Differences between Treadmill and Cycle Ergometer Cardiopulmonary Exercise Testing Results in Triathletes and Their Association with Body Composition and Body Mass Index

Low- and moderate-intensity aerobic exercise improves the physiological acclimatization of lowlanders on the Tibetan plateau

This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high altitudes (HA), considering the physiological challenges of hypoxic conditions. Overall, 121 lowlanders who had lived on the Tibetan Plateau for >2 years and were still living at HA during the measurements were randomly classified into four groups. Each individual of the low-intensity (LI), moderate-intensity (MI), and high-intensity (HI) groups performed 20 sessions of aerobic exercise at HA (3680 m) over 4 weeks, while the control group (CG) did not undergo any intervention. Physiological responses before and after the intervention were observed. The LI and MI groups experienced significant improvement in cardiopulmonary fitness (0.27 and 0.35 L/min increases in peak oxygen uptake [V ˙ $\dot{\mathrm{V}}$ O2peak], both p < 0.05) after exercise intervention, while the hematocrit (HCT) remained unchanged (p > 0.05). However, HI exercise was less efficient for cardiopulmonary fitness of lowlanders (0.02 L/min decrease inV ˙ $\dot{\mathrm{V}}$ O2peak, p > 0.05), whereas both the HCT (1.74 %, p < 0.001) and glomerular filtration rate (18.41 mL/min, p < 0.001) increased with HI intervention. Therefore, LI and MI aerobic exercise, rather than HI, can help lowlanders in Tibet become more acclimated to the HA by increasing cardiopulmonary function and counteracting erythrocytosis.

Assessment of Maximal Oxygen Uptake (VO2 Max) in Athletes and Nonathletes Assessed in Sports Physiology Laboratory

BACKGROUND

 Athletes' physical prowess plays a crucial role in their ability to succeed in any sporting endeavor. Each athlete on the field must have an exceptional aerobic capacity to withstand fierce competition and stringent regulatory guidelines. Maximal oxygen uptake (VO2 max) is a quantitative measure of aerobic capacity and is regarded as one of the most reliable indicators of cardiorespiratory and overall physical fitness of an individual by sports physiologists. The study aims to evaluate the VO2 max of athletes in comparison with nonathletes during treadmill and lower limb cycle ergometry exercises as assessed in the Sports Physiology Laboratory of a rural medical college. Treadmill exercise and bicycle ergometer exercise are the most common to perform as indoor aerobic exercises to assess one's physical fitness. Both these tests are equally useful in eliciting cardiac and vascular responses, so both these modalities were used to assess aerobic fitness.

METHODS

 This cross-sectional study, which examined participants aged 17-25, included 30 athletes (cases) and 120 age- and sex-matched controls. The VO2 max was evaluated using the Metabolic Module of Lab Chart Software, which was investigated through the PowerLab data acquisition system, AD Instruments (Bella Vista, NSW, Australia).

RESULTS

 The mean age of male athletes was 20.51 ± 2.69 years and of female athletes was 20.53 ± 1.62 years. The mean and standard deviation of VO2 max on the treadmill for male cases was 52.37 ± 8.78 mL/kg/min and for female cases was 40.96 ± 4.06 mL/kg/min, and on a cycle ergometer for male cases was 45.21 ± 9.43 mL/kg/min and for female cases was 34.32 ± 5.12 mL/kg/min. For the control group, the mean age of control males was 21.2 ± 2.62 years and of control females was 20.36 ± 1.5 years. The mean and standard deviation of VO2 max on the treadmill for control males was 33.35 ± 3.77 mL/kg/min and for control females was 25.09 ± 7.07 mL/kg/min, and on the cycle ergometer for control males was 34.17 ± 2.75 mL/kg/min and for control females was 24.15 ± 5.35 mL/kg/min.

CONCLUSION

This study showed significantly (p < 0.001) higher VO2 max levels in athletes of both genders compared to their age- and sex-matched controls upon exercise on the treadmill and cycle ergometer. This study underscores the significance of better cardiorespiratory fitness in athletes than nonathletes, giving pertinent insights about their aerobic capacity, which is precisely measured and expressed in terms of VO2.

Effects of constant-load exercise and high-intensity interval training on reliever medication consumption and peak expiratory flow in individuals with asthma: a randomised controlled trial

Introduction

The effect of aerobic training on reliever medication consumption (short-acting β2-agonist (SABA)) and peak expiratory flow (PEF) in participants with asthma is poorly known. The comparison between constant-load exercise (CLE) and high-intensity interval training (HIIT) in these outcomes has never been tested. The purpose of the present study was to compare the effects of CLE or HIIT in SABA consumption and PEF improvement during an exercise programme in subjects with asthma.

Methods

Clinically stable participants were randomised into CLE (n=27; 70-85% of the maximal load (Wmax)) or HIIT (n=28; 80-140% Wmax). The programme lasted 12 weeks (two sessions per week, 40 min per session), and the intensity was based on cardiopulmonary exercise testing (CPET). PEF was assessed before and after each exercise session. SABA was used if PEF was <70%. Clinical control (Asthma Control Questionnaire (ACQ)-6), CPET and aerobic fitness were also assessed before and after the intervention.

Results

Both groups were similar at baseline. CLE and HIIT reduced SABA consumption throughout the intervention (p<0.05). Before training, 14 patients required SABA before exercising, but only one needed it after the intervention. Changes in post-exercise PEF were lower in the CLE group than in the HIIT group (1.6±25.3 versus 10.3±13.7%). Both groups improved aerobic fitness (10.1±12.8% versus 5.7±15.6%) and clinical asthma control; however, only the HIIT group achieved a minimal clinically important difference in the ACQ-6 post-intervention (-0.23±1.06 versus -0.52±0.73 Δ score).

Conclusion

CLE and HIIT reduced SABA consumption; however, only HIIT increased PEF and asthma clinical control after the intervention. These results reinforce the importance of exercise training in moderate-to-severe asthma.

Is the Ventilatory Efficiency in Endurance Athletes Different?-Findings from the NOODLE Study

Background: Ventilatory efficiency (VE/VCO2) is a strong predictor of cardiovascular diseases and defines individuals' responses to exercise. Its characteristics among endurance athletes (EA) remain understudied. In a cohort of EA, we aimed to (1) investigate the relationship between different methods of calculation of VE/VCO2 and (2) externally validate prediction equations for VE/VCO2. Methods: In total, 140 EA (55% males; age = 22.7 ± 4.6 yrs; BMI = 22.6 ± 1.7 kg·m-2; peak oxygen uptake = 3.86 ± 0.82 L·min-1) underwent an effort-limited cycling cardiopulmonary exercise test. VE/VCO2 was first calculated to ventilatory threshold (VE/VCO2-slope), as the lowest 30-s average (VE/VCO2-Nadir) and from whole exercises (VE/VCO2-Total). Twelve prediction equations for VE/VCO2-slope were externally validated. Results: VE/VCO2-slope was higher in females than males (27.7 ± 2.6 vs. 26.1 ± 2.0, p < 0.001). Measuring methods for VE/VCO2 differed significantly in males and females. VE/VCO2 increased in EA with age independently from its type or sex (β = 0.066-0.127). Eleven equations underestimated VE/VCO2-slope (from -0.5 to -3.6). One equation overestimated VE/VCO2-slope (+0.2). Predicted and observed measurements differed significantly in nine models. Models explained a low amount of variance in the VE/VCO2-slope (R2 = 0.003-0.031). Conclusions: VE/VCO2-slope, VE/VCO2-Nadir, and VE/VCO2-Total were significantly different in EA. Prediction equations for the VE/VCO2-slope were inaccurate in EA. Physicians should be acknowledged to properly assess cardiorespiratory fitness in EA.

Cardiorespiratory fitness (V̇O2peak) across the adult lifespan in persons with multiple sclerosis and matched healthy controls

OBJECTIVES

Cardiorespiratory fitness (measured as peak oxygen uptake; V̇O2peak) is a well-established health predictor in the general population and in persons with multiple sclerosis (pwMS). We aimed to investigate differences in V̇O2peak between age groups and the prevalence of V̇O2peak impairments across the adult lifespan in pwMS compared to age- and sex-matched healthy controls (HC).

DESIGN

Cross-sectional study.

METHODS

Data from 469 pwMS (EDSS range 1.0-7.0), who carried out graded cardiopulmonary exercise testing during their rehabilitation stay at the Valens clinic from 07/2010 to 10/2022, were retrospectively analyzed. Data from 21,063 HC were extracted from previously published studies containing normative reference values.

RESULTS

With advanced age (i.e., across age groups), a continuous deterioration of V̇O2peak was observed in both pwMS and HC. Within all age groups, V̇O2peak was reduced in pwMS compared to HC with deficits ranging from 29 % to 40 % for females (p < .05), and from 30 % to 41 % for males (p < .05). However, no age ∗ group interaction was observed in neither males (p = .626) nor females (p = .557). With V̇O2peak impairments defined as values below the 5th percentile of HC, a high prevalence was observed in pwMS, with values ranging from 48 % to 100 % across age groups.

CONCLUSIONS

The present data provide evidence for a parallel deterioration of V̇O2peak in pwMS and matched controls with advancing age, coinciding with a high prevalence of impairments in V̇O2peak already present in young adulthood in pwMS. Understanding the extent of impairments as well as the age trajectories of cardiorespiratory fitness in pwMS is crucial for designing optimal rehabilitative and preventive interventions.

Exercise testing for young athletes

With increasing competitiveness across the sporting landscape, there is a need for more research into monitoring and managing the young athlete, as the needs of a young athlete are vastly different to those of an older athlete who is already established in their respective sport. As the age of sports specialisation seems to decrease, exercise testing in the younger cohort of athletes is crucial for safety and long-term success. This article provides a comprehensive summary of available testing and monitoring methods that can be used to assist young athletes as they mature and attempt to excel in their chosen sport.

Estimated standard values of aerobic capacity according to sex and age in a Japanese population: A scoping review

Aerobic capacity is a fitness measure reflecting the ability to sustain whole-body physical activity as fast and long as possible. Identifying the distribution of aerobic capacity in a population may help estimate their health status. This study aimed to estimate standard values of aerobic capacity (peak oxygen uptake [Formula: see text] and anaerobic threshold [AT]/kg) for the Japanese population stratified by sex and age using a meta-analysis. Moreover, the comparison of the estimated standard values of the Japanese with those of other populations was performed as a supplementary analysis. We systematically searched original articles on aerobic capacity in the Japanese population using PubMed, Ichushi-Web, and Google Scholar. We meta-analysed [Formula: see text] (total: 78,714, men: 54,614, women: 24,100) and AT (total: 4,042, men: 1,961, women: 2,081) data of healthy Japanese from 21 articles by sex and age. We also searched, collected and meta-analysed data from other populations. Means and 95% confidence intervals were calculated. The estimated standard values of [Formula: see text] (mL/kg/min) for Japanese men and women aged 4-9, 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 47.6, 51.2, 43.2, 37.2, 34.5, 31.7, 28.6, and 26.3, and 42.0, 43.2, 33.6, 30.6, 27.4, 25.6, 23.4, and 23.1, respectively. The AT/kg (mL/kg/min) for Japanese men and women aged 20-29, 30-39, 40-49, 50-59, 60-69, and 70-79 years were 21.1, 18.3, 16.8, 15.9, 15.8, and 15.2, and 17.4, 17.0, 15.7, 15.0, 14.5, and 14.2, respectively. Herein, we presented the estimated standard values of aerobic capacity according to sex and age in a Japanese population. In conclusion, aerobic capacity declines with ageing after 20-29 years of age. Additionally, aerobic capacity is lower in the Japanese population than in other populations across a wide range of age groups. Standard value estimation by meta-analysis can be conducted in any country or region and for public health purposes.

Comparison of Cardiovascular Response to Lower Body and Whole Body Exercise Among Sedentary Young Adults

Background Cardiovascular responses to exercise are essential indicators of cardiovascular health and fitness. Understanding how different types of exercise, such as lower-body and whole-body exercises, impact these responses is crucial for designing effective fitness programs and assessing cardiovascular function. Aim This study aimed to compare the cardiovascular response of young adults during lower-body exercise using a bicycle ergometer and whole-body exercise on a treadmill. Methods Thirty-two healthy young adults participated in this study. Each participant completed two exercise sessions on separate days: lower-body exercise on a bicycle ergometer with a fixed cadence of 60 rpm with a breaking resistance of 1.75 kg and whole-body exercise on a treadmill with a speed of 1.7 mph and a 10% grade. Heart rate (HR), systolic blood pressure (BP), and diastolic BP were measured at rest and immediately after a three-minute exercise. Data were analyzed using paired t-tests to compare the cardiovascular responses between the two exercise modalities. Results A total of 17 male and 15 female young adults with a mean age of 20.87±1.43 years participated in the study. The male and female participants had similar ages (p =0.56) and body mass indexes (p = 0.1). There was a higher HR (129.16±2.67 versus 150.87±3.23, p<0.0001) and systolic BP (127.29±2.34 versus 144.9±4.16, p<0.0001) and lower diastolic BP (68.97±2.41 versus 62.97±2.31, p<0.0001) in whole body exercise on treadmill compared to lower body exercise in bicycle ergometer. The effect size was large enough as Cohen's d was 7.33, 5.13, and 2.54 for HR, systolic BP, and diastolic BP, respectively. Conclusion In sedentary young adults, treadmill exercise led to higher HR, systolic BP, and lower diastolic BP than bicycle ergometer exercise. Increased muscle recruitment might result in higher energy expenditure, increasing the HR and systolic BP to deliver oxygen and nutrients to the working muscles. Further research is needed to understand the mechanisms and long-term implications for precise exercise recommendations and better cardiovascular health management.

The relevance of body composition assessment for the rating of perceived exertion in trained and untrained women and men

Introduction: Mechanic power output (MPO) and oxygen consumption (VO2) reflect endurance capacity and are often stated relative to body mass (BM) but less often per skeletal muscle mass (SMM). Rating of perceived exertion (RPE) has previously shown conflicting results between sexes at submaximal intensities. Individual body composition, however, largely differs due to sex and training status. It was the aim of this study to evaluate RPE of untrained and trained individuals of both sexes considering body composition and to estimate whether RPE could be improved as a tool to determine endurance capacity. Methods: The study included 34 untrained adults (age 26.18 ± 6.34 years, 18 women) and 29 endurance trained (age 27.86 ± 5.19, 14 women) who were measured for body composition (InBody 770, InBody Europe B.V., Germany) and tested on a treadmill (Pulsar, H/P/Cosmos, Germany) for aerobic capacity (Metalyzer 3B, Cortex Biophysik GmbH, Germany) in an all-out exercise test applying the Bruce-protocol. VO2, MPO, heart rate (HR), and RPE were obtained at each exercise stage. VO2 and MPO were calculated per BM and SMM. RPE values were correlated with absolute VO2 and MPO, as well as relative to BM, and SMM. HR values and the parameters' standardized values served for comparison to standard procedures. Results: VO2 and MPO were higher in men compared to women and in trained compared to untrained participants. No differences between groups and sexes exist when VO2 and MPO were calculated per BM. When calculated per SMM, VO2 and MPO indicate opposite results already at low intensity stages of exercise test. RPE values had highest correlation with MPO per SMM (R2 = 0.8345) compared to absolute MPO (R2 = 0.7609), or MPO per BM (R2 = 0.8176). Agreement between RPE and MPO per SMM was greater than between RPE and HR (p = 0.008). Conclusion: Although RPE represents a subjective value at first glance, it was shown that RPE constitutes a valuable tool to estimate endurance capacity, which can be further enhanced if individual body composition is considered. Furthermore, MPO and VO2 should be considered relative to SMM. These findings might help to avoid over-exertion, especially among untrained people, by adjusting the training intensity for each subject according to the individual strain evaluated in an exercise test based on individual body composition.

Translational and Rotational Postural Aberrations Are Related to Pulmonary Functions and Skill-Related Physical Fitness Components in Collegiate Athletes

This study assessed the relationship between body posture displacements, cardiopulmonary exercise testing (CPET), and skill-related physical fitness tests. One hundred male (60%) and female collegiate athletes (22.2 ± 4 yrs) with normal body mass indexes (BMI up to 24.9) were assessed via the PostureScreen Mobile^® app to quantify postural displacements such as head, thorax, and pelvis rotations and translations. CPET and physical performance tests, including the agility t-test, vertical jump test, stork static balance test (SSBT), and dynamic Y-balance test (YBT), were performed. Spearman correlation (r) and p-values are reported. The postural parameters were found to have moderate-to-high associations with the CPET and agility test, moderate correlations with the vertical jump test and SSBT (head and pelvic postures only), and weak correlations with the YBT. As the postural parameters were more asymmetric, both the CPET and performance skills scores were worse. For example: (1) a medium positive correlation was found between cranio-vertebral angle (CVA) and the vertical jump test (r = 0.54; p-value < 0.001) and SSBT (r = 0.57; p-value < 0.001), while a strong negative correlation was found between CVA and the agility test (r = -0.86; p-value < 0.001). (2) A strong positive correlation was found between CVA and oxygen uptake efficiency slope, load watts VO2 at VT, VO2/kg, and load watts at the respiratory compensation point (RCP) (r = 0.65 and r = 0.71; p < 0.001). Conversely, a significant negative correlation was found between CVA and VE/VO2 at VT (r = -0.61; p < 0.001). Postural rotations and translations of the head, thorax, and pelvis were statistically correlated with the physical performance skills and CPET in the young collegiate athletes. There were moderate-to-high associations with cardiopulmonary functions and the agility tests, moderate correlations with the vertical jump test, and weak correlations with the YBT. Postural alignment may be important for optimal physical performance and optimal cardiopulmonary function. Further research is necessary to elucidate the reasons for these correlations found in our sample of young and healthy athletes.

Impact of COVID-19 Infection on Cardiorespiratory Fitness, Sleep, and Psychology of Endurance Athletes-CAESAR Study

COVID-19 has a deteriorating impact on health which is especially important for endurance athletes (EAs) who need to maintain continuity of training. The illness affects sleep and psychology, which influence sport performance. The aims of this study were: (1) to assess the consequences of mild COVID-19 on sleep and psychology and (2) to assess the consequences of mild COVID-19 on cardiopulmonary exercise test (CPET) results. A total of 49 EAs (males = 43, 87.76%; females = 6, 12.24%; age = 39.9 ± 7.8 years; height = 178.4 ± 6.8 cm; weight = 76.3 ± 10.4 kg; BMI = 24.0 ± 2.6 kg·m^-2) underwent a maximal cycling or running CPET pre- and post-COVID-19 and completed an original survey. Exercise performance deteriorated after COVID-19 (maximal oxygen uptake, VO_2max = 47.81 ± 7.81 vs. 44.97 ± 7.00 mL·kg·min^-1 pre- and post-infection, respectively; p < 0.001). Waking up at night affected the heart rate (HR) at the respiratory compensation point (RCP) (p = 0.028). Sleep time influenced pulmonary ventilation (p = 0.013), breathing frequency (p = 0.010), and blood lactate concentration (Lac) (p = 0.013) at the RCP. The maximal power/speed (p = 0.046) and HR (p = 0.070) were linked to the quality of sleep. Stress management and relaxation techniques were linked with VO_2max (p = 0.046), maximal power/speed (p = 0.033), and maximal Lac (p = 0.045). Cardiorespiratory fitness deteriorated after mild COVID-19 and was correlated with sleep and psychological indices. Medical professionals should encourage EAs to maintain proper mental health and sleep after COVID-19 infection to facilitate recovery.

Validity of the Maximal Heart Rate Prediction Models among Runners and Cyclists

Maximal heart rate (HRmax) is a widely used measure of cardiorespiratory fitness. Prediction of HRmax is an alternative to cardiopulmonary exercise testing (CPET), but its accuracy among endurance athletes (EA) requires evaluation. This study aimed to externally validate HRmax prediction models in the EA independently for running and cycling CPET. A total of 4043 runners (age = 33.6 (8.1) years; 83.5% males; BMI = 23.7 (2.5) kg·m^-2) and 1026 cyclists (age = 36.9 (9.0) years; 89.7% males; BMI = 24.0 (2.7) kg·m^-2) underwent maximum CPET. Student t-test, mean absolute percentage error (MAPE), and root mean square error (RMSE) were applied to validate eight running and five cycling HRmax equations externally. HRmax was 184.6 (9.8) beats·min^-1 and 182.7 (10.3) beats·min^-1, respectively, for running and cycling, p = 0.001. Measured and predicted HRmax differed significantly (p = 0.001) for 9 of 13 (69.2%) models. HRmax was overestimated by eight (61.5%) and underestimated by five (38.5%) formulae. Overestimated HRmax amounted to 4.9 beats·min^-1 and underestimated HRmax was in the range up to 4.9 beats·min^-1. RMSE was 9.1-10.5. MAPE ranged to 4.7%. Prediction models allow for limited precision of HRmax estimation and present inaccuracies. HRmax was more often underestimated than overestimated. Predicted HRmax can be implemented for EA as a supplemental method, but CPET is the preferable method.

The Influence of Nutrition and Physical Activity on Exercise Performance after Mild COVID-19 Infection in Endurance Athletes-CESAR Study

COVID-19 and imposed restrictions are linked with numerous health consequences, especially among endurance athletes (EA). Unfavorable changes in physical activity and nutrition may affect later sports and competition performance. The aims of this study were: (1) to assess the impact of COVID-19 infection and pandemic restrictions on the nutrition and physical activity of EAs and (2) to compare them with the results of cardiopulmonary exercise testing (CPET). In total, 49 EAs (nmale = 43, nfemale = 6, mean age = 39.9 ± 7.8 year., height = 178.4 ± 6.8 cm, weight = 76.3 ± 10.4 kg; BMI = 24.0 ± 2.6 kg·m−2) underwent pre- and post-COVID-19 CPET and fulfilled the dietary and physical activity survey. COVID-19 infection significantly deteriorated CPET performance. There was a reduction in oxygen uptake and in heart rate post-COVID-19 (both p < 0.001). Consuming processed meat and replacing meat with plant-based protein affected blood lactate concentration (p = 0.035). Fat-free mass was linked with consuming unsaturated fatty acids (p = 0.031). Adding salt to meals influenced maximal speed/power (p = 0.024) and breathing frequency (p = 0.033). Dietary and Fitness Practitioners and Medical Professionals should be aware of possible COVID-19 infection and pandemic consequences among EA. The results of this study are a helpful guideline to properly adjust the treatment, nutrition, and training of EA.

COVID-19 and athletes: Endurance sport and activity resilience study-CAESAR study

Background: The COVID-19 pandemic and imposed restrictions influenced athletic societies, although current knowledge about mild COVID-19 consequences on cardiopulmonary and physiologic parameters remains inconclusive. This study aimed to assess the impact of mild COVID-19 inflection on cardiopulmonary exercise test (CPET) performance among endurance athletes (EA) with varied fitness level. Materials and Methods: 49 EA (n_male = 43, n_female = 6, mean age = 39.94 ± 7.80 yr, height = 178.45 cm, weight = 76.62 kg; BMI = 24.03 kgm^-2) underwent double treadmill or cycle ergometer CPET and body analysis (BA) pre- and post-mild COVID-19 infection. Mild infection was defined as: (1) without hospitalization and (2) without prolonged health complications lasting for >14 days. Speed, power, heart rate (HR), oxygen uptake (VO₂), pulmonary ventilation, blood lactate concentration (at the anaerobic threshold (AT)), respiratory compensation point (RCP), and maximum exertion were measured before and after COVID-19 infection. Pearson's and Spearman's r correlation coefficients and Student t-test were applied to assess relationship between physiologic or exercise variables and time. Results: The anthropometric measurements did not differ significantly before and after COVID-19. There was a significant reduction in VO₂ at the AT and RCP (both p < 0.001). Pre-COVID-19 VO₂ was 34.97 ± 6.43 ml kg·min^-1, 43.88 ± 7.31 ml kg·min^-1 and 47.81 ± 7.81 ml kg·min^-1 respectively for AT, RCP and maximal and post-COVID-19 VO₂ was 32.35 ± 5.93 ml kg·min^-1, 40.49 ± 6.63 ml kg·min^-1 and 44.97 ± 7.00 ml kg·min^-1 respectively for AT, RCP and maximal. Differences of HR at AT (p < 0.001) and RCP (p < 0.001) was observed. The HR before infection was 145.08 ± 10.82 bpm for AT and 168.78 ± 9.01 bpm for RCP and HR after infection was 141.12 ± 9.99 bpm for AT and 165.14 ± 9.74 bpm for RCP. Time-adjusted measures showed significance for body fat (r = 0.46, p < 0.001), fat mass (r = 0.33, p = 0.020), cycling power at the AT (r = -0.29, p = 0.045), and HR at RCP (r = -0.30, p = 0.036). Conclusion: A mild COVID-19 infection resulted in a decrease in EA's CPET performance. The most significant changes were observed for VO₂ and HR. Medical Professionals and Training Specialists should be aware of the consequences of a mild COVID-19 infection in order to recommend optimal therapeutic methods and properly adjust the intensity of training.

Modeling Physiological Predictors of Running Velocity for Endurance Athletes

Background: Properly performed training is a matter of importance for endurance athletes (EA). It allows for achieving better results and safer participation. Recently, the development of machine learning methods has been observed in sports diagnostics. Velocity at anaerobic threshold (V_AT), respiratory compensation point (V_RCP), and maximal velocity (V_max) are the variables closely corresponding to endurance performance. The primary aims of this study were to find the strongest predictors of V_AT, V_RCP, V_max, to derive and internally validate prediction models for males (1) and females (2) under TRIPOD guidelines, and to assess their machine learning accuracy. Materials and Methods: A total of 4001 EA (n_males = 3300, n_females = 671; age = 35.56 ± 8.12 years; BMI = 23.66 ± 2.58 kg·m^-2; VO_2max = 53.20 ± 7.17 mL·min^-1·kg^-1) underwent treadmill cardiopulmonary exercise testing (CPET) and bioimpedance body composition analysis. XGBoost was used to select running performance predictors. Multivariable linear regression was applied to build prediction models. Ten-fold cross-validation was incorporated for accuracy evaluation during internal validation. Results: Oxygen uptake, blood lactate, pulmonary ventilation, and somatic parameters (BMI, age, and body fat percentage) showed the highest impact on velocity. For V_AT R² = 0.57 (1) and 0.62 (2), derivation RMSE = 0.909 (1); 0.828 (2), validation RMSE = 0.913 (1); 0.838 (2), derivation MAE = 0.708 (1); 0.657 (2), and validation MAE = 0.710 (1); 0.665 (2). For V_RCP R² = 0.62 (1) and 0.67 (2), derivation RMSE = 1.066 (1) and 0.964 (2), validation RMSE = 1.070 (1) and 0.978 (2), derivation MAE = 0.832 (1) and 0.752 (2), validation MAE = 0.060 (1) and 0.763 (2). For V_max R² = 0.57 (1) and 0.65 (2), derivation RMSE = 1.202 (1) and 1.095 (2), validation RMSE = 1.205 (1) and 1.111 (2), derivation MAE = 0.943 (1) and 0.861 (2), and validation MAE = 0.944 (1) and 0.881 (2). Conclusions: The use of machine-learning methods allows for the precise determination of predictors of both submaximal and maximal running performance. Prediction models based on selected variables are characterized by high precision and high repeatability. The results can be used to personalize training and adjust the optimal therapeutic protocol in clinical settings, with a target population of EA.