Sex-specific differences of cardiopulmonary fitness and pulmonary function in exercise-based rehabilitation of patients with long-term post-COVID-19 syndrome.

BACKGROUND: Post-COVID-19 Syndrome (PCS) entails a spectrum of symptoms, including fatigue, reduced physical performance, dyspnea, cognitive impairment, and psychological distress. Given the effectiveness of exercise-based rehabilitation for PCS, this study examined the efficacy of rehabilitation for PCS patients, focusing on sex-specific differences. METHODS: Prospective cohort study during inpatient rehabilitation. Cardiopulmonary exercise testing and spirometry were performed at admission and discharge. Questionnaires were used to assess fatigue, health-related quality of life, wellbeing, and workability for up to 6 months. RESULTS: 145 patients (36% female, 47.1 ± 12.7 years; 64% male, 52.0 ± 9.1 years; p = 0.018) were referred to rehabilitation 262.0 ± 128.8 days after infection (female, 285.5 ± 140.6 days; male, 248.8 ± 112.0 days; p = 0.110). Lead symptoms included fatigue/exercise intolerance (81.4%), shortness of breath (74.5%), and cognitive dysfunction (52.4%). Women presented with higher relative baseline exercise capacity (82.0 ± 14.3%) than males (68.8 ± 13.3%, p < 0.001), but showed greater improvement in submaximal workload (p = 0.026). Men exhibited higher values for FEV1, FEV1/VC, PEF, and MEF and lower VC at baseline (p ≤ 0.038), while FEV1/VC improvement more in women (p = 0.027). Higher baseline fatigue and lower wellbeing was detected in women and correlated with impaired pulmonary function (p < 0.05). Disease perception including fatigue, health-related quality of life, wellbeing and workability improved with rehabilitation for up to six-month. CONCLUSIONS: Rehabilitation improves cardiopulmonary fitness, pulmonary function and disease burden in women and men with long-term PCS. Women with PCS may benefit from intensified respiratory muscle training. Clinical assessment should include cardiopulmonary exercise testing and pulmonary function tests and fatigue assessments for all PCS patients to document limitations and tailor therapeutical strategies.

Recalibrated FRIEND equation for peak oxygen pulse is accurate in endurance athletes: the NOODLE study.

Peak oxygen pulse (O2Ppeak) is an important index of cardiorespiratory fitness (CRF). The FRIEND database is a global source of reference values for CRF. However, no reference equation is tailored for endurance athletes (EA) to predict O2Ppeak. Here, we adjusted the well-established FRIEND equation for O2Ppeak to the characteristics of the EA population. 32 (34.0%) female EA and 62 (66.0%) male well-trained EA underwent maximal cardiopulmonary exercise test on a treadmill. V̇O2max was 4.5 ± 0.5 L min-1 in males and 3.1 ± 0.4 L min-1 in females. O2Ppeak was 23.6 ± 2.8 mL beat-1 and 16.4 ± 2.0 mL beat-1 for males and females, respectively. Firstly, we externally validated the original FRIEND equation. Secondly, using multiple linear regression, we adjusted the FRIEND equation for O2Ppeak to the population of EA. The original FRIEND equation underestimated O2Ppeak for 2.9 ± 2.9 mL beat-1 (P < .001) in males and 2.2 ± 2.1 mL beat-1 (P < .001) in females. The updated equation was 1.36 + 1.07 (23.2 · 0.09 · age - 6.6 [if female]). The new equation explained 62% of the variance and significantly predicted O2Ppeak (R2 = 0.62, ß = 0.78, P < .001). The error of the EA-adjusted model was 0.1 ± 2.9 mL beat-1 (P = .82) and 0.2 ± 2.1 mL beat-1 (P = .65) for males and females respectively. Recalibration of the original FRIEND equation significantly enhances its accuracy among EA. The error of the EA-adjusted model was negligible. A new recalibrated equation should be used to predict O2Ppeak in the population of EA.

Accuracy of smartwatches for the remote assessment of exercise capacity.

Exercise capacity is a strong independent predictor of cardiovascular and all-cause mortality. The utilization of well-established submaximal tests of exercise capacity such as the 6-min walk test (6MWT), 3-min step test (3MST) and 10-chair rise test (10CRT) in the community would improve patient care but requires remote monitoring technology. Consumer grade smartwatches provide such an opportunity, however, their accuracy in measuring physiological responses to these tests is unclear. The aim of this study was to determine the accuracy of consumer grade smartwatches in assessing exercise capacity to develop a framework for remote, unsupervised testing. 16 healthy adults (7 male (44%), age median 27 [interquartile range (IQR) 26,29] years) performed 6MWTs using two protocols: (1) standard-straight 30 m laps (6MWT-standard) and 2) continuous lap-circular 240 m laps around a park (6MWT-continuous lap), 3MSTs and 10CRTs. Each one of these four tests was performed three times across two clinic visits. Each participant was fitted with a Garmin Vivoactive4 and Fitbit Sense smartwatch to measure three parameters: distance, step counts and heart rate (HR) response. Reference measures were a meter-wheel, hand tally counter and ECG, respectively. Mean HR was measured at rest, peak exercise and recovery. Agreement was measured using Bland-Altman analysis for repeated measures and summarized as median absolute percentage errors (MAPE). Distance during 6MWT-continuous lap had better agreement than during 6MWT-standard for both Garmin (MAPE: 6.4% [3.0, 10.4%] versus 20.1% [13.9, 28.4%], p < 0.001) and Fitbit (8.0% [2.9, 10.1% versus 18.8% [15.2, 28.1%], p < 0.001). Garmin measured step count more accurately than Fitbit (MAPE: 1.8% [0.9, 2.9%] versus 8.0% [2.6, 12.3%], p < 0.001). Irrespective of test, both devices showed excellent accuracy in measuring HR at rest and recovery (≤ 3%), while accuracy decreased during peak exercise (Fitbit: ~ 12% and Garmin: ~ 7%). In young adults without mobility difficulties, exercise capacity can be measured remotely using standardized tests and consumer grade smartwatches.

Assessing the repeatability of expiratory flow limitation during incremental exercise in healthy adults.

We sought to determine the repeatability of EFL in healthy adults during incremental cycle exercise. We hypothesized that the repeatability of EFL would be "strong" when assessed as a binary variable (i.e., absent or present) but "poor" when assessed as a continuous variable (i.e., % tidal volume overlap). Thirty-two healthy adults performed spirometry and an incremental cycle exercise test to exhaustion on two occasions. Standard cardiorespiratory variables were measured at rest and throughout exercise, and EFL was assessed by overlaying tidal expiratory flow-volume and maximal expiratory flow-volume curves. The repeatability of EFL was determined using Cohen's κ for binary assessments of EFL and intraclass correlation (ICC) for continuous measures of EFL. During exercise, n = 12 participants (38%) experienced EFL. At peak exercise, the repeatability of EFL was "minimal" (κ = 0.337, p = 0.145) when assessed as a binary variable and "poor" when measured as a continuous variable (ICC = 0.338, p = 0.025). At matched levels of minute ventilation during high-intensity exercise (i.e., >75% of peak oxygen uptake), the repeatability of EFL was "weak" when measured as a binary variable (κ = 0.474, p = 0.001) and "moderate" when measured as a continuous variable (ICC = 0.603, p < 0.001). Our results highlight the day-to-day variability associated with assessing EFL during exercise in healthy adults.

Reduced cardiovascular and metabolic responses during eccentric stepping exercise: A pilot study.

This study compared cardiovascular and metabolic responses during concentric and eccentric stepping. Eight participants (5 m, 3f; 22 ± 2 years) performed maximal concentric and eccentric ramp incremental tests on a modified stepping ergometer. Subsequently, three randomized 15-min constant-power tests were performed (1) concentric stepping at 90% of the concentric lactate threshold (LT), (2) eccentric stepping at the same power, and (3) eccentric stepping at the same oxygen uptake (V̇O2). At equivalent power (36 ± 6 W, p = 0.62), eccentric stepping resulted in 46 ± 8% lower V̇O2, 16 ± 6% lower heart rate (HR), and 11 ± 5% lower mean arterial blood pressure compared to concentric (p < 0.01). Matching V̇O2 required 65 ± 19% more power during eccentric stepping (p < 0.01). During this test, eccentric V̇O2 and HR continued to increase, resulting in a 22 ± 29% higher V̇O2 and 19 ± 16% higher HR in the final minute (p < 0.001). Reduced cardiorespiratory demand during eccentric stepping at the same power as concentric demonstrates a higher eccentric power is required to produce the same V̇O2. However, despite being below the concentric LT, eccentric V̇O2 and HR continued to increase past the predicted steady state, indicating a higher exercise intensity.

Changes in the force-time curve during a repeat power ability assessment using loaded countermovement jumps.

Background: Repeat power ability (RPA) assessments traditionally use discrete variables, such as peak power output, to quantify the change in performance across a series of jumps. Rather than using a discrete variable, the analysis of the entire force-time curve may provide additional insight into RPA performance. The aims of this study were to (1) analyse changes in the force-time curve recorded during an RPA assessment using statistical parametric mapping (SPM) and (2) compare the differences in the force-time curve between participants with low and high RPA scores, as quantified by traditional analysis. Materials and Methods: Eleven well-trained field hockey players performed an RPA assessment consisting of 20 loaded countermovement jumps with a 30% one repetition maximum half squat load (LCMJ20). Mean force-time series data was normalized to 100% of the movement duration and analysed using SPM. Peak power output for each jump was also derived from the force-time data and a percent decrement score calculated for jumps 2 to 19 (RPA%dec). An SPM one-way ANOVA with significance accepted at α = 0.05, was used to identify the change in the force-time curve over three distinct series of jumps across the LCMJ20 (series 1 = jumps 2-5, series 2 = jumps 9-12 and series 3 = jumps 16-19). A secondary analysis, using an independent T-test with significance accepted at p < 0.001, was also used to identify differences in the force-time curve between participants with low and high RPA%dec. Results: Propulsive forces were significantly lower (p < 0.001) between 74-98% of the movement compared to 0-73% for changes recorded during the LCMJ20. Post hoc analysis identified the greatest differences to occur between jump series 1 and jump series 2 (p < 0.001) at 70-98% of the movement and between jump series 1 and jump series 3 (p < 0.001) at 86-99% of the movement. No significant differences were found between jump series 2 and jump series 3. Significant differences (p < 0.001) in both the braking phase at 44-48% of the jump and the propulsive phase at 74-94% of the jump were identified when participants were classified based on low or high RPA%dec scores (with low scores representing an enhanced ability to maintain peak power output than high scores). Conclusion: A reduction in force during the late propulsive phase is evident as the LCMJ20 progresses. SPM analysis provides refined insight into where changes in the force-time curve occur during performance of the LCMJ20. Participants with the lower RPA%dec scores displayed both larger braking and propulsive forces across the LCMJ20 assessment.

Consumer-priced wearable sensors combined with deep learning can be used to accurately predict ground reaction forces during various treadmill running conditions.

Ground reaction force (GRF) data is often collected for the biomechanical analysis of running, due to the performance and injury risk insights that GRF analysis can provide. Traditional methods typically limit GRF collection to controlled lab environments, recent studies have looked to combine the ease of use of wearable sensors with the statistical power of machine learning to estimate continuous GRF data outside of these restrictions. Before such systems can be deployed with confidence outside of the lab they must be shown to be a valid and accurate tool for a wide range of users. The aim of this study was to evaluate how accurately a consumer-priced sensor system could estimate GRFs whilst a heterogeneous group of runners completed a treadmill protocol with three different personalised running speeds and three gradients. Fifty runners (25 female, 25 male) wearing pressure insoles made up of 16 resistive sensors and an inertial measurement unit ran at various speeds and gradients on an instrumented treadmill. A long short term memory (LSTM) neural network was trained to estimate both vertical ( G R F v ) and anteroposterior ( G R F a p ) force traces using leave one subject out validation. The average relative root mean squared error (rRMSE) was 3.2% and 3.1%, respectively. The mean ( G R F v ) rRMSE across the evaluated participants ranged from 0.8% to 8.8% and from 1.3% to 17.3% in the ( G R F a p ) estimation. The findings from this study suggest that current consumer-priced sensors could be used to accurately estimate two-dimensional GRFs for a wide range of runners at a variety of running intensities. The estimated kinetics could be used to provide runners with individualised feedback as well as form the basis of data collection for running injury risk factor studies on a much larger scale than is currently possible with lab based methods.

Validity and Reliability of Movesense HR+ ECG Measurements for High-Intensity Running and Cycling.

Low-cost, portable devices capable of accurate physiological measurements are attractive tools for coaches, athletes, and practitioners. The purpose of this study was primarily to establish the validity and reliability of Movesense HR+ ECG measurements compared to the criterion three-lead ECG, and secondarily, to test the industry leader Garmin HRM. Twenty-one healthy adults participated in running and cycling incremental test protocols to exhaustion, both with rest before and after. Movesense HR+ demonstrated consistent and accurate R-peak detection, with an overall sensitivity of 99.7% and precision of 99.6% compared to the criterion; Garmin HRM sensitivity and precision were 84.7% and 87.7%, respectively. Bland-Altman analysis compared to the criterion indicated mean differences (SD) in RR' intervals of 0.23 (22.3) ms for Movesense HR+ at rest and 0.38 (18.7) ms during the incremental test. The mean difference for Garmin HRM-Pro at rest was -8.5 (111.5) ms and 27.7 (128.7) ms for the incremental test. The incremental test correlation was very strong (r = 0.98) between Movesense HR+ and criterion, and moderate (r = 0.66) for Garmin HRM-Pro. This study developed a robust peak detection algorithm and data collection protocol for Movesense HR+ and established its validity and reliability for ECG measurement.

The Kinematic and Electromyographic Analysis of Roller Skating at Different Speeds on a Treadmill: A Case Study.

Elite athletes in speed roller skates perceive skating to be a more demanding exercise for the groin when compared to other cyclic disciplines, increasing their risk of injury. The objective of this study was to monitor the kinematic and electromyographic parameters of roller speed skaters, linearly, on a treadmill, and to compare different skating speeds, one at 20 km/h and one at 32 km/h, at a 1° inclination. The acquisition was carried out by placing an inertial sensor at the level of the first sacral vertebra, and eight surface electromyographic probes on both lower limbs. The kinematic and electromyographic analysis on the treadmill showed that a higher speed requires more muscle activation, in terms of maximum and average values and co-activation, as it not only increases the intrinsic muscle demand in the district, but also the athlete's ability to coordinate the skating technique. The present study allows us to indicate not only how individual muscle districts are activated during skating on a surface different from the road, but also how different speeds affect the overall district load distributions concerning effective force, which is essential for the physiotherapist and kinesiologist for preventive and conditional purposes, while also considering possible variations in the skating technique in linear advancement.

The Validity of a Dual-Force Plate for Assessing Counter-Movement Jump Performance.

The objective of this study was to assess the concurrent validity of the Kunwei force plate system in relation to variables during a counter-movement jump (CMJ) task, in comparison to the Kistler in-ground force plate system, which is considered the "gold standard". METHODS: In a single testing session, the Kunwei force plates were placed directly on top of the in-ground Kistler force plate. This allowed for the simultaneous collection of vertical ground reaction forces from 30 participants (male, age = 22.8 ± 2.8 years, body mass = 74.3 ± 12.3 kg, height 178.2 ± 4.6 cm) during CMJ tests. The consistency between force plate systems was assessed using ordinary least products regression (OLPR) with bootstrapped 95% confidence intervals and the Interclass Correlation Coefficient (ICC). RESULTS: There was no fixed or proportional bias in the CMJ variables measured between the force plate systems. The variables exhibited a strong correlation across the force plates during the CMJ task (ICC > 0.950, p < 0.01). CONCLUSION: The findings of this study indicate that there was no statistical difference between the Kunwei and Kistler force plate systems when evaluating common CMJ strategy and outcome variables, which are considered the gold standard. Hence, the Kunwei force plate can be regarded as a reliable substitute for the established industry benchmark in evaluating the force-time characteristics of the CMJ. Researchers, athletes, and coaches have the option to utilize this affordable and portable choice as a substitute for the more expensive laboratory-based force plate system. This alternative allows for the precise measurement of CMJ performance and force-time variables.

Validation of VO2max Prediction Using International Formulae for Young Saudi Men.

Objectives: In this study, we aimed to assess the maximal oxygen uptake (VO2max) of young, healthy, non-athletic Saudi men using maximum graded exercise with instant breath-by-breath analysis and to compare this value to the predicted VO2max by international formulae. Methods: In this cross-sectional study, 88 young non-athletic normal-weight Saudi subjects were recruited from Eastern Province of Saudi Arabia with mean age (21.3 ± 1.5 years), weight: (64.7 ± 7.5 kg), height: (172.3 ± 6.1 cm) and body mass index: (21.8 ± 2.1). All subjects were interviewed and examined for eligibility, after which they performed maximum graded exercise testing on a treadmill to obtain VO2max. The predicted VO2max was also generated using the following formulae (Edvardsen, Fairbarns, FRIENDS, Hansen, and Jones). Results: The mean measured VO2max was 41.9 ± 7.2 ml/kg/min. While the predicted VO2max using the formulae were: Edvardsen = 66.8 ± 7.9, Fairbarns = 64.1 ± 4.7, FRIENDS = 53.5 ± 2.2, Hansen = 42.8 ± 0.54, and Jones = 50.9 ± 5.1 ml/kg/min. There was a significant difference between all the predicted VO2max and the measured one using the paired t-test (P < 0.001), except for the Hansen's predicted value (P = 0.212). The effect size index (Cohen's d) for the comparison of Hansen's VO2max and measured VO2max was trivial and equal to 0.13. The Bland-Altman test showed good agreement between the measured and Hansen's predicted VO2max. Conclusion: This study demonstrated the mean VO2max value of young, healthy, and non-athletic Saudi men. This value was lower than Western values, which might be due to low physical activity or racial differences. Most international formulae overestimate the VO2max in this population, except for the Hansen equation. Therefore, Hansen's predicted VO2max might be the best available reference value for the diagnosis and prognosis of young Saudi individuals undergoing maximum exercise testing.

Effects of different levels of physical activity on arterial stiffness and physical fitness performance in firefighters.

Background: Firefighters have lower levels of physical activity while on call. It is critical to understand the impact of firefighters' physical activity on arterial stiffness. This study classified groups by physical activity level and combined peripheral vascular monitor measurement to explore the relationships between the level of physical activity and cardiovascular (CV) risk and physical fitness (PF) of firefighters, as well as the acute response to arterial stiffness (AS) following maximal aerobic exercise test (MAET) intervention. Methods: The International Physical Activity Questionnaire (IPAQ) was used to classify the participants into 3 groups: low, moderate, and high level of physical activity group, respectively. A total of 36 participants were recruited, 12 in each group. Participants were assessed for body composition, rest brachial-ankle pulse wave velocity (baPWV), handgrip strength (HGS), maximal oxygen uptake (V̇O2max), and MAET baPWV. Results: In the three groups, significant differences were observed in V̇O2max, HGS, relative fat mass (%FM), body mass index (BMI), muscle mass ratio (MMR), and Rest baPWV (p < 0.05). After maximal aerobic exercise, the MAET baPWV values decreased significantly in all groups (all p < 0.001). Rest baPWV was significantly correlated with firefighters' age, seniority, metabolic equivalents (METs), height and muscle mass (MM) (p < 0.05). Conclusions: Firefighters with high levels of physical activity had better body composition and physical fitness and lower Rest baPWV. In all three groups, baPWV was lower after the MAET than before it. Therefore, regardless of a firefighter's level of physical activity, high-intensity aerobic exercise may have a beneficial effect on arterial stiffness.

The intra-day and inter-day reliability of a 6-second Wingate to determine maximal peak power in endurance-trained athletes.

Determining an athlete's maximal peak power (MPP) is crucial in profiling endurance sports participants. While short (3 to 6 seconds) all-out efforts have been validated for MPP assessment, prior studies mainly involved non-endurance trained athletes. This study aimed to assess the intra- and inter-day reliability of a 6-second Wingate test for MPP determination in endurance athletes. Endurance-trained participants (22 males, 5 females) completed nine 6-second Wingate tests over four days (3 trials at baseline, 2 trials on each subsequent day). Analysis revealed no systematic differences in MPP (F(4.09, 106.3) = 1.88, p = 0.117) or time to peak power (χ2 (8) = 5.23, p = 0.732) across the trials. Reliability, assessed through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM), was excellent across all trials (ICC = 0.95, SEM = 40.0W, SEM% = 3.7%). Absolute reliability improved when selecting the average or the best MPP values from each day (SEM% = 2.7% and 2.9%, respectively). Within-day reliability was consistently rated as excellent, with the best values on the 4th day of tests. No significant differences in MPP values occurred between the first and second 6-second Wingate tests on days 1 to 3, with both trials demonstrating similar reliability values (SEM%: 3.2% vs 2.8%, for the first and second trials, respectively). The test also demonstrated a good sensitivity to detect a meaningful change in MPP values. In conclusion, the 6-second Wingate test proves reliable for determining MPP in endurance-trained athletes. Two trials are recommended on the first day of testing, with a single MPP likely sufficient to determine the athlete's MPP on subsequent days.

Subdiaphragmatic activity-related artifacts in myocardial perfusion scintigraphy.

BACKGROUND: Myocardial perfusion imaging (MPI) with single photon emission computed tomography is an established non-invasive technique for assessing myocardial ischemia. This method involves the intravenous administration of a radiopharmaceutical that accumulates in the heart muscle proportional to regional blood flow. However, image quality and diagnostic accuracy can be compromised by various technical and patient-related factors, including high non-specific radiopharmaceutical uptake in abdominal organs such as the stomach, intestines, liver, and gall-bladder, leading to subdiaphragmatic artifacts. These artifacts are particularly problematic for evaluating inferior wall perfusion and often necessitate repeated imaging, which decreases gamma camera availability and prolongs imaging times. CONCLUSIONS: Despite numerous investigated techniques to reduce interfering gastrointestinal activity, results have been inconsistent, and current MPI guidelines provide scant information on effective procedures to mitigate this issue. Based on our experience, some possible approaches to reducing artifacts include choosing stress testing with an exercise stress test, when possible, late imaging, fluid intake, and consuming carbonated water immediately before imaging.

Unilateral Plyometric Jump Training Shows Significantly More Effective than Bilateral Training in Improving Both Time to Stabilization and Peak Landing Force in Single-Leg Lend and Hold Test: A Randomized Multi-Arm Study Conducted Among Young Male Basketball Players.

Enhancing peak landing forces and ensuring faster stabilization in the lower limbs during jumping activities can significantly improve performance and decrease the risk of injury among basketball players. This study aimed to compare the effects of unilateral (uPJT) and bilateral plyometric jump training (bPJT) programs on various performance measures, including countermovement jump (CMJ), squat jump (SJ), and single-leg land and hold (SLLH) test outcomes, assessed using force plates. A randomized multi-arm study design was employed, comprising two experimental groups (n = 25; uPJT and n = 25; bPJT) and one control group (n = 25), conducted with youth male regional-level basketball players (16.3 ± 0.6 years old). Participants underwent assessment twice, both before and after an 8-week intervention training period. The uPJT program exclusively involved plyometric drills (e.g., vertical jump exercises; horizontal jump exercises) focusing on single-leg exercises, whereas the bPJT program utilized drills involving both legs simultaneously. The outcomes analyzed included CMJ peak landing force, CMJ peak power, SJ peak force, SJ maximum negative displacement, SLLH time to stabilization, and SLLH peak landing force. The control group exhibited significantly greater SLLH time to stabilization compared to both the uPJT (p < 0.001) and bPJT (p < 0.030) groups. Additionally, time to stabilization was also significantly higher in bPJT than in uPJT (p = 0.042). Comparisons between groups in regards SLLH peak landing force after intervention revealed that the value was significantly smaller in uPJT than in bPJT (p = 0.043) and control (p < 0.001). In the remaining outcomes of CMJ and SJ, both uPJT and bPJT showed significant improvement compared to the control group (p > 0.05), although there was no significant difference between them. In conclusion, our study suggests that utilizing uPJT is equally effective as bPJT in enhancing performance in bilateral jump tests. However, it significantly outperforms bPJT in improving time to stabilization and peak landing forces during single-leg land and hold test. uPJT could be advantageous not for maximizing performance but also for potentially decreasing injury risk by enhancing control and balance during single-leg actions, which are common in basketball.

Dynamics of gas exchange and heart rate signal entropy in standard cardiopulmonary exercise testing during critical periods of growth and development.

Standard cardiopulmonary exercise testing (CPET) produces a rich dataset but its current analysis is often limited to a few derived variables such as maximal or peak oxygen uptake (V̇O2). We tested whether breath-by-breath CPET data could be used to determine sample entropy (SampEn) in 81 healthy children and adolescents (age 7-18 years old, equal sex distribution). To overcome challenges of the relatively small time-series CPET data size and its nonstationarity, we developed a Python algorithm for short-duration physiological signals. Comparing pre- and post-ventilatory threshold (VT1) CPET phases, we found: (1) SampEn decreased by 9.46% for V̇O2 and 5.01% for V̇CO2 (p < 0.05), in the younger, early-pubertal participants; and (2) HR SampEn fell substantially by 70.8% in the younger and 77.5% in the older participants (p < 0.001). Across all ages, females exhibited greater HR SampEn than males during both pre- and post VT1 CPET phases by 14.10% and 23.79%, respectively, p < 0.01. In females, late-pubertal had 17.6% lower HR SampEn compared to early-pubertal participants (p < 0.05). Breath-by-breath gas exchange and HR data from CPET are amenable to SampEn analysis that leads to novel insight into physiological responses to work intensity, and sex and maturational effects.

A detailed analysis of body composition in relation to cardiopulmonary exercise test indices.

A cardiopulmonary exercise test (CPET) is a test assessing an individual's physiological response during exercise. Results may be affected by body composition, which is best evaluated through imaging techniques like magnetic resonance imaging (MRI). The aim of this study was to assess relationships between body composition and indices obtained from CPET. A total of 234 participants (112 female), all aged 50 years, underwent CPETs and whole-body MRI scans (> 1 million voxels). Voxel-wise statistical analysis of tissue volume and fat content was carried out with a method called Imiomics and related to the CPET indices peak oxygen consumption (V̇O2peak), V̇O2peak scaled by body weight (V̇O2kg) and by total lean mass (V̇O2lean), ventilatory efficiency (V̇E/V̇CO2-slope), work efficiency (ΔV̇O2/ΔWR) and peak exercise respiratory exchange ratio (RERpeak). V̇O2peak showed the highest positive correlation with volume of skeletal muscle. V̇O2kg negatively correlated with tissue volume in subcutaneous fat, particularly gluteal fat. RERpeak negatively correlated with tissue volume in skeletal muscle, subcutaneous fat, visceral fat and liver. Some associations differed between sexes: in females ΔV̇O2/ΔWR correlated positively with tissue volume of subcutaneous fat and V̇E/V̇CO2-slope with tissue volume of visceral fat, and, in males, V̇O2peak correlated positively to lung volume. In conclusion, voxel-based Imiomics provided detailed insights into how CPET indices were related to the tissue volume and fat content of different body structures.

Congenital Long QT Syndrome Unmasked by Albuterol in an Adolescent with Asthma.

BACKGROUND: Patients with congenital long QT syndrome (LQTS) are prone to ventricular dysrhythmia but may be initially asymptomatic with a normal QTc interval on resting electrocardiogram (ECG). Albuterol is listed as a medication that poses a "special risk" to patients with congenital LQTS, but its effects have been rarely described. We present a case of previously unknown, asymptomatic congenital LQTS unmasked by albuterol in an adolescent with asthma. CASE REPORT: A 12-year-old girl with a history of asthma presented to the emergency department (ED) with shortness of breath, wheezing, and tachycardia for 24 h, consistent with acute asthma exacerbation. She received two doses of her home albuterol inhaler 2 h prior to presentation. Initial ECG demonstrated a QTc of 619 ms. Her remaining history, clinical examination, and laboratory workup, including electrolytes, were unremarkable. She was observed with cardiac monitoring before being discharged from the ED in stable condition for next-day outpatient pediatric cardiology follow-up. Resting office ECGs revealed QTcs from 440-470 ms. Exercise stress test revealed QTc prolongation of 520 ms and 500 ms at minute-2 and minute-4 of recovery, respectively. Genetic testing revealed heterozygous pathogenic variants in KCNQ1, consistent with type 1 LQTS. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Albuterol may be a cause of marked QTc prolongation in ED patients with underlying congenital LQTS, which can be a diagnostic clue in previously unidentified patients. Extreme QTc prolongation also serves as an indication in the ED for Cardiology consultation, laboratory evaluation for electrolyte imbalances, and observation with cardiac monitoring.