Strength Training Increases Insulin-Mediated Glucose Uptake, GLUT4 Content, and Insulin Signaling in Skeletal Muscle in Patients With Type 2 Diabetes

Abstract

Strength training represents an alternative to endurance training for patients with type 2 diabetes. Little is known about the effect on insulin action and key proteins in skeletal muscle, and the necessary volume of strength training is unknown. A total of 10 type 2 diabetic subjects and 7 healthy men (control subjects) strength-trained one leg three times per week for 6 weeks while the other leg remained untrained. Each session lasted no more than 30 min. After strength training, muscle biopsies were obtained, and an isoglycemic-hyperinsulinemic clamp combined with arteriofemoral venous catheterization of both legs was carried out. In general, qualitatively similar responses were obtained in both groups. During the clamp, leg blood flow was higher (P < 0.05) in trained versus untrained legs, but despite this, arterio-venous extraction glucose did not decrease in trained legs. Thus, leg glucose clearance was increased in trained legs (P < 0.05) and more than explained by increases in muscle mass. Strength training increased protein content of GLUT4, insulin receptor, protein kinase B-␣/␤, glycogen synthase (GS), and GS total activity. In conclusion, we found that strength training for 30 min three times per week increases insulin action in skeletal muscle in both groups. The adaptation is attributable to local contraction-mediated mechanisms involving key proteins in the insulin signaling cascade. Diabetes 53: 294 -305, 2004 I t is an established finding that aerobic endurance training increases insulin action in patients with type 2 diabetes (1-9), and also that the effect of training is predominantly located to the skeletal muscle (10). Glycemic control also improves along with training (11). Furthermore, with the increased insulin action, the need for insulin to mediate the clearance of a given amount of glucose is lessened. Thus, the need for exogenous insulin or oral hypoglycemic agents is decreased (12). Apart from the beneficial effects on glucose metabolism, physical training also exerts marked improvement on most of the components of the metabolic syndrome (13).Despite the scientific evidence of the therapeutic effect of exercise training, it is a well-known clinical experience that it is often very difficult to engage the patients into taking exercise on a regular basis, and even if one succeeds, the adherence is disappointing. The majority of patients with type 2 diabetes are overweight and have usually been sedentary for the major part of their lives. For many reasons, both psychological and sociological, they are not likely to take up endurance training. Obesity may even be a physical problem in the performance of exercise, especially endurance-type exercises.For patients with type 2 diabetes, resistance training probably represents an attractive exercise modality, but little is known about the overall effect, and the effect in muscle has not been studied. Furthermore, dose-response studies on resistance training effects have not been carried out. To provide support for the recommendations about...

Heterogeneity in limb fatty acid kinetics in type 2 diabetes

“…Physical inactivity or muscle disuse is linked to the development of insulin resistance and type 2 diabetes [12,13], whereas exercise training can reduce insulin resistance [14,15]. The present findings of a marked difference in limb palmitate kinetics between arm and leg might be interpreted from the perspective of a different activity pattern between the two extremities.…”

“…Physical inactivity or muscle disuse is recognised as one of the risk factors for the development of insulin resistance and type 2 diabetes [12,13]. Against this, it has been shown that exercise training can reduce insulin resistance in the leg of diabetic patients [14,15]. Recently, evidence has been presented for heterogeneity towards lipolysis in human skeletal muscles [16].…”

Long-standing, insulin-treated type 2 diabetes patients with complications respond well to short-term resistance and interval exercise training

“…Previous resistance-type exercise intervention studies in uncomplicated T2D patients have applied higher-intensity exercise and reported strength increases between 25 and 75% (29,(56)(57)(58)(59)(60). Some of these intervention studies report significant improvements in HbA 1c (56,57), and glucose area under the curve (58,61).…”

Effect of exercise training on neuromuscular function of elbow flexors and knee extensors of type 2 diabetic patients

“…Resistance training in particular has been seen to improve both muscle strength and 20 mass as well as insulin sensitivity (Brooks et al, 2007;Cauza et al, 2005;Dunstan et 21 al., 2002;Holten et al, 2004;LeBrasseur et al, 2011;Mann et al, 2014). For these 22 reasons, it may be desirable that type 2 diabetes patients would begin an appropriate 23 exercise training program as soon as possible after diagnosis to prevent, or at least 24 limit, the decline in neuromuscular function.…”