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Background During the SARS‐CoV2 pandemic, there has been increase in hyperinflammatory presentation in previously healthy children with a variety of cardiac manifestations. Our objective is to describe the cardiac manifestations found in an international cohort of 55 pediatric cases with multi‐system inflammatory syndrome (MIS‐C) during the SARS‐CoV2 pandemic. Methods and Results We reviewed data on previously healthy pediatric patients (≤18 years) with structurally normal hearts who presented at hospitals in the United States, United Kingdom, Spain and Pakistan with MIS‐C and had consultation with a pediatric cardiologist. Data collected included demographics, clinical presentation, laboratory values, electrocardiographic abnormalities, echocardiographic findings and initial therapies. A total of 55 patients presented with MIS‐C. Thirty‐five patients (64%) had evidence of decreased left ventricular function, 17 (31%) had valvulitis, 12 (22%) with pericardial effusion and 11 (20%) with coronary abnormalities. Twenty‐seven (49%) required ICU admission and 24 (44%) had evidence of shock. Eleven patients (20%) fulfilled complete Kawasaki disease criteria and had lower NT pro‐BNP, D‐dimer and ferritin levels compared with those who did not fulfill criteria. Electrophysiologic abnormalities occurred in 6 patients and included complete atrioventricular (AV) block, transient AV block and ventricular tachycardia. Conclusions We describe the first international cohort of pediatric patients with MIS‐C during the SARS‐CoV2 pandemic with a range of cardiac manifestations. This paper brings awareness and alertness to the global medical community to recognize these children during the pandemic and understand the need for early cardiology evaluation and follow‐up.

There is evidence to suggest athletes have adopted recombinant human erythropoietin (rHuEPO) dosing regimens that diminish the likelihood of being caught by direct detection techniques. However, the temporal response in physiology, performance, and Athlete Biological Passport (ABP) parameters to such regimens is not clearly understood. Participants were assigned to a high-dose only group (HIGH, n = 8, six rHuEPO doses of 250 IU/kg over two weeks), a combined high micro-dose group (COMB, n = 8, high-dose plus nine rHuEPO micro-doses over a further three weeks), or one of two placebo control groups who received saline in the same pattern as the HIGH (HIGH-PLACEBO, n = 4) or COMB (COMB-PLACEBO, n = 4) groups. Temporal changes in physiology and performance were tracked by graded exercise test (GXT) and haemoglobin mass assessment at baseline, after high dose, after micro-dose (COMB and COMB-PLACEBO only) and after a four-week washout. Venous blood samples were collected throughout the baseline, rHuEPO administration, and washout periods to determine the haematological and ABP response to each dosing regimen. Physiological adaptations induced by a two-week rHuEPO high-dose were maintained by rHuEPO micro-dosing for at least three weeks. However, all participants administered rHuEPO registered at least one suspicious ABP value during the administration or washout periods. These results indicate there is sufficient sensitivity in the ABP to detect use of high rHuEPO doping regimens in athletic populations and they provide important empirical examples for use by anti-doping experts. Copyright © 2017 John Wiley & Sons, Ltd.

ObjectivesCompetitive endurance athletes commonly undertake periods of overload training in the weeks prior to major competitions. This investigation examined the effects of two seven-day high-intensity overload training regimes (HIT) on performance and physiological characteristics of competitive cyclists.DesignThe study was a matched groups, controlled trial.MethodsTwenty-eight male cyclists (mean ± SD, Age: 33±10 years, Mass 74±7 kg, VO2 peak 4.7±0.5 L·min−1) were assigned to a control group or one of two training groups for seven consecutive days of HIT. Before and after training cyclists completed an ergometer based incremental exercise test and a 20-km time-trial. The HIT sessions were ∼120 minutes in duration and consisted of matched volumes of 5, 10 and 20 second (short) or 15, 30 and 45 second (long) maximal intensity efforts.ResultsBoth the short and long HIT regimes led to significant (p<0.05) gains in time trial performance compared to the control group. Relative to the control group, the mean changes (±90% confidence limits) in time-trial power were 8.2%±3.8% and 10.4%±4.3% for the short and long HIT regimes respectively; corresponding increases in peak power in the incremental test were 5.5%±2.7% and 9.5%±2.5%. Both HIT (short vs long) interventions led to non-significant (p>0.05) increases (mean ± SD) in VO2 peak (2.3%±4.7% vs 3.5%±6.2%), lactate threshold power (3.6%±3.5% vs 2.9%±5.3%) and gross efficiency (3.2%±2.4% vs 5.1%±3.9%) with only small differences between HIT regimes.ConclusionsSeven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists.

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In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling, and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p < 0.05), but not the start section of hypoxia and heat-stress trials compared to the control trials. In contrast, there was no significant change in trial or section MPO for hyperoxic or pre-cooling conditions compared to the control condition (p > 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p < 0.05), while informed feedback improved overall trial MPO (p < 0.05). However, positive, neutral and no feedback had no significant effect on overall trial or section MPO (p > 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception.

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Aim To identify factors associated with baseline prolonged corrected QT (QTc) and higher risk of QTc prolongation during follow‐up in patients with Rett syndrome (RTT). Method A retrospective review of patients receiving an electrocardiogram (ECG) between June 2012 and June 2018 was performed. Age, methyl‐CpG binding protein 2 gene (MECP2) mutation, RTT Severity Scale (RSSS) score, breathing abnormalities, seizure frequency, medications, and ECG parameters were collected. Prolonged QTc was defined as greater than or equal to 460ms. Comparisons at baseline and during follow‐up were made. Results In total, 129 unique patients (all female) had 349 ECGs. At baseline, 12 (9.3%) had a prolonged QTc (median 474ms, interquartile range 470–486ms) and were more likely to have moderate/severe breathing abnormalities (66.7% vs 24.8%; p=0.005) and take selective serotonin reuptake inhibitors (SSRIs) (41.7% vs 15.4%; p=0.04). There was no difference in age, RSSS score, seizures, or mutation. Twenty‐six developed prolonged QTc during a median follow‐up of 1 year 7 months (interquartile range 0–3y 6mo). QTc prolongation was associated with p.(Thr158Met) mutation versus the remaining six common mutations (hazard ratio 4.1, 95% confidence interval 1.4–12.0; p=0.01) but not with age, RSSS score, seizures, breathing abnormalities, or SSRIs. Interpretation Breathing abnormalities and SSRIs were associated with baseline QTc prolongation and those with p.(Thr158Met) mutation were more likely to develop prolonged QTc over time. Identification of patients with prolonged QTc warrants increased clinical monitoring. What this paper adds Breathing abnormalities and selective serotonin reuptake inhibitors are associated with prolonged baseline corrected QT (QTc). Development of QTc prolongation is associated with the p.(Thr158Met) mutation.