A verification phase adds little value to the determination of maximum oxygen uptake in well-trained adults.

PURPOSE: The objective was to investigate if performing a sub-peak or supra-peak verification phase following a ramp test provides additional value for determining 'true' maximum oxygen uptake ( V ˙ O2). METHODS: 17 and 14 well-trained males and females, respectively, performed two ramp tests each followed by a verification phase. While the ramp tests were identical, the verification phase differed in power output, wherein the power output was either 95% or 105% of the peak power output from the ramp test. The recovery phase before the verification phase lasted until capillary blood lactate concentration was ≤ 4 mmol·L-1. If a V ˙ O2 plateau occurred during ramp test, the following verification phase was considered to provide no added value. If no V ˙ O2 plateau occurred and the highest V ˙ O2 ( V ˙ O2peak) during verification phase was < 97%, between 97 and 103%, or > 103% of V ˙ O2peak achieved during the ramp test, no value, potential value, and certain value were attributed to the verification phase, respectively. RESULTS: Mean (standard deviation) V ˙ O2peak during both ramp tests was 64.5 (6.0) mL·kg-1·min-1 for males and 54.8 (6.2) mL·kg-1·min-1 for females. For the 95% verification phase, 20 tests showed either a V ˙ O2 plateau during ramp test or a verification V ˙ O2peak < 97%, indicating no value, 11 showed potential value, and 0 certain value. For the 105% verification phase, the values were 26, 5, and 0 tests, respectively. CONCLUSION: In well-trained adults, a sub-peak verification phase might add little value in determining 'true' maximum V ˙ O2, while a supra-peak verification phase adds no value.

Using Machine Learning-Based Algorithms to Identify and Quantify Exercise Limitations in Clinical Practice: Are We There Yet?

INTRODUCTION: Well-trained staff is needed to interpret cardiopulmonary exercise tests (CPET). We aimed to examine the accuracy of machine learning-based algorithms to classify exercise limitations and their severity in clinical practice compared with expert consensus using patients presenting at a pulmonary clinic. METHODS: This study included 200 historical CPET data sets (48.5% female) of patients older than 40 yr referred for CPET because of unexplained dyspnea, preoperative examination, and evaluation of therapy progress. Data sets were independently rated by experts according to the severity of pulmonary-vascular, mechanical-ventilatory, cardiocirculatory, and muscular limitations using a visual analog scale. Decision trees and random forests analyses were calculated. RESULTS: Mean deviations between experts in the respective limitation categories ranged from 1.0 to 1.1 points (SD, 1.2) before consensus. Random forests identified parameters of particular importance for detecting specific constraints. Central parameters were nadir ventilatory efficiency for CO 2 , ventilatory efficiency slope for CO 2 (pulmonary-vascular limitations); breathing reserve, forced expiratory volume in 1 s, and forced vital capacity (mechanical-ventilatory limitations); and peak oxygen uptake, O 2 uptake/work rate slope, and % change of the latter (cardiocirculatory limitations). Thresholds differentiating between different limitation severities were reported. The accuracy of the most accurate decision tree of each category was comparable to expert ratings. Finally, a combined decision tree was created quantifying combined system limitations within one patient. CONCLUSIONS: Machine learning-based algorithms may be a viable option to facilitate the interpretation of CPET and identify exercise limitations. Our findings may further support clinical decision making and aid the development of standardized rating instruments.

Accelerometer Metrics: Healthy Adult Reference Values, Associations with Cardiorespiratory Fitness, and Clinical Implications.

PURPOSE: Accelerometer-assessed physical activity (PA) can be summarized using cut-point-free or population-specific cut-point-based outcomes. We aimed to 1) examine the interrelationship between cut-point-free (intensity gradient (IG) and average acceleration (AvAcc)) and cut-point-based accelerometer metrics, 2) compare the association between cardiorespiratory fitness (CRF) and cut-point-free metrics to that with cut-point-based metrics in healthy adults aged 20 to 89 yr and patients with heart failure, and 3) provide age-, sex-, and CRF-related reference values for healthy adults. METHODS: In the COmPLETE study, 463 healthy adults and 67 patients with heart failure wore GENEActiv accelerometers on their nondominant wrist and underwent cardiopulmonary exercise testing. Cut-point-free (IG: distribution of intensity of activity across the day; AvAcc: proxy of volume of activity) and traditional (moderate-to-vigorous and vigorous activity) metrics were generated. The "interpretablePA" R-package was developed to translate findings into clinical practice. RESULTS: IG and AvAcc yield complementary information on PA with both IG ( P = 0.009) and AvAcc ( P < 0.001) independently associated with CRF in healthy individuals (adjusted R2 = 73.9%). Only IG was independently associated with CRF in patients with heart failure ( P = 0.043, adjusted R2 = 38.4%). The best cut-point-free and cut-point-based model had similar predictive value for CRF in both cohorts. We produced age- and sex-specific reference values and percentile curves for IG, AvAcc, moderate-to-vigorous PA, and vigorous PA for healthy adults. CONCLUSIONS: IG and AvAcc are strongly associated with CRF and thus indirectly with the risk of noncommunicable diseases and mortality, in healthy adults and patients with heart failure. However, unlike cut-point-based metrics, IG and AvAcc are comparable across populations. Our reference values provide a healthy age- and sex-specific comparison that may enhance the translation and utility of cut-point-free metrics in clinical practice.

Physical activity and brain health in patients with atrial fibrillation.

BACKGROUND AND PURPOSE: Vascular brain lesions, such as ischemic infarcts, are common among patients with atrial fibrillation (AF) and are associated with impaired cognitive function. The role of physical activity (PA) in the prevalence of brain lesions and cognition in AF has not been investigated. METHODS: Patients from the multicenter Swiss-AF cohort study were included in this cross-sectional analysis. We assessed regular exercise (RE; at least once weekly) and minutes of weekly PA using a validated questionnaire. We studied associations with ischemic infarcts, white matter hyperintensities, cerebral microbleeds, and brain volume on brain magnetic resonance imaging and with global cognition measured with a cognitive construct (CoCo) score. RESULTS: Among 1490 participants (mean age = 72 ± 9 years), 730 (49%) engaged in RE. In adjusted regression analyses, RE was associated with a lower prevalence of ischemic infarcts (odds ratio [OR] = 0.78, 95% confidence interval [CI] = 0.63-0.98, p = 0.03) and of moderate to severe white matter hyperintensities (OR = 0.78, 95% CI = 0.62-0.99, p = 0.04), higher brain volume (ß-coefficient = 10.73, 95% CI = 2.37-19.09, p = 0.01), and higher CoCo score (ß-coefficient = 0.08, 95% CI = 0.03-0.12, p < 0.001). Increasing weekly PA was associated with higher brain volume (ß-coefficient = 1.40, 95% CI = 0.65-2.15, p < 0.001). CONCLUSIONS: In AF patients, RE was associated with a lower prevalence of ischemic infarcts and of moderate to severe white matter disease, with larger brain volume, and with better cognitive performance. Prospective studies are needed to investigate whether these associations are causal. Until then, our findings suggest that patients with AF should be encouraged to remain physically active.

Low Cardiorespiratory Fitness Post-COVID-19: A Narrative Review.

Patients recovering from COVID-19 often report symptoms of exhaustion, fatigue and dyspnoea and present with exercise intolerance persisting for months post-infection. Numerous studies investigated these sequelae and their possible underlying mechanisms using cardiopulmonary exercise testing. We aimed to provide an in-depth discussion as well as an overview of the contribution of selected organ systems to exercise intolerance based on the Wasserman gears. The gears represent the pulmonary system, cardiovascular system, and periphery/musculature and mitochondria. Thirty-two studies that examined adult patients post-COVID-19 via cardiopulmonary exercise testing were included. In 22 of 26 studies reporting cardiorespiratory fitness (herein defined as peak oxygen uptake-VO2peak), VO2peak was < 90% of predicted value in patients. VO2peak was notably below normal even in the long-term. Given the available evidence, the contribution of respiratory function to low VO2peak seems to be only minor except for lung diffusion capacity. The prevalence of low lung diffusion capacity was high in the included studies. The cardiovascular system might contribute to low VO2peak via subnormal cardiac output due to chronotropic incompetence and reduced stroke volume, especially in the first months post-infection. Chronotropic incompetence was similarly present in the moderate- and long-term follow-up. However, contrary findings exist. Peripheral factors such as muscle mass, strength and perfusion, mitochondrial function, or arteriovenous oxygen difference may also contribute to low VO2peak. More data are required, however. The findings of this review do not support deconditioning as the primary mechanism of low VO2peak post-COVID-19. Post-COVID-19 sequelae are multifaceted and require individual diagnosis and treatment.

4000ers of the Alps-So beautiful, so dangerous: An analysis of falls in the Swiss Alps between 2009-2020.

BACKGROUND: This study aimed to analyze falls regarding their demographic characteristics, severity, frequency over time, and the localization of injuries while high-altitude mountaineering in the Swiss Alps. METHODS: Data on fall-related emergencies during mountaineering between 2009 to 2020 from the Swiss Alpine Club central registry were analyzed retrospectively. The variables age, sex, time of occurrence, severity of an event quantified by NACA-Score (National Advisory Committee for Aeronautics Score), and injury localization were examined descriptively. Changes in injury severity, number of total emergencies, and fatal emergencies over time were analyzed using linear regression models. RESULTS: Out of 1347 (28.7%) victims of fall-related emergencies, 1027 were men (76.2%) and 320 (23.8%) women. Around 70% of the cases happened during summer in July and August. The mean age was 49.9 ± 14.9 years for men and 51.3 ± 14.4 years for women with no between-sex difference. Higher NACA-Scores were found in men than women (3.6 ± 2.2 vs. 3.1 ± 1.6; p < 0.01). Approximately 80% of all victims originated from the countries close to the Alps (Switzerland, Germany, Italy, France, and Austria). There was a slight decrease of total cases (R2 = 0.104) and fatal cases over time (R2 = 0.183). NACA-Scores decreased over time (R2 = 0.168). Likewise, risk aversion decreased over time as the severity of emergencies decreased. Injuries occurred predominantly at the extremities (90%). Out of all cases, 228 fatal emergencies (16.9%) could be identified of which 82 occurred while climbing one of the classic 4000ers. CONCLUSIONS: The decrease of the number and severity implies that security standards of the average alpinist have in tendency increased. Nevertheless, the high number of emergencies on classic 4000ers implies that despite the potentially improved security standards, many tours on famous mountains still have high requirements in terms of alpine skills.

Has Being Lost While High-Altitude Mountaineering Become Less Frequent? A Retrospective Analysis from the Swiss Alps.

BACKGROUND: High-altitude mountaineering is becoming more popular. Despite technical developments such as global positioning systems, mountaineers still lose their way. This study aimed to analyze characteristics of alpinists that lost their way while high-altitude mountaineering in Switzerland. MATERIAL AND METHODS: Data from the central registry of the Swiss Alpine Club between 2009 and 2020 were retrospectively analyzed. Changes in the number of cases and severity of injuries over time were examined using simple linear regression models. Descriptive analyses were performed for age, time of emergency occurrence, and factors associated with being lost. The Mann-Whitney U test assessed between-sex comparisons. RESULTS: Of the 4596 emergency cases during the observation period, 275 cases (5.9%) were due to being lost (76.4% male). A mean of 22.9 ± 9.6 cases per year was detected. The number of cases did not change significantly over time. Similarly, this was the case for the NACA-Score (National Advisory Committee for Aeronautics Score) with the majority of mountaineers remaining uninjured (77.8%). The median age was 42 (35-54) years for the full sample and 45 (35-56) years and 40 (33-48) years for males and females, respectively. Fog or weather changes, exhaustion, and inadequate tour planning (time and darkness) were frequently documented by rescuers as perceived reasons for being lost. Regarding the time of emergency occurrence, three peaks were detected, around 10 am, 5 pm, and 8 pm. CONCLUSIONS: Our findings show that the number of emergencies due to being lost was stable during the 12-year period. Furthermore, we presented factors that might be associated with losing one's way during mountaineering. These results may form an important basis for future studies determining risk factors for being lost and the prevention of such emergencies.

Methodological aspects for accelerometer-based assessment of physical activity in heart failure and health.

BACKGROUND: For valid accelerometer-assessed physical activity (PA) data, several methodological aspects should be considered. We aimed to 1) visualize the applicability of absolute accelerometer cut-offs to classify PA intensity, 2) verify recommendations to measure PA over 7 days by examining inter-day variability and reactivity, 3) examine seasonal differences in PA, and 4) recommend during which 10 h day period accelerometers should be worn to capture the most PA in patients with heart failure (HEART) and healthy individuals (HEALTH). METHODS: Fifty-six HEART (23% female; mean age 66 ± 13 years) and 299 HEALTH (51% female; mean age 54 ± 19 years) of the COmPLETE study wore accelerometers for 14 days. Aim 1 was analyzed descriptively. Key analyses were performed using linear mixed models. RESULTS: The results yielded poor applicability of absolute cut-offs. The day of the week significantly affected PA in both groups. PA-reactivity was not present in either group. A seasonal influence on PA was only found in HEALTH. Large inter-individual variability in PA timing was present. CONCLUSIONS: Our data indicated that absolute cut-offs foster inaccuracies in both populations. In HEART, Sunday and four other days included in the analyses seem sufficient to estimate PA and the consideration of seasonal differences and reactivity seems not necessary. For healthy individuals, both weekend days plus four other days should be integrated into the analyses and seasonal differences should be considered. Due to substantial inter-individual variability in PA timing, accelerometers should be worn throughout waking time. These findings may improve future PA assessment. TRIAL REGISTRATION: The COmPLETE study was registered at clinicaltrials.gov ( NCT03986892 ).

Protocol for a systematic review and meta-analysis of observational studies examining the impact of COVID-19 safety measures on physical activity patterns in adults.

BACKGROUND: The primary objective of this study is twofold: (1) to examine the effect of COVID-19 safety measures, enacted to prevent transmission of SARS-nCOV-2, on total physical activity in the adult general population (≥ 18 years) and (2) to analyze the impact of the factor "severity of safety measures" on potential changes in physical activity. The secondary objective is to investigate the effects of safety measures on the respective PA intensities, i.e., sedentary behavior, light, moderate, and vigorous physical activity. METHODS: A systematic literature search will be performed in the following online databases: Medline (on Ovid), Web of Science, Scopus, L.OVE Coronavirus disease by Epistemonikos, and ProQuest Dissertations & Theses A&I. All obtained citations will undergo title and abstract as well as full-text screening by two independent reviewers. Observational studies investigating the effects of safety measures on physical activity patterns in the adult general population will be included. The standardized mean difference in total physical activity per time unit between pre- and during COVID-19 or between normative data and during COVID-19 will be the primary outcome. The standardized mean difference in sedentary time, light, moderate, and vigorous physical activity will be assessed as secondary outcomes. Eligible studies will be divided between the reviewers for data extraction using a pilot-tested data form. Risk of bias assessment will be performed using a standard assessment tool. If suitable, a random-effects meta-analysis and meta-regression with a unit of safety measure severity as the independent variable will be performed. DISCUSSION: This study will synthesize available data reporting the effect of COVID-19 safety measures on physical activity patterns in adults. Furthermore, we will incorporate a unit for the severity of safety measures for better generalizability of the results. These findings will be of great value for public health policymaking and estimating future health consequences. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021231039.

Counteracting Physical Inactivity during the COVID-19 Pandemic: Evidence-Based Recommendations for Home-Based Exercise.

To reduce transmission of the coronavirus, from its initial outbreak in 2019 up to now, various safety measures have been enacted worldwide by the authorities that have likely led to reduced physical activity levels in the general population. This short communication aims to briefly outline the deteriorative consequences of physical inactivity on parameters of physical fitness and ultimately to highlight associated increases of cardiovascular disease risk and mortality. Finally, evidence-based practical recommendations for exercise that can be performed at home are introduced, to help avoid physical inactivity and therefore maintain or achieve good physical health.

Characteristics of Victims of Fall-Related Accidents during Mountain Hiking.

The study evaluated characteristics of non-fatal mountain hiking accidents caused by falls. Questionnaires were sent to mountain hikers who suffered a fall-related accident in Tyrol (Austria) during a 3-year period. The questionnaire included details of socio-demographic data, physical activity, medication intake, defective vision, breaks, fluid intake, level of fatigue, muscle soreness, use of backpacks, use of hiking sticks, and type of shoes. Data of 405 individuals (57% females and 43% males) were included in the analyses. Victims were 56 ± 15 years of age, had a body mass index of 24.8 ± 3.5, and indicated 4.2 ± 3.9 h/week regular physical activity. A defective vision was reported by 70% of the victims, breaks were frequent (in 80%), and alcohol intake was rare (4%) among the interviewed hikers. Subjective level of fatigue was low and only 5% reported muscle soreness. A backpack was carried by 83% of the victims and the average weight was higher in males compared to females. The majority (61%) of the victims wore ankle-height hiking shoes with a profiled sole. Victims of non-fatal falls in mountain hiking are older than the general population of mountain hikers and are often afflicted with defective vision.