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This study examined the effects of a moderately intense seven-week running intervention on the hippocampal volume and depressive symptoms of young men (20-31 years of age) from the general population (N = 21). A within-subjects-design involving a two-week baseline period before the running intervention, and two subsequent intervention cycles was applied. At four time points of assessment (t 1 : start of the study; t 2 : end of baseline period/start of the intervention; t 3 : end of the first intervention cycle; t 4 : end of the 2nd intervention cycle/study end) magnetic resonance imaging was performed and symptoms related to depression were assessed employing the Center for Epidemiological Studies Depression (CES-D) Scale. The intervention resulted in a significant increase in the estimated maximum oxygen uptake (VO 2 max), measured with a standardized walking test (average increase from 42.07 ml*kg - 1 *min - 1 to 46.07 ml*kg - 1 *min - 1 ). The CES-D scores decreased significantly over the course of the running intervention (average decrease from 12.76 to 10.48 on a 20-point scale). Significant volumetric increases in the hippocampus were found, most notably after the first intervention cycle in the left (average increase from 613.41 mm³ to 620.55 mm³) and right hippocampal tail (average increase from 629.77 mm³ to 638.17 mm³). These findings provide new evidence regarding the temporal dynamics of hippocampal changes following engagement in physical activity., Competing Interests: Declarations. Ethical approval: The study was approved by the authorized ethics committee (GZ. 39/24/63 ex 2021/22). Consent for publication: All participant gave written informed consent for both study participation and publication. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Purpose: This study aimed to develop two regression equations to predict maximal oxygen consumption (VO 2max ) using non-exercise data from a substantial cohort of healthy Iranian adult males. Additionally, this study sought to examine the predictive accuracy of these equations across four different levels of physical activity. Methods: A total of 126 participants (age: 34.9 ± 11.3 years, body mass index [BMI]: 24.9 ± 2.7 kg/m², and body fat percentage [BF%]: 18.3 ± 4.9) completed a maximal graded exercise test to measure VO 2max , with a mean of 45.0 ± 3.4 ml.kg -1 .min -1 . Participants also provided information on age, current physical activity rating (PA-R), and either BMI or BF% to estimate VO 2max using Jackson and colleagues' regression equations. The PA-R was assessed via a standardized questionnaire and categorized into four levels: sedentary, low, moderate, and high. Results: The key findings from this study indicate that both original models significantly underestimated actual VO 2max in a large cohort of Iranian adults (both, p  < .001 and mean differences exceeding 2.19 ml.kg -1 .min -1 ). Nevertheless, these models provided accurate predictions for VO 2max among individuals with moderate levels of physical activity (both, p  > .08 and mean differences between 0.51 and 1.03 ml.kg -1 .min -1 ). Furthermore, the models demonstrated moderate validity, as evidenced by an intraclass correlation coefficient (ICC) of 0.841 and a coefficient of variation averaging 10.9%, with a range from 8.5% to 13.6%. Conclusions: While Jackson's two non-exercise models showed limited accuracy in predicting VO 2max among Iranian healthy male adults, they exhibited reasonable precision, particularly among moderately active men.

Background: Evidence regarding the performance-related effects of Actovegin is limited, despite legislated restrictions being in place for this supplement within sport settings., Objectives: Our study examined the effects of Actovegin on physiological responses and performance during maximal cardiopulmonary exercise in collegiate athletes., Methods: A randomized, double-blind, placebo-controlled experimental design was adopted. Moderately trained collegiate athletes from various sports were randomly allocated to placebo ( n = 8) or Actovegin ( n = 8) groups. All athletes consumed three capsules across each day for seven days of loading. Athletes underwent two separate cardiopulmonary exercise tests one week apart. Separate 2 × 2 mixed ANOVAs and effect sizes (ηp2) were used to assess for between- and within-group differences., Results: A significant time * group effect ( p = 0.036, ηp2 = 0.278) was observed in systolic blood pressure. Significant main effects were only observed for time in several variables, with increases in peak oxygen uptake (VO 2 ) ( p < 0.001, ηp2 = 0.893), peak minute ventilation ( p = 0.004, ηp2 = 0.456), ventilatory equivalents for carbon dioxide ( p = 0.002, ηp2 = 0.517), oxygen pulse ( p = 0.006, ηp2 = 0.434), VO 2 at first ventilatory threshold ( p = 0.002, ηp2 = 0.520), velocity at second ventilatory threshold ( p < 0.001, ηp2 = 0.997), VO 2 at second ventilatory threshold ( p < 0.001, ηp2 = 0.628), and peak velocity ( p = 0.010, ηp2 = 0.386), and a decrease in respiratory exchange ratio ( p < 0.001, ηp2 = 0.695)., Conclusions: Our findings suggest that although physiological and performance alterations were evident with Actovegin supplementation during cardiopulmonary exercise, no further benefits beyond those obtained with a placebo were attained.

Purpose: The primary aims of this study were to examine the effects of 9 weeks of aerobic training, comprising three 30-min sessions per week, on V̇O 2max , inhibitory control, and plasma brain-derived neurotrophic factor (BDNF) levels among adolescents aged 16-19 years., Methods: One hundred twenty-one untrained or recreationally active adolescents from a Danish high school were enrolled in the study, with 58 females (17.8 ± 0.8 years) and 27 males (18.0 ± 0.9 years) completing it. Participants were randomly divided into three groups performing aerobic training at either moderate-intensity (MIT: 60%-70% heart rate reserve [HRR]) or high-intensity (HIT: 80%-100% HRR) or a passive control group (CON) continuing their habitual lifestyle. Both the training groups exercised for 3×30 min per week for 9 weeks using a combination of cycling and running. Before and after the intervention period maximal oxygen uptake (V̇O 2max ) and the primary outcomes (inhibitory control measured by a modified flanker task, and resting plasma levels of BDNF) were evaluated., Results: After the intervention period, the HIT group demonstrated a larger increase in V̇O 2max compared to both the CON and MIT groups, while no significant effects were observed on inhibitory control or plasma BDNF levels in any training group. However, compared to the CON group, the HIT group exhibited a tendency for greater improvement in the flanker interference score (accuracy), attributable to enhanced accuracy on the incongruent stimuli from pre to post., Conclusion: Aerobic training in adolescents increased cardiorespiratory fitness in an intensity-dependent manner, but no clear effects were observed on neither inhibitory control nor resting plasma BDNF levels., Clinical Trial Registration: ClinicalTrials.gov: NCT02075944., (© 2024 The Author(s). Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

A non-exercise method equation using seismocardiography for estimating V̇O 2 peak (SCG V̇O 2 peak) has previously been validated in healthy subjects. However, the performance of the SCG V̇O 2 peak within a trained population is unknown, and the ability of the model to detect changes over time is not well elucidated. Forty-seven sub-elite football players were tested at the start of pre-season (SPS) and 36 players completed a test after eight weeks at the end of the pre-season (EPS). Testing included an SCG V̇O 2 peak estimation at rest and a graded cardiopulmonary exercise test (CPET) on a treadmill for determination of V̇O 2 peak. Agreement between SCG V̇O 2 peak and CPET V̇O 2 peak showed a large underestimation at SPS (bias ± 95% CI: -9.9 ± 1.8, 95% Limits of Agreement: 2.2 to -22.0 mL·min -1  kg -1 ). At EPS no interaction (p = 0.3590) but a main effect of time (p < 0.0001) and methods (p < 0.0001) was observed between SCG and CPET V̇O 2 peak. No correlation in V̇O 2 peak changes was observed between SCG and CPET (r = -20.0, p = 0.2484) but a fair agreement in classifying the correct directional change in V̇O 2 peak with the SCG method was found (Cohen's κ coefficient = 0.28 ± 0.25). Overall, the SCG V̇O 2 peak method lacks accuracy and despite being able to estimate group changes, it was incapable of detecting individual changes in V̇O 2 peak following a pre-season period in sub-elite football players. The SCG algorithm needs to be further adjusted and the accuracy and precision improved for the method to be applicable for use within a trained population., (© 2024 The Author(s). European Journal of Sport Science published by Wiley‐VCH GmbH on behalf of European College of Sport Science.)

Aims: Submaximal tests estimating VO 2 max have inherent biases; hence, using VO 2 max estimations from the same test is essential for reducing this bias. This study aimed to establish sex- and age-specific reference values for estimated VO 2 max using the Åstrand-test (Å-test) and the Ekblom-Bak test (EB-test). We also assessed the effects of age, exercise level, and BMI on VO 2 max estimations., Methods: We included men and women (20-69 years) from the Swedish working population participating in Health Profile Assessments between 2010 and 2020. Excluding those on heart rate-affecting medicines and smokers, n = 263,374 for the Å-test and n = 95,043 for the EB-test were included. VO 2 max reference values were based on percentiles 10, 25, 40, 60, 75, and 90 for both sexes across 5-year age groups., Results: Estimated absolute and relative VO 2 max were for men 3.11 L/min and 36.9 mL/min/kg using the Å-test, and 3.58 L/min and 42.4 mL/min/kg using the EB-test. For women, estimated absolute and relative VO 2 max were 2.48 L/min and 36.6 mL/min/kg using the Å-test, and 2.41 L/min and 35.5 mL/min/kg using the EB-test. Higher age (negative), higher exercise level (positive), and higher BMI (negative) were associated with estimated VO 2 max using both tests. However, explained variance by exercise on estimated VO 2 max was low, 10% for the Å-test and 8% for the EB-test, and moderate for BMI, 23% and 29%., Conclusion: We present reference values for estimated VO 2 max from two submaximal cycle tests. Age, exercise, and BMI influenced estimated VO 2 max. These references can be valuable in clinical evaluations using the same submaximal tests., (© 2024. The Author(s).)

During prolonged running at moderate-to-high intensity, running economy (RE) deteriorates and attainable maximal oxygen consumption (VO 2max ) decreases. Whether these changes appear similarly in trained and untrained runners exercising at the same relative intensity is not clear. We recruited 10 trained runners (TR) and 10 active adults (AA), and compared RE and attainable VO 2max before and after 1 h of running at 70% of VO 2max . Submaximal VO 2 increased more (p = 0.019) in AA (0.20 ± 0.13 L min -1 ) than in TR (0.07 ± 0.05 L min -1 ). Attainable VO 2max decreased in AA (-0.21 ± 0.15 L min -1 , p = 0.002), but remained unchanged in TR (-0.05 ± 0.10 L min -1 , p = 0.18). Relative intensity (i.e., VO 2 /attainable VO 2max ), increased more (p = 0.001) in AA (8.3 ± 4.4%) than in TR (2.6 ± 1.9%). These results demonstrate that the ability to resist changes in RE and VO 2max following prolonged running is superior in trained versus untrained runners, when exercising at the same relative intensity., (© 2024 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Background: Oxygen uptake (VO 2 ) 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 2max using somatic or submaximal CPET variables. Thus, this study aimed to: (1) derive prediction models for maximal VO 2 (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 . VO 2 at 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 2max based on variables at AT was R 2 =0.81, at RCP was R 2 =0.91, at AT and RCP was R 2 =0.91 and for somatic-only was R 2 =0.43., Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO 2max based 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., Competing Interests: SW received payment for leading CPET workshops at IX Małopolskich Warsztatach Niewydolności Serca. The author has no other competing interest to declare, PK, PS, IC, MP, AK No competing interests declared, TK has received funding from the Institute of Sport - National Research Institute. The author has received consulting fees for regular coaching and consulting work with private clients, Polish Triathlon Federation and The Triathlon Squad professional triathlon team. The author has no other competing interests to declare, (© 2023, Wiecha et al.)

Maximal oxygen uptake and exercise performance typically decline with age. However, there are indications of preserved vascular function and blood flow regulation during arm exercise. Yet, it is unknown if this potential physiological preservation with age is mirrored in peripheral metabolic capacity and V̇o 2 /W ratio. Thus, to investigate the effects of aging in the arms, we measured metabolic and vascular responses to 6-min bouts of dynamic handgrip exercise at 40% and 80% of maximal work rate (WR max ) in 11 young (26 ± 2 yr) and 12 old (80 ± 6 yr) males, applying Doppler-ultrasound combined with blood samples from a deep forearm vein. At baseline, the old had a larger arterial diameter compared with young ( P < 0.001). During exercise, the two groups reached the same WR max . V̇o 2 , blood flow, and oxygen supply were higher (40%WR max ; 80%WR max , all P < 0.01), and arteriovenous oxygen difference was lower (80%WR max , P < 0.02), in old compared with young. Old also had a higher oxygen excess at 80%WR max ( P < 0.01) than young, whereas no difference in muscle diffusion or oxygen extraction was detected. Only young exhibited an increase in intensity-induced arterial dilation ( P < 0.05), and they had a lower mean arterial pressure than old at 80%WR max ( P < 0.001). V̇o 2 /W (40%WR max ; 80%WR max ) was reduced in old compared with young (both P < 0.05). In conclusion, in old and young males with a similar handgrip WR max , old had a higher V̇o 2 during 80%WR max intensity, achieved by an increased blood flow. This may be a result of the available cardiac output reserve, compensating for reduced work efficiency and attenuated vascular response observed in old. NEW & NOTEWORTHY Contrasting the typically observed decline in V̇o 2max with age, the current study reveals an age-related increase in forearm metabolic capacity during handgrip exercise in old, mediated by an increased forearm blood flow. Exercise with a small muscle mass in arms, where central components of the oxygen transport are not limiting, allows old to attain a similar maximal work rate as young despite their increased V̇o 2 /W ratio.

Background: Assessment of maximal oxygen consumption is important in both general community and occupational settings. Validity and reliability tests are needed to indicate the functionality of the cardiopulmonary system., Objective: This study aimed to establish a maximal oxygen consumption (VO2max) prediction model using anthropometric and demographic variables for young adults in Iran., Methods: This cross-sectional study was conducted on 64 healthy young men aged 19-29 years. Oxygen consumption was measured directly and the prediction models to estimate VO2max were determined by multiple linear regression. The accuracy of the prediction models was considered using regression coefficient (R), coefficient of determination (R2), and standard error of estimate (SEE)., Results: The average VO2max was 44.02±4.31 ml/kg/min. Significant correlations were found between the measured VO2max and the anthropometric and demographic variables (r = 0.16-0.86, P < 0.05). Three significant regression models with acceptable accuracy were developed (R2 = 0.67-0.71, SEE = 3.19-3.21)., Conclusion: The predictive models consisted of 3-5 variables as significant predictors of VO2max and had acceptable accuracy for Iranian young adults. The proposed models are a simple and valid tool that can be used to estimate the VO2max in the field and in laboratory settings.

Background: Cardiovascular capacity, expressed as maximal oxygen uptake (VO 2max ), is a strong predictor of health and fitness and is considered a key measure of physiological function in the healthy adult population. The purpose of this study was to validate a specific step test (StepTest4all) as an adequate procedure to estimate cardiovascular capacity in young adults., Methods: The sample was composed of 56 participants, including 19 women (aged 21.05 ± 2.39 years, body mass = 57.50 ± 6.64 kg, height = 1.62 ± 0.05 m, body mass index = 22.00 ± 2.92 kg/m 2 ) and 37 men (aged 22.05 ± 3.14 years, body mass = 72.50 ± 7.73 kg, height = 1.76 ± 0.07 m, body mass index = 23.34 ± 2.17 kg/m 2 ). Participants were included in one of the following groups: (i) the group used to predict the VO 2max , and (ii) the group used to validate the prediction model. All participants performed the StepTest4all protocol. The step height and the intensity of the effort was determined individually. Heart rate and oxygen uptake were measured continuously during rest, effort, and recovery phases. The validation process included the following three stages: (i) mean data comparison, (ii) simple linear regression, and (iii) Bland-Altman analysis., Results: The linear regression retained, as significant predictors of the VO 2max , sex ( p < 0.001) and heart rate recovery for one minute ( p = 0.003). The prediction equation revealed a high relationship between measurements (R 2 = 63.0%, SEE = 5.58). The validation procedure revealed non-significant differences ( p > 0.05) between the measured and estimated maximal oxygen uptake, high relationship (R 2 = 63.3%), and high agreement with Bland-Altman plots. Thus, VO 2max can be estimated with the formula: VO 2max = 22 + 0.3 · (HRR 1min ) + 12 · (sex), where HRR 1min is the magnitude of the HR decrease (bpm) in one minute immediately after the step was stopped, and sex: men = 1, women = 0., Conclusions: The StepTest4all is an adequate procedure to estimate cardiovascular capacity, expressed as VO 2max , in young adults. In addition, it is possible to determine the qualitative level of cardiovascular capacity from the heart rate recovery for one minute, more specifically, poor: <20, moderate: 20 to 34, good: 35 to 49, and excellent: ≥50. This procedure has the benefit of being simple to apply and can be used by everyone, even at home, without specialist supervision.

Aims: Accurate interpretation of cardiopulmonary exercise testing (CPET) relies on age, gender, and exercise modality-specific reference values. To date, clinically applicable CPET reference values derived from a source population of endurance athletes (EAs) have been lacking. The purpose of this study was to generate CPET reference values for use in the clinical assessment of EA., Methods and Results: Prospective data accrued during the clinical care of healthy EA were used to derive CPET reference values and to develop novel equations for V˙O2peak. The performance of these equations was compared to the contemporary standard of care equations and assessed in a discrete EA validation cohort. A total of 272 EA (age = 42 ± 15 years, female = 31%, V˙O2peak = 3.6 ± 0.83 L/min) met inclusion criteria and comprised the derivation cohort. V˙O2peak prediction equations derived from general population cohorts described a modest amount of V˙O2peak variability [R2 = 0.58-0.70, root mean square error (RMSE) = 0.46-0.54 L/min] but were mis-calibrated (calibration-in-the-large = 0.45-1.18 L/min) among EA leading to significant V˙O2peak underestimation. Newly derived, externally validated V˙O2peak prediction equations for EA that included age, sex, and height for both treadmill (R2 = 0.74, RMSE = 0.42 L/min) and cycle ergometer CPET (Cycle: R2 = 0.69, RMSE = 0.42 L/min) demonstrated improved accuracy., Conclusion: Commonly used V˙O2peak prediction equations derived from general population cohorts perform poorly among competitive EA. Newly derived CPET reference values including novel V˙O2peak prediction equations may improve the clinical utility of CPET in this rapidly growing patient population., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

This study aimed to investigate whether anticipatory cardiorespiratory responses vary depending on the intensity of the subsequent exercise bout, and whether anticipatory cardiorespiratory adjustments contribute importantly to enhancing exercise performance during high-intensity exercise. Eleven healthy men were provided advance notice of the exercise intensity and a countdown to generate anticipation during 10 min prior to exercise at 0, 50, 80 or 95% maximal work-rate (Experiment 1). A different group of subjects (n = 15) performed a time to exhaustion trial with or without anticipatory countdown (Experiment 2). In Experiment 1, heart rate (HR), oxygen uptake (V O2 ) and minute ventilation (V E ) during pre-exercise resting period increased over time and depended on the subsequent exercise intensity. Specifically, there was already a 7.4% increase in HR from more than 5 min prior to the start of exercise at 95% maximal work-rate, followed by progressively augmented increases of 12.5% between 2 and 3 min before exercise, 24.4% between 0 and 1 min before exercise. In Experiment 2, the initial HR for the first 10 s of exercise in the task with anticipation was 11.4% larger compared to without anticipation (p < 0.01), and the difference in HR between the two conditions decreased in a time-dependent manner. In contrast, the initial increases in V O2 and V E were significantly lower in the task with anticipation than that without anticipation. The time to exhaustion during high-intensity exercise was 14.6% longer under anticipation condition compared to no anticipation (135 ± 26 s vs. 119 ± 26 s, p = 0.003). In addition, the enhanced exercise performance correlated positively with increased HR response just before and immediately after exercise onset (p < 0.01). These results showed that anticipatory cardiorespiratory adjustments (feedforward control) via the higher brain that operate before starting exercise may play an important role in minimizing the time delay of circulatory response and enhancing performance after onset of high-intensity exercise in man., (© 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Cardiopulmonary exercise testing (CPET) on a treadmill (TE) or cycle ergometry (CE) is a common method in sports diagnostics to assess athletes' aerobic fitness and prescribe training. In a triathlon, the gold standard is performing both CE and TE CPET. The purpose of this research was to create models using CPET results from one modality to predict results for the other modality. A total of 152 male triathletes (age = 38.20 ± 9.53 year; BMI = 23.97 ± 2.10 kg·m -2 ) underwent CPET on TE and CE, preceded by body composition (BC) analysis. Speed, power, heart rate (HR), oxygen uptake (VO 2 ), respiratory exchange ratio (RER), ventilation (VE), respiratory frequency (fR), blood lactate concentration (LA) (at the anaerobic threshold (AT)), respiratory compensation point (RCP), and maximum exertion were measured. Random forests (RF) were used to find the variables with the highest importance, which were selected for multiple linear regression (MLR) models. Based on R 2 and RF variable selection, MLR equations in full, simplified, and the most simplified forms were created for VO 2AT , HR AT , VO 2RCP , HR RCP , VO 2max , and HR max for CE (R 2 = 0.46-0.78) and TE (R 2 = 0.59-0.80). By inputting only HR and power/speed into the RF, MLR models for practical HR calculation on TE and CE (both R 2 = 0.41-0.75) were created. BC had a significant impact on the majority of CPET parameters. CPET parameters can be accurately predicted between CE and TE testing. Maximal parameters are more predictable than submaximal. Only HR and speed/power from one testing modality could be used to predict HR for another. Created equations, combined with BC analysis, could be used as a method of choice in comprehensive sports diagnostics.

Purpose: Investigate difference, agreement, and bias between maximal oxygen consumption (VO 2 max) measured by indirect calorimetry and the Heart Rate Ratio Method (HRRM) for estimating VO 2 max using measured and age-predicted maximum heart rate (HRmax) in a sample of middle-aged and older adults., Methods: Eleven men and nine women (age: 61.8 ± 8.5 years, VO 2 max: 36.6 ± 9.5 mL/kg/min, N = 20) had their VO 2 max measured via a maximal graded exercise test and confirmed using a verification bout on a treadmill ergometer. Participants' VO 2 max was estimated via the HRRM using measured and age-predicted HRmax. Difference, agreement, and bias between methods were assessed using a one-way repeated measures Analysis of Variance (ANOVA), Lin's concordance correlation coefficient, and Bland-Altman plots, respectively., Results: There were no statistical differences between methods of assessing VO 2 max, F(1.13, 21.47) = 0.583, p = 0.473, generalized eta-squared = 0.012. The standard error of the estimate (SEE) for the HRRM using measured or predicted HRmax was 5.2% and 5.6% of the mean VO 2 max, respectively. Both HRRM predictions had poor agreement with VO 2 max (r c  ≤ 0.40). There was a systematic bias to underestimate as VO 2 max increased for HRRM using measured HRmax, F(1, 18) = 17.40, p < 0.001, and when using an age-predicted HRmax, F(1, 18) = 13.39, p = 0.002., Conclusion: Both versions of the HRRM have poor agreement, relatively large SEEs, and a bias to misrepresent VO 2 max. When possible, VO 2 max should be measured via a maximal graded exercise test with indirect calorimetry for middle-aged and older adults., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Maximal oxygen uptake (VO 2 max) declines with advancing age and is a predictor of morbidity and mortality risk. The purpose here was to assess the utility of constant load tests performed either above or below peak work rate obtained from a graded exercise test for verification of VO 2 max in older adults. Twenty-two healthy older adults (9M, 13F, 67 ± 6 years, BMI: 26.3 ± 5.1 kg·m -2 ) participated in the study. Participants were asked to complete two experimental trials in a randomized, counterbalanced cross-over design. Both trials (cycle ergometer) consisted of (1) an identical graded exercise test (ramp) and (2) a constant load test at either 85% (CL85; n = 22) or 110% (CL110; n = 20) of the peak work rate achieved during the associated ramp (performed 10-min post ramp). No significant differences were observed for peak VO 2 (L·min -1 ) between CL85 (1.86 ± 0.72; p = 0.679) or CL110 (1.79 ± 0.73; p = 0.200) and the associated ramp (Ramp85, 1.85 ± 0.73; Ramp110, 1.85 ± 0.57). Using the study participant's mean coefficient of variation in peak VO 2 between the two identical ramp tests (2.9%) to compare individual differences between constant load tests and the associated ramp revealed 19/22 (86%) of participants achieved a peak VO 2 during CL85 that was similar or higher versus the ramp, while only 13/20 (65%) of participants achieved a peak VO 2 during CL110 that was similar or higher versus the ramp. These data indicate that if a verification of VO 2 max is warranted when testing older adults, a constant load effort at 85% of ramp peak power may be more likely to verify VO 2 max as compared to an effort at 110% of ramp peak power., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

The purpose of this study was to analyze the influence of grade of obesity on the probability of achieving a VO2 plateau and threshold secondary criteria for verifying VO2max during a treadmill walk test in youths with obesity. Therefore, 72 youths with obesity (aged 8-16) performed an incremental treadmill walk test to exhaustion during which oxygen uptake (VO2), minute ventilation (VE), heart rate (HR) and rating of perceived exertion were continuously measured. HR corresponding to a "hard" level of perceived exertion was reported and expressed as a percentage of the predicted HRmax. The rate of achievement of criteria for validation VO2max (VO2 plateau; HR>95% theoretical HRmax; RER>1.0; rating of perceived exertion ≥ "hard") was compared between participants with grade I and grade II obesity. 37% of the participants achieved a VO2 plateau and 23% achieved both an HR>95% and RER >1.0. Youths with grade II obesity had lower minute ventilation (p<0.01) tended to be more likely to reach an HR>95% (OR = 0.33; P=0.06) and a "hard" rating of perceived exertion than grade I (OR = 4.5; P=0.07). However, there was no influence of grade of obesity on the achievement of VO2 plateau, and RER>1.0.

This paper aims to test the hypothesis whereby freely chosen running pace is less effective than pace controlled by a steady-state physiological variable. Methods Eight runners performed four maximum-effort 3000 m time trials on a running track. The first time trial (TT1) was freely paced. In the following 3000 m time trials, the pace was controlled so that the average speed (TT2), average V˙O 2 (TT3) or average HR (TT4) recorded in TT1 was maintained throughout the time trial. Results: Physiologically controlled pace was associated with a faster time (mean ± standard deviation: 740 ± 34 s for TT3 and 748 ± 33 s for TT4, vs. 854 ± 53 s for TT1; p < 0.01), a lower oxygen cost of running (200 ± 5 and 220 ± 3 vs. 310 ± 5 mLO 2 ·kg -1 ·km -1 , respectively; p < 0.02), a lower cardiac cost (0.69 ± 0.08 and 0.69 ± 0.04 vs. 0.86 ± 0.09 beat·m -1 , respectively; p < 0.01), and a more positively skewed speed distribution (skewness: 1.7 ± 0.9 and 1.3 ± 0.6 vs. 0.2 ± 0.4, p < 0.05). Conclusion: Physiologically controlled pace (at the average V˙O 2 or HR recorded in a freely paced run) was associated with a faster time, a more favorable speed distribution and lower levels of physiological strain, relative to freely chosen pace. This finding suggests that non-elite runners do not spontaneously choose the best pace strategy.

The purpose of this study was to investigate the effects of high-volume endurance training on the development of maximal oxygen uptake (VO 2max ) in physically active boys and girls between the ages of 12 and 15 years, using a longitudinal design. The children participated in organized training in sports clubs for an average of 7-10 hours per week, with one group undertaking a high volume of endurance training (~7 hours per week; End boys, n = 23 and End girls, n = 17) and the other group having a primary focus on technical and tactical skill development, undertaking low volumes of endurance training (~1.6 hours per week; non-End boys, n = 29 and non-End girls, n = 9). VO 2max and anthropometrics were assessed at age 12, 13, and 15. At age 12, VO 2max was 58.9 (5.6), 65.5 (7.2), 56.5 (6.5), and 58.8 (7.9) mL·kg -1 ·min -1 in End girls, End boys, non-End girls, and non-End boys, respectively. Over the three years, there was no difference between the training groups in the development of VO 2max independent of scaling. In boys, VO 2max relative to body mass (BM) did not change from age 12 to 15, while VO 2max tended to decrease relative to fat-free mass (FFM). In girls, VO 2max relative to BM decreased slightly from age 12 to 15, with no changes over the years relative to FFM. The present longitudinal study suggests that in growing active children during puberty, high volumes of systematic endurance training do not have an additional effect on VO 2max compared with similar volume of training mainly aiming at developing motor skills., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Computer simulations, using the "P i double-threshold" mechanism of muscle fatigue postulated previously (the first threshold initiating progressive reduction in work efficiency and the second threshold resulting in exercise intolerance), demonstrated that several parameters of the skeletal muscle bioenergetic system can affect maximum oxygen consumption (V̇O 2max ), critical power (CP), and oxygen consumption (V̇O 2 ) on-kinetics in skeletal muscle. Simulations and experimental observations together demonstrate that endurance exercise training increases oxidative phosphorylation (OXPHOS) activity and/or each-step activation (ESA) intensity, the latter, especially in the early stages of training. Here, new computer simulations demonstrate that an endurance training-induced increase in OXPHOS activity and decrease in peak P i (Pi peak ), at which exercise is terminated because of exercise intolerance, result in increased V̇O 2max and CP, speeding of the primary phase II of V̇O 2 on-kinetics, and decreases V̇O 2 slow component magnitude, consistent with their observed behavior in vivo. It is possible, but remains unknown, whether there is a contribution to this behavior of an increase in the critical P i (Pi crit ), above which the additional ATP usage underlying the slow component begins, and a decrease in the activity of the additional ATP usage (k add ). Thus, we offer a mechanism, involving P i accumulation, Pi crit and Pi peak , of the training-induced adaptations in V̇O 2max , CP, and the primary and slow component phases of V̇O 2 on-kinetics that was absent in the literature. NEW & NOTEWORTHY A mechanism of the training-induced changes in V̇O 2max , critical power, and V̇O 2 on-kinetics in skeletal muscle reported in the literature is postulated. It involves the self-driving "P i double-threshold" mechanism of muscle fatigue underlying exercise inefficiency, the slow component of the V̇O 2 on-kinetics, and termination of exercise. It is proposed that an increase in OXPHOS activity and decrease in peak P i at which exercise terminates are responsible for the training-induced changes in the muscle bioenergetic system.

Background and Objectives: Obesity or overweight is associated with many health risk factors and preventable mortality. Even people with normal weight and without history of obesity or overweight should avoid weight gain to reduce health risks factors. In this regard Latin aerobic dances involved in Zumba ® practice make this modality motivating for people. Apart from weight loss and VO2 peak benefits, Zumba practice is also interesting by the increase in adherence which can also avoid weight regain. The aim was to systematically review the scientific literature about the effects of any randomized intervention of Zumba ® practice on total fat mass (%) and maximum oxygen consumption (VO 2peak ), besides establishing directions for the clinical practice., Evidence Acquisition: Two systematic searches were conducted in two electronic databases following the PRISMA guidelines. The eligibility criteria were (a) outcomes: body mass or VO 2peak data including mean and standard deviation (SD) before and after Zumba ® intervention, (b) study design: randomized controlled trial (RCT) and (c) language: English. GRADE guidelines were used to assess the quality of evidence. A meta-analysis was performed to determine mean differences. Nine and four studies were selected for fat mass percentage and VO 2peak in the systematic review, respectively. However, only eight studies for fat mass percentage and three for VO 2peak could be included in the meta-analysis., Evidence Synthesis: The overall standardized mean difference for fat mass was -0.25 with a 95% CI from -0.67 to 0.16 with a p-value of 0.69, with large heterogeneity. On the other hand, the overall effect size for VO 2peak was 0.53 (95% CI from 0.04 to 1.02 with a p-value of 0.03) with large heterogeneity., Conclusions: Based on the evidence, we cannot conclude that Zumba ® is effective at reducing body mass but it may improve VO 2peak . However, the limited number of studies that met the inclusion criteria makes it too early to reach a definite conclusion, so more research is needed.

Until recently, it was thought that maximal oxygen uptake (VO 2max ) was elicited only in middle-distance events and not the sprint or marathon distances. We tested the hypothesis that VO 2max can be elicited in both the sprint and marathon distances and that the fraction of time spent at VO 2max is not significantly different between distances., Methods: Seventy-eight well-trained males (mean [SD] age: 32 [13]; weight: 73 [9] kg; height: 1.80 [0.8] m) performed the University of Montreal Track Test using a portable respiratory gas sampling system to measure a baseline VO 2max . Each participant ran one or two different distances (100 m, 200 m, 800 m, 1500 m, 3000 m, 10 km or marathon) in which they are specialists., Results: VO 2max was elicited and sustained in all distances tested. The time limit (Tlim) at VO 2max on a relative scale of the total time (Tlim at VO 2max %Ttot) during the sprint, middle-distance, and 1500 m was not significantly different ( p > 0.05). The relevant time spent at VO 2max was only a factor for performance in the 3000 m group, where the Tlim at VO 2max %Ttot was the highest (51.4 [18.3], r = 0.86, p = 0.003)., Conclusions: By focusing on the solicitation of VO 2max , we demonstrated that the maintenance of VO 2max is possible in the sprint, middle, and marathon distances.

Purpose : This study analyzed the physiological response during Yo-Yo Intermittent Recovery Level 1 (YYIR1) test and re-test by in-field ergospirometry and time-series analyses of respiratory parameters. Methods : Ten moderately trained males (23.4 ± 2.01 years, VO 2peak = 56.81 ± 10.75 mL·kg -1 ·min -1 ) completed three running trials including two separate YYIR1 tests and an independent maximal performance running test with time-series analyses of gas exchange parameters. Physiological response was assessed during all tests by determination of blood lactate levels (including calculation of individual lactate threshold), heart rate, oxygen consumption and respiratory exchange ratio (RER). Results : Modeling of YYIR1 test mean VO 2 uptake kinetics over all participants revealed that VO 2 increased rapidly after the individual lactate threshold (11.49 ± 0.66 km∙h -1 at 3.83 ± 0.42 mmol∙L -1 ) was reached with ~95% VO 2peak at ~50% of the test duration (test, VO 2 50% = 95.17 ± 8.74% of VO 2peak ; re-test, VO 2 50% = 96.78 ± 7.04% of VO 2peak ). However, and despite identical YYIR1 test performance (1568 ± 364.6 m vs. 1568 ± 449.7 m, CV = 4.59%), mean VO 2peak during YYIR1 test was 8.81 ± 5.6% higher than YYIR1 re-test ( p = .027). Importantly, correlation of VO 2peak with YYIR1 test performance was weak (R 2 = 0.28, p = .115). Conclusions : We conclude that the YYIR1 test should not be used to estimate VO 2peak . Further studies on direct determination of gas exchange parameters during different YYI test variants are warranted.

Purpose: While maximum blood flow influences one's maximum rate of oxygen consumption (V̇O 2 max), with so many indices of vascular function, it is still unclear if vascular function is related to V̇O 2 max in healthy, young adults. The purpose of this study was to determine if several common vascular tests of conduit artery and resistance artery function provide similar information about vascular function and the relationship between vascular function and V̇O 2 max., Methods: Twenty-two healthy adults completed multiple assessments of leg vascular function, including flow-mediated dilation (FMD), reactive hyperemia (RH), passive leg movement (PLM), and rapid onset vasodilation (ROV). V̇O 2 max was assessed with a graded exercise test on a cycle ergometer., Results: Indices associated with resistance artery function (e.g., peak flow during RH, PLM, and ROV) were generally related to each other (r = 0.47-77, p < .05), while indices derived from FMD were unrelated to other tests (p < .05). Absolute V̇O 2 max (r = 0.57-0.73, p < .05) and mass-specific V̇O 2 max (r = 0.41-0.46, p < .05) were related to indices of resistance artery function, even when controlling for factors like body mass and sex. FMD was only related to mass-specific V̇O 2 max after statistically controlling for baseline artery diameter (r = 0.44, p < .05)., Conclusion: Indices of leg resistance artery function (e.g., peak flow during RH, PLM, and ROV) relate well to each other and account for ~30% of the variance in V̇O 2 max not accounted for by other factors, like body mass and sex. Vascular interventions should focus on improving indices of resistance artery function, not conduit artery function, when seeking to improve exercise capacity., (© 2020 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Three to 5 cycling tests to exhaustion allow prediction of time to exhaustion (TTE) at power output based on calculation of critical power (CP). We aimed to determine the accuracy of CP predictions of TTE at power outputs habitually endured by cyclists. Fourteen endurance-trained male cyclists underwent 4 randomized cycle-ergometer TTE tests at power outputs eliciting ( i ) mean Wingate anaerobic test (WAnT mean ), ( ii ) maximal oxygen consumption, ( iii ) respiratory compensation threshold (VT 2 ), and ( iv ) maximal lactate steady state (MLSS). Tests were conducted in duplicate with coefficient of variation of 5%-9%. Power outputs were 710 ± 63 W for WAnT mean , 366 ± 26 W for maximal oxygen consumption, 302 ± 31 W for VT 2 and 247 ± 20 W for MLSS. Corresponding TTE were 00:29 ± 00:06, 03:23 ± 00:45, 11:29 ± 05:07, and 76:05 ± 13:53 min:s, respectively. Power output associated with CP was only 2% lower than MLSS (242 ± 19 vs. 247 ± 20 W; P < 0.001). The CP predictions overestimated TTE at WAnT mean (00:24 ± 00:10 mm:ss) and MLSS (04:41 ± 11:47 min:s), underestimated TTE at VT 2 (-04:18 ± 03:20 mm:ss; P < 0.05), and correctly predicted TTE at maximal oxygen consumption. In summary, CP accurately predicts MLSS power output and TTE at maximal oxygen consumption. However, it should not be used to estimate time to exhaustion in trained cyclists at higher or lower power outputs (e.g., sprints and 40-km time trials). Novelty CP calculation enables to predict TTE at any cycling power output. We tested those predictions against measured TTE in a wide range of cycling power outputs. CP appropriately predicted TTE at maximal oxygen consumption intensity but err at higher and lower cycling power outputs.

In the present randomised-controlled trial we investigated the effect of reduced-exertion high-intensity interval training (REHIT) training frequency (2, 3, or 4 sessions/week for 6 weeks) on maximal aerobic capacity in 42 inactive individuals (13 women; mean ± SD age: 25 ± 5 years, maximal aerobic capacity: 35 ± 5 mL·kg -1 ·min -1 ). Changes in maximal aerobic capacity were not significantly different between the 3 groups (2 sessions/week: +10.2%; 3 sessions/week: +8.1%; 4 sessions per week: +7.3%). In conclusion, a training frequency of 2 sessions/week is sufficient for REHIT to improve maximal aerobic capacity. Novelty We demonstrate that reducing REHIT training frequency from 3 or 4 to 2 sessions/week does not attenuate improvements in the key health marker of maximal aerobic capacity.

The aim of this study was to determine the physiological variables that predict competition performance during a CrossFit competition. Fifteen male amateur CrossFit athletes (age, 35 ± 9 years; CrossFit experience, 40 ± 27 months) performed a series of laboratory-based tests (incremental load test for deep full squat and bench press; squat, countermovement and drop jump tests; and incremental running and Wingate tests) that were studied as potential predictors of CrossFit performance. Thereafter, they performed the five Workouts of the Day (WODs) corresponding to the CrossFit Games Open 2019, and we assessed the relationship between the laboratory-based markers and CrossFit performance with regression analyses. Overall CrossFit performance (i.e., final ranking considering the sum of all WODs, as assessed by number of repetitions, time spent in exercises or weight lifted) was significantly related to jump ability, mean and peak power output during the Wingate test, relative maximum strength for the deep full squat and the bench press, and maximum oxygen uptake (VO 2max ) and speed during the incremental test (all p < 0.05, r = 0.58-0.75). However, the relationship between CrossFit Performance and most laboratory markers varied depending on the analyzed WOD. Multiple linear regression analysis indicated that measures of lower-body muscle power (particularly jump ability) and VO 2max explained together most of the variance (R 2 = 81%, p < 0.001) in overall CrossFit performance. CrossFit performance is therefore associated with different power-, strength-, and aerobic-related markers.

Cardiorespiratory fitness, as assessed through peak oxygen uptake (VO 2peak ), is a powerful health indicator. We aimed to evaluate the influence of several candidate causal genetic variants on VO 2peak level in untrained Han Chinese people. A total of 1009 participants (566 women; age [mean ± SD] 40 ± 14 years, VO 2peak 29.9 ± 7.1 mL/kg/min) performed a maximal incremental cycling test for VO 2peak determination. Genomic DNA was extracted from peripheral whole blood, and genotyping analysis was performed on 125 gene variants. Using age, sex, and body mass as covariates, and setting a stringent threshold p -value of 0.0004, only one single nucleotide polymorphism (SNP), located in the gene encoding angiotensin-converting enzyme (rs4295), was associated with VO 2peak (β = 0.87; p < 2.9 × 10 -4 ). Stepwise multiple regression analysis identified a panel of three SNPs (rs4295 = 1.1%, angiotensin II receptor type 1 rs275652 = 0.6%, and myostatin rs7570532 = 0.5%) that together accounted for 2.2% ( p = 0.0007) of the interindividual variance in VO 2peak . Participants carrying six 'favorable' alleles had a higher VO 2peak (32.3 ± 8.1 mL/kg/min) than those carrying only one favorable allele (24.6 ± 5.2 mL/kg/min, p < 0.0001). In summary, VO 2peak at the pre-trained state is partly influenced by several polymorphic variations in candidate genes, but they represent a minor portion of the variance.

Purpose: To determine the impact of interval training frequency in elite endurance athletes. It was hypothesized that two longer sessions would elicit greater performance improvements and physiological adaptation than four shorter sessions at the same intensity., Methods: Elite cross-country skiers and biathletes were randomly assigned to either a high-frequency group (HF group) (5 M, 1 F, age 22 (19-26), VO 2max 67.8 (65.5-70.2) mL/kg/min) doing four short interval sessions per week or a low-frequency group (LF group) (8 M, 1 F, age 22 (18-23), VO 2max 70.7 (67.0-73.9) mL/kg/min) doing two longer interval sessions. All interval sessions were performed at ~85% of maximum heart rate, and groups were matched for total weekly training volume. Pre- and post-intervention, athletes completed an 8 km rollerski time-trial, maximal oxygen uptake (VO 2max ) test, and an incremental, submaximal exercise test., Results: The LF group had a statistically significant improved time-trial performance following the intervention ( p = 0.04), with no statistically significant changes in the HF group. Similarly, percentage utilization of VO 2max at anaerobic threshold ( p = 0.04) and exercise economy ( p = 0.01) were statistically significantly improved following the intervention in the LF group only. No statistically significant changes in VO 2max were observed in either group., Conclusions: Two longer interval sessions appear superior to four shorter sessions per week in promoting endurance adaptations and performance improvements in elite endurance athletes. Despite matched training volume and exercise intensity, the larger, more concentrated exercise stimulus in the LF group appears to induce more favorable adaptations. The longer time between training sessions in the LF group may also have allowed athletes to recover more effectively and better "absorb" the training. These findings are in line with the "best practice" observed by many of the world's best endurance athletes.

Long-term rehabilitative strategies are important for individuals with well-healed burn injuries. Such information is particularly critical because patients are routinely surviving severe burn injuries given medical advances in the acute care setting. The purpose of this study was to test the hypothesis that a 6-mo community-based exercise training program will increase maximal aerobic capacity (V̇o 2max ) in subjects with prior burn injuries, with the extent of that increase influenced by the severity of the burn injury (i.e., percent body surface area burned). Maximal aerobic capacity (indirect calorimetry) and skeletal muscle oxidative enzyme activity (biopsy of the vastus lateralis muscle) were measured pre- and postexercise training in noninjured control subjects ( n = 11) and in individuals with well-healed burn injuries ( n = 13, moderate body surface area burned; n = 20, high body surface area burned). Exercise training increased V̇o 2max in all groups (control: 15 ± 5%; moderate body surface area: 11 ± 3%; high body surface area: 11 ± 2%; P < 0.05), though the magnitude of this improvement did not differ between groups ( P = 0.7). Exercise training also increased the activity of the skeletal muscle oxidative enzymes citrate synthase ( P < 0.05) and cytochrome c oxidase ( P < 0.05), an effect that did not differ between groups ( P = 0.2). These data suggest that 6 mo of progressive exercise training improves V̇o 2max in individuals with burn injuries and that the magnitude of body surface area burned does not lessen this adaptive response.

Background : Although several equations for predicting VO 2max in children and adolescents have been reported, the validity of application of these equations to the Korean population has not been verified. The purpose of study was to develop and validate regression models to estimate maximal oxygen uptake (VO 2max ) using a newly developed 20 m progressive shuttle test (20 m PST) protocol in Korean male ( n = 80, 15.3 ± 1.86 years) and female ( n = 81, 15.5 ± 1.73 years) adolescents aged 13-18 years. Methods : The modified 20 m PST was performed and the VO 2max was assessed in a sample of 161 participants. The participants underwent a treadmill test (TT) in the laboratory and the modified 20 m PST in a gymnasium. For the validation study, the participants performed the TT with a stationary metabolic cart and the 20 m PST with a portable metabolic cart once. In addition, they performed the 20 m PST two more times to establish test-retest reliability. Results : The mean VO 2max (49.6 ± 8.7 mL·kg -1 ·min -1 ) measured with the potable metabolic cart was significantly higher than that measured in the graded exercise test with the stationary metabolic cart (46.6 ± 8.9 mL·kg -1 ·min -1 , p < 0.001) using the new 20 m PST protocol. The standard error of the estimate (SEE) between these two measurements was 1.35 mL·kg -1 ·min -1 . However, the VO 2max derived from the newly developed equation was 46.7 ± 7.3 mL·kg -1 ·min -1 ( p > 0.05) and the SEE was 2.90 mL·kg -1 ·min -1 . The test and retest trials of the 20 m PST yielded comparable results (laps, r = 0.96; last speed, r = 0.93). Conclusions : Our data suggest that the new 20 m PST protocol is valid and reliable and that the equation developed in this study provides a valid estimate of VO 2max in Korean male and female adolescents aged 13-18 years.

Purpose: To develop accurate and practical prediction models of maximal oxygen consumption (VO 2 max) using the Young Men's Christian Association (YMCA)-step test in South Korean adults., Methods: In total, 568 adults (20-66 years) were included in this study. To develop and cross-validate prediction models of VO 2 max, the total sample was divided into 80% training and 20% testing using a simple random sampling method. VO 2 max was measured using the maximal-graded exercise treadmill test. Sex, age, 1-min recovery heart rate, body weight, and height were measured as potential predictors. Each test was conducted within a 2- to 3-day interval, ensuring sufficient rest. Preliminary prediction models were developed from training datasets, which were cross-validated using regression analyses and/or repeated-measures analysis of variance. The accuracy of prediction models was evaluated using R 2 , standard error of estimate (SEE), and mean difference (MD) against a criterion-measured VO 2 max., Results: The average age and VO 2 max were 43.5 ± 12.9 years and 39.1 ± 7.5 ml/kg/min, respectively. For model development, three practical models with acceptable accuracy were developed (R 2  = 0.56-0.61; SEE = 4.74-5.01). For model cross-validation, significant relationships between the criterion-measured and predicted VO 2 max were observed in all three models (R 2  = 0.56-0.61; SEE = 4.62-4.88). The difference between criterion-measured and predicted VO 2 max was not significant in the models (MD =- 0.03 to - 0.14)., Conclusions: The prediction models included 3-5 variables as significant predictors of VO 2 max and had acceptable accuracy in a large sample of South Korean adults. The selected models provide a simple and practical method to estimate VO 2 max using the YMCA-step test for South Korean adults.

Background The purpose of this study was to examine the level of physical activity (PA) and maximal aerobic capacity (VO2max) among office workers of the Pars Special Economic Energy Zone in Iran with different body mass indexes (BMIs). Materials and methods This research was descriptive, and a correlation of variables was applied as its execution method. Administrative staff of two centers were randomly selected from 20 to 30 administrative centers of the Pars Special Economic Energy Zone, Assaluyeh, Iran, and included 294 male employees who were willing to participate in this research and who met the inclusion criteria (being in the age range of 20-60 years, lacking specific diseases, and who had enough physical fitness to do PA) who were purposefully selected. Results The age-adjusted means for the PA score (7.93 ± 1.12) and VO2max (48.66 ± 6.95) mL/min/kg were calculated. After adjusting for other variables, significant difference was found between BMI and age (β = 0.20; p = 0.005), BMI and VO2max (β = 0.302; p = 0.001), as well as BMI and the total PA score (β = -0.304; p = 0.045). Conclusions The results of this study showed low levels of PA (work, exercise and leisure) and respiratory capacity in the administrative staff of the oil and gas industry, which is associated with overweight and obesity.

Background: Long-term trend analyses of cardiorespiratory fitness (VO 2 max) in the general population are limited., Objectives: To describe trends in VO 2 max from 1995 to 2017 in the Swedish working force and to study developments across categories of sex, age, education, and geographic regions., Methods: A total of 354 277 participants (44% women, 18-74 years) who participated in a nationwide occupational health service screening between 1995 and 2017 were included. Changes in standardized mean values of absolute (L/min) and relative (mL/min/kg) VO 2 max, and the proportion with low (<32) relative VO 2 max are reported. VO 2 max was estimated using a submaximal cycle test., Results: Absolute VO 2 max decreased by -6.7% (-0.19 L/min) in the total population. Relative VO 2 max decreased by -10.8% (-4.2 mL/min/kg) with approximately one-third explained by a simultaneous increase in body mass. Decreases in absolute fitness were more pronounced in men vs women (8.7% vs 5.3%), in younger vs older (6.5% vs 2.3%), in short (11.4%) vs long (4.5%) education, and in rural vs urban regions (6.5% vs 3.5%), all P < 0.001. The proportions with low VO 2 max increased from 27% to 46% (P < 0.001)., Conclusion: Between 1995 and 2017, there was a steady and pronounced decline in mean cardiorespiratory fitness in Swedish adults. Male gender, young age, short education, and living in a rural area were predictive of greater reductions. The proportion with low cardiorespiratory fitness almost doubled. Given the strong associations between cardiorespiratory fitness and multiple morbidities and mortality, preventing further decreases is a clear public health priority, especially for vulnerable groups., (© 2018 The Authors. Scandinavian Journal of Medicine & Science In Sports Published by John Wiley & Sons Ltd.)

Aim: We examined the Fick components together with mitochondrial O 2 affinity (p50 mito ) in defining O 2 extraction and O 2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER)., Methods: Seven individuals performed 2 incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and 2 on a 1-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO 2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50 mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibres and muscle mass measured with magnetic resonance imaging in relation to peak leg O 2 delivery., Results: The ex vivo p50 mito increased from 0.06 ± 0.02 to 0.17 ± 0.04 kPa with varying substrate supply and O 2 flux rates from 9.84 ± 2.91 to 16.34 ± 4.07 pmol O 2 ·s -1 ·μg -1 respectively. O 2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O 2 delivery and lower mitochondrial excess capacity. There was a significant relationship between O 2 extraction and mitochondrial excess capacity and p50 mito that was unrelated to blood flow and mean transit time., Conclusion: O 2 extraction varies with mitochondrial respiration rate, p50 mito and O 2 delivery. Mitochondrial excess capacity maintains a low p50 mito which enhances O 2 diffusion from microvessels to mitochondria during exercise., (© 2018 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.)

We examined maximal oxygen consumption responses following exercise training to demonstrate the limitations associated with threshold-based dichotomous classification of responders and non-responders and proposed alternative methods for classification. Specifically, we: 1) calculated individual probabilities of response, and 2) classified individuals using response confidence intervals (CI) and reference points of zero and a smallest worthwhile change of 0.5 METs. Our findings support the use of individual probabilities and individual CIs to improve the accuracy in non-response classification., (© 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Pomegranate extract (POMx) has been suggested as an ergogenic aid due to its rich concentration of polyphenols, which are proposed to enhance nitric oxide bioavailability, thereby improving the efficiency of oxygen usage and, consequently, endurance exercise performance. Although acute POMx supplementation improves aerobic exercise performance in untrained individuals, trained athletes appear to require chronic supplementation for a similar effect. Furthermore, the combination of POMx with a thiol antioxidant may prove more effective than POMx alone, due to the protective effects of thiols on nitric oxide. Thus, this study hypothesized that multiday POMx supplementation would decrease the oxygen uptake (VO 2 ) required by trained cyclists to perform submaximal exercise and increase performance during a time trial, and that thiol (N-acetylcysteine [NAC]) cosupplementation would enhance these effects. Eight cyclists completed four 8-day supplementation periods: POMx only, NAC only, POMx + NAC (BOTH), and placebo. Following supplementation, they performed submaximal cycling and a 5-min time trial, with VO 2 and muscle oxygen saturation (SmO 2 ) being recorded. A three-way (POMx × NAC × Intensity) repeated-measures analysis of variance with a Fisher's least significant difference post hoc assessment was performed for dependent variables (p ≤ .05). VO 2 during submaximal exercise was reduced with POMx versus placebo (-2.6 ml·min -1 ·kg -1 , p = .009) and BOTH (-2.5 ml·min -1 ·kg -1 , p < .05) and increased with NAC (+1.9 ml·min -1 ·kg -1 , p < .03), despite no main effect of treatment on SmO 2 or performance. It appears that POMx's high polyphenol content reduced the VO 2 required during submaximal exercise. However, NAC cosupplementation annulled this effect; thus, NAC may interact with nitric oxide to reduce its bioavailability.

Recent acute studies have shown that high-intensity resistance circuit-based (HRC) training in hypoxia increases metabolic stress. However, no intervention studies have yet proven their effectiveness. This study aimed to analyze the effect of 8 weeks of HRC in hypoxia on aerobic performance, resting energy expenditure (REE), repeat sprint ability (RSA) and hematological variables. Twenty-eight subjects were assigned to hypoxia (FiO 2  = 15%; HRC hyp : n = 15; age: 24.6 ± 6.8 years; height: 177.4 ± 5.9 cm; weight: 74.9 ± 11.5 kg) and normoxia (FiO 2  = 20.9%; HRC norm : n = 13; age: 23.2 ± 5.2 years; height: 173.4 ± 6.2 cm; weight: 69.4 ± 7.4 kg) groups. Each training session consisted of two blocks of three exercises (Block 1: bench press, leg extension, front pull down; 2: deadlift, elbow flexion, ankle extension). Each exercise was performed at 6 repetitions maximum. Participants exercised twice weekly for 8 weeks and before and after the training program blood test, REE, RSA and treadmill running test were performed. Fatigue index in the RSA test was significantly decreased in the HRC hyp (-0.9%; P < .01; ES = 2.75) but not in the HRC norm . No changes were observed in REE and hematological variables. Absolute (4.5%; P = .014; ES = 0.42) and relative (5.2%; P = .008; ES = 0.43) maximal oxygen uptake (VO 2 max), speed at VO 2 max (4%; P = .010; ES = 0.25) and time to exhaustion (4.1%; P = .012; ES = 0.26) were significantly increased in HRC hyp but not in the HRC norm . No significant differences between groups were found. Compared with normoxic conditions, 8 weeks of HRC training under hypoxic conditions efficiently improves aerobic performance and RSA without changes in REE and red blood O 2 -carrying capacity., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: To compare peak oxygen uptake (VO 2peak ) and exercise efficiency between upper-body poling (UBP) and arm crank ergometry (ACE) in able-bodied (AB) and paraplegic participants (PARA)., Methods: Seven PARA and eleven AB upper-body trained participants performed four 5-min submaximal stages, and an incremental test to exhaustion in UBP and ACE. VO 2peak was the highest 30-s average during the incremental test. Metabolic rate (joule/second = watt) at fixed power outputs of 40, 60, and 80 W was estimated using linear regression analysis on the original power-output-metabolic-rate data and used to compare exercise efficiency between exercise modes and groups., Results: VO 2peak did not significantly differ between UBP and ACE (p = 0.101), although peak power output was 19% lower in UBP (p < 0.001). Metabolic rate at fixed power outputs was 24% higher in UBP compared to ACE (p < 0.001), i.e., exercise efficiency was lower in UBP. PARA had 24% lower VO 2peak compared to AB (p = 0.010), although there were no significant differences in peak power output between PARA and AB (p = 0.209)., Conclusions: In upper-body-trained PARA and AB participants, VO 2peak did not differ between UBP and ACE, indicating that these two test modes tax the cardiovascular system similarly when the upper body is restricted. As such, the 19% lower peak power output in UBP compared to ACE may be explained by the coinciding lower efficiency.

Critical flicker frequency (CFF) threshold is a visual discrimination task designed to assess cortical neural arousal, where higher values are associated with increased information processing and improved cognitive function. Previous studies using CFF assessments before and after exercise have only used one type of exercise (e.g., short, fatiguing, steady state, time to exhaustion, etc.). Therefore, the purpose of this study was to determine the effect of exercise type and intensity on neural arousal. 22 recreational runners (10 men, 12 women; age 25 ± 6 years) volunteered to participate in the study. They completed a VO 2max test (short, fatiguing trial), and three 30-min treadmill runs (longer, steady-state trials) at rating of perceived exertion (RPE) levels of 13, 15, and 17. Before and after each exercise test, subjects were asked to complete the CFF test; M tot and M di were calculated, which are the average and difference of the ascending/descending frequency trials, respectively. There were no main effects found for either intensity (p = 0.641) or time (p = 0.283); there was, however, a significant interaction found (intensity*time; p = 0.001). In the VO 2max test and in the longer, steady-state runs at RPE13 and 15, there was no change in M tot . There was a significant increase in M tot after the run at RPE17 (p = 0.019). For M di , the VO 2max test elicited a significant decrease (p = 0.005), but there was no change after the steady-state runs. The results suggest that short, fatiguing and longer, steady-state exercise affect cortical neural arousal differently. Increases in arousal, and perhaps the related domain of information processing, are more likely to come from steady-state exercise at a vigorous intensity.

Background: Ergogenic effects of caffeine (CAF) ingestion have been observed in different cycling exercise modes, and have been associated with alterations in ratings of perceived exertion (RPE). However, there has been little investigation of maximal oxygen uptake (VO 2MAX ) test outcomes., Aim: This study aimed to verify whether CAF may reduce RPE, thereby improving maximal incremental test (MIT) outcomes such as VO 2MAX , time to exhaustion and peak power output (W PEAK )., Methods: Nine healthy individuals performed three MITs (25 W/min until exhaustion) in a random, counterbalanced fashion after ingestion of CAF, placebo perceived as caffeine (PLA), and no supplementation (baseline control). VO 2 was measured throughout the test, while RPE was rated according to overall and leg effort sensations. The power output corresponding to submaximal (RPE = 14 according to the 6-20 Borg scale) and maximal RPE was recorded for both overall (O-RPE 14 and O-RPE MAX ) and leg RPE (L-RPE 14 and L-RPE MAX )., Results: VO 2MAX did not change significantly between MITs; however, CAF and PLA increased time to exhaustion (↑ ∼18.7% and ∼17.1%, respectively; p < .05) and W PEAK (↑ ∼13.0% and ∼11.8%, respectively; p < .05) when compared with control. When compared with control, CAF ingestion reduced submaximal and maximal overall and leg RPEs, the effect being greater in maximal (likely beneficial in O-RPE MAX and L-RPE MAX ) than submaximal RPE (possibly beneficial in O-RPE 14 and L-RPE 14 ). Similar results were found when participants ingested PLA., Conclusions: Compared with control, CAF and PLA improved MIT performance outcomes such as time to exhaustion and W PEAK , without altering VO 2MAX values. CAF effects were attributed to placebo.

In 1978, Peter Habeler and Reinhold Messner climbed Everest without supplemental O 2 . Subsequently, Oelz et al. (Oelz O, Howald H, Di Prampero PE, Hoppeler H, Claassen H, Jenni R, Bühlmann A, Ferretti G, Brückner JC, Veicsteinas A, Gussoni M, Cerretelli P. J Appl Physiol (1985) 60: 1734-1742, 1986) assessed their cardiopulmonary function, finding no advantageous physiological attributes to explain their success, and leading West (West JB. High Life: A History of High-Altitude Physiology and Medicine. New York: Oxford University, 1998) to suggest that grit and determination were more important. In 1985, Charlie Houston, John Sutton, and Al Cymerman hosted a scientific project assessing a simulated ascent of Everest (OE II) at the U.S. Army Research Institute of Environmental Medicine. Included were measurements of O 2 transport. In particular, mixed venous Po 2 was measured at/near maximal exercise, for calculating pulmonary O 2 -diffusing capacity. A serendipitous observation was made: while both V̇o 2max and mixed venous Po 2 fell with altitude (as expected), it was how they fell-in direct proportion-that was remarkable. It later became clear that this reflected diffusion limitation of O 2 transport from muscle microvessels to the mitochondria, and that this last step in O 2 transport plays a major role in limiting V̇o 2max . Thus, how Habeler and Messner made it up Everest without bottled O 2 and no special cardiopulmonary attributes might be explained if their muscle O 2 -diffusing capacity, which depends largely on muscle capillarity, was unusually high. Oelz et al. mention that muscle capillary density was substantially-40%-above normal, but did not suggest that this accounted for the climbers' success. Therefore, high muscle capillarity, enhancing diffusive unloading of O 2 , may have been a major enabling physiological attribute for Habeler and Messner and that OE II, by chance, played a key role in bringing this to light.

Background: Cardiorespiratory fitness (VO 2max ) is an excellent predictor of chronic disease morbidity and mortality risk. Guidelines recommend individuals undertake exercise training to improve VO 2max for chronic disease reduction. However, there are large inter-individual differences between exercise training responses. This systematic review is aimed at identifying genetic variants that are associated with VO 2max trainability., Methods: Peer-reviewed research papers published up until October 2016 from four databases were examined. Articles were included if they examined genetic variants, incorporated a supervised aerobic exercise intervention; and measured VO 2max /VO 2peak pre and post-intervention., Results: Thirty-five articles describing 15 cohorts met the criteria for inclusion. The majority of studies used a cross-sectional retrospective design. Thirty-two studies researched candidate genes, two used Genome-Wide Association Studies (GWAS), and one examined mRNA gene expression data, in addition to a GWAS. Across these studies, 97 genes to predict VO 2max trainability were identified. Studies found phenotype to be dependent on several of these genotypes/variants, with higher responders to exercise training having more positive response alleles than lower responders (greater gene predictor score). Only 13 genetic variants were reproduced by more than two authors. Several other limitations were noted throughout these studies, including the robustness of significance for identified variants, small sample sizes, limited cohorts focused primarily on Caucasian populations, and minimal baseline data. These factors, along with differences in exercise training programs, diet and other environmental gene expression mediators, likely influence the ideal traits for VO 2max trainability., Conclusion: Ninety-seven genes have been identified as possible predictors of VO 2max trainability. To verify the strength of these findings and to identify if there are more genetic variants and/or mediators, further tightly-controlled studies that measure a range of biomarkers across ethnicities are required.

The aims of the present study were to provide reference values for time to exhaustion (TTE) on a modified Balke treadmill protocol, and to perform a cross-validation of TTE as a measure of maximal oxygen consumption (VO 2max ), in Norwegian men and women 20-85 years of age. Reference values for TTE were derived from a national sample of 765 subjects. An additional sample of 119 subjects was included in the cross-validation (total n = 884), where prediction equations for VO 2max was established. A decline in TTE was seen with increased age. Prediction of VO 2max in an independent dataset (n = 319) resulted in a R 2  = 0.78 and standard error of the estimate = 4.55 mL/kg/min. The observed-predicted bias was small (mean difference <1.24 mL/kg/min), whereas random error was considerable (95% limits of agreement ± 7.11-9.70 mL/kg/min) across age in both men and women. Despite limitations concerning the prediction of VO 2max on an individual level, TTE from the Balke protocol is a good measure of aerobic fitness in adults across a range of settings, and could be evaluated according to the suggested reference values., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

In HIV-infected individuals, impaired mitochondrial function may contribute to cardiometabolic disease as well as to fatigue and frailty. Aerobic exercise improves total body energy reserves; however, its impact at the cellular level is unknown. We assessed alterations in cellular bioenergetics in peripheral blood mononuclear cells (PBMC) before and after a 12-week aerobic exercise study in sedentary HIV-infected subjects on stable antiretroviral therapy who successfully completed a 12-week aerobic exercise program. In this prospective study, participants underwent supervised 20-40 min of light aerobic exercise (walking or jogging) performed three times per week for 12 weeks, gradually increasing to maintain an intensity of 50%-80% of heart rate reserve. Maximal aerobic capacity (VO 2MAX ) was assessed by a graded exercise test on a cycle ergometer before and after completion of the study. PBMC from compliant subjects (attended at least 70% of exercise sessions) were assessed for mitochondrial respiration using the Seahorse XF24 Bio-Analyzer. Seven of 24 enrolled subjects were compliant with the exercise regimen. In these individuals, a significant increase (p = .04) in VO 2MAX over 12 weeks was found with a median increase of 14%. During the same interval, a 2.45-fold increase in PBMC mitochondrial respiratory capacity (p = .04), a 5.65-fold increase in spare respiratory capacity (p = .01), and a 3.15-fold (p = .04) increase in nonmitochondrial respiration was observed. Aerobic exercise improves respiration at the cellular level. The diagnostic and prognostic value of such improved cellular respiration in the setting of chronic HIV warrants further investigation.

The purpose of this study was to examine the physiological characteristics of an elite centenarian cyclist who, at 101 yr old, established the 1-h cycling record for individuals ≥100 yr old (24.25 km) and to determine the physiological factors associated with his performance improvement 2 yr later at 103 yr old (26.92 km; +11%). Before each record, he performed an incremental test on a cycling ergometer. For 2 yr, he trained 5,000 km/yr with a polarized training that involved cycling 80% of mileage at "light" rate of perceived exertion (RPE) ≤12 and 20% at "hard" RPE ≥15 at a cadence between 50 and 70 rpm. His body weight and lean body mass did not change, while his maximal oxygen consumption (V̇o 2max ) increased (31-35 ml·kg -1 ·min -1 ; +13%). Peak power output increased from 90 to 125 W (+39%), mainly because of increasing the maximal pedaling frequency (69-90 rpm; +30%). Maximal heart rate did not change (134-137 beats/min) in contrast to the maximal ventilation (57-70 l/min, +23%), increasing with both the respiratory frequency (38-41 cycles/min; +8%) and the tidal volume (1.5-1.7 liters; +13%). Respiratory exchange ratio increased (1.03-1.14) to the same extent as tolerance to V̇co 2 In conclusion, it is possible to increase performance and V̇o 2max with polarized training focusing on a high pedaling cadence even after turning 100 yr old. NEW & NOTEWORTHY This study shows, for the first time, that maximal oxygen consumption (+13%) and performance (+11%) can still be increased between 101 and 103 yr old with 2 yr of training and that a centenarian is able, at 103 yr old, to cover 26.9 km/h in 1 h., (Copyright © 2017 the American Physiological Society.)

Purpose: To determine whether maximal oxygen uptake (VO 2 max) could be predicted accurately and reliably from a 2-step, perceptually-regulated exercise test (PRET) in healthy adults., Methods: Sixteen participants (31.7 ± 11.3 years, 3 females) completed three PRETs (separated by 24-72 h) and one maximal, perceptually-regulated, graded exercise test (PRETmax) on a motorized treadmill. Oxygen uptake (VO 2 ) and heart rate (HR) were recorded during each test. VO 2 values for RPE range 9-15 were extrapolated to RPE 20 and age-predicted maximal HR (HRmax) using individual linear regression analysis to predict VO 2 max values compared to measured VO 2 max., Results: VO 2 and HR values were consistent between each of four RPE levels of the PRET. ICC values ranged between 0.76 and 0.85. Predicted VO 2 max from both methods were lower than measured VO 2 max (p < 0.01). Limits of agreement (LoA) for measured (41.4 ± 5.3 ml kg -1  min -1 ) versus predicted VO 2 max from each of the three PRETs using RPE20 were -1.2 ± 15.6, -1.0 ± 7.2 and -2.1 ± 5.5 and for HRmax were -1.8 ± 4.2; -2.6 ± 4.2 and -2.4 ± 4.4 ml kg -1  min -1 for PRET 1, 2 and 3, respectively., Conclusions: The step PRET elicited significant and reliable increases in VO 2 across the four RPE levels, but under-estimated treadmill VO 2 max. However, there was better agreement between measured and predicted VO 2 max when extrapolated to HRmax. As evidence indicates the underestimation of VO 2 max is explained by the difference in the mode of exercise, the step PRET provides a simple and convenient test of cardiorespiratory fitness.

Previously it has been reported that reduced-exertion high-intensity interval training (REHIT; total training time of 3 × 10 min per week) improves maximal aerobic capacity in both sedentary men and women, but improves insulin sensitivity in men only. The aim of the present study was to determine whether there is a true sex difference in response to REHIT, or that these findings can be explained by the large interindividual variability in response inherent to all exercise training. Thirty-five sedentary participants (18 women; mean ± SD age for men and women, respectively: age, 33 ± 9 and 36 ± 9 years; body mass index, 25.1 ± 2.1 and 24.1 ± 3.5 kg·m -2 ; maximal aerobic capacity, 38.6 ± 8.3 and 31.6 ± 4.6 mL·kg -1 ·min -1 ) completed a 6-week REHIT programme consisting of eighteen 10-min unloaded cycling sessions with 1 (first session) or 2 (all other sessions) "all-out" 10-20-s sprints against a resistance of 5% of body mass. Maximal aerobic capacity and oral glucose tolerance test-derived insulin sensitivity were determined before and after training. REHIT was associated with an increase in maximal aerobic capacity (2.54 ± 0.65 vs. 2.78 ± 0.68 L·min -1 , main effect of time: p < 0.01), a trend toward reduced plasma insulin area-under-the-curve (AUC; 6.7 ± 4.8 vs. 6.1 ± 4.0 IU·min -1 ·mL -1 , p = 0.096), but no significant change in plasma glucose AUC or the Cederholm index of insulin sensitivity. Substantial interindividual variability in response to REHIT was observed for all variables, but there was no significant effect of sex. In conclusion, REHIT improves the key health marker of aerobic capacity within a minimal total training time-commitment. There is large interindividual variability in responses to REHIT, but sex differences in the responses are not apparent.

Background: Participation in aerobic exercise generates increased cardiorespiratory fitness, which results in a protective factor for cardiovascular disease and all-cause mortality. High-intensity interval training might cause higher increases in cardiorespiratory fitness in comparison with moderate-intensity continuous training; nevertheless, current evidence is not conclusive. To our knowledge, this is the first study to test the effect of high-intensity interval training with total load duration of 7.5 min per session., Methods: A randomized controlled trial will be performed on two groups of healthy, sedentary male volunteers (n = 44). The study protocol will include 24 exercise sessions, three times a week, including aerobic training on a treadmill and strength training exercises. The intervention group will perform 15 bouts of 30 s, each at an intensity between 90 % and 95 % of maximal heart rate. The control group will complete 40 min of continuous exercise, ranging between 65 % and 75 % of maximal heart rate. The primary outcome measure to be evaluated will be maximal oxygen uptake (VO2max), and systolic and diastolic blood pressure will be evaluated as secondary outcome measures. Waist circumference, body mass index, and body composition will also be evaluated., Discussion: Epidemiological evidence shows the link between VO2max and its association with chronic conditions that trigger CVD. Therefore, finding ways to improve VO2max and reduce blood pressure it is of vital importance to public health., Trial Registration: NCT02288403 . Registered on 4 November 2014.

To assess the validity of postexercise measurements in estimating peak oxygen uptake (V̇O2peak) in swimming, we compared oxygen uptake (V̇O2) measurements during supramaximal exercise with various commonly adopted methods, including a recently developed heart rate - V̇O2 modelling procedure. Thirty-one elite swimmers performed a 200-m maximal swim where V̇O2 was measured breath-by-breath using a portable gas analyzer connected to a respiratory snorkel, 1 min before, during, and 3 min postexercise. V̇O2peak(-20-0) was the average of the last 20 s of effort. The following postexercise measures were compared: (i) first 20-s average (V̇O2peak(0-20)); (ii) linear backward extrapolation (BE) of the first 20 s (BE(20)), 30 s, and 3 × 20-, 4 × 20-, and 3 or 4 × 20-s averages; (iii) semilogarithmic BE at 20 s (LOG(20)) and at the other same time intervals as in linear BE; and (iv) predicted V̇O2peak using mathematical modelling (pV̇O2(0-20)]. Repeated-measures ANOVA and post-hoc Bonferroni tests compared V̇O2peak (criterion) and each estimated value. Pearson's coefficient of determination (r(2)) was used to assess correlation. Exercise V̇O2peak(-20-0) (mean ± SD 3531 ± 738 mL·min(-1)) was not different (p > 0.30) from pV̇O2(0-20) (3571 ± 735 mL·min(-1)), BE(20) (3617 ± 708 mL·min(-1)), or LOG(20) (3627 ± 746 mL·min(-1)). pV̇O2(0-20) was very strongly correlated with exercise V̇O2peak (r(2) = 0.962; p < 0.001), and showed a low standard error of the estimate (146 mL·min(-1), 4.1%) and the lowest mean difference (40 mL·min(-1); 1.1%). We confirm that the new modelling procedure based on postexercise V̇O2 and heart rate measurements is a valid and accurate procedure for estimating V̇O2peak in swimmers and avoids the estimation bias produced by other methods.