VO2max Research Articles

Associations of Cardiovascular Health Metrics in Childhood and Adolescence With Arterial Health Indicators in Adolescence: The PANIC Study.

Our aim was to assess the relationships of cardiovascular health metrics, cardiorespiratory fitness, lean mass, and fat percentage with arterial structure and function from childhood to adolescence. Five hundred four children aged 6 to 9 years were examined in the PANIC (Physical Activity and Nutrition in Children) study at baseline, 2 and 8 years later. The associations of adjusted American Heart Association cardiovascular health metrics (smoking status, body mass index-SD score, moderate-to-vigorous physical activity, diet quality, plasma total cholesterol, systolic blood pressure, plasma glucose categorized into poor, intermediate, and ideal), the American Heart Association cardiovascular health score, cardiorespiratory fitness measured by maximal oxygen uptake in a bicycle exercise test, lean mass and fat percentage with carotid intima-media thickness (cIMT) and pulse wave velocity (PWV) were analyzed cross-sectionally and longitudinally in 277 participants at age 15 to 17 years. Higher American Heart Association cardiovascular health score at baseline was associated with lower PWV at 8-year follow-up (ß, -0.19 [95% CI, -0.32 to -0.05]). Higher body mass index-SD score and systolic blood pressure were associated with higher cIMT (ß, 0.18 [95% CI, 0.05-0.31]); and (ß, 0.13 [95% CI, 0.00-0.25]; respectively) and PWV (ß, 0.20 [95% CI, 0.07-0.34]) and (ß, 0.13 [95% CI, 0.00-0.26]; respectively) at 8-year follow-up. Higher moderate-to-vigorous physical activity was associated with higher cIMT (ß, 0.25 [95% CI, 0.07-0.43]); yet lower PWV (ß, -0.25 [95% CI, -0.44 to -0.06]) at 8-year follow-up. Better cardiorespiratory fitness (ß, 0.29 [95% CI, 0.08-0.51]) and higher lean mass (ß, 0.51 [95% CI, 0.03-0.98]) were associated with higher cIMT after accounting for American Heart Association cardiovascular health score at 8-year follow-up. While our results suggest that higher cardiometabolic risk factors in childhood may exert unfavorable effects on arterial health during adolescence, we demonstrated the complexity of relationships between cardiovascular health metrics and arterial health indicators in childhood and adolescence. We found different associations of cardiovascular health metrics with cIMT and PWV in childhood and adolescence, calling for caution when interpreting the results of various cardiovascular risk factors with measures of arterial health, particularly in youth. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01803776.

The Role of Digital Smart Wearable Technology in VO2MAX Measurement to Support Athlete Performance and Public Health

This study employed the systematic literature review to investigate to what extent digital smart wearable technology was used in measuring VO2MAX to support athlete performance and public health. To achieve the goal, data were obtained from articles searched through Google Scholar. The search was conducted in September 2024 using the following keywords: (Smart Wearable OR Wearable Technology AND VO2MAX OR VO2 Max OR Cardiorespiratory Fitness AND Athlete Performance OR Sports Performance OR Athletic Performance AND Public Health OR General Population OR Health Monitoring). The articles were selected by considering predetermined inclusion and exclusion criteria. For example, to be included in this review, the articles should be published in Scopus-indexed journals. Additionally, the publication period should be from 2019 to 2024. Based on this timeframe, 1,110 articles were found. Furthermore, they were screened again in multiple stages, and 16 articles that fit the theme and met the inclusion requirements were selected. During the article selection, this study followed the PRISMA guidelines. The results confirmed that wearable technology played an important role in athlete performance optimization through real-time monitoring of VO2MAX. The device enables exercise adjustments based on metrics such as heart rate and diurnal variations, which can improve exercise effectiveness and reduce the risk of injury. Interestingly, it also contributes significantly to improving public health by promoting active lifestyles, monitoring health parameters, and supporting self-health management, especially for the elderly and individuals with chronic diseases. Nonetheless, technical challenges, such as measurement accuracy, data synchronization issues, and user education needs, must be addressed for wearables to be optimally utilized. With proper development, wearable technology has great potential to improve athlete performance and public health. Keywords: Role, Digital Technology, Smart Wearable, VO2MAX, Athlete Performance, Public Health

Effect of Glycated Haemoglobin (HBA1c) on Cardiorespiratory Fitness (CRF) in a Population with Type 2 Diabetes Mellitus (T2DM): A Cross-Sectional Study

Background and Objective: The aim of this study was to evaluate cardiorespiratory fitness (CRF) measures, maximal oxygen consumption (VO2 max), and minute ventilation/carbon dioxide production (VE/VCO2 slope and others) among the T2DM population based on glycated haemoglobin (HBA1c). Material and Methods: The present study comprised a cross-sectional design, with two groups, based on HbA1c values (≤7 and ≥7.1). Laboratory samples were taken to evaluate glycated haemoglobin and fasting blood glucose (FBS). Cardiopulmonary exercise testing was performed to calculate various fitness-related parameters. Data analysis: An independent t-test was used to analyse the outcomes in the two groups. p < 0.05 was considered significant. Linear regression was used to examine the influence of predictor variables on dependent variables. Results: A total of 70 patients agreed to participate in the study, with 19 females and 51 males. The mean (standard deviation) BMI (body mass index) of all participants was 29.7(5.2), the mean (SD) weight was 84.4 (18.9) kg, and the mean height was 167.4 (23) cm. The average age of the individuals was 52 ± 8 years. The independent t-test revealed a significant difference between the two groups in terms of CRF measures. Conclusions: The current research identified the presence of poor glycaemic control and cardiorespiratory fitness measures among the Brazilian population with T2DM. HBA1c, duration of diabetes, age, and BMI can be employed to predict the ventilatory threshold (VT) and VO2 max.

PROSPECTIVE ASSOCIATIONS OF PHYSICAL ACTIVITY AND SEDENTARY TIME IN ADOLESCENCE WITH CARDIOMETABOLIC RISK IN YOUNG ADULTHOOD.

Purpose: The relationship between sedentary time, physical activity, and cardiometabolic risk factors during the transition from adolescence to adulthood remain uncertain. We examined the prospective associations of sedentary time and physical activity at age 15 with cardiometabolic risk markers at age 24.Methods: We used data from the Physical Activity among Norwegian Children Studies (PANCS). Sedentary time, moderate-to-vigorous physical activity (MVPA), and vigorous physical activity (VPA) were measured by accelerometry. Outcomes included body mass index (BMI), waist circumference, visceral fat, maximal oxygen uptake (VO2max), systolic blood pressure, LDL-cholesterol, insulin, high-sensitivity CRP, and a clustered risk Z-score. The prospective associations were modelled through regression.Results: A total of 731 boys and girls participated at age 9 (2005-2006) and 15 (2011-2012), and 258 of these participated again at age 24 (2019-2021). Multiple imputation was performed for all eligible individuals (n = 708). Each standard deviation increase (min/day) in sedentary time at age 15 was associated with lower VO2max at age 24 (β: -1.6 ml/kg/min; 95%CI: -2.8, -0.5). Each standard deviation increase (min/d) in MVPA (β: 1.6 ml/kg/min; 95%CI: 0.8, 2.4) and VPA (β: 1.6 ml/kg/min; 95%CI: 0.8, 2.4) at age 15 were associated with higher VO2max at age 24. VPA in adolescence was further inversely associated with visceral fat mass (β: -41 g; 95%CI: -78, -3), insulin level (β: -4.3 pmol/L; 95%CI: -8.2, -0.4), and the clustered risk Z-score (β: -0.09; 95%CI: -0.18, -0.01) in young adulthood. Childhood BMI modified the association of both MVPA and VPA with clustered risk, with the greatest magnitude of association observed in the highest BMI tertile.Conclusions: Physical activity, especially of vigorous intensity, during adolescence appear to beneficially affect cardiometabolic health in young adulthood. These health benefits may be most pronounced among overweight/obese youth.

Minute Ventilation/Carbon Dioxide Production Slope Could Predict Short- and Long-Term Prognosis of Patients After Acute Decompensated Heart Failure

(1) Background: Heart failure (HF) leads to functional disability and major cardiovascular events (MACEs). Cardiopulmonary exercise testing (CPET) is the gold standard for assessing aerobic capacity and prognostic stratification. This study aimed to evaluate the predischarge CPET variables in patients with acute decompensated HF and identify the submaximal CPET variables with prognostic value. (2) Methods: A retrospective cohort study was conducted at a tertiary center in Taiwan. Patients surviving their first episode of decompensated HF and undergoing predischarge CPET (February 2017 to January 2023) were analyzed. Follow-up was conducted until a MACE or administrative censoring (up to 5 years). Cox regression identified the significant predictors of MACE. (3) Results: The study included 553, 485, and 267 patients at the 3-month, 1-year, and 5-year follow-ups, respectively. MACE rates were 15.0%, 34.2%, and 50.9%. The VE/VCO2 slope was a significant predictor of MACE at all intervals. A VE/VCO2 slope >38.95 increased the risk of MACE by 2.49-fold at 3 months and 1.81-fold at 1 year (both p < 0.001). A slope > 37.35 increased the 5-year MACE risk by 1.75-fold (p = 0.002). (4) Conclusions: The VE/VCO2 slope is a significant submaximal CPET predictor of MACE in patients post-acute decompensated HF for both short- and long-term outcomes.

Time Spent Near Maximal Oxygen Uptake During Exercise at Different Regions of the Severe-Intensity Domain.

Faricier, R, Fleitas-Paniagua, PR, Iannetta, D, Millet, GY, Keir, DA, and Murias, JM. Time spent near maximal oxygen uptake during exercise at different regions of the severe-intensity domain. J Strength Cond Res XX(X): 000-000, 2024-This study applied the critical power (CP) model and several bouts of constant-power exercise within different regions of the severe-intensity domain to determine whether there exists an optimal intensity to maximize time spent near V̇o2peak. Subjects visited the laboratory 9 times. After a ramp-incremental test to determine V̇o2peak and peak power output (POpeak), 9 active individuals (5 females) performed 4 constant-power bouts to task failure between 65 and 100%POpeak to estimate CP and total finite work above CP (W'). Subjects then completed 4 additional exhaustive trials predicted to result in task failure in ∼3, 6, 9, and 12 minutes. Time spent at V̇o2peak was calculated as the duration at which V̇o2 ≥ 95% of the trial-specific V̇o2peak. The level of significance set for the study was p < 0.05. Mean CP and W' were 201 ± 48 W and 17.6 ± 8.4 kJ, respectively. For each bout, time to task failure was 2.7 ± 0.5, 6.3 ± 0.6, 9.5 ± 1.2, and 13.1 ± 3.1 minutes for the 3-, 6-, 9-, and 12-minute conditions. Time spent at V̇o2peak during the 3-minute trial (45 ± 22 seconds) was shorter than during the 9-minute (204 ± 104 seconds; p = 0.002) and 12-minute trials (260 ± 155 seconds; p < 0.001). The 6-minute trial (117 ± 46 seconds) had shorter (p = 0.005) time spent at V̇o2peak compared with the 12-minute trial. At least when performing single bouts of exercise, intensities closer to CP (i.e., those sustainable for ∼9 minutes or longer) seem preferable compared with POs in the upper regions of the severe-intensity domain to maximize time at V̇o2peak.

Addressing mental health challenges in college students: A biomechanical approach to mitigating stress and cognitive load through physical intervention strategies

The main objective of this investigation is to find out how biomechanical actions, such as physical activity programs, balanced adjustments, and mindfulness-based posture correction, are successful at reducing Cognitive Load (CL) and levels of stress among college students. Mechanical adjustments decreased stress, physical activity reduced CL, and mindfulness-based posture correction improved Mental Health (MH), according to a long-term experiment with 28 students from four distinct educational fields. Investigators examined students’ stress, CL, and BH levels monthly. The outcome results dealt with all three predictions. A student’s Perceived Stress Scale (PSS) score dropped from 24.66 to 18.10 (mean difference = 6.56, t = 4.82, p = 0.0001) after experiencing practical changes, demonstrating a significant decrease in stress levels. Following the exercise support, CL, as determined by the NASA Task Load Index (NASA-TLX), dropped from 65.38 to 54.23 (mean difference = 11.15, t = 5.29, p = 0.00005). Ratings for BH increased significantly after exercising mindfulness-based posture correction (from 78.63 to 85.13; mean difference = −6.50, t = −4.92, p = 0.00007). The median variation in PF (VO2 Max) went from 40.46 to 45.11 (t = −3.78, p = 0.0012), and the difference in value was −4.65.

An Online Training Program Was Effective on Improving Physical Performance and Body Composition in U20 Soccer Players During the COVID-19 Quarantine

Abstract It is recommended for athletes keep training to reduce the negative effects of detraining. This study aimed to verify the effects of a 15-week online training intervention during a pandemic quarantine in body composition and physical capacity of highly trained soccer players. Sixteen male under-20 soccer players were assessed after the first period of COVID-19 quarantine (March 2020 to September 2020; 170 days), and after the second period of COVID-19 quarantine (November 2020 to February 2021, 107 days). Body composition, vertical jump height, hamstring maximum strength and aerobic capacity were assessed. The online training program was performed during the second lockdown. In comparison with first pre assessments, results showed that fat mass (−0.95 ± 1.27), free fat mass (1.22 ± 1.19), squat jump height (5.36 ± 1.99) and counter movement jump (3.19 ± 3.77) were significantly improved (P &lt; 0.05). However, there were no significant changes in total body mass, hamstring eccentric strength, and Yo-Yo IR1 after online training (P &gt; 0.05). In summary, the findings of this study highlight the importance of carrying out a training program during a period of absence from traditional soccer training, in order to maintain the level of physical capacities of youth soccer players.

Assessment and repeatability of aerobic capacity using the Chester Step Test among current, former, and never smokers.

Cigarette smoking contributes to reduced cardiorespiratory performance, which may improve upon cessation. Consequently, former smokers' cardiorespiratory fitness should not be significantly different from that of never-smokers. This study aims to compare V̇O2max values among current, former, and never smokers and assess the repeatability of measurements using the Chester Step Test (CST). V̇O2max measurements were available from a total of 70 subjects (23 current, 23 former, and 24 never-smokers) and showed significant repeatability. Current smokers had the worst aerobic capacity, with a mean VO2max ± SD of 38.8 ± 4.5, which was significantly lower than the VO2max of 41.62 ± 3.8 in never-smokers (p < 0.0001) and 41.43 ± 4.6 in former smokers (p < 0.0001). No significant differences were observed between never-smokers and former smokers. V̇O2max estimates by CST were reproducible and showed that the aerobic capacity of individuals who smoke is substantially inferior compared to never and former smokers. Improvement in cardiorespiratory performance following smoking cessation may have important implications for smoking cessation, especially for those smokers who perceive enhanced physical performance as a tangible benefit.

Validating the Use of Continuous Glucose Monitors With Nondiabetic Recreational Runners.

Continuous glucose monitors (CGMs) are becoming increasingly popular among endurance athletes despite unconfirmed accuracy. We assessed the concurrent validity of the FreeStyle Libre 2 worn on 2 different sites at rest, during steady-state running, and postprandial. Thirteen nondiabetic, well-trained recreational runners (age = 40 [8]y, maximal aerobic oxygen consumption = 46.1 [6.4]mL·kg-1·min-1) wore a CGM on the upper arm and chest while treadmill running for 30, 60, and 90minutes at intensities corresponding to 50%, 60%, and 70% of maximal aerobic oxygen consumption, respectively. Glucose was measured by manually scanning CGMs and obtaining a finger-prick capillary blood glucose sample. Mean absolute relative difference, time in range, and continuous glucose Clarke error grid analysis were used to compare paired CGM and blood glucose readings. Across all intensities of steady-state running, we found a mean absolute relative difference of 13.8 (10.9) for the arm and 11.4 (9.0) for the chest. The coefficient of variation exceeded 70%. Approximately 47% of arm and 50% of chest paired glucose measurements had an absolute difference ≤10%. Continuous glucose Clarke error grid analysis indicated 99.8% (arm) and 99.6% (chest) CGM data fell in clinically acceptable zones A and B. Time-in-range analysis showed reduced accuracy at lower glucose levels. However, CGMs accurately detected trends in mean glucose readings over time. CGMs are not valid for point glucose monitoring but appear to be valid for monitoring glucose trends during steady-state exercise. Accuracy is similar for arm and chest. Further research is needed to determine whether CGMs can detect important events such as hypoglycemia during exercise.

Age- and Gender-Specific Reference Values for Physical Performance in Tunisian Youth Basketball Players

Background/Objectives: Physical performance is becoming increasingly critical in basketball, as it directly influences players’ agility, power, and endurance. This study aimed to assess the progression of body composition and physical performance metrics across different ages and genders, establishing age- and gender-specific reference values for Tunisian basketball athletes. Methods: A total of 469 Tunisian basketball players (239 boys and 230 girls) were assessed and grouped by age. Anthropometric measures—including standing and sitting height, body mass, leg length, body mass index, fat mass, fat-free mass, body fat percentage, wingspan, and leg muscle volume—were collected alongside physical performance metrics. Performance tests included countermovement and squat jumps, change-of-direction speed, maximal oxygen uptake, flexibility, the five-jump test, and 5 m, 10 m, and 20 m sprints with and without the ball. Normative data were generated based on age and gender categories. Results: The findings revealed significant age-related improvements in both anthropometric and performance parameters. Boys consistently outperformed girls in physical and fitness-related measures, with gender differences becoming more pronounced with age. Stepwise regression analyses indicated that, for boys, body fat percentage, leg muscle volume, standing height, and wingspan were the best predictors of physical performance. For girls, body fat percentage, standing height, and sitting height were identified as key predictors. Conclusions: The newly established Tunisian reference values for physical performance in youth basketball provide valuable benchmarks that can support the development of explosive power and strength in players, aiding in talent identification and potentially enhancing individual and team performance outcomes.

Effects of variation in exercise training load on cognitive performances and neurotrophic biomarkers in patients with coronary artery disease.

This study compared the effects of linear (LP) and nonlinear (NLP) training periodization on cognitive functions, neurotrophic biomarkers [plasma brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1)], and cathepsin-B in patients with coronary artery disease (CAD). Forty-four patients with CAD reported to our laboratory on two occasions to undergo testing procedures before and after training sessions, and were then blindly randomized to NLP or LP for 36 training sessions. Visit 1 included blood samples and a maximal cardiopulmonary exercise testing to get maximal oxygen uptake (V̇o2peak). Visit 2 included cognitive functions assessment. Thirty-nine patients completed the study (LP: n = 20, NLP: n = 19), with no observed changes in cognitive performances after the training intervention in either group. IGF-1 concentration decreased in both groups (time-effect: P < 0.001), whereas BDNF concentration increased (time-effect: P < 0.05) without group interaction, and cathepsin-B did not change after the intervention. Associations were found between ΔV̇o2peak and ΔBDNF (R2 = 0.18, P = 0.04), and ΔIGF-1 and Δshort-term/working memory (R2 = 0.17, P = 0.01) in the pooled sample, with ΔIGF-1 and ΔBDNF accounting for 10% of the variance in Δshort-term/working memory. In the LP group, associations were found between ΔV̇o2peak and ΔBDNF (R2 = 0.45, P = 0.02), ΔBDNF and Δshort-term/working memory (R2 = 0.62, P = 0.004), ΔIGF-1 and Δshort-term/working memory (R2 = 0.31, P = 0.01), and ΔIGF-1 and Δexecutive function (R2 = 0.22, P = 0.04). This study indicates that linear and nonlinear training periodization led to an increase in BDNF, and a decrease in IGF-1, without change in cognitive function in individuals with stable CAD.NEW & NOTEWORTHY We used a novel and supervised iso-energetic training, integrating both moderate- and high-intensity aerobic exercises. Our findings indicate that greater variation in training load did not yield cognitive enhancements, although both protocols exhibited positive effects on brain-derived neurotrophic factor (BDNF) levels. Moreover, this study establishes a clear positive association between short-term and working memory and neurotrophic biomarkers. In addition, the independent predictive value of change in insulin-like growth factor-1 (IGF-1) on improvement in short-term and working memory highlight the close relationship between neurotrophic markers and cognition. Consequently, our results advocate for exercise training interventions targeting neurotrophic biomarkers to enhance cognitive function among individuals with coronary artery disease.

Carbon monoxide supplementation: evaluating its potential to enhance altitude training effects and cycling performance in elite athletes.

Altitude training is a cornerstone for endurance athletes for improving blood variables and performance, with optimal effects observed at ∼2,300-2,500 meters above sea level (m.a.s.l.). However, elite cyclists face challenges such as limited access to such altitudes, inadequate training facilities, and high expenses. To address these issues, a novel method involving daily exposure to carbon monoxide (CO) has been proposed to amplify altitude training adaptations at suboptimal altitudes. Thirty-one male cyclists were assigned to three groups: Live-High Train-High with CO inhalation (LHTHCO), Live-High Train-High (LHTH), and Live-Low Train-Low (LLTL). The LHTHCO group underwent CO inhalation twice daily in the afternoon/evening to elevate carboxyhemoglobin concentration to ∼10%. Hematological variables, in vivo muscle oxidative capacity, and physiological indicators of cycling performance were assessed before and after a 3-week altitude training camp at 2,100 m.a.s.l. LHTHCO demonstrated a larger increase in hemoglobin mass (Hbmass) compared to both LHTH and LLTL. Although there were no statistical differences between LHTHCO and LHTH in submaximal and maximal performance measures, LHTHCO displayed greater improvements in 1-min maximal power output during incremental testing (Wmax), power output at lactate threshold, and maximal oxygen consumption (V̇o2max) compared to LLTL. LHTH demonstrated a larger improvement than LLTL in Wmax and V̇o2max, with no group differences in Hbmass or submaximal measures. Muscle oxidative capacity did not differ between groups. These findings suggest that combining moderate-altitude training with daily CO inhalation promotes hematological adaptations more effectively than moderate altitude alone and enhances cycling performance metrics in cyclists more than sea-level training.NEW & NOTEWORTHY Three weeks of training at moderate altitude with exposure to low doses of CO can significantly enhance hematological adaptations in elite cyclists compared to moderate-altitude training alone. Cycling performance determinants improved more with CO inhalation at moderate altitude compared to sea-level training, whereas there were no differences in submaximal and maximal performance measures compared to moderate-altitude training alone. This study highlights the potential of CO supplementation as an effective adjunct to altitude training regimens.

A Novel Method to Predict Carbohydrate and Energy Expenditure During Endurance Exercise Using Measures of Training Load.

Sports nutrition guidelines recommend carbohydrate (CHO) intake be individualized to the athlete and modulated according to changes in training load. However, there are limited methods to assess CHO utilization during training sessions. We aimed to (1) quantify bivariate relationships between both CHO and overall energy expenditure (EE) during exercise and commonly used, non-invasive measures of training load across sessions of varying duration and intensity and (2) build and evaluate prediction models to estimate CHO utilization and EE with the same training load measures and easily quantified individual factors. This study was undertaken in two parts: a primary study, where participants performed four different laboratory-based cycle training sessions, and a validation study where different participants performed a single laboratory-based training session using one of three exercise modalities (cycling, running, or kayaking). The primary study included 15 cyclists (five female; maximal oxygen consumption [ O2max], 51.9 ± 7.2mL/kg/min), the validation study included 21 cyclists (seven female; O2max 53.5 ± 11.0mL/kg/min), 20 runners (six female; O2max 57.5 ± 7.2mL/kg/min), and 18 kayakers (five female; O2max 45.6 ± 4.8mL/kg/min). Training sessions were quantified using six training load metrics: two using heart rate, three using power, and one using perceived exertion. Carbohydrate use and EE were determined separately for aerobic (gas exchange) and anaerobic (net lactate accumulation, body mass, and O2 lactate equivalent method) energy systems and summed. Repeated-measures correlations were used to examine relationships between training load and both CHO utilization and EE. General estimating equations were used to model CHO utilization and EE, using training load alongside measures of fitness and sex. Models were built in the primary study and tested in the validation study. Model performance is reported as the coefficient of determination (R2) and mean absolute error, with measures of calibration used for model evaluation and for sport-specific model re-calibration. Very-large to near-perfect within-subject correlations (r = 0.76-0.96) were evident between all training load metrics and both CHO utilization and EE. In the primary study, all models explained a large amount of variance (R2 = 0.77-0.96) and displayed good accuracy (mean absolute error; CHO = 16-21g [10-14%], EE = 53-82kcal [7-11%]). In the validation study, the mean absolute error ranged from 16-50g [15-45%] for CHO models to 53-182kcal [9-31%] for EE models. The calibrated mean absolute error ranged from 9-20g [8-18%] for CHO models to 36-72kcal [6-12%] for EE models. At the individual level, there are strong linear relationships between all measures of training load and both CHO utilization and EE during cycling. When combined with other measures of fitness, EE and CHO utilization during cycling can be estimated accurately. These models can be applied in running and kayaking when used with a calibration adjustment.

No effect of aerobic fitness on exercise-induced diaphragm fatigue in females.

We tested the hypothesis that the incidence and magnitude of diaphragm fatigue following high-intensity exercise would be lower in females with a high aerobic capacity (Hi-Fit) compared with healthy females with an average aerobic fitness (Avg-Fit). Participants were assigned to groups based on their peak O2 uptake (V̇o2peak) obtained during cycle exercise: Hi-Fit n = 9, V̇o2peak ≥ 56.1 ± 3.4 mL·kg-1·min-1 versus Avg-Fit n = 9, V̇o2peak ≤ 35.7 ± 4.9 mL·kg-1·min-1. On the second day, diaphragm fatigue was assessed before and after constant load exercise test to exhaustion. Magnetic stimulation of the phrenic nerve roots was used to nonvolitionally assess diaphragm fatigue by measurement of transdiaphragmatic twitch pressure (Pdi,tw). Both groups exercised at >90% of V̇o2peak for a similar duration (Hi-Fit: 546.1 ± 177.8 vs. Avg-Fit: 559.3 ± 175.0 s, P = 0.9). Diaphragm fatigue was defined as a ≥15% reduction in Pdi,tw, approximately two times greater than the coefficient of variation. The mean group average reduction in Pdi,tw following exercise in the Hi-Fit (17.5%) and Avg-Fit groups (12.2%) was not different between groups (P = 0.2). The Hi-Fit group performed exercise at a higher absolute work rate that elicited significantly greater ventilatory work and inspiratory muscle force output. The Hi-Fit group did not experience greater fatigue compared with the Avg-Fit group, which we attribute to a greater reliance on accessory respiratory muscle recruitment, to training-induced increases in the aerobic capacity of the diaphragm, or a combination of the two. In summary, aerobic fitness is not predictive of exercise-induced diaphragm fatigue in healthy females.NEW & NOTEWORTHY We hypothesized that females with a high aerobic capacity would be resistant to exercise-induced diaphragm fatigue relative to healthy but untrained females. We assessed the pressure generated by the diaphragm following exhaustive exercise by stimulating the phrenic nerves. The magnitude and incidence of fatigue were similar between groups. Despite having higher ventilatory demands during exercise highly trained females were resistant to greater diaphragm fatigue. Aerobic fitness is not predictive of exercise-induced diaphragm fatigue in females.

Efficient removal of nitrate and ammonium by strain Pseudomonas poae EH-E3 under acidic pH and low-temperature conditions

The combined effect of low temperature and an acidic environment may restrict the growth and metabolic activity of microorganisms involved in nitrogen removal. To overcome poor biological nitrogen removal efficiency during low-temperature treatment of acidic wastewater, a novel pure strain of Pseudomonas poae EH-E3 was successfully isolated and screened based on its strong heterotrophic nitrification and aerobic denitrification capacity. Strain EH-E3 could completely eliminate inorganic nitrogen sources of nitrate within 30h and ammonium within 20h at 15 °C and pH 5.0, with corresponding removal efficiencies for total nitrogen of 95.13% and 91.35%, respectively. Nitrogen balance testing indicated that strain EH-E3 removed 43.25% of ammonium, 45.72% of nitrate, and 51.20% of nitrite in the form of gaseous products. Enzyme activity assays revealed that the specific activities of ammonia monooxygenase, nitrate reductase, and nitrite reductase were 0.533, 0.956, and 0.011 U/mg proteins, respectively. These findings suggest that strain EH-E3 has strong potential for use in low-temperature treatment of acidic wastewater.

Middle cerebral artery blood velocity and end-tidal carbon dioxide responses to moderate intensity cycling in children, adolescents, and adults.

This study investigated the middle cerebral artery blood velocity (MCAv) response to constant work-rate moderate-intensity cycling exercise in 21 children (9.3 ± 0.8 yr), 17 adolescents (12.3 ± 0.4 yr), and 20 young adults (23.6 ± 2.4 yr). Participants completed an incremental ramp test to exhaustion on a cycle ergometer to determine maximal oxygen uptake and gas exchange threshold (GET) before completing three 6-min transitions at a moderate intensity (90% GET) on separate visits. On each visit, bilateral MCAv was measured by transcranial Doppler ultrasonography and breath-by-breath end-tidal carbon dioxide ([Formula: see text]) via a metabolic cart. Data were ensemble-averaged for each participant and analyzed using a monoexponential model. Absolute MCAv was significantly higher throughout exercise in children and adolescents compared with adults (P < 0.001). Children had a significantly lower relative increase in MCAv from baseline (∼12%) compared with adolescents (∼20%) and adults (∼18%, P < 0.040). All adolescents and adults had a monoexponential rise in MCAv and [Formula: see text], but this was observed in only eight children. Children and adolescents had a significantly faster MCAv time constant (τ, 12 ± 6 and 14 ± 8 s, respectively) compared with adults (27 ± 9 s, P < 0.001). MCAv τ was positively associated with faster [Formula: see text] τ in adolescents (r = 0.70, P = 0.002) but not in children (r = -0.20, P = 0.640). Time- and amplitude-based response parameters of MCAv kinetics were significantly associated with [Formula: see text] kinetics in adults (r = 0.50-0.74, P ≤ 0.025), but not in children (r = -0.19 to -0.48, P > 0.227). These findings suggest that the transition from childhood to adulthood impacts the MCAv response to exercise and the relationships between [Formula: see text] and MCAv kinetics during exercise.NEW & NOTEWORTHY This is the first study to find that children have smaller increases in Δ%MCAv (∼12%) during moderate-intensity exercise compared with adolescents and adults (∼18%-20%). Furthermore, MCAv kinetics were significantly faster in children and adolescents, compared with adults. MCAv kinetic responses were significantly and positively associated with [Formula: see text] kinetics in adults, but not in children. These novel data also suggest that the regulatory role of [Formula: see text] on MCAv during exercise begins to strengthen during adolescence.

Heat Strain in Different Hot Environments Hiking in Wildland Firefighting Garments.

Wildland firefighters can work at high intensity in hot environments for extended periods of time. The resulting heat strain may be modified by the environmental conditions (i.e., ambient temperature and humidity [RH]) even at equal wet-bulb globe temperatures. This investigation assessed if a hot and dry condition would create greater strain than moderate and high humidity at equivalent wet-bulb globe temperature (28°C). Twelve participants (age 24±2 y) walked at 40-50% maximum aerobic capacity for 90 and 40 min separated by a 20 min rest in dry (40°C, 20% RH), moderate-humidity (34°C, 50% RH), and high-humidity (29°C, 90% RH) conditions wearing fire resistant jacket, pants, gloves, and helmet with the neck and face exposed. Peak core temperature was higher in moderate-humidity (38.9±0.2°C, p=0.01) and high-humidity (38.9±0.6°C, p<0.01) than dry condition (38.5±0.3°C). Average net heat gain was less in dry (33±22 W) compared to moderate-humidity (38±23 W, p<0.01) and high-humidity (39±28 W, p<0.01). Peak heart rate (174±14 bpm, p=0.94), Physiological Strain Index (7.7±1.4 score, p=0.99), perceived exertion (8±2 rating, p=0.97), and Perceptual Strain Index (7.3±1.6 score, p=0.99) were not different in high-humidity compared to the dry condition (167±19 bpm, 6.9±1.3 score, 6±2 rating, 7.3±1.7 score, respectively). Whole-body sweat rate (15±6 mL/min, p=0.58) and thermal sensation (7±1 rating, p=0.37) were not different. Hiking in a humid condition while wearing protective garments creates greater exertional heat strain compared to a dry condition of equivalent wet-bulb globe temperature. Wildland firefighters should consider extra strategies to mitigate hyperthermia when humidity is high.

КОНДИЦІЙНЕ ТРЕНУВАННЯ КІБЕРСПОРТСМЕНІВ З ВИКОРИСТАННЯМ МОБІЛЬНИХ ДОДАТКІВ

The issue of insufficient physical activity among computer game players remains relevant. This study proposes a solution based on the comprehensive use of gaming-oriented mobile applications for the conditioning training of esports athletes. A sequential pedagogical experiment was conducted to determine the effectiveness of esports athletes applying an aerobic-focused conditioning training program (slow running). The program’s unique feature is its implementation in a remote format using mobile applications for planning, execution, control, and performance evaluation. It is based on an original concept of implementing running training in the form of a mobile running application (the so-called “exergame”) with a game-like nature (“Zombies, Run!”). The program was designed for a six-week implementation. Its effectiveness was determined by evaluating the dynamics of indicators: 1600 m run time; calculated maximal oxygen consumption (VO2 max); and heart rate (HR). Subjective attitudes towards the program’s physical loads were assessed using the Rating of Perceived Exertion (RPE) scale and the Physical Activity Satisfaction Needs scale. It was found that esports athletes significantly (p&lt;0.05) improved their 1600 m run time, VO2 max, and HR indicators under the influence of the slow running program. Along with the volume and intensity increase of the running load, a decrease in RPE scale indicators was observed. The obtained data confirmed the advantages of the comprehensive use of mobile applications for normalizing the motor activity of esports athletes in the form of conditioning training. Both the remote format of planning and accounting and the game format of activities contributed to increasing the engagement of esports athletes in physical activity. The effectiveness of the slow running training program for esports athletes using mobile applications was established in terms of increasing physical activity (regular, organized physical activity), improving physical fitness (duration and volume of slow running), enhancing physical condition (VO2 max, HR), and interest in physical activity (adherence).

Exploring the physical activity levels of egyptian women with premenstrual syndrome: a preliminary study

Background and Study Aim. Premenstrual syndrome (PMS) affects a significant proportion of women, impacting their daily lives and well-being. The association between physical activity levels, the prevalence of premenstrual syndrome (PMS), and the severity of PMS remains debatable. Therefore, this study aimed to identify physical activity levels among a cohort of Egyptian females with PMS. Material and Methods. This study included one hundred females with PMS. Physical activity levels, anaerobic power, aerobic capacity, BMI, and dysmenorrhea were investigated. PMS severity was assessed using the Premenstrual Syndrome Scale (PMSS), and the females' physical activity was evaluated using the International Physical Activity Questionnaire (IPAQ). The 1-mile submaximal test and the Running-Based Anaerobic Sprint Test (RAST) were used to assess aerobic capacity and anaerobic power, respectively. Results. The findings revealed a significant association between PMS severity and physical activity (p &lt; 0.05). There was no significant difference in aerobic capacity among those with mild, moderate, and severe PMS (p &gt; 0.05). There was no significant association between PMS severity and marital status (p &gt; 0.05), whereas there was a significant association with dysmenorrhea (p &lt; 0.05), especially among moderate and severe PMS sufferers. Females with severe PMS had a significantly higher BMI than those with mild PMS (p &lt; 0.05) and those with moderate PMS (p &lt; 0.05). Mild and moderate PMS females showed no significant difference in BMI (p &gt; 0.05). Conclusions. It can be concluded that physical activity levels and BMI may affect PMS. Therefore, being physically active and maintaining a normal-range BMI might reduce PMS severity.