title: Changes in gene expression in responders and nonresponders to a low-intensity walking intervention.
abstract: OBJECTIVE
  Daily physical activity remains an effective strategy to prevent obesity and type 2 diabetes. However, the metabolic response to exercise training is variable, and the precise clinical and molecular determinants that mark the metabolic improvements remain unknown. We tested the hypothesis that clinical improvements in glucose control after low-intensity exercise in individuals with impaired glucose tolerance (IGT) are coupled to alterations in skeletal muscle gene expression.
  
  
  METHODS
  We investigated 14 overweight individuals with IGT before and after a 4-month low-intensity unsupervised walking exercise intervention. Clinical and anthropometric measurements and glucose tolerance were determined before and after the intervention. Skeletal muscle biopsy specimens were obtained for mRNA expression analysis.
  
  
  RESULTS
  Waist circumference and work capacity during cycle ergometry were improved in individuals who achieved normal glucose tolerance (NGT) after exercise training (IGT-NGT; n = 9) but in not individuals who remained IGT (IGT-IGT; n = 5). Pretraining glycemic control was better in IGT-NGT compared with IGT-IGT. mRNA expression of mitochondrial markers and transcription factors was increased in IGT-NGT after exercise intervention and normalized to levels measured in a separate cohort of nonexercised individuals with NGT. Conversely, these markers were unaltered after exercise intervention in IGT-IGT.
  
  
  CONCLUSIONS
  Normalization of metabolic control can be achieved after low-intensity exercise in individuals with IGT. This can be tracked with increased mRNA expression of mitochondrial and metabolic genes in skeletal muscle. However, for individuals presenting with a greater derangement in glycemia, the potential for clinical and metabolic improvements after this low-intensity unsupervised exercise protocol appears to be limited.
authors: Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
authors: Megan E
authors: ME
authors: Osler
authors: Center for Family and Community Medicine, Karolinska Institutet, Huddinge, Sweden.
authors: Tomas
authors: T
authors: Fritz
authors: Department of Molecular Medicine and Surgery, Clinical Physiology, Karolinska Institutet, Stockholm, Sweden.
authors: Kenneth
authors: K
authors: Caidahl
authors: Department of Physiology and Pharmacology, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
authors: Anna
authors: A
authors: Krook
authors: Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden Department of Physiology and Pharmacology, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden juleen.zierath@ki.se.
authors: Juleen R
authors: JR
authors: Zierath
authors: Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden Department of Physiology and Pharmacology, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.
authors: Harriet
authors: H
authors: Wallberg-Henriksson
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000378:metabolism; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D015870:Gene Expression; D005819:Genetic Markers / Q000235:genetics; D018149:Glucose Intolerance / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control; D050177:Overweight / Q000235:genetics* / Q000517:prevention & control; D012333:RNA, Messenger / Q000378:metabolism; D016896:Treatment Outcome; D055105:Waist Circumference / Q000235:genetics; D016138:Walking / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D005819:Genetic Markers; D012333:RNA, Messenger