No abstract

Eccentric ergometer training (EET) is increasingly being proposed as a therapeutic strategy to improve skeletal muscle strength in various cardiorespiratory diseases, due to the principle that lengthening muscle actions lead to high force-generating capacity at low cardiopulmonary load. One clinical population that may particularly benefit from this strategy is chronic obstructive pulmonary disease (COPD), as ventilatory constraints and locomotor muscle dysfunction often limit efficacy of conventional exercise rehabilitation in patients with severe disease. While the feasibility of EET for COPD has been established, the nature and extent of adaptation within COPD muscle is unknown. The aim of this study was therefore to characterize the locomotor muscle adaptations to EET in patients with severe COPD, and compare them with adaptations gained through conventional concentric ergometer training (CET). Male patients were randomized to either EET (n = 8) or CET (n = 7) for 10 weeks and matched for heart rate intensity. EET patients trained on average at a workload that was three times that of CET, at a lower perception of leg fatigue and dyspnea. EET led to increases in isometric peak strength and relative thigh mass (p < 0.01) whereas CET had no such effect. However, EET did not result in fiber hypertrophy, as morphometric analysis of muscle biopsies showed no increase in mean fiber cross-sectional area (p = 0.82), with variability in the direction and magnitude of fiber-type responses (20% increase in Type 1, p = 0.18; 4% decrease in Type 2a, p = 0.37) compared to CET (26% increase in Type 1, p = 0.04; 15% increase in Type 2a, p = 0.09). EET had no impact on mitochondrial adaptation, as revealed by lack of change in markers of mitochondrial biogenesis, content and respiration, which contrasted to improvements (p < 0.05) within CET muscle. While future study is needed to more definitively determine the effects of EET on fiber hypertrophy and associated underlying molecular signaling pathways in COPD locomotor muscle, our findings promote the implementation of this strategy to improve muscle strength. Furthermore, contrasting mitochondrial adaptations suggest evaluation of a sequential paradigm of eccentric followed by concentric cycling as a means of augmenting the training response and attenuating skeletal muscle dysfunction in patients with advanced COPD.

Results demonstrate associations between MVPA and high sitting time and weight loss outcomes among bariatric patients in the long term. The implications for long-term weight management and concomitant health outcomes highlight the need for appropriate follow-up and interventions in this unique high-risk patient population.

Objective: To evaluate the precision of the iDXA for total body composition and fat distribution measurements in severely obese patients. Design and Methods: Sixty-five severely obese participants with a mean age of 46 6 11years, BMI of 49 6 6 kg/m 2 , and a mean body mass of 137.3 6 20.9 kg took part in this investigation. Two consecutive iDXA scans with repositioning of the total body were conducted for each participant. The coefficient of variation (CV), the root-mean-square (RMS) averages of standard deviations of repeated measurements, the corresponding 95% least significant change, and Intraclass Correlations (ICC) were calculated. Results: Precision expressed as % CV, for total body bone mineral content, fat free mass, total body fat, total body lean, and % total body fat were 1.08%, 0.94%, 0.90%, 1.00%, 0.79%, respectively. Precision was 1.44% for gynoid fat distribution and 1.64% for android fat (AF) distribution. The ICCs in all DXA measurements were 0.99 with % AF having the lowest at 0.96. Conclusions:The GE Lunar iDXA TM demonstrated excellent precision for total body composition assessments and is the first study to assess reproducibility in severely obese individuals.

This study demonstrated that physical exertion can increase postural sway in hemiparetic participants which could possibly lead to an increased risk of falling in these individuals.