The effect of two exercise modalities on skeletal muscle capillary ultrastructure in individuals with type 2 diabetes.

Type 2 diabetes is associated with microvascular dysfunction, but little is known about how capillary ultrastructure is affected by exercise training. To investigate the effect of two types of exercise training on skeletal muscle capillary ultrastructure and capillarization in individuals with type 2 diabetes, 21 individuals with type 2 diabetes were allocated (randomized controlled trial) to 11 weeks of aerobic exercise training consisting of either moderate-intensity endurance training (END; n = 10) or low-volume high-intensity interval training (HIIT; n = 11). Skeletal muscle biopsies (m vastus lateralis) were obtained before and after the training intervention. At baseline, there was no difference in capillarization, capillary structure, and exercise hyperemia between the two groups. After the training intervention, capillary-to-fiber ratio increased by 8% ± 3% in the END group (P < 0.05) and was unchanged in the HIIT group with no difference between groups. Endothelium thickness increased (P < 0.05), basement membrane thickness decreased (P < 0.05), and the capillary lumen tended (P = 0.07) to increase in the END group, whereas these structural indicators were unchanged after HIIT. In contrast, skeletal muscle endothelial nitric oxide synthase (eNOS) increased after HIIT (P < 0.05), but not END, whereas there was no change in vascular endothelial growth factor (VEGF), superoxide dismutase (SOD)-2, or NADPH oxidase after both training protocols. In contrast to END training, HIIT did not alter capillarization or capillary structure in individuals with type 2 diabetes. In conclusion, HIIT appears to be a less effective strategy to treat capillary rarefaction and reduce basement thickening in type 2 diabetes.

Resveratrol blunts the positive effects of exercise training on cardiovascular health in aged men.

Ageing is thought to be associated with decreased vascular function partly due to oxidative stress. Resveratrol is a polyphenol, which in animal studies has been shown to decrease atherosclerosis, and improve cardiovascular health and physical capacity, in part through its effects on Sirtuin 1 signalling and through an improved antioxidant capacity. We tested the hypothesis that resveratrol supplementation enhances training-induced improvements in cardiovascular health parameters in aged men. Twenty-seven healthy physically inactive aged men (age: 65 ± 1 years; body mass index: 25.4 ± 0.7 kg m(-2); mean arterial pressure (MAP): 95.8 ± 2.2 mmHg; maximal oxygen uptake: 2488 ± 72 ml O2 min(-1)) were randomized into 8 weeks of either daily intake of either 250 mg trans-resveratrol (n = 14) or of placebo (n = 13) concomitant with high-intensity exercise training. Exercise training led to a 45% greater (P < 0.05) increase in maximal oxygen uptake in the placebo group than in the resveratrol group and to a decrease in MAP in the placebo group only (-4.8 ± 1.7 mmHg; P < 0.05). The interstitial level of vasodilator prostacyclin was lower in the resveratrol than in the placebo group after training (980 ± 90 vs. 1174 ± 121 pg ml(-1); P < 0.02) and muscle thromboxane synthase was higher in the resveratrol group after training (P < 0.05). Resveratrol administration also abolished the positive effects of exercise on low-density lipoprotein, total cholesterol/high-density lipoprotein ratio and triglyceride concentrations in blood (P < 0.05). Resveratrol did not alter the effect of exercise training on the atherosclerosis marker vascular cell adhesion molecule 1 (VCAM-1). Sirtuin 1 protein levels were not affected by resveratrol supplementation. These findings indicate that, whereas exercise training effectively improves several cardiovascular health parameters in aged men, concomitant resveratrol supplementation can blunt these effects.

Comparative Effectiveness of Low-Volume Time-Efficient Resistance Training Versus Endurance Training in Patients With Heart Failure.

PURPOSE: Cardiorespiratory fitness is positively related to heart failure (HF) prognosis, but lack of time and low energy are barriers for adherence to exercise. We, therefore, compared the effect of low-volume time-based resistance exercise training (TRE) with aerobic moderate-intensity cycling (AMC) on maximal and submaximal exercise capacity, health-related quality of life, and vascular function. METHODS: Twenty-eight HF patients (New York Heart Association class I-II) performed AMC (n = 14) or TRE (n = 14). Maximal and submaximal exercise capacity, health-related quality of life, and vascular function were evaluated before and after a 6-wk training intervention with 3 training sessions per week. The AMC group and the TRE group trained for 45 and 25 min per training session, respectively. During the training sessions, the TRE and AMC groups trained at 60 ± 4% and 59 ± 2% (mean ± standard deviation) of (Equation is included in full-text article.)O2peak, respectively. RESULTS: The energy expenditure was significantly greater in AMC than in TRE (P < .05). The (Equation is included in full-text article.)O2peak and Wattpeak increased in AMC group (P < .001) and TRE group (P = .001), with no differences between groups. Six-minute walk distance also increased in both groups (AMC, P = .006 and TRE, P = .036), with no difference between groups. Health-related quality of life improved equally in the 2 groups, whereas vascular function did not change in either group. CONCLUSION: These results demonstrate that AMC and TRE equally improved exercise capacity and health-related quality of life in lower New York Heart Association-stage HF patients, despite less time required as well as lower energy expenditure during TRE than during AMC. Therefore, TRE might represent a time-efficient exercise modality for improving adherence to exercise in patients with class I-II HF.

Effect of endurance versus resistance training on quadriceps muscle dysfunction in COPD: a pilot study.

INTRODUCTION: Exercise is an important countermeasure to limb muscle dysfunction in COPD. The two major training modalities in COPD rehabilitation, endurance training (ET) and resistance training (RT), may both be efficient in improving muscle strength, exercise capacity, and health-related quality of life, but the effects on quadriceps muscle characteristics have not been thoroughly described. METHODS: Thirty COPD patients (forced expiratory volume in 1 second: 56% of predicted, standard deviation [SD] 14) were randomized to 8 weeks of ET or RT. Vastus lateralis muscle biopsies were obtained before and after the training intervention to assess muscle morphology and metabolic and angiogenic factors. Symptom burden, exercise capacity (6-minute walking and cycle ergometer tests), and vascular function were also assessed. RESULTS: Both training modalities improved symptom burden and exercise capacity with no difference between the two groups. The mean (SD) proportion of glycolytic type IIa muscle fibers was reduced after ET (from 48% [SD 11] to 42% [SD 10], P<0.05), whereas there was no significant change in muscle fiber distribution with RT. There was no effect of either training modality on muscle capillarization, angiogenic factors, or vascular function. After ET the muscle protein content of phosphofructokinase was reduced (P<0.05) and the citrate synthase content tended increase (P=0.08) but no change was observed after RT. CONCLUSION: Although both ET and RT improve symptoms and exercise capacity, ET induces a more oxidative quadriceps muscle phenotype, counteracting muscle dysfunction in COPD.