The effect of insulin treatment and exercise modality on skeletal muscle fiber size in streptozotocin-induced type 1 diabetic rats
type: CreativeWork
description: Severe Type 1 Diabetes Mellitus (T1DM) is known to have several negative effects on skeletal muscle mass, a condition known as diabetic myopathy. One of these effects is the atrophy of the glycolytic muscle fibers. However, the role of intensity of insulin treatment and exercise modality in attenuating this loss in fiber cross-sectional area (CSA) specifically has yet to be determined. The purpose of this investigation was to determine the effects of 12 weeks of differing intensity of insulin therapy and exercise modality on the CSA of plantaris muscle fibers, identified by myosin heavy chain (MHC) of STZ-induced T1DM rats. Rats were divided into control sedentary (CS), T1DM-sedentary (DCT - conventional versus DIT- intensive insulin therapy, blood glucose 9-15mmol/l and 7-9mmol/l, respectively) and T1DM-exercised (DRE- resistance, DHE-endurance, DCE-combined training, blood glucose 9-15mmol/l) groups. Exercises consisted of repeated weighted ladder climbs (50%, 75%, 90%, and 100% pre-determined max. carrying capacity, 1.1 m, 80°) or treadmill running (27 m/min, 6% grade, 1hr) 5 days/week for 12 weeks. DCE animals performed resistance and endurance exercise on alternating days. Following 12 weeks, diabetic sedentary (DCT, DIT) and diabetic exercised (DRE, DHE, DCE) groups did not differ in body weight (BW) or plantaris whole-muscle weight, except where DIT BW was significantly greater than DRE (P0.05) or aerobic exercise (DHE) in some instances (all fibers expressing fast MHC’s except MHCIIx/IIb and MHCiib – P0.05). Surprisingly, DIT exhibited significantly larger MHCIIa and fewer hybrid fibers than any other group. MHCI fibers were unaffected by either diabetes or exercise, however, exercised animals displayed changes in percent fiber composition, including a significant proportion of hybrid fibers, that appeared to indicate a shift in fiber type particularly from MHCIIx to MHCIIa. Resistance exercise, whether alone (DRE) or in conjunction with aerobic training (DC…
abstract: Severe Type 1 Diabetes Mellitus (T1DM) is known to have several negative effects on skeletal muscle mass, a condition known as diabetic myopathy. One of these effects is the atrophy of the glycolytic muscle fibers. However, the role of intensity of insulin treatment and exercise modality in attenuating this loss in fiber cross-sectional area (CSA) specifically has yet to be determined. The purpose of this investigation was to determine the effects of 12 weeks of differing intensity of insulin therapy and exercise modality on the CSA of plantaris muscle fibers, identified by myosin heavy chain (MHC) of STZ-induced T1DM rats. Rats were divided into control sedentary (CS), T1DM-sedentary (DCT - conventional versus DIT- intensive insulin therapy, blood glucose 9-15mmol/l and 7-9mmol/l, respectively) and T1DM-exercised (DRE- resistance, DHE-endurance, DCE-combined training, blood glucose 9-15mmol/l) groups. Exercises consisted of repeated weighted ladder climbs (50%, 75%, 90%, and 100% pre-determined max. carrying capacity, 1.1 m, 80°) or treadmill running (27 m/min, 6% grade, 1hr) 5 days/week for 12 weeks. DCE animals performed resistance and endurance exercise on alternating days. Following 12 weeks, diabetic sedentary (DCT, DIT) and diabetic exercised (DRE, DHE, DCE) groups did not differ in body weight (BW) or plantaris whole-muscle weight, except where DIT BW was significantly greater than DRE (P0.05) or aerobic exercise (DHE) in some instances (all fibers expressing fast MHC’s except MHCIIx/IIb and MHCiib – P0.05). Surprisingly, DIT exhibited significantly larger MHCIIa and fewer hybrid fibers than any other group. MHCI fibers were unaffected by either diabetes or exercise, however, exercised animals displayed changes in percent fiber composition, including a significant proportion of hybrid fibers, that appeared to indicate a shift in fiber type particularly from MHCIIx to MHCIIa. Resistance exercise, whether alone (DRE) or in conjunction with aerobic training (DC…
author: Nickels, John Z
language: en_ca
keywords: type 1 diabetes mellitus, diabetic myopathy, skeletal muscle, insulin, exercise, muscle fiber cross-sectional area
date published: 2017-06-02
date modified: 2026-07-27T21:55:58Z
provider: Western University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Western Ontario

PropertyValue
property ID: Handle
value: https://hdl.handle.net/20.500.14721/27403