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BackgroundThe increasing age of coronary artery disease (CAD) patients and the occurrence of sarcopenia in the elderly population accompanied by 'fear of moving' and hospitalization in these patients often results in a substantial loss of skeletal muscle mass and muscle strength. Cardiac rehabilitation can improve exercise tolerance and muscle strength in CAD patients but less data describe eventual morphological muscular changes possibly by more difficult access to imaging techniques. Therefore the aim of this study is to assess and quantify the reliability and validity of an easy applicable method, the ultrasound (US) technique, to measure the diameter of rectus femoris muscle in comparison to the muscle dimensions measured with CT scans.Methods45 older CAD patients without cardiac event during the last 9 months were included in this study. 25 patients were tested twice with ultrasound with a two day interval to assess test-retest reliability and 20 patients were tested twice (once with US and once with CT) on the same day to assess the validity of the US technique compared to CT as the gold standard. Isometric and isokinetic muscle testing was performed to test potential zero-order correlations between muscle diameter, muscle volume and muscle force.ResultsAn intraclass correlation coefficient (ICC) of 0.97 ((95%CL: 0.92 - 0.99) was found for the test-retest reliability of US and the ICC computed between US and CT was 0.92 (95%CL: 0.81 - 0.97). The absolute difference between both techniques was 0.01 ± 0.12 cm (p = 0.66) resulting in a typical percentage error of 4.4%. Significant zero-order correlations were found between local muscle volume and muscle diameter assessed with CT (r = 0.67, p = 0.001) and assessed with US (r = 0.49, p < 0.05). Muscle strength parameters were also significantly correlated with muscle diameter assessed with both techniques (range r = 0.45-r = 0.61, p < 0.05).ConclusionsUltrasound imaging can be used as a valid and reliable measurement tool to assess the rectus femoris muscle diameter in older CAD patients.

This study compares the reliability and reproducibility of flow-mediated dilatation (FMD) and peripheral arterial tonometry (PAT) to assess endothelial function. Eighteen volunteers with coronary heart disease underwent simultaneous testing of FMD by means of brachial artery ultrasound scanning and PAT with the EndoPAT 2000. The subjects underwent both tests twice with an interval of 30 minutes and the same protocol was repeated 2 days later. The within-day variability was lower for the FMD measurements than for the PAT measurements (10% versus 18%; p < 0.05). The between-day variability was similar (11%). A significant correlation was found between PAT and FMD (r = 0.57, p < 0.001). The typical errors of measurements for FMD were lower than those for PAT. In conclusion, in this study, FMD demonstrated the best reliability for the within- and between-day and separate day measurements when compared to PAT.

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BackgroundIt is widely accepted that genetic variability might explain a large part of the observed heterogeneity in aerobic capacity and its response to training. Significant associations between polymorphisms of different genes with muscular strength, anaerobic phenotypes and body composition have been reported. Muscular endophenotypes are positively correlated with aerobic capacity, therefore, we tested the association of polymorphisms in twelve muscular related genes on aerobic capacity and its response to endurance training.Methods935 Coronary artery disease patients (CAD) who performed an incremental exercise test until exhaustion at baseline and after three months of training were included. Polymorphisms of the genes were detected using the invader assay. Genotype-phenotype association analyses were performed using ANCOVA. Different models for a genetic predisposition score (GPS) were constructed based on literature and own data and were related to baseline and response VO2 scores.ResultsCarriers of the minor allele in the R23K polymorphism of the glucocorticoid receptor gene (GR) and the ciliary neurotrophic factor gene (CNTF) had a significantly higher increase in peakVO2 after training (p < 0.05). Carriers of the minor allele (C34T) in the adenosine monophosphate deaminase (AMPD1) gene had a significantly lower relative increase (p < 0.05) in peakVO2. GPS of data driven models were significantly associated with the increase in peakVO2 after training.ConclusionsIn CAD patients, suggestive associations were found in the GR, CNTF and the AMPD1 gene with an improved change in aerobic capacity after three months of training. Additionally data driven models with a genetic predisposition score (GPS) showed a significant predictive value for the increase in peakVO2.

GPS for muscular phenotypes showed to be associated with baseline KES, muscle diameter, and the response to training in cardiac rehabilitation patients.

We aimed to investigate the effect of exercise on endothelium-dependent vasodilator function assessed simultaneously in the brachial artery and in the distal arterial bed by flow-mediated dilation and the pulse amplitude tonometry method, respectively, in coronary artery disease patients. The study included 146 patients with stable coronary artery disease (123 men, mean age 62 ± 9 years) who participated in the Cardiac Rehabilitation and Genetics of Exercise performance study. All patients completed a 12-week supervised cardiac rehabilitation programme (three sessions per week at an intensity of 80% of the heart rate reserve). At baseline and upon completion of the training, we measured brachial artery diameters by means of ultrasound scanning (linear array transducer of 12 MHz) and simultaneously assessed pulse amplitudes in the fingertip using a pulse amplitude tonometry device both at rest and after reactive hyperaemia induced by a 5-min forearm cuff occlusion. Peak oxygen uptake significantly increased (+22%; p < 0.0001) and flow-mediated dilation improved from 10.0% to 13.1% (+37%; p < 0.0001), whereas the reactive hyperaemia index of the pulse amplitude tonometry method remained unchanged (p = 0.47) following exercise-based cardiac rehabilitation. However, the basal digital pulse amplitude (+58%; p < 0.001) increased as a result of training, as did the digital pulse amplitude after reactive hyperaemia (+22%; p < 0.05). Exercise-based cardiac rehabilitation is associated with an improvement in endothelial function, as can be measured by flow-mediated dilation but not by the reactive hyperaemia index of the pulse amplitude tonometry method.

Knee extensor muscular endurance and its response after training are the strongest muscular predictors in explaining peakVO2 and its response in CAD patients.