative time-saving training modality that affects subcellular morphology and volumetric content of lipid droplets in skeletal muscle of type 2 diabetic patients.

AB - This study compared the effects of moderate-intensity endurance training and high-intensity interval training on fiber type-specific subcellular volumetric content and morphology of lipid droplets and mitochondria in skeletal muscles of type 2 diabetic patients. Sixteen sedentary type 2 diabetic patients (57 ± 7 yr old) were randomized to complete 11 wk of either 40-min cycling at 50% peak workload (Endurance, n = 8) or 10 1-min cycling intervals at 95% peak workload separated by 1 min of recovery (High-Intensity Interval, n = 8), three times per week. Assessments for cardiorespiratory fitness, body composition, glycemic control, together with muscle biopsies were performed before and after the intervention. Morphometric analyses of lipid droplets and mitochondria were conducted in the subcellular fractions of biopsied muscle fibers using quantitative electron microscopy. The training intervention increased cardiorespiratory fitness, lowered fat mass, and improved nonfasting glycemic control (P < 0.05), with no difference between training modalities. In the subsarcolemmal space, training decreased lipid droplet volume (P < 0.003), and high-intensity interval, but not endurance, training reduced the size of lipid droplets, specifically in type 2 fibers (P < 0.001). No training-induced change in intermyo-fibrillar lipid droplets was observed in both fiber types. Subsarcolemmal mitochondrial volume was increased by high-intensity interval (P = 0.02), but not endurance, training (P = 0.79). Along with improvement in glycemic control, low-volume high-intensity interval training is an alternative time-saving training modality that affects subcellular morphology and volumetric content of lipid droplets in skeletal muscle of type 2 diabetic patients.

KW - Faculty of Science

KW - Lipid droplets

KW - Mitochondria

KW - Skeletal muscle

KW - Stereology

KW - Insulin sensitivity

U2 - 10.1152/ajpendo.00161.2018

DO - 10.1152/ajpendo.00161.2018

M3 - Journal article

C2 - 30016151

SN - 0193-1849

VL - 315

SP - E872-E884

JO - American Journal of Physiology: Endocrinology and Metabolism

JF - American Journal of Physiology: Endocrinology and Metabolism

IS - 5

ER -