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Role of skeletal muscle‐fibre type in regulation of glucose metabolism in middle‐aged subjects with impaired glucose tolerance during a long‐term exercise and dietary intervention
Author(s) -
Venojärvi M.,
Puhke R.,
Hämäläinen H.,
Marniemi J.,
Rastas M.,
Rusko H.,
Nuutila P.,
Hänninen O.,
Aunola S.
Publication year - 2005
Publication title -
diabetes, obesity and metabolism
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.445
H-Index - 128
eISSN - 1463-1326
pISSN - 1462-8902
DOI - 10.1111/j.1463-1326.2004.00466.x
Subject(s) - medicine , endocrinology , impaired glucose tolerance , insulin resistance , skeletal muscle , vastus lateralis muscle , type 2 diabetes , carbohydrate metabolism , insulin , glycogen , diabetes mellitus
Aim: The aim of this study was to investigate the role of skeletal muscle fibre type in the regulation of glucose metabolism in middle‐aged obese subjects with impaired glucose tolerance (IGT) during a 2‐year exercise and dietary intervention. Methods: Muscle biopsies (musculus vastus lateralis) were taken from 22 subjects belonging to the intervention group of the Finnish Diabetes Prevention Study [1]. According to their myosin heavy chain (MHC) profile at the baseline, the subjects were divided into two groups: IGT slow (n = 10) with a high proportion of MHC I isoforms and IGT fast (n = 12) with a high proportion of MHC II isoforms in the vastus lateralis muscle. The intervention consisted of dietary counselling, strength and power training and/or aerobic exercise. The amount of exercise was the same in both groups; the exercise frequency was 5.1 ± 2.7 h/week in the IGT slow and 5.1 ± 2.8 h/week in the IGT fast group. Results: Fasting glucose (p < 0.05), 2‐h glucose (p < 0.05), fasting insulin (p < 0.05), haemoglobin A1c (HbA 1c ) (p < 0.01) and insulin resistance (p < 0.05) [homeostasis model assessment for insulin resistance (HOMA‐IR)] decreased in the IGT fast group, whereas only the 2‐h glucose and HbA 1c concentrations decreased in the IGT slow group. The amount of the glycogen synthase kinase‐3‐αβ (GSK‐3‐αβ) decreased in the IGT fast group (p < 0.05). Exercise training increased the lactate dehydrogenase (LDH) (p < 0.01), LDH‐1 (p < 0.05) and citrate synthase (CS) (p < 0.05) activities in the vastus lateralis muscle in the IGT slow group, but only the CS activity (p < 0.05) in the IGT fast group. Conclusions: The glucose metabolism improved both in the IGT slow and IGT fast group during the 2‐year exercise and dietary intervention. The change was more prominent in the IGT fast group than in the IGT slow group, associated with the decrease of the GSK‐αβ protein expression in skeletal muscle. The exercise training improved both glycolytic and oxidative capacity in the vastus lateralis muscle. The glycolytic capacity improved in the IGT slow group and the oxidative capacity in both groups.