Nine months of combined training improves ex vivo skeletal muscle metabolism in individuals with type 2 diabetes

Context: Type 2 diabetes (T2D) has features of disordered lipid and glucose metabolism, due in part to reduced mitochondrial content. Objective: Our objective was to investigate effects of different types of exercise on mitochondrial content and substrate oxidation in individuals with T2D (ancillary study of the randomized controlled trial Health Benefits of Aerobic and Resistance Training in Individuals with Type 2 Diabetes, HART-D). Intervention: T2D individuals were randomized to aerobictraining (AT, n = 12), resistance training (RT, n = 18), combination training(ATRT, n = 12), or nonexercise control (n = 10). Blooddraws, peakoxygen consumption tests, dual-energy x-ray absorptiometry scans and muscle biopsies of vastus lateralis were performed before and after 9 months. Ex vivo substrate oxidations ((CO2)-C-14), mitochondrial content, and enzyme activities were measured. Glycated hemoglobin A(1c) and free fatty acids were also determined. Results: Mitochondrial content increased after RT and ATRT. Octanoate oxidation increased after AT and ATRT, whereas palmitate, pyruvate, and acetate oxidations increased in all exercise groups. Exercise-induced responses in mitochondrial DNA were associated with improvements in peak oxygen consumption, beta-hydroxyacyl-coenzyme A dehydrogenase activity, and palmitate oxidation. Conclusions: Nine months of AT and RT significantly improved most aspects of skeletal muscle mitochondrial content and substrate oxidation, whereas the combination improved all aspects. These exercise responses were associated with clinical improvements, indicating that long-term training, especially combination, is an effective lifestyle therapy for individuals with T2D by way of improving muscle substrate metabolism. (J Clin Endocrinol Metab 98: 1694-1702, 2013

Coronary artery calcification across ethnic groups in Singapore

Annals of the Academy of Medicine Singapore429432-436AAMS

Effect of Oral Creatine Supplementation on Single-Effort Sprint Performance in Elite Swimmers

Oral supplementation with creatine monohydrate (Cr.H2O) has been reported to increase muscle creatine phosphate levels. The aim of the present study was to determine the effect of such supplementation on performance of a single-effort sprint by elite swimmers. Thirty-two elite swimmers (M = 18, F = 14; age = 17-25 years) from the Australian Institute of Sport were tested on two occasions, 1 week apart. Tests performed were 25-m, 50-m, and 100-m maximal effort sprints (electronically timed with dive start, swimmers performing their best stroke), each with approximately 10 min active recovery. A 10-s maximal leg ergometry test was also undertaken. Swimmers were divided into two groups matched for sex, stroke/event, and sprint time over 50 m, and groups were randomly assigned to 5 days of Cr.H2O supplementation (4 · day-1 × 5 g Cr.H2O + 2 g sucrose, n = 16) or placebo (4 · day-1 × 5 g Polycose + 2 g sucrose, n = 16) prior to the second trial. Results revealed no significant differences between the group means for sprint times or between 10-s maximal leg ergometry power and work. This study does not support the hypothesis that creatine supplementation enhances single-effort sprint ability of elite swimmers.</p