28.6. Weight reduction and exercise training improve glucose metabolism

Public examination of a doctoral dissertation in the field of exercise medicine

Doctoral candidate: MHSc Mika Venojärvi

Time and venue: 28.6.2011 at 12 noon, Mediteknia Auditorium, Kuopio Campus

The prevalence of type 2 diabetes is rapidly increasing worldwide, and yet its primary prevention and treatment are still a challenge. However, there is a great amount of evidence of the risk factors such as obesity and physical inactivity that are the main nongenetic determinants of the disease. Lifestyle interventions, including diet and physical exercise, can result in a reduction of around 50–60% in diabetes incidence and the beneficial effect persists even after the individual lifestyle counselling has stopped. Short‐term randomized studies have confirmed that physical training based on endurance and/or resistance exercises can also improve blood glucose control in type 2 diabetics.

The aim of this study was to clarify the role of exercise training with dietary counselling on heat shock proteins, adipokines and glucose metabolism in middle‐aged subjects with impaired glucose tolerance. Additionally, in rats we tested the hypothesis that a stronger, non‐damaging, metabolic stress may provide greater tissue protection against atrophic and degenerative changes after immobilization.

Both spontaneous physical activity and intensive exercise increased the HSP60 and HSP72 expressions in the lateral gastrocnemius muscle in rats. Similarly, in the subjects with impaired glucose tolerance (IGT), cytoprotection was improved in the skeletal muscle tissue, as shown by increased expression of mitochondrial HSP60 and GRP75 after exercise‐diet intervention. Moreover, oxidative stress was reduced as shown by decreased serum levels of uric acid and protein carbonyls in the IGT subjects after exercise‐diet intervention.

This study has shown that after the intervention period, the amount of glycogen synthase kinase‐3‐αβ (GSK‐3‐αβ) protein decreased and GSK‐ß contents tended to decrease in the IGT subjects who had proportionately more MHC II isoforms in their skeletal muscle. This is a novel finding, suggesting a metabolic pathway that is sensitive to exercise and dietary intervention. Significant weight reduction and improved aerobic capacity was achieved in responders. These improvements led up to restoration of insulin sensitivity and increased circulating adiponectin and decreased leptin levels without changes in skeletal muscle GLUT‐4 expressions or cholesterol metabolism in responders. In the non‐responders without weight reduction no changes took place.

In conclusion, this study provides new evidences on the vulnerability of the subjects to impaired glucose tolerance and supports promotion of weight reduction and long‐term exercise training to improve insulin sensitivity in skeletal muscle.

The doctoral dissertation of Master of Health Sciences Mika Venojärvi, entitled Roles of exercise training with dietary counselling and muscle fibre composition in the regulation of glucose metabolism in middle-aged subjects with impaired glucose tolerance will be examined at the Faculty of Health Sciences. The opponent in the public examination will be Professor Shuzo Kumagai of the University of Kyushu, Japan, and the custos will be Professor Emeritus Osmo Hänninen of the University of Eastern Finland.

 

Photo available for download at http://www.uef.fi/vaitoskuvat

 

Contact: Mika Venojärvi, mika.venojarvi@turkuamk.fi, GSM 044 907 5479

Publishing year: 2011

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