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.

The COVID-19 pandemic and imposed restrictions were strong stress factors for young people, especially students. Increased alcohol consumption, smoking cigarettes, usage of heated tobacco products, and other stimulants are common methods of coping with anxiety. However, they can have serious negative health effects. A survey consisting of 12 questions related to mental health and psychoactive substance taking habits was distributed among Polish students between 22 February 2021 and 3 April 2021. A total of 1323 participants met all inclusion criteria (n_females = 1021, n_males = 297, n_{other gender} = 5). The mean age was 22 years old (±4.17); 47.62% were medical university students. A total of 71.92% reported negative impact, 8.25% did not notice changes, and 12.58% declared a positive pandemic impact on their mental health. A total of 12.58% declared an increase, 70.22% did not see any differences, and 17.20% reported a decrease in their psychoactive substance usage tendency due to the pandemic. Worse perceived psychologic well-being was correlated with a higher tendency to use tobacco (p < 0.001) and alcohol (p < 0.001), and not with marijuana and products containing tetrahydrocannabinol (p = 0.136), and hard drugs (p = 0.799). The majority of participants declared a negative pandemic impact on mental health and did not report significant changes in psychoactive substance taking habits. Medical personnel should be aware of the current situation and apply for proper prevention and treatment programs.

The COVID-19 pandemic has changed the way many people live. To assess its impact on sleep quality and quantity, blue light exposure, and the mental health of Polish university students, a cross-sectional survey was conducted. Almost half of the participants were medical students (47.62%; n = 630). The majority of students were suffering from insomnia (58.13%, n = 769). Almost every third student was sleeping less than 7 h a day (30.39%, n = 402). Our study showed that a short sleep duration correlates with poorer mental health outcomes. Respondents who declared sadness and depression were more likely to suffer from insomnia (OR = 5.6997, 95% CI: 4.3641–7.4441). Difficulty with tasks was also more likely to co-occur with insomnia (OR = 5.4723, 95% CI: 4.3007 to 6.9630). The results of this study showed that the COVID-19 pandemic contributed to the deterioration of sleep quality and quantity as well as the psychological well-being of Polish students. It is important to take steps to promote proper sleeping habits to alleviate the risk of mental health disorders in this group of people.

In recent years, numerous prognostic models have been developed to predict VO2max. Nevertheless, their accuracy in endurance athletes (EA) stays mostly unvalidated. This study aimed to compare predicted VO2max (pVO2max) with directly measured VO2max by assessing the transferability of the currently available prediction models based on their R², calibration-in-the-large, and calibration slope. 5,260 healthy adult EA underwent a maximal exertion cardiopulmonary exercise test (CPET) (84.76% male; age 34.6±9.5 yrs.; VO2max 52.97±7.39 mL·min^-1·kg^-1, BMI 23.59±2.73 kg·m^-2). 13 models have been selected to establish pVO2max. Participants were classified into four endurance subgroups (high-, recreational-, low- trained, and “transition”) and four age subgroups (18–30, 31–45, 46–60, and ≥61 yrs.). Validation was performed according to TRIPOD guidelines. pVO2max was low-to-moderately associated with direct CPET measurements (p>0.05). Models with the highest accuracy were for males on a cycle ergometer (CE) (Kokkinos R² = 0.64), females on CE (Kokkinos R² = 0.65), males on a treadmill (TE) (Wasserman R² = 0.26), females on TE (Wasserman R² = 0.30). However, selected models underestimated pVO2max for younger and higher trained EA and overestimated for older and lower trained EA. All equations demonstrated merely moderate accuracy and should only be used as a supplemental method for physicians to estimate CRF in EA. It is necessary to derive new models on EA populations to include routinely in clinical practice and sports diagnostic.

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.

The restrictions implemented to prevent the spread of the SARS-CoV-2 virus have impacted the majority of life domains. To evaluate their potential consequences on physical activity (PA) and dietary habits among Polish undergraduates, a survey consisting of the IPAQ-SF, authors’ questions based on the Polish National Institute of Public Health recommendations, and authors’ questions scaled −5/0/5 on personal opinion was created and administered between 22 February and 3 April 2021. A total of 1323 students met the study conditions (1021 females, 297 males, 5 did not specify gender, mean age: 22 years old (SD = 4), mean BMI = 22.27 kg/m² (SD = 3.87)). A total of 27.21% of students were in the low, 48.53% in the moderate, and 24.26% in the high PA group. A total of 71.94% estimated that the pandemic had a negative impact on their PA, 8.16% no impact, and 19.9% a positive impact. A total of 35.5% had an insufficient intake of vegetables, 34.3% declared adding salt to meals, and 31.6% ate animal-based products the majority of days in a week or every day. A total of 51.02% assessed the impact of the pandemic on their nutrition as negative, 20.11% did not notice changes, and 28.87% reported a positive impact on their dietary habits. Most of the students saw harmful pandemic effects on their diet and PA compared to the times before restrictions. This can lead to a higher prevalence of non-communicable diseases (NCDs) in the future.