Cardiopulmonary exercise testing (CPET) is the method of choice to assess aerobic fitness. Previous research was ambiguous as to whether treadmill (TE) and cycle ergometry (CE) results are transferrable or different between testing modalities in triathletes. The aim of this paper was to investigate the differences in HR and VO₂ at maximum exertion between TE and CE, at anaerobic threshold (AT) and respiratory compensation point (RCP) and evaluate their association with body fat (BF), fat-free mass (FFM) and body mass index (BMI). In total, 143 adult (n = 18 female), Caucasian triathletes had both Tr and CE CPET performed. The male group was divided into 40 years (n = 45). Females were aged between 18 and 46 years. Body composition was measured with bioelectrical impedance before tests. Differences were evaluated using paired t-tests, and associations were evaluated in males using multiple linear regression (MLR). Significant differences were found in VO₂ and HR at maximum exertion, at AT and at RCP between CE and TE testing, in both males and females. VO_2AT was 38.8 (±4.6) mL/kg/min in TE vs. 32.8 (±5.4) in CE in males and 36.0 (±3.6) vs. 32.1 (±3.8) in females (p < 0.001). HR_AT was 149 (±10) bpm in TE vs. 136 (±11) in CE in males and 156 (±7) vs. 146 (±11) in females (p < 0.001). VO₂max was 52 (±6) mL/kg/min vs. 49 (±7) in CE in males and 45.3 (±4.9) in Tr vs. 43.9 (±5.2) in females (p < 0.001). HRmax was 183 (±10) bpm in TE vs. 177 (±10) in CE in males and 183 (±9) vs. 179 (±10) in females (p < 0.001). MLR showed that BMI, BF and FFM are significantly associated with differences in HR and VO₂ at maximum, AT and RCP in males aged >40. Both tests should be used independently to achieve optimal fitness assessments and further training planning.

Background: Oxygen uptake (VO₂) is one of the most important measures of fitness and critical vital sign. Cardiopulmonary exercise testing (CPET) is a valuable method of assessing fitness in sport and clinical settings. There is a lack of large studies on athletic populations to predict VO_2maxusing somatic or submaximal CPET variables. Thus, this study aimed to: (1) derive prediction models for maximal VO₂(VO_2max) based on submaximal exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations.Methods: Four thousand four hundred twenty-four male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (n_runners= 1998; n_cyclist= 656), model building (n_runners= 666; n_cyclist= 219), and validation (n_runners= 666; n_cyclist= 219). Random forest was used to select the most significant variables. Models were derived and internally validated with multiple linear regression.Results: Runners were 36.24±8.45 years; BMI = 23.94 ± 2.43 kg·m⁻²; VO_2max=53.81±6.67 mL·min⁻¹·kg⁻¹. Cyclists were 37.33±9.13 years; BMI = 24.34 ± 2.63 kg·m⁻²; VO_2max=51.74±7.99 mL·min⁻¹·kg⁻¹. VO₂at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO_2maxbased on variables at AT was R²=0.81, at RCP was R²=0.91, at AT and RCP was R²=0.91 and for somatic-only was R²=0.43.Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO_2maxbased on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations.Funding: No external funding was received for this work.

Since traditional sport-specific training or exercise programs do not create enough stimulus to improve the function of the respiratory muscles, the rationale to introduce respiratory muscle training (RMT) emerged. RMT is associated with improved endurance performance and pulmonary function, and it reduced respiratory fatigue, perceived exertion, or breathlessness. The purpose of this article is to provide coaches with tools to select the appropriate form of RMT in the context of the athletes' needs, using appropriate methods, techniques, devices, and testing protocols. The video abstract is presented in Supplemental Digital Content as SDC 1.

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.

Background: Respiratory muscle training (RMT) has been investigated in the context of improved athletic performance and pulmonary function. However, psychophysiological costs of RMT remain understudied. Voluntary isocapnic hyperpnoea (VIH) and inspiratory pressure threshold loading (IPTL) are widely applied RMT methods. The main purposes of this study were to assess whether RMT induces additional load on well-trained triathletes and determine differences in RMT-induced load between sexes and applied methods.Materials and Methods: 16 well-trained triathletes (n = 16, 56% males) underwent 6 weeks of VIH or IPTL program with progressive overload. Blood markers, subjective measures, cardiac indices, near-infrared spectroscopy indices, inspiratory muscle fatigue, and RMT-induced training load were monitored pre-, in and post-sessions. We used multiple ANOVA to investigate effects of sex, training method, and time on measured parameters.Results: There were significant interactions for acid-base balance (p = 0.04 for sex, p < 0.001 for method), partial carbon dioxide pressure (p = 0.03 for sex, p < 0.001 for method), bicarbonate (p = 0.01 for method), lactate (p < 0.001 for method), RMT-induced training load (p = 0.001 for method for single session, p = 0.03 for method per week), average heart rate (p = 0.03 for sex), maximum heart rate (p = 0.02 for sex), intercostales muscle oxygenation (p = 0.007 for testing week), and intercostales muscle oxygenation recovery (p = 0.003 for testing week and p = 0.007 for method).Conclusion: We found that RMT induced additional load in well-trained triathletes. Elicited changes in monitored variables depend on sex and training method. VIH significantly increased subjective training load measures. IPTL was associated with disbalance in blood gasometry, increase in lactate, and reports of headaches and dizziness. Both methods should be applied with consideration in high-performance settings.

Study aim : POWERbreathe® S-Index Test is an accessible and functional evaluation of inspiratory muscle strength. The main purpose of this study is to present guidelines that allow to successfully apply the test in sports settings with high accuracy, robustness, and repeatability. Material and methods : Review of available literature and professional guidelines regarding traditional spirometry testing and POWERbreathe® trainers’ application was performed. The obtained information was summarized, analyzed, and interpreted to create POWERbreathe® S-Index Test guidelines and recommendations for practitioners. POWERbreathe® K4 and K5 (POWERbreathe International Ltd., Southam, UK) devices paired with Breathe-Link Live Feedback Software (POWERbreathe International Ltd., Southam, UK) were considered during the analysis and guidelines creation. Results : We recommend performing POWERbreathe® S-Index Test with 8 forceful and dynamic inspiratory maneuvers from residual volume to full inspiratory capacity, divided into 2–3 series of 2–3 maneuvers, in a standing position, after respiratory warm-up. Conclusion : POWERbreathe® S-Index Test may be a useful tool to measure functional inspiratory muscle strength in athletes. When performed with the presented guidelines, it can be successfully applied in sports settings with high accuracy, robustness, and repeatability.