Fig. 1Fasting blood glucose levels (A) and blood glucose area under the curve (AUC) responses to intraperitoneal glucose tolerance tests (B) during the first and last weeks of exercise training; Zucker lean control (ZLC-Con), non-exercised Zucker diabetic fatty (ZDF-Con), and exercised Zucker diabetic fatty (ZDF-Ex). Values are presented as mean±standard error of mean.
Fig. 2Changes in blood glucose levels during the (A) first and (B) last weeks of exercise training in the Zucker lean control (ZLC-Con), non-exercised Zucker diabetic fatty (ZDF-Con), and exercised Zucker diabetic fatty (ZDF-Ex) rats at 0 (baseline), 15, 30, 60, 90, and 120 minutes after glucose administration (2 g/kg). Values are presented as mean±standard error of mean. aP<0.05 vs. ZLC-Con, bP<0.001 vs. ZLC-Con, cP<0.05 vs. ZDF-Con, dP<0.001 vs. ZDF-Con.
Fig. 3(A) Glucose transporter 4 (GLUT4) protein levels assessed by Western blot and immunofluorescence assay in the skeletal muscle of the (B) Zucker lean control (ZLC-Con), (C) non-exercised Zucker diabetic fatty (ZDF-Con), and (D) exercised Zucker diabetic fatty (ZDF-Ex) rats. Paraffin sections were incubated with GLUT4 antibody (1:1,000) and then with a fluorescein isothiocyanate-conjugated secondary antibody (1:50). Values are presented as mean±standard error of mean (immunofluorescence assay, ×400; scale bar=50 µm).
Fig. 4Immunohistochemistry was performed on the medial gastrocnemius muscle from the (A) Zucker lean control (ZLC-Con), (B) non-exercised Zucker diabetic fatty (ZDF-Con), and (C) exercised Zucker diabetic fatty (ZDF-Ex) rats. Paraffin sections of the muscle were immunostained with fast myosin heavy chain (MHC II) antibody (1:2,000 dilution). MHC I fibers were calculated from the unstained areas, and MHC II fibers were calculated from the stained areas, which appear dark (×100, scale bar=50 µm). The percentage of (D) MHC I-positive and (E) MHC II-positive areas were calculated using Innerview 2.0 software (Lumenera). Values are presented as mean±standard error of mean.
Table 1Body weight and gastrocnemius muscle characteristics
Variable |
ZLC-Con |
ZDF-Con |
ZDF-Ex |
Body weight, g |
272±5.35 |
364.5±13.57a (P=0.002) |
371.5±17.42 (P=0.925) |
Muscle weight, mg |
586.25±17.60 |
505±15.14 (P=0.070) |
556.25±30.85 (P=0.285) |
Muscle weight/body weight, mg/g |
2.16±0.09 |
1.39±0.03b (P=0.000) |
1.50±0.18 (P=0.512) |
Table 2Grip-strength test
Variable |
ZLC-Con |
ZDF-Con |
ZDF-Ex |
Grip strength, g |
1,099.48±50.55 |
704.74±53.73a (P=0.009) |
918.09±99.05 (P=0.141) |
Grip strength/muscle weight, g/g |
1,877.39±78.67 |
1,389.86±64.22 (P=0.072) |
1,671.94±210.02 (P=0.344) |
Grip strength/body weight, g/g |
4.04±0.18 |
1.93±0.08b (P=0.000) |
2.52±0.37 (P=0.248) |
Table 3Changes in weekly exercise performance
Training week |
Maximum weight lifted, g |
Maximum weight lifted/body weight, g/g |
Week 1 |
240±12.25 |
1.77±0.18 |
Week 2 |
330±21.21 |
1.62±0.08 |
Week 3 |
420±46.19 |
1.77±0.10 |
Week 4 |
497.5±36.14 |
1.83±0.07 |
Week 5 |
625±31.75a
|
2.12±0.03 |
Week 6 |
670±34.88 |
2.13±0.02 |
Week 7 |
745±26.3 |
2.15±0.01 |
Week 8 |
785±2.89 |
2.13±0.09 |
Interaction (P) |
<0.001 |
0.511 |