Training-induced adaptations in muscle morphology, including their magnitude and individual variation, remain relatively unknown in elite athletes. We reported changes in rowing performance and muscle morphology during the general and competitive preparation phases in elite rowers. Nineteen female rowers completed 8 weeks of general preparation, including concurrent endurance and high-load resistance training (HLRT). Seven rowers were monitored during a subsequent 16 weeks of competitive preparation, including concurrent endurance and resistance training with additional plyometric loading (APL). Vastus lateralis muscle volume, physiological cross-sectional area (PCSA), fascicle length, and pennation angle were measured using 3D ultrasonography. Rowing ergometer power output was measured as mean power in the final 4 minutes of an incremental test. Rowing ergometer power output improved during general preparation [+2 ± 2%, effect size (ES) = 0.22, P = 0.004], while fascicle length decreased (−5 ± 8%, ES = −0.47, P = 0.020). Rowing power output further improved during competitive preparation (+5 ± 3%, ES = 0.52, P = 0.010). Here, morphological adaptations were not significant, but demonstrated large ESs for fascicle length (+13 ± 19%, ES = 0.93), medium for pennation angle (−9 ± 15%, ES = −0.71), and small for muscle volume (+8 ± 13%, ES = 0.32). Importantly, rowers showed large individual differences in their training-induced muscle adaptations. In conclusion, vastus lateralis muscles of elite female athletes are highly adaptive to specific training stimuli, and adaptations largely differ between individual athletes. Therefore, coaches are encouraged to closely monitor their athletes' individual (muscle) adaptations to better evaluate the effectiveness of their training programs and finetune them to the athlete's individual needs.
Background and Purpose: Decreased muscle mass and muscle strength are independent predictors of poor postoperative recov- ery in patients with esophageal cancer. If there is an association between muscle mass and muscle strength, physiotherapists are able to measure muscle strength as an early predictor for poor postoperative recovery due to decreased muscle mass. Therefore, in this cross-sectional study, we aimed to investigate the association between muscle mass and muscle strength in predominantly older patients with esophageal cancer awaiting esophagectomy prior to neoadjuvant chemoradiation. Methods: In patients with resectable esophageal cancer eligible for surgery between March 2012 and October 2015, we used computed tomographic scans to assess muscle mass and compared them with muscle strength measures (hand- grip strength, inspiratory and expiratory muscle strength, 30 seconds chair stands test). We calculated Pearson correla- tion coefficients and determined associations by multivariate linear regression analysis. Results and Discussion: A tertiary referral center referred 125 individuals to physiotherapy who were eligible for the study; we finally included 93 individuals for statistical analysis. Mul- tiple backward regression analysis showed that gender (95% confidence interval [CI], 2.05-33.82), weight (95% CI, 0.39- 1.02), age (95% CI, −0.91 to −0.04), left handgrip strength (95% CI, 0.14-1.44), and inspiratory muscle strength (95% CI, 0.08-0.38) were all independently associated with muscle surface area at L3. All these variables together explained 66% of the variability (R2) in muscle surface area at L3 (P < .01). Conclusions: This study shows an independent association between aspects of muscle strength and muscle mass in patients with esophageal cancer awaiting surgery, and phys- iotherapists could use the results to predict muscle mass on the basis of muscle strength in preoperative patients with esophageal cancer.
Skeletal muscle-related symptoms are common in both acute coronavirus disease (Covid)-19 and post-acute sequelae of Covid-19 (PASC). In this narrative review, we discuss cellular and molecular pathways that are affected and consider these in regard to skeletal muscle involvement in other conditions, such as acute respiratory distress syndrome, critical illness myopathy, and post-viral fatigue syndrome. Patients with severe Covid-19 and PASC suffer from skeletal muscle weakness and exercise intolerance. Histological sections present muscle fibre atrophy, metabolic alterations, and immune cell infiltration. Contributing factors to weakness and fatigue in patients with severe Covid-19 include systemic inflammation, disuse, hypoxaemia, and malnutrition. These factors also contribute to post-intensive care unit (ICU) syndrome and ICU-acquired weakness and likely explain a substantial part of Covid-19-acquired weakness. The skeletal muscle weakness and exercise intolerance associated with PASC are more obscure. Direct severe acute respiratory syndrome coronavirus (SARS-CoV)-2 viral infiltration into skeletal muscle or an aberrant immune system likely contribute. Similarities between skeletal muscle alterations in PASC and chronic fatigue syndrome deserve further study. Both SARS-CoV-2-specific factors and generic consequences of acute disease likely underlie the observed skeletal muscle alterations in both acute Covid-19 and PASC.
