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Pitman BM, Semmler JG. Reduced short-interval intracortical inhibition after eccentric muscle damage in human elbow flexor muscles. J Appl Physiol 113: 929 -936, 2012. First published July 26, 2012 doi:10.1152/japplphysiol.00361.2012.-The purpose of this study was to use paired-pulse transcranial magnetic stimulation (TMS) to examine the effect of eccentric exercise on short-interval intracortical inhibition (SICI) after damage to elbow flexor muscles. Nine young (22.5 Ϯ 0.6 yr; mean Ϯ SD) male subjects performed maximal eccentric exercise of the elbow flexor muscles until maximal voluntary contraction (MVC) force was reduced by ϳ40%. TMS was performed before, 2 h after, and 2 days after exercise under Rest and Active (5% MVC) conditions with motor-evoked potentials (MEPs) recorded from the biceps brachii (BB) muscle. Peripheral electrical stimulation of the brachial plexus was used to assess maximal Mwaves, and paired-pulse TMS with a 3-ms interstimulus interval was used to assess changes in SICI at each time point. The eccentric exercise resulted in a 34% decline in strength (P Ͻ 0.001), a 41% decline in resting M-wave (P ϭ 0.01), changes in resting elbow joint angle (10°, P Ͻ 0.001), and a shift in the optimal elbow joint angle for force production (18°, P Ͻ 0.05) 2 h after exercise. This was accompanied by impaired muscle strength (27%, P Ͻ 0.001) and increased muscle soreness (P Ͻ 0.001) 2 days after exercise, which is indicative of muscle damage. When the test MEP amplitudes were matched between sessions, we found that SICI was reduced by 27% in resting and 23% in active BB muscle 2 h after exercise. SICI recovered 2 days after exercise when muscle pain and soreness were present, suggesting that delayed onset muscle soreness from eccentric exercise does not influence SICI. The change in SICI observed 2 h after exercise suggests that eccentric muscle damage has widespread effects throughout the motor system that likely includes changes in motor cortex. exercise; motor control; TMS; motor cortex UNACCUSTOMED ECCENTRIC EXERCISE involving the repetitive lengthening of muscle is known to cause significant damage to the ultrastructural and cytoskeletal components of muscle fibers (1) and an impairment in the excitation-contraction coupling process (59). The consequences of this exercise-induced muscle damage are a long-lasting decline in muscle strength, a shift in the optimal muscle length for force generation, muscle swelling, and an increase in passive muscle tension or stiffness (46). Furthermore, muscle pain develops 1 or 2 days after the exercise, which is thought to reflect increased release of noxious chemicals from damaged muscle (39). This delayed onset muscle soreness (DOMS) is not discernible at rest but is elicited under mechanical stimulation such as pressure, stretching, or contraction of the affected muscle (45), which can produce debilitating and long-lasting effects on muscle function (7).Along with these changes in the muscle, several lines of evidence suggest that eccentric muscle damage pro...

Background Anemia frequently coexists with atrial fibrillation (AF) and has been variably associated with worse outcomes. We performed a systematic review and meta‐analysis to comprehensively assess the effect of anemia on mortality, stroke/systemic thromboembolism, and bleeding events in patients with AF. Methods MEDLINE and Embase were searched from inception until May 2020. Studies examining associations of anemia with the above outcomes in AF patients were included, and maximally adjusted hazard ratios (HRs) meta‐analysed. PROSPERO registration number CRD42020171113. Results Twenty‐eight studies involving 365 484 patients (41% female, mean age 74.7 years) were included. The average study follow‐up ranged from 0.2 to 4.0 years, and the prevalence of anemia was 16%. Anemia was associated with a 78% increase in all‐cause mortality (HR, 1.78; 95% confidence interval [CI], 1.44–2.20), 60% increase in cardiovascular mortality (HR, 1.60; 95% CI, 1.17–2.19), 134% increase in noncardiovascular mortality (HR, 2.34; 95% CI, 1.58–3.47) 15% increase in stroke/systemic thromboembolism (HR, 1.15; 95% CI, 1.01–1.31), 78% increase in major bleeding (HR, 1.78; 95% CI, 1.54–2.05), and 77% increase in gastrointestinal bleeding (HR, 1.77; 95% CI, 1.23–2.55). Sensitivity analyses including studies that reported odds ratios did not result in any material change. Conclusion Anemia is a frequently observed comorbidity in patients with AF, and is associated with an increased risk of all‐cause, cardiovascular and noncardiovascular mortality, stroke/systemic thromboembolism, and major and gastrointestinal bleeding. Future studies are required to explore the causes of anemia in AF, and whether investigation and treatment may be clinically beneficial in affected individuals.