Diet but not aerobic exercise training reduces skeletal muscle TNF-alpha in overweight humans

Diabetologia. 2004 Apr;47(4):630-7. doi: 10.1007/s00125-004-1373-z.

Abstract

Aims/hypothesis: Our aim was to test the hypothesis that TNF-alpha protein levels in skeletal muscle are important in mediating the improvements in glucose homeostasis that are associated with diet and exercise regimens intended to reduce cardiovascular risk.

Methods: We recruited 20 people with a body mass index of 32.1 +/- 1.2 kg/m2 (mean +/- SEM) and one other component of the metabolic syndrome. The average age was 51.2 +/- 8.1 years (mean +/- SD). Of the 20 subjects, 6 were men and 14 were women. All subjects completed an 8-week control period, followed by randomisation to 8 weeks of moderate cycling exercise (30 min, three times per week) or to a diet with the following characteristics: low in saturated fat, high in fibre, low glycaemic index, rich in complex carbohydrates.

Results: Diet induced a small reduction in body mass index (3.0 +/- 0.7%, p<0.05), although weight loss was not intended. Exercise training increased maximum oxygen consumption by 12 +/- 6% (p<0.05). Both interventions reduced fasting plasma insulin levels by about 20%. Diet reduced skeletal muscle TNF-alpha protein by 54 +/- 10% (p<0.05), an effect that was independent (p=0.94 in covariate analysis) of the small concurrent weight loss (-2.8 +/- 0.7 kg). Levels of GLUT4 protein were unchanged in the diet group. In contrast, exercise training did not significantly change TNF-alpha protein expression, but GLUT4 protein expression increased by 105 +/- 37% (p<0.05).

Conclusions/interpretation: These data indicate that the metabolic benefits of a diet aimed at cardiovascular risk reduction are associated with a decrease in skeletal muscle TNF-alpha protein.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Anaerobic Threshold / physiology
  • Blood Glucose / metabolism
  • Diet*
  • Diet, Diabetic
  • Exercise / physiology*
  • Female
  • Glucose Transporter Type 4
  • Homeostasis / physiology
  • Humans
  • Insulin / blood
  • Lipids / blood
  • Longitudinal Studies
  • Male
  • Monosaccharide Transport Proteins / metabolism
  • Muscle Proteins / metabolism
  • Muscle, Skeletal / metabolism*
  • Obesity / diet therapy
  • Obesity / metabolism*
  • Obesity / therapy*
  • Oxygen Consumption / physiology
  • Physical Fitness / physiology*
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • Blood Glucose
  • Glucose Transporter Type 4
  • Insulin
  • Lipids
  • Monosaccharide Transport Proteins
  • Muscle Proteins
  • SLC2A4 protein, human
  • Tumor Necrosis Factor-alpha