Submitted to: Diabetes Care
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2006
Publication Date: 12/18/2006
Citation: Brooks, N.E., Layne, J.E., Gordon, P.L., Roubenoff, R., Nelson, M.E., Castaneda-Sceppa, C. 2006. Strength training improves muscle quality and insulin sensitivity in older Hispanics with type 2 diabetes. Diabetes Care. 4(1):19-27. Interpretive Summary: Hispanic individuals have a higher prevalence of diabetes. This leads to a greater incidence of disease and an increased risk of death. Muscle mass plays an important role in regulation of energy and of breakdown and usage of glucose, amino acids, and fat. Strength training is a good way to increase the size of skeletal muscle. However, there is not a large amount of scientific information about strength training in older diabetic individuals. Because of this, the objective of this study was to determine changes in strength, muscle size of skeletal muscle fibers, and insulin resistance after strength training. Sixty-two community dwelling Hispanic older adults (>55 y) with type 2 diabetes were enrolled in the study. These individuals were split into two groups: strength training plus standard of care (ST group) or standard of care only (CON group) for 16 weeks. Strength measurements, skeletal muscle samples and blood samples were taken at baseline and after 16 weeks. Muscle quality increased by 62% after 16 weeks of strength training compared with the control group. Skeletal muscle type I fiber increased by 21% in size and type II fibers by 19%. Insulin resistance was reduced by 25% in the ST group. There were also significant changes in free-fatty acids (decrease by 13%), C-reactive protein (decrease by 20%) and adiponectin (increase by 28%) with strength training as compared to control subjects. Thus, we conclude that 16 weeks of strength training improves muscle quality and fiber size as well as various blood measures of the health status of Hispanic older adults with diabetes, a high risk patient population.
Technical Abstract: Hispanics have an increased risk of morbidity and mortality due to their high prevalence of diabetes. Body composition, particularly skeletal muscle, plays an important role in glycemic control and lipid metabolism. Strength training is the most effective means to increase muscle mass but limited data on the effects of strength training in skeletal muscle of elderly diabetics is available. We determine the influence of strength training on insulin resistance, muscle quality and the role of skeletal muscle hypertrophy in metabolic control. Sixty-two community dwelling Hispanics (>55 y) with type 2 diabetes were randomized to 16 weeks of strength training plus standard care (ST group) or standard care (CON group). Skeletal muscle biopsies and biochemical measures were taken at baseline and after 16 weeks. The ST group show improved muscle quality (mean+/-SE: 26+/-3) vs CON (-4+/-2, p<0.0001) and increased type I (860+/-252mu m2) and type II fiber cross-sectional area (720+/-285mu m2) compared to CON (type I: -164+/-290mu m2, p=0.007; and type II: -130+/-336mu m2, p=0.04). This was accompanied by reduced insulin resistance (ST: median[range] -0.74[3.56] vs CON: 0.83[3.79], p=0.03); serum free-fatty-acids (ST: -84+/-30mu mol/L vs CON: 149+/-48mu mol/L, p<0.0001); and C-Reactive Protein (ST: -1.3[2.9]mg/L vs CON: 0.4[2.3]mg/L, p=0.05). Serum adiponectin increased with ST (1018ng/ml) compared to CON (-1162ng/ml, p<0.0001). Strength training improves muscle quality and the metabolic profile of a high risk population of older Hispanics with diabetes.