Benjamin Smith

Skeletal muscle wasting is common and insidious in patients who receive maintenance hemodialysis treatment for the management of ESRD. The objective of this study was to determine whether 12 wk of high-intensity, progressive resistance training (PRT) administered during routine hemodialysis treatment could improve skeletal muscle quantity and quality versus usual care. Forty-nine patients (62.6 +/- 14.2 yr; 0.3 to 16.7 yr on dialysis) were recruited from the outpatient hemodialysis unit of the St. George Public Hospital (Sydney, Australia). Patients were randomized to PRT + usual care (n = 24) or usual care control only (n = 25). The PRT group performed two sets of 10 exercises at a high intensity (15 to 17/20 on the Borg Scale) using free weights, three times per week for 12 wk during routine hemodialysis treatment. Primary outcomes included thigh muscle quantity (cross-sectional area [CSA]) and quality (intramuscular lipid content via attenuation) evaluated by computed tomography scan. Secondary outcomes included muscle strength, exercise capacity, body circumference measures, proinflammatory cytokine C-reactive protein, and quality of life. There was no statistically significant difference in muscle CSA change between groups. However, there were statistically significant improvements in muscle attenuation, muscle strength, mid-thigh and mid-arm circumference, body weight, and C-reactive protein in the PRT group relative to the nonexercising control group. These findings suggest that patients with ESRD can improve skeletal muscle quality and derive other health-related adaptations solely by engaging in a 12-wk high-intensity PRT regimen during routine hemodialysis treatment sessions. Longer training durations or more sensitive analysis techniques may be required to document alterations in muscle CSA.

AIMS: Two-dimensional (2D) speckle echocardiography enables objective assessment of left ventricular function through the analysis of myocardial strain, which can be measured by different speckle-tracking software. The aim of this study was to compare two different commercially available cardiac ultrasound systems and their manufacturer-specific speckle-tacking software for the quantification of global myocardial strain in a healthy population. METHODS AND RESULTS: Twenty-eight healthy subjects (age: 38 +/- 12, 64% males) underwent two 2D echocardiograms within the same day using different cardiac ultrasound systems: Vivid 7 (GE Ultrasound, Horten, Norway) and Artida 4D (Toshiba Medical Systems). Standard apical and short-axis views of the left ventricle were obtained in each subject with a frame-rate range of 60 +/- 20 frames/s. Global longitudinal, radial, and circumferential strain values were analysed using their respective speckle-tracking software for Vivid (2D-strain EchoPac PC v.7.0.1, GE Healthcare, Horten, Norway) and Toshiba systems (2D Wall Motion Tracking, Toshiba Medical Systems). Global strain values were estimated from the average of regional left ventricular strain values. Agreement between the two systems and software was assessed by Bland-Altman method. Mean left ventricular ejection fraction was 59 +/- 7%. Global longitudinal, radial, and circumferential strain values were, respectively, -21.95 +/- 1.8, 46.97 +/- 5.5, and -23.18 +/- 3.3% when using 2D-strain EchoPac and -22.28 +/- 2.1, 40.74 +/- 4.3, and -27.17 +/- 4.7% when 2D Wall Motion Tracking was used (P = NS). Limits of agreement between both speckle-tracking software were narrower for global longitudinal strain (-2.25 to 3.65) than for radial and circumferential strain (-2.23 to 12.44 and -1.36 to 10.54, respectively). CONCLUSION: Two commercially available speckle-tracking software appear to be comparable when quantifying left ventricular function in a healthy population. Global longitudinal strain is a more robust parameter than radial and circumferential strain for the assessment of myocardial function when different cardiac ultrasound systems are used for analysis.