Effects of streptozotocin-induced diabetes, physical training and their combination on collagen biosynthesis in rat skeletal muscle

Different types of resistance training in type 2 diabetes mellitus: effects on glycaemic control, muscle mass and strength

BACKGROUND

Resistance training has become a mainstay of exercise training in type 2 diabetes mellitus (T2DM). However, it remains controversial whether hypertrophy resistance training (HRT) is superior to endurance resistance training (ERT) with regard to its effects on glycaemic control, muscle mass and strength.

METHODS

Thirty-two patients with T2DM (13 men and 19 women; 64.8 ± 7.8 years) were randomly assigned to either eight weeks of HRT (n = 16; 2 sets, 10-12 repetitions, 70% of the one-repetition maximum (1-RM)) or ERT (n = 16; 2 sets, 25-30 repetitions, 40% 1-RM). In addition, all patients participated in aerobic exercise training (AET; 1 hour/day on 2 non-consecutive days/week; cycle ergometer; 70% of heart rate reserve).

RESULTS

After eight weeks of intervention, there were time but not group effects for reduced glucose and fructosamine levels, weight, BMI, waist circumference, subcutaneous abdominal fat, resting heart rate, systolic and diastolic blood pressure; muscle mass of the arms and physical exercise capacity increased significantly. Significant time and group effects were documented for maximum strength of the chest, with a greater increase for HRT than ERT (p = 0.01).

CONCLUSIONS

Specific maximal resistance training of the chest muscles led to superior gain in strength as compared to endurance resistance training. This, however, did not translate into superior values of glycaemic control, weight, waist circumference, muscle mass and physical work capacity, which all improved significantly by a similar magnitude in both groups. Since overall effects of both protocols were comparable, both may be offered to patients according to their personal preference.

Effects of streptozotocin-induced diabetes and physical training on gene expression of extracellular matrix proteins in mouse skeletal muscle

Diabetes induces changes in the structure and function of the extracellular matrix (ECM) in many tissues. We investigated the effects of diabetes, physical training, and their combination on the gene expression of ECM proteins in skeletal muscle. Mice were divided to control (C), training (T), streptozotocin-induced diabetic (D), and diabetic training (DT) groups. Training groups (T, DT) performed 1, 3, or 5 wk of endurance training on a treadmill. Gene expression of calf muscles was analyzed using microarray and quantitative PCR. Training group samples were collected 24 h after the last training session. Diabetes affected the gene expression of several collagens (types I, III, IV, V, VI, and XV), some noncollagenous glycoproteins, and proteoglycans (e.g., elastin, thrombospondin-1, laminin-2, decorin). Reduced gene expression of collagens in diabetic skeletal muscle was partially attenuated as a result of physical training. In diabetes, mRNA expression of the basement membrane (BM) collagens decreased and that of noncollagenous glycoproteins increased. This may change the structure of the BM in a less collagenous direction and affect its properties.

Influences of aging and caloric restriction on the transcriptional profile of skeletal muscle from rhesus monkeys

In laboratory rodents, caloric restriction (CR) retards several age-dependent physiological and biochemical changes in skeletal muscle, including increased steady-state levels of oxidative damage to lipids, DNA, and proteins. We have previously used high-density oligonucleotide arrays to show that CR can prevent or delay most of the major age-related transcriptional alterations in the gastrocnemius muscle of C57BL/6 mice. Here we report the effects of aging and adult-onset CR on the gene expression profile of 7,070 genes in the vastus lateralis muscle from rhesus monkeys. Gene expression analysis of aged rhesus monkeys (mean age of 26 years) was compared with that of young animals (mean age of 8 years). Aging resulted in a selective up-regulation of transcripts involved in inflammation and oxidative stress, and a down-regulation of genes involved in mitochondrial electron transport and oxidative phosphorylation. Middle-aged monkeys (mean age of 20 years) subjected to CR since early adulthood (mean age of 11 years) were studied to determine the gene expression profile induced by CR. CR resulted in an up-regulation of cytoskeletal protein-encoding genes, and also a decrease in the expression of genes involved in mitochondrial bioenergetics. Surprisingly, we did not observe any evidence for an inhibitory effect of adult-onset CR on age-related changes in gene expression. These results indicate that the induction of an oxidative stress-induced transcriptional response may be a common feature of aging in skeletal muscle of rodents and primates, but the extent to which CR modifies these responses may be species-specific.