Improving glucose tolerance by muscle-damaging exercise

Abstract

Tissue damage is regarded as an unwanted medical condition to be avoided. However, introducing tolerable tissue damages has been used as a therapeutic intervention in traditional and complementary medicine to cure discomfort and illness. Eccentric exercise is known to cause significant necrosis and insulin resistance of skeletal muscle. The purpose of this study was to determine the magnitude of muscle damage and blood glucose responses during an oral glucose tolerance test (OGTT) after eccentric training in 21 young participants. They were challenged by 5 times of 100-meter downhill sprinting and 20 times of squats training at 30 pounds weight load for 3 days, which resulted in a wide spectrum of muscle creatine kinase (CK) surges in plasma, 48 h after the last bout of exercise. Participants were then divided into two groups according the magnitude of CK increases (low CK: +48% ± 0.3; high CK: +137% ± 0.5, P < 0.05). Both groups show comparable decreases in blood glucose levels in OGTT, suggesting that this muscle-damaging exercise does not appear to decrease but rather improve glycemic control in men. Conclusion: The result of the study rejects the hypothesis that eccentric exercise decreases glucose tolerance. Improved glucose tolerance with CK increase implicates a beneficial effect of replacing metabolically weaker muscle fibers by eccentric exercise in Darwinian natural selection fashion.

Slow-velocity eccentric-only resistance training improves symptoms of type 2 diabetic mellitus patients by regulating plasma MMP-2 and -9

“…These findings indicated that slow-velocity eccentric-only resistance training improved glucose-related indicators and enhanced insulin sensitivity in T2DM patients. These results aligned with previous research conducted by Ho et al [12] However, slow-velocity eccentric-only resistance training may have limited effectiveness in improving lipid-related indicators (lipid control level) in T2DM patients. This study suggested that the unique slow-velocity eccentric-only resistance training model may have less effect on lipid interventions.…”

“…[3,8,9] Members of the matrix metalloproteinases (MMPs) family, especially MMP-2 and -9, play a very important role in skeletal muscle ECM homeostasis [10,11] due to their ability to degrade skeletal muscle ECM collagen fibrillar proteins. [12] Many findings believe that the correlation between insulin resistance in skeletal muscle and collagen fiber deposition in ECM is attributable to the dysregulated expression of MMPs. Exercise is a universally accepted component of the nonpharmacologic treatment for T2DM.…”

“…[15] Another study showed that eccentric contraction training increased skeletal muscle MMPs expression more compared to concentric contraction training, [16] which may promote skeletal muscle ECM remodeling [17] and improve skeletal muscle insulin sensitivity. [12] Currently, although a large number of studies have shown that resistance training improves T2DM, few studies have been reported on the effects of eccentric training on people with T2DM [18] and its mechanisms. In this study, we investigated the feasibility and mechanism of slow-velocity eccentric-only resistance training on T2DM based on the results of insulin-resistant ECM collagen deposition in skeletal muscle with T2DM and the remodeling effect of eccentric training on skeletal muscle based on the role of MMP-2 and -9 in regulating extracellular matrix homeostasis.…”