Increments in skeletal muscle GLUT-1 and GLUT-4 after endurance training in humans

Am J Physiol. 1996 Mar;270(3 Pt 1):E456-62. doi: 10.1152/ajpendo.1996.270.3.E456.


We investigated the time course of training-induced changes in the expression of GLUT-1 and GLUT-4 in human skeletal muscle. Seven healthy males trained for 2 h/day (approximately 60% pretraining VO2peak) for 31 days (31D). Muscle biopsies were obtained before training (PRE) and after 5 (5D) and 31 days (31D) of training. Training resulted in progressive increases in muscle GLUT-4 with increasing training duration (PRE<5D<31D; P<0.01). Muscle GLUT-1 content was also increased (P<0.05) after training; however, the increase was not observed until 31D (131%). Increases in muscle hexokinase (HK) activity were complete by 5D (P<0.01). Muscle malate dehydrogenase activity was not elevated after 5D of training but was increased (+35%; P<0.01) at 31D. Results from this study show that increases in both GLUT-4 and HK represent early training-induced adaptations to prolonged exercise training. As training progresses, further increases in GLUT-4, but not HK, occur in conjunction with an increase in muscle mitochondrial potential and GLUT-1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biopsy
  • Exercise
  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Hexokinase / metabolism
  • Humans
  • Malate Dehydrogenase / metabolism
  • Male
  • Monosaccharide Transport Proteins / metabolism*
  • Muscle Proteins*
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / physiology*
  • Physical Endurance*
  • Regression Analysis
  • Time Factors


  • Glucose Transporter Type 1
  • Glucose Transporter Type 4
  • Monosaccharide Transport Proteins
  • Muscle Proteins
  • SLC2A1 protein, human
  • SLC2A4 protein, human
  • Malate Dehydrogenase
  • Hexokinase