No abstract

Structural changes within the human retinal vasculature may reflect systemic vascular changes associated with various cardiovascular and metabolic disorders. Recent data suggest that systemic exposure from a range of modifiable lifestyle and environmental risk factors (e.g., diet, physical activity, and smoking) may affect the morphology of the retinal vasculature. Being easily accessible and non-invasively visualized, the retinal microvasculature therefore can be a clinically useful biomarker of reversible sub-clinical physiologic deviation of the systemic circulation as results of such unfavorable exposures. Importantly, quantitative analysis of the retinal microvasculature may be utilized as a prognostic tool, allowing for targeted vascular therapies before the onset of overt cardiovascular and metabolic disorders. This review summarizes the modifiable lifestyle and environmental risk factors that affect retinal microvascular structure and the possible clinical implications of such relationships.

Aims/hypothesis: Basal plasma concentration of asymmetric dimethylarginine (ADMA), an endogenous, competitive inhibitor of nitric oxide synthase, is elevated in patients with type 2 diabetes. ADMA may contribute to the endothelial dysfunction and associated vascular complications observed in individuals with type 2 diabetes. The present study investigated the effect of 12 weeks of supervised walking exercise on plasma ADMA concentration in women aged 65-74 years with type 2 diabetes. Materials and methods:Fourteen women (aged 69 ± 3 yrs) with uncomplicated type 2 diabetes, completed 12 weeks of supervised, moderate-intensity walking at an intensity equivalent to their individual gas-exchange threshold. Blood was sampled for ADMA concentration before and after a 6-week intervention-free control period, and again after 6 and 12 weeks of exercise training.Results: Plasma ADMA concentration was found to be significantly lower after 12-weeks of exercise training when compared with baseline (0 wk) measurements. These results were accompanied by significant increases in time to exhaustion, relative and absolute peak oxygen uptake, and oxygen uptake at gas-exchange threshold. Conclusion/interpretation:Regular, moderate-intensity exercise decreases circulating ADMA concentrations in older women with type 2 diabetes. These results suggest that ADMA may play a role in the training-induced reduction in cardiovascular disease risk seen with exercise training in individuals with type 2 Diabetes.

Improved plasma inflammatory profile and decreased plasma fibrinogen concentration is induced by regular walking, independent of glycaemic control. These factors may mediate the improved haemorheology associated with exercise training in metabolic disorders.

Type 2 diabetes accelerates and exacerbates the age-related decline in heart rate variability (HRV) and impairment of hemorheology. While exercise training is one of the cornerstone therapies for managing type 2 diabetes, little is known about the optimum dose of exercise training for the improvement of HRV and/or hemorheology. PURPOSE:To investigate HRV and hemorheology adaptations to 12 wk of varied-dose treadmill walking in women aged 65-74 yr with type 2 diabetes. METHODS:Fifteen subjects with uncomplicated type 2 diabetes (Age: 69 ± 2 yr; BMI: 30 ± 5 kg·m-2; VO2peak: 20.3 ± 3.1 ml·kg -1 ·min -1 ) were randomly allocated into two exercise training groups (Group 1: 2 x 60 min·wk -1 or Group 2: 4 x 30 min·wk -1 ). The exercise program was 12 wk and the exercise intensity was set and adjusted every 6 wk to equal 100% of each individual's gas-exchange threshold. Time domain indices of HRV included i. the standard deviation of RR intervals (SDNN) ii. the square root of the mean of squared differences between successive intervals (RMSSD). Frequency domain indices of HRV included: log-transformed low and high frequency (lnLF and lnHF, respectively) power. Red blood cell (RBC) aggregation was measured in plasma and a standard aggregating solution (3% dextran 70 kDa), and RBC deformability was determined via ektacytometry. Dependent variables were measured before (wk -6 and 0), during (wk 6) and after (wk 12) the walking program. RESULTS:Twelve weeks of exercise training significantly improved VO2peak, time to exhaustion, and the gas-exchange threshold (p < 0.05), independent of exercise group. While exercise training did not improve glycemic control, high-density lipoprotein concentration increased by 7.5% for both groups (p = 0.01). Exercise training reduced RBC aggregation in plasma by -6.6% and in dextran-70 by -12.2% (p < 0.05), and improved RBC deformability by 3.4% (p < 0.05) for both groups. No change in HRV was observed for Group 1, whereas SDNN, RMSSD and lnHF power were improved in Group 2 (p < 0.05). (No relationships reported)PURPOSE: To investigate the feasibility of administering testosterone therapy as an adjunct to exercise rehabilitation in elderly hypogonadal males with stable chronic heart failure. Secondly, to obtain preliminary data on the impact of testosterone supplementation on important health outcomes. METHODS:Patients (N=40) were randomly allocated to a testosterone (T) or a placebo group (P) before engaging in a twice-weekly program of aerobic/resistance exercise for 12 weeks. RESULTS: Patient attrition was 30% but 28 patients attended all 24 exercise sessions and received all six fortnightly injections of T or P. Analysis of Covariance (ANCOVA), using baseline value as a covariate, indicated similar mean±SE improvements in peak aerobic capacity (15.3±1.2 vs 17.9±1.2 and 17.1±0.9 vs 19.2±0.9 ml·kg·min -1 ; P=0.84) and grip strength (39.2±2.4 vs 42.3±2.1 and 43.8±2.0 and 45.2±2.5 kg; P=0.38) for T and P, respectively, whereas greater reductions in body weight (P=0.04) and body mass index (P...