Muscular Atrophy

Rotator cuff disorders are among the most frequent musculoskeletal causes of shoulder pain, weakness, and limited movement. In many individuals with rotator cuff disease, the damaged muscles gradually shrink (muscle atrophy) and become replaced by fat tissue (fatty infiltration), particularly involving the supraspinatus and infraspinatus muscles. These structural changes can impair shoulder function, reduce the likelihood of successful tendon repair surgery, and increase the risk of recurrent tears. Magnetic resonance imaging (MRI) is the established standard for assessing rotator cuff muscle health, but it is expensive, time-consuming, and not suitable for all individuals. Musculoskeletal ultrasound offers an accessible, real-time alternative, and shear wave elastography (SWE) adds the capability to quantitatively measure tissue stiffness. The purpose of this study is to evaluate the diagnostic accuracy and validity of combining conventional ultrasound with shear wave elastography to assess rotator cuff muscle quality, specifically fatty infiltration and muscle atrophy, in comparison with reference MRI or CT scans. Participants aged 18 years or older with suspected rotator cuff disorders who have had a qualifying shoulder MRI or CT scan within the previous 12 months will undergo an ultrasound and shear wave elastography examination of the affected shoulder. Researchers will calculate shear wave velocity and muscle occupation ratios to assess muscle stiffness and volume, and compare these results to validated MRI grading scales (the Goutallier classification for fat infiltration and the Warner staging system for muscle atrophy).

The purpose of this study is to investigate the effects of a 12-week flexi band resistance training program compared to different whole-body electromyostimulation (WB-EMS) exercise programs on muscle strength, body composition (in particular muscle mass), cardiorespiratory fitness, inflammation, and patient-reported subjective outcomes (e.g. quality of life, fatigue, performance status) in patients with malignant disease undergoing curative or palliative anti-cancer treatment.

The goal of this intervention trial is to characterize skeletal muscle atrophy in healthy, young adults during short term bedrest. The main questions it aims to answer are: How much do skeletal muscle volume, strength, and fatigue resistance decline during bedrest? How much does whole-body insulin sensitivity change during bedrest? How do mitochondrial function and protein synthesis change during bedrest? Participants will undergo the following tests before and after a free-living control period and before and after a 5 day period of strict horizontal bedrest: * Magnetic resonance imaging of the thigh muscles * Strength testing of the thigh muscles * Insulin sensitivity testing in response to a mixed meal * Exogenous glucose oxidation in response to a mixed meal * Muscle biopsies from the thigh muscles * Blood samples

The primary aims of this study are to determine the effect of percussive massage (30 min/session, 2 sessions/day, daily) during 10 days of unilateral limb immobilization on preserving muscle, vascular, and mitochondrial function. The following hypotheses will be tested: Hypothesis 1: Percussive massage will attenuate the loss of size, strength and endurance over the immobilization period compared to the control group, as measured by MRI, maximal isometric and isokinetic force production and muscle endurance test using Biodex dynamometry. Hypothesis 2: Percussive massage will attenuate the loss of vascular function and blood flow compared to the control group as measured by passive leg movement and femoral artery blood flow. Hypothesis 3: Percussive massage will attenuate the loss of skeletal muscle mitochondrial function and decrease H2O2 production during immobilization compared to the control group, as measured by high-resolution respirometry.