Low frequency of the "plateau phenomenon" during maximal exercise in elite British athletes

The Detrimental Effects of Bedrest: Premature Cardiovascular Aging and Dysfunction

Bedrest as an experimental paradigm or as an in-patient stay for medical reasons has negative consequences for cardiovascular health. The effects of severe inactivity parallel many of the changes experienced with natural aging but over a much shorter duration. Cardiac function is reduced, arteries stiffen, neural reflex responses are impaired, and metabolic and oxidative stress responses impose burden on the heart and vascular systems. The effect of these changes is revealed in studies of integrative function. Aerobic fitness progressively deteriorates with bedrest and tolerance of upright posture is rapidly impaired. In this review we consider the similarities of aging and bedrest-induced cardiovascular deconditioning. We concur with many recent clinical recommendations that early and regular mobility with upright posture will reduce likelihood of hospital-associated disability related to bedrest.

Physiological and Mechanical Responses to a Graded Exercise Test in Traditional Rowing

Maximum oxygen consumption and maximum power output are critical measures for training prescription in endurance sports such as rowing. The objective of this investigation was twofold: to compare the physiological and mechanical responses of female and male traditional rowers during a graded exercise test and to establish reference values in this specific rowing modality that have not yet been documented, unlike in Olympic rowing. Twenty-one highly trained/national level rowers participated in the study: 11 female (age: 30.1 ± 10.6 years, height: 167.3 ± 5.0 cm, body mass: 61.9 ± 4.9 kg) and 10 males (age: 33.5 ± 6.6 years, height: 180.8 ± 6.9 cm, body mass: 74.4 ± 6.9 kg). Significant differences (p < 0.05) were found in rowing performance between sexes, with a very large effect size (d = 7.2). The peak power output for the female rowers was 180.9 ± 11.4 W and 287.0 ± 17.7 W for the male rowers. The female rowers reached a VO2max of 51.2 ± 6.6 mL/kg/min at a mean of 174.5 ± 12.9 W, while the males' VO2max was 62.1 ± 4.7 mL/kg/min at a mean of 280.0 ± 20.5 W. These differences in VO2max and maximal aerobic capacity were significant (p < 0.05), with a large (d = 1.9) and very large (d = 6.2) effect size, respectively. A moderate association between VO2max, and rowing performance expressed in watts per kilogram of muscle mass was observed in the female rowers (r = 0.40, p = 0.228). For the male rowers, the correlation between VO2max and relative peak power output in watts per kilogram of body mass was strong (r = 0.68; p = 0.031). This study highlights the differences in the kinetics of ventilatory and mechanical parameters between female and male rowers and the importance of these differences for specific physical preparation in traditional rowing.

Acute Effects of Sprint Interval Training and Chronic Effects of Polarized Training (Sprint Interval Training, High Intensity Interval Training, and Endurance Training) on Choice Reaction Time in Mountain Bike Cyclists

This study evaluated the acute effects of sprint interval training and chronic effects of polarized training on choice reaction time in cyclists. Twenty-six mountain bike cyclists participated in the study and were divided into experimental (E) and control (C) groups. The cyclists trained for 9-weeks and performed five training sessions each week. Types of training sessions: (1) sprint interval training (SIT) which consisted of 8-16, 30 s repetitions at maximal intensity, (2) high-intensity interval training (HIIT) included 5 to 7, 5-min efforts at an intensity of 85-95% maximal aerobic power (Pmax), and (3) endurance training (ET) performed at an intensity of 55-60% Pmax, lasting 120--180 min. In each week the cyclists performed: in group E a polarized training program, which included 2 × SIT, 1 × HIIT and 2 × ET, while in group C 2 × HIIT and 3 × ET. Before (acute effects) and after the 9-week training period (chronic effects) participants performed laboratory sprint interval testing protocol (SITP), which consisted of 12 maximal repetitions lasting 30 s. During SITP maximal and mean anaerobic power, as well as lactate ion concentration and blood pH were measured. Choice reaction time (RT) was measured 4-times: before and immediately after the SITP test-before and after the 9-week training period. Evaluated the average choice RT, minimal choice RT (shortest reaction), maximal choice RT (longest reaction), and the number of incorrect reactions. Before the training period as acute effects of SITP, it was observed: a shorter average choice RT (F = 13.61; p = 0.001; η2 = 0.362) and maximal choice RT (F = 4.71; p = 0.040; η2 = 0.164), and a decrease the number of incorrect reactions (F = 53.72; p = 0.000; η2 = 0.691), for E and C groups. After the 9-week training period, chronic effects showed that choice RT did not change in any of the cyclists' groups. Only in the E group after the polarized training period, the number of incorrect reactions decreased (F = 49.03; p = 0.000; η2 = 0.671), average anaerobic power increased (F = 8.70; p = 0.007; η2 = 0.274) and blood pH decreased (F = 27.20; p = 0.000; η2 = 0.531), compared to the value before the training period. In conclusion, a shorter choice RT and a decrease in the number of incorrect reactions as acute effects of SITP, and a decrease in the number of incorrect reactions and higher average power as chronic effects of the polarized training program are beneficial for mountain bike cyclists.

Is there really a proportional relationship between VO2max and body weight? A review article

Maximum oxygen uptake (VO_2max) is a “gold standard” in aerobic capacity assessment, playing a vital role in various fields. However, ratio scaling (VO2maxbw), the present method used to express relative VO_2max, should be suspected due to its theoretical deficiencies. Therefore, the aim of the study was to revise the quantitative relationship between VO_2max and body weight (bw). Dimensional analysis was utilized to deduce their theoretical relationship, while linear or nonlinear regression analysis based on four mathematical models (ratio scaling, linear function, simple allometric model and full allometric model) were utilized in statistics analysis to verify the theoretical relationship. Besides, to investigate the effect of ratio scaling on removing body weight, Pearson correlation coefficient was used to analyze the correlation between VO2maxbw and bw. All the relevant data were collected from published references. Dimensional analysis suggested VO_2max be proportional to bw23. Statistics analysis displayed that four mathematical expressions were VO_2max = 0.047bw (p<0.01, R² = 0.68), VO_2max = 0.036bw+0.71 (p<0.01, R² = 0.76), VO_2max = 0.10bw^0.82 (p<0.01, R² = 0.93) and VO_2max = 0.23bw^0.66–0.48 (p<0.01, R² = 0.81) respectively. Pearson correlation coefficient showed a significant moderately negative relation between VO2maxbw and bw (r = -0.42, p<0.01), while there was no correlation between VO2maxbw0.82 and bw (r = 0.066, p = 0.41). Although statistics analysis did not fully verify the theoretical result, both dimensional and statistics analysis suggested ratio scaling distort the relationship and power function be more appropriate to describe the relationship. Additionally, we hypothesized that lean mass, rather than body weight, plays a more essential role in eliminating the gap between theoretical and experimental b values, and is more appropriate to standardize VO_2max, future studies can focus more on it.

Incremental and decremental cardiopulmonary exercise testing protocols produce similar maximum oxygen uptake in athletes

The aim of the study was to evaluate and compare the maximal oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max) achieved during incremental and decremental protocols in highly trained athletes. Nineteen moderate trained runners and rowers completed, on separate days, (i) an initial incremental \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max test (INC) on a treadmill, followed by a verification phase (VER); (ii) a familiarization of a decremental test (DEC); (iii) a tailored DEC; (iv) a test with decremental and incremental phases (DEC-INC); (v) and a repeated incremental test (INC_F). During each test \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O₂, carbon dioxide production, ventilation, heart and breath rates and ratings of perceived exertion were measured. No differences were observed in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max between INC (61.3 ± 5.2 ml kg⁻¹ min⁻¹) and DEC (61.1 ± 5.1 ml kg⁻¹ min⁻¹; average difference of ~ 11.58 ml min⁻¹; p = 0.831), between INC and DEC-INC (60.9 ± 5.3 ml kg⁻¹ min⁻¹; average difference of ~ 4.8 ml min⁻¹; p = 0.942) or between INC and INC_F (60.7 ± 4.4 ml kg⁻¹ min⁻¹; p = 0.394). \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max during VER (59.8 ± 5.1 ml kg⁻¹ min⁻¹) was 1.50 ± 2.20 ml kg⁻¹ min⁻¹ lower (~ 2.45%; p = 0.008) compared with values measured during INC. The typical error in the test-to-test changes for evaluating \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max over the five tests was 2.4 ml kg⁻¹ min⁻¹ (95% CI 1.4–3.4 ml kg⁻¹ min⁻¹). Decremental tests do not elicit higher \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O_2max than incremental tests in trained runners and rowers, suggesting that a plateau in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{\mathrm{V}}$$\end{document}V˙O₂ during the classic incremental and verification tests represents the maximum ceiling of aerobic power.

The Oxygen Uptake Plateau-A Critical Review of the Frequently Misunderstood Phenomenon

A flattening of the oxygen uptake–work rate relationship at severe exercise indicates the achievement of maximum oxygen uptake \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left({\text{VO}}_{2\max } \right)$$\end{document}VO2max. Unfortunately, a distinct plateau \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left( {{{\text{VO}}}_{2} {\text{pl}}} \right)$$\end{document}VO2pl at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2maxis not found in all participants. The aim of this investigation was to critically review the influence of research methods and physiological factors on the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence. It is shown that many studies used inappropriate definitions or methodical approaches to check for the occurrence of a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl. In contrast to the widespread assumptions it is unclear whether there is higher \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence in (uphill) running compared to cycling exercise or in discontinuous compared to continuous incremental exercise tests. Furthermore, most studies that evaluated the validity of supramaximal verification phases, reported verification bout durations, which are too short to ensure that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max have been achieved by all participants. As a result, there is little evidence for a higher \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl incidence and a corresponding advantage for the diagnoses of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max when incremental tests are supplemented by supramaximal verification bouts. Preliminary evidence suggests that the occurrence of a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl in continuous incremental tests is determined by physiological factors like anaerobic capacity, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2}$$\end{document}VO2-kinetics and accumulation of metabolites in the submaximal intensity domain. Subsequent studies should take more attention to the use of valid \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2} {\text{pl}}$$\end{document}VO2pl definitions, which require a cut-off at ~ 50% of the submaximal \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2}$$\end{document}VO2 increase and rather large sampling intervals. Furthermore, if verification bouts are used to verify the achievement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{{2{\text{peak}}}}$$\end{document}VO2peak/\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\text{VO}}}_{2\max }$$\end{document}VO2max, it should be ensured that they can be sustained for sufficient durations.

Conventional Testing Produces Submaximal Values for Oxygen Uptake in Elite Runners

PURPOSE

This study aimecd to investigate whether elite athletes could reach higher values of maximal oxygen uptake (V˙O2max) during a decremental exercise test in comparison with a traditional incremental test, as recently demonstrated in trained individuals.

METHODS

Nine male runners (age 25.8 [5.1] y, season best 10-km time 31:19 [1:50]) performed, on different days, 3 maximal uphill (5% grade) running exercise tests in fixed order: an incremental test (INC1), a V-shape exercise test (where speed started at 0.5 km·h-1 higher than the top stage finished during INC1 and was slowly decreased during 5.5 min, when it was again increased in similar fashion to the INC tests), and a final incremental test (INC2).

RESULTS

V˙O2max during the V-shape exercise test was higher than during INC1 (6.3% [3.0%], P = .01), although running speed was lower (16.6 [1.7] vs 17.9 [1.6] km·h-1, P = .01). Performance was similar between INC1 and INC2, but V˙O2max during INC2 was higher than INC1 (P < .001). During the V-shape exercise test, 5 participants reached the incremental part of the test, but V˙O2 did not increase (ΔV˙O2=52 [259] mL·min-1, P = .67), despite higher running speed (approximately 1.1 km·h-1, P < .01). Heart rate, pulmonary ventilation, breathing rate, and respiratory exchange ratio measured at V˙O2max were not different between tests.

CONCLUSION

A decremental exercise test of sufficient intensity can produce higher V˙O2max than a traditional incremental test, even in elite athletes, and this is maintained during a subsequent incremental test.

Influence of Biomechanical Parameters on Performance in Elite Triathletes along 29 Weeks of Training

The purpose of the study was to assess how the modification of biomechanical parameters influences the performance of elite triathletes. Four elite international triathletes participated in this study. The anthropometric method ISAK was used to estimate the triathlete’s body composition. For the physiological and biomechanical parameters, a running test (RT) was performed on an outdoor track, with the participants wearing the Stryd Summit Footpod (Stryd, Boulder, CO, USA). The pre-test took place in the last week of an adaptation mesocycle; then, after 29 weeks of training, the triathletes performed the post-test. A within-subject repeated measures design was used to assess changes in the anthropometric, physiological and biomechanical parameters. Pearson correlations (r) were applied to determine the relationship between the performance at different intensities (VT1, VT2 and MAS) and the biomechanical parameters. Concerning the anthropometric characteristics, significant differences were found in the summation (Σ) of skinfold (8.1 cm); as a consequence, the % fat mass was reduced (1.2%). Significant differences were found in the physiological values (VO2 and % VO2max), speed and biomechanical parameters, such as step length normalized, to the specific physiological intensity of the short-distance triathlon, the VT2. Therefore, performance improvement in the running segment could not only be explained by physiological changes, but also by biomechanical parameters changes.

Is a verification phase needed to determine [Formula: see text]O2max across fitness levels?

INTRODUCTION

Current methods (plateau/secondary criteria) to determine maximal oxygen consumption ([Formula: see text]O_2max) are inconsistently achieved leading some to suggest the use of a verification phase (VP) to confirm [Formula: see text]O_2max.

PURPOSE

To provide further evidence for the inclusion of a VP to confirm [Formula: see text]O_2max in different fitness levels.

METHODS

Forty-nine participants (22 females; 21.9 ± 2.6 years, 24.3 ± 2.8 kg m^-2, 45.27 ± 7.68 mL kg^-1 min^-1) had their [Formula: see text]O₂ and heart rate measured during three graded exercise tests (GXT) on separate days each followed by a VP of differing intensity (85%, 95%, 105% final workload). Participants were divided into groups using norms adapted from American College of Sports Medicine [Formula: see text]O_2max guidelines (30.47-61.47 mL kg^-1 min^-1). [Formula: see text]O_2max was confirmed if the [Formula: see text]O_2peak on the VP or an additional GXT was within ± 2 × typical error of the [Formula: see text]O_2peak attained on the first GXT. There was no effect of test number so the third GXT was not included in comparison with VP.

RESULTS

The [Formula: see text]O_2peak from the first GXT was not different than either value attained following the VP at 95 or 105% workload or a second GXT (p > 0.999). The 85% VP [Formula: see text]O_2peak was lower than the first GXT [Formula: see text]O_2peak (p = 0.002). The VP confirmed the GXT [Formula: see text]O_2peak on 73% of VP (no differences among fitness levels). Submaximal VP (85 and 95%) was less effective as 65% and 51% of participants achieved a higher [Formula: see text]O_2peak on one of the GXT.

CONCLUSION

The use of a VP at 105% or a second GXT was able to confirm the [Formula: see text]O_2max value attained across a range of fitness levels.

Progress Update and Challenges on V . O2max Testing and Interpretation

The maximal oxygen uptake ( V . O2max) is the primary determinant of endurance performance in heterogeneous populations and has predictive value for clinical outcomes and all-cause mortality. Accurate and precise measurement of V . O2max requires the adherence to quality control procedures, including combustion testing and the use of standardized incremental exercise protocols with a verification phase preceded by an adequate familiarization. The data averaging strategy employed to calculate the V . O2max from the breath-by-breath data can change the V . O2max value by 4-10%. The lower the number of breaths or smaller the number of seconds included in the averaging block, the higher the calculated V . O2max value with this effect being more prominent in untrained subjects. Smaller averaging strategies in number of breaths or seconds (less than 30 breaths or seconds) facilitate the identification of the plateau phenomenon without reducing the reliability of the measurements. When employing metabolic carts, averaging intervals including 15-20 breaths or seconds are preferable as a compromise between capturing the true V . O2max and identifying the plateau. In training studies, clinical interventions and meta-analysis, reporting of V . O2max in absolute values and inclusion of protocols and the averaging strategies arise as imperative to permit adequate comparisons. Newly developed correction equations can be used to normalize V . O2max to similar averaging strategies. A lack of improvement of V . O2max with training does not mean that the training program has elicited no adaptations, since peak cardiac output and mitochondrial oxidative capacity may be increased without changes in V . O2max.

Effect of intensive prior exercise on muscle fiber activation, oxygen uptake kinetics, and oxygen uptake plateau occurrence

Purpose

We tested the hypothesis that the described increase in oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2)-plateau incidence following a heavy-severe prior exercise is caused by a steeper increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain.

Methods

Twenty-one male participants performed a standard ramp test, a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max verification bout, an unprimed ramp test with an individualized ramp slope and a primed ramp test with the same ramp slope, which was preceded by an intensive exercise at 50% of the difference between gas exchange threshold and maximum workload. Muscle fiber activation was recorded from vastus lateralis, vastus medialis, and gastrocnemius medialis using a surface electromyography (EMG) device in a subgroup of 11 participants. Linear regression analyses were used to calculate the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-(\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP) and EMG-(∆RMS/∆P) ramp test kinetics.

Results

Twenty out of the 21 participants confirmed their \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{{\text{2max}}}}$$\end{document}V˙O2max in the verification bout. The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence in these participants did not differ between the unprimed (n = 8) and primed (n = 7) ramp test (p = 0.500). The \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Delta \dot{V}{\text{O}}_{{2}} /\Delta P$$\end{document}ΔV˙O2/ΔP was lower in the primed compared to the unprimed ramp test (9.40 ± 0.66 vs. 10.31 ± 0.67 ml min⁻¹ W⁻¹, p < 0.001), whereas the ∆RMS/∆P did not differ between the ramp tests (0.62 ± 0.15 vs. 0.66 ± 0.14% W⁻¹; p = 0.744).

Conclusion

These findings do not support previous studies, which reported an increase in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2-plateau incidence as well as steeper increases in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2}}$$\end{document}V˙O2 and muscle fiber activation in the submaximal intensity domain following a heavy-severe prior exercise.

Relationship Between the Skin Surface Temperature Changes During Sprint Interval Testing Protocol and the Aerobic Capacity in Well-Trained Cyclists

The study investigated whether changes in body surface temperature in a sprint interval testing protocol (SITP) correlated with aerobic capacity in cyclists. The study involved 21 well-trained cyclists. Maximal aerobic power and maximal oxygen uptake relative to lean body mass (LBM-P(max) and LBM-VO(2max), respectively) were determined by incremental exercise testing on a cycle ergometer. SITP was administered 48 hours later and involved four 30-s maximal sprints interspersed with 90-s active recovery. Body surface temperature was recorded at the temple and arm and the delta difference between baseline temperature and temperature measured immediately after the first sprint (DeltaTt(1) and DeltaTa(1), respectively) and 80 seconds after the fourth sprint (DeltaTt(4) and DeltaTa(4)), respectively) was calculated. Significant correlations were found between DeltaTt4 and LBM-Pmax and LBM-VO(2max) (r=0.63 and r=0.75, respectively) with no significant change in DeltaTa(1) or DeltaTa(4). Body surface temperature, measured at the temple region, can be used to indirectly assess aerobic capacity during maximal sprint exercise.

Changes in Triathletes' Performance and Body Composition During a Specific Training Period for a Half-Ironman Race

The number of recreational athletes completing a Half-Ironman triathlon has increased exponentially in recent years. However, there is a lack of research on how to train for this kind of an event. The purpose of this study was thus to analyse triathletes’ changes in performance and body composition following a triathlon-specific training period. Fourteen male amateur triathletes completed a 7-week period of general training and a 13-week period of specific training for a Half-Ironman triathlon. Anthropometric measures and performance tests were carried out to assess the effects of the specific training program. Results showed that the pre-test value of VO_2max for cycling was inversely correlated not only with the percentage of change in cycling performance, but also with the percentage change in several variables of running performance. In swimming, inverse correlations were observed between the time of the first 800 m test and the time percentage change for this test, but not with the percentage change in the performance of other segments of the race. Moreover, the somatotype component of endomorphy and the fat mass percentage of the first anthropometry were highly correlated with the percentage change in VO_2max in the run segment. These results highlight the importance of providing individualised training, considering that the same training program had a different impact on recreational triathletes belonging to the same group. Amateur athletes with higher initial performance levels probably need a greater amount of training to achieve improved adaptation.

Oxygen uptake plateau occurrence depends on oxygen kinetics and oxygen deficit accumulation

We tested the hypothesis that participants with an oxygen uptake ( V ˙ O 2 ) plateau during incremental exercise exhibit a lower VO₂ -deficit (VO_2DEF )-accumulation in the submaximal intensity domain due to faster ramp and square wave O₂ -kinetics. Twenty-six male participants performed a standard ramp test (increment: 30 W·min^-1 ), a ramp test with an individualized ramp slope and a two-step (moderate and severe) square wave exercise followed by a V ˙ O 2 m a x -verification bout. VO_2DEF was calculated by the difference between individualized ramp test V ˙ O₂ and V ˙ O₂ -demand estimated from steady-state V ˙ O₂ -kinetics. Twenty-four participants verified their V ˙ O_2max in the verification test. Ten of them showed a plateau in the individualized ramp test. VO_2DEF at the end of this ramp test (4.34 ± 0.60 vs 4.54 ± 0.43 L) was not different between the plateau and the non-plateau group (P > 0.05). The plateau group had a significantly (P < 0.05) lower VO_2DEF 2 minutes before termination of the individualized ramp test (2.24 ± 0.40 vs 2.78 ± 0.33 L). This coincided with a shorter mean response time (43 ± 9 vs 53 ± 7 seconds), a higher increase in V ˙ O₂ per W (10.1 ± 0.2 vs 9.2 ± 0.5 mL·min^-1 ·W^-1 ) at the individualized ramp test as well as shorter time constants of moderate (36 ± 6 vs 48 ± 7 seconds) and severe (62 ± 9 vs 86 ± 10 seconds) square wave kinetics (all P < 0.05). We conclude that the V ˙ O₂ -plateau occurrence requires a fast V ˙ O₂ -kinetics and a low VO_2DEF -accumulation at intensities below V ˙ O_2max .

Assessment of the physical fitness of road cyclists in the step and ramp protocols of the incremental test

BACKGROUND

The incremental test in laboratory conditions is a method commonly used to evaluate the maximal oxygen uptake and peak power output, which are the good predictors of cycling performance. But the best-designed protocol remains unknown. Therefore, the aim of this study was to examine the physiological and biochemical responses in the incremental ramp on cycle ergometer and to compare with the commonly used step in young road cyclists.

METHODS

Fifty-seven road cyclists took part in the experiment. The tests included two visits to the laboratory during which the anthropometric measurements, incremental test on a cycle ergometer, and examination of acid-base balance and blood lactate concentration were made. A randomly selected half of the subjects made, as the first one, the STEP (50W·3min-1) Test and the RAMP Test (~0,27W·sec-1) a week later. The remaining cyclists made tests in the reverse order.

RESULTS

The peak power output obtained in the RAMP was significantly higher than obtained in the STEP by 18.13W (P<0.05). The maximal oxygen uptake was higher by 1.5 (mL∙kg-1∙min-1) during the RAMP (P<0.05). The postexercise blood lactate concentration was significantly higher by 0.94 mmol∙L-1(P<0.05) in STEP.

CONCLUSIONS

We recommend the use of RAMP Test with linearly increasing workload to determine peak power output, maximal oxygen uptake and ventilatory threshold to precisely programming and control training of young road cyclists.

Time of VO(2)max plateau and post-exercise oxygen consumption during incremental exercise testing in young mountain bike and road cyclists

The purpose of this study was to compare markers of glycolytic metabolism in response to the Wingate test and the incremental test in road and mountain bike cyclists, who not different performance level and aerobic capacity. All cyclists executed the Wingate test and incremental test on a cycle ergometer. Maximal power and average power were determined during the Wingate test. During the incremental test the load was increased by 50 W every 3 min, until volitional exhaustion and maximal aerobic power (APmax), maximal oxygen uptake (VO2max), and time of VO(2)max plateau (Tplateau) were determined. Post-exercise measures of oxygen uptake (VO(2)post), carbon dioxide excretion, (VCO(2)post), and the ratio between VCO(2)/VO(2) (RERpost) were collected for 3 min immediately after incremental test completion. Arterialized capillary blood was drawn to measure lactate (La-) and hydrogen (H+) ion concentrations in 3 min after each test. The data demonstrated significant differences between mountain bike and road cyclists for Tplateau, VO(2)post, VCO(2)post, La- which was higher-, and RERpost which was lower-, in mountain bike cyclists compare with road cyclists. No differences were observed between mountain bike and road cyclists for APmax, VO(2)max, H(+) and parameters measured in the Wingate test. Increased time of VO2max plateau concomitant to larger post-exercise La- and VO(2) values suggests greater anaerobic contribution during incremental testing efforts by mountain bike cyclists compared with road cyclists.

Validity of oxygen uptake cut-off criteria in plateau identification during horizontal treadmill running

BACKGROUND

When determining achievement of maximal oxygen uptake (V̇O2max) during treadmill running using speed increments, the V̇O2 cut-off criteria applied during plateau identification is often not justified, not protocol specific, or not related to actual change in V̇O2 (ΔV̇O2) with speed increment, which can influence plateau achievement rates between studies. The purpose of this study was to compare plateau incidence using an individualised plateau criteria approach based on a "percentage" ΔV̇O2 compared to using previously established criteria of ΔV̇O2≤2.1 mL∙kg-1∙min-1 not developed on running speed.

METHODS

Fifty-four males completed a ramp horizontal treadmill test with 0.5 or 1.0 km∙h-1 per minute (km∙h-1∙min-1) speed increments to measure V̇O2max. Average Δ V̇O2 for the each 1-minute speed increment was determined and used to develop individualised cut-off criteria deemed to be a plateau: a final ΔV̇O2 of less than 50% of the average change elicited between consecutive speed increments during the test (V̇O2≤50%); plateau incidence using this was compared to ΔV̇O2≤2.1 mL∙kg-1∙min-1 (V̇O2≤2.1).

RESULTS

Mean ΔV̇O2 was 1.74±0.59 and 3.09±0.59 mL∙kg-1∙min-1 for 0.5 and 1.0 km∙h-1∙min-1increments respectively. V̇O2 cut-off criteria were met by 48%/65% (1.0 km∙h-1∙min-1) (P=0.234) and 53%/100% (0.5 km∙h-1∙min-1) (P=0.003) for V̇O2≤50% and V̇O2≤2.1 respectively.

CONCLUSIONS

Use of V̇O2≤2.1 resulted in distortedly high plateau achievement, particularly for smaller speed increments where the V̇O2-speed relationship was actually less than V̇O2≤2.1 making its use inappropriate. Use of V̇O2≤50% may be a suitable alternative, but as a plateau was not consistently demonstrated, application of cut-off criteria should not be a requirement in deciding whether one's achieved V̇O2max.

Assessment of endpoint criteria and perceived barriers during maximal cardiorespiratory fitness testing among pregnant women

BACKGROUND

A plateau in volume of oxygen consumption (VO2) is the primary indicator for determining if an individual has reached their maximal aerobic capacity. However, secondary criteria can also be used to identify maximal effort (i.e. lactate level, rating of perceived exertion [RPE], percent of age-predicted maximal heart rate [HR] and respiratory exchange ratio [RER]). Age and gender-specific secondary criteria have been developed for the general population, but no secondary criteria have been established for pregnant women. The primary purpose of this study was to analyze secondary endpoint criteria during VO2max testing among pregnant women. A secondary purpose was to identify emotional and physical barriers pregnant women have that may prevent them from reaching maximal effort.

METHODS

Twenty-five pregnant women (age= 30.0±3.6 years; gestation age= 22.1±1.4 weeks, pre-pregnancy BMI= 23.68±4.04 kg/m2) participated. Each participant completed a Bruce protocol treadmill test and maximal HR, RER, lactate, and RPE were assessed and compared to standards. Barriers were assessed immediately postexercise via open-ended questions.

RESULTS

The mean VO2max was 32.9±8.8 mL/kg/min. Mean RPEmax was 17.6±1.8 versus the standard of RPE≥17 (P=0.12). Percent of age-predicted HRmax was 88.0±6.8% versus the standard of ≥95% (P<0.001). Immediate postexercise lactate was 6.8±2.4mM versus the standard of ≥8 mM (P=0.03). Maximal RER was 1.2±0.2 versus the standard of RERmax ≥1.1 (P=0.08).

CONCLUSIONS

Our data provide preliminary evidence that secondary criteria may need to be adjusted for pregnant women. Additionally, physical and emotional barriers may be enhanced by pregnancy (e.g. pain, discomfort, anxiety, health concerns), and may limit the performance of pregnant women during maximal exercise.

The effects of menstrual cycle phase on the incidence of plateau at V˙O2max and associated cardiorespiratory dynamics

The purpose of this study was to examine the effect of menstrual cycle phase on maximal oxygen uptake (V˙O2max) and associated cardiodynamic responses. A total of 16 active females volunteered of which n = 10 formed the non-oral contraceptive pill group (n-OCP), displaying a regular menstrual cycle of 28·4 ± 2·2 days (age 20·6 ± 1·6 years, height 169·9 ± 6·4 cm, mass 68·7 ± 7·9 kg) and n = 6 formed the oral contraceptive pill group (OCP) (monophasic pill) (age 21·7 years ± 2·16, height 168·1 cm ± 6·8 cm, mass 61·6 ± 6·8 kg). Each completed four incremental exercise tests for determination of V˙O2max, cardiac output, stroke volume and heart rate. Each test was completed according to the phases of the menstrual cycle as determined through salivary analysis of 17-β oestrodiol and progesterone. Non-significant differences were observed for V˙O2max across phases and between groups (P>0·05) with additional non-significant differences for Q˙max, HR_max and SV_max between groups. For ∆ V˙O2 during the final 60 s of the V˙O2max trial, significant differences were observed between OCP and n-OCP (P<0·05) with OCP showing zero V˙O2 plateaus in three pseudo-phases. Significant difference observed for a-vO_2dif n-OCP between premenstruation and menstruation at 30-100% V˙O2max (P<0·05). Data suggest that the V˙O2 -plateau is effected by monophasic oral contraceptive pill, furthermore these data imply that V˙O2max test outcome is independent of menstrual cycle phase but caution should be applied when evaluating maximal oxygen uptake in females who are administered a monophasic oral contraceptive pill.

Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable

The maximum rate of O2 uptake (i.e., V̇o2max), as measured during large muscle mass exercise such as cycling or running, is widely considered to be the gold standard measurement of integrated cardiopulmonary-muscle oxidative function. The development of rapid-response gas analyzers, enabling measurement of breath-by-breath pulmonary gas exchange, has facilitated replacement of the discontinuous progressive maximal exercise test (that produced an unambiguous V̇o2-work rate plateau definitive for V̇o2max) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investigations and enables measurement of the gas exchange threshold, exercise efficiency, and V̇o2 kinetics, a V̇o2-work rate plateau is not an obligatory outcome. This shortcoming has led to investigators resorting to so-called secondary criteria such as respiratory exchange ratio, maximal heart rate, and/or maximal blood lactate concentration, the acceptable values of which may be selected arbitrarily and result in grossly inaccurate V̇o2max estimation. Whereas this may not be an overriding concern in young, healthy subjects with experience of performing exercise to volitional exhaustion, exercise test naïve subjects, patient populations, and less motivated subjects may stop exercising before their V̇o2max is reached. When V̇o2max is a or the criterion outcome of the investigation, this represents a major experimental design issue. This CORP presents the rationale for incorporation of a second, constant work rate test performed at ~110% of the work rate achieved on the initial ramp test to resolve the classic V̇o2-work rate plateau that is the unambiguous validation of V̇o2max. The broad utility of this procedure has been established for children, adults of varying fitness, obese individuals, and patient populations.

Optimal criteria and sampling interval to detect a V̇O2 plateau at V̇O2max in patients with metabolic syndrome

This study sought to determine the optimal criteria and sampling interval to detect a V̇O2 plateau at V̇O2max in patients with metabolic syndrome. Twenty-three participants with criteria-defined metabolic syndrome underwent a maximal graded exercise test. Four different sampling intervals and three different V̇O2 plateau criteria were analysed to determine the effect of each parameter on the incidence of V̇O2 plateau at V̇O2max. Seventeen tests were classified as maximal based on attainment of at least two out of three criteria. There was a significant (p < 0.05) effect of 15-breath (b) sampling interval on the incidence of V̇O2 plateau at V̇O2max across the ≤ 50 and ≤ 80 mL ∙ min(-1) conditions. Strength of association was established by the Cramer's V statistic (φc); (≤ 50 mL ∙ min(-1) [φc = 0.592, p < 0.05], ≤ 80 mL ∙ min(-1) [φc = 0.383, p < 0.05], ≤ 150 mL ∙ min(-1) [φc = 0.246, p > 0.05]). When conducting maximal stress tests on patients with metabolic syndrome, a 15-b sampling interval and ≤ 50 mL ∙ min(-1) criteria should be implemented to increase the likelihood of detecting V̇O2 plateau at V̇O2max.

Neurovascular Control and Cardiac Structure in Amateur Runners with Hypertension

PURPOSE

The neurovascular mechanisms underlying hypertension are minimized by exercise training. However, it is not known whether previously trained individuals with hypertension would have deleterious repercussion of this disease. Our aim was to investigate the neurovascular control and the cardiac structure of athletes with hypertension.

METHODS

Muscle sympathetic nerve activity (MSNA) (microneurography), baroreflex sensitivity (intravenous infusion of phenylephrine and nitroprusside), arterial stiffness (pulse wave velocity and echotracking), and cardiac structure (echocardiography) were evaluated in 17 runners with hypertension (42 ± 1 yr) and 20 normotensive (43 ± 1 yr) amateur runners.

RESULTS

Runners with hypertension had higher MSNA (+24% burst frequency, P = 0.02; +24%, burst incidence, P < 0.01), left ventricular mass (+22%, P < 0.01), septum wall thickness (+9%, P = 0.04), posterior wall thickness (+11%, P = 0.04), and left atrium (+11%, P < 0.001) compared with normotensive runners. Baroreflex control of heart rate was lower in runners with hypertension during increase (P = 0.05) but not during decrease (P = 0.11) of systolic blood pressure when compared with normotensive runners. There was no difference between groups in baroreflex control of MSNA during increase (P = 0.38) and decrease (P = 0.36) of diastolic blood pressure. Pulse wave velocity (P = 0.71) and carotid variables: intima media thickness (P = 0.18), diameter (P = 0.09), and distension (P = 0.79) were similar between groups.

CONCLUSIONS

Sympathetic overactivity seems to be involved in the underlying mechanisms of hypertension in amateur runners. Alterations in cardiac structure and decreased baroreflex control of heart rate suggest limited protection from exercise training. However, baroreflex control of MSNA and elastic properties of artery are preserved in this population.

Physical Exercise Keeps the Brain Connected: Biking Increases White Matter Integrity in Patients With Schizophrenia and Healthy Controls

It has been shown that learning a new skill leads to structural changes in the brain. However, it is unclear whether it is the acquisition or continuous practicing of the skill that causes this effect and whether brain connectivity of patients with schizophrenia can benefit from such practice. We examined the effect of 6 months exercise on a stationary bicycle on the brain in patients with schizophrenia and healthy controls. Biking is an endemic skill in the Netherlands and thus offers an ideal situation to disentangle the effects of learning vs practice. The 33 participating patients with schizophrenia and 48 healthy individuals were assigned to either one of two conditions, ie, physical exercise or life-as-usual, balanced for diagnosis. Diffusion tensor imaging brain scans were made prior to and after intervention. We demonstrate that irrespective of diagnosis regular physical exercise of an overlearned skill, such as bicycling, significantly increases the integrity, especially of motor functioning related, white matter fiber tracts whereas life-as-usual leads to a decrease in fiber integrity. Our findings imply that exercise of an overlearned physical skill improves brain connectivity in patients and healthy individuals. This has important implications for understanding the effect of fitness programs on the brain in both healthy subjects and patients with schizophrenia. Moreover, the outcome may even apply to the nonphysical realm.

Gender differences in game responses during badminton match play

The aim of this study was to evaluate possible gender differences in match play activity pattern [rally duration, rest time between rallies, effective playing time, and strokes performed during a rally] and exercise intensity (heart rate [HR], blood lactate [La], and subjective ratings of perceived exertion [RPE]) during 9 simulated badminton matches in male (n = 8) and female (n = 8) elite junior (16.0 ± 1.4 years) players. Results showed significant differences (all p < 0.05; effect size (ES) = 0.80-1.56) between male and female players in the activity pattern of match play, with male players engaged in longer rallies (6.8 ± 4.8 vs. 5.7 ± 3.1 seconds), executing more strokes per rally (6.4 ± 4.8 vs. 4.7 ± 2.8) and resting more between rallies (10.5 ± 8.8 vs. 8.8 ± 7.2 seconds) than female players. No clear differences (all p > 0.05; ES = -0.33 to 0.08) were observed between female or male players in average HR (174 ± 7 vs. 170 ± 9 b·min(-1)), %HRmax (89.2 ± 4.0% vs. 85.9 ± 4.3%), La (2.5 ± 1.3 vs. 3.2 ± 1.8 mmol·L(-1)), and RPE values (14.2 ± 1.9 vs. 14.6 ± 1.8) during match play, although male players spent more time (moderate effect sizes) at intensities between 81 and 90% HRmax (35.3 ± 17.9 vs. 25.3 ± 13.6; p < 0.05; ES = 0.64) in the second game. There seemed to be a trend toward an increased playing intensity (i.e., higher HR, La, and RPE) from the first to the second game, highlighting the higher exercise intensity experienced during the last part of the match. The clear between-gender differences in activity patterns induced only slightly different physiological responses.

The validity of the Moxus Modular metabolic system during incremental exercise tests: impacts on detection of small changes in oxygen consumption

PURPOSE

We investigated the accuracy of the Moxus Modular Metabolic System (MOXUS) against the Douglas Bag Method (DBM) during high-intensity exercise, and whether the two methods agreed when detecting small changes in [Formula: see text] between two consecutive workloads ([Formula: see text]).

METHODS

Twelve trained male runners performed two maximal incremental running tests while gas exchange was analyzed simultaneously by the two systems using a serial setup for four consecutive intervals of 30 s on each test. Comparisons between methods were performed for [Formula: see text], [Formula: see text], fractions of expired O2 (FeO2) and CO2 (FeCO2) and [Formula: see text].

RESULTS

The MOXUS produced significant higher (mean ± SD, n = 54) readings for [Formula: see text] (80 ± 200 mL min(-1), p = 0.005) and [Formula: see text] (2.9 ± 4.2 L min(-1), p < 0.0001), but not FeO2 (-0.01 ± 0.09). Log-transformed 95 % limits of agreement for readings between methods were 94-110 % for [Formula: see text], 97-108 % for [Formula: see text] and 99-101 % for FeO2. [Formula: see text] for two consecutive measurements was not different between systems (120 ± 110 vs. 90 ± 190 mL min(-1) for MOXUS and DBM, respectively, p = 0.26), but agreement between methods was very low (r = 0.25, p = 0.12).

DISCUSSION

Although it was tested during high-intensity exercise and short sampling intervals, the MOXUS performed within the acceptable range of accuracy reported for automated analyzers. Most of the differences between equipments were due to differences in [Formula: see text]. Detecting small changes in [Formula: see text] during an incremental test with small changes in workload, however, might be beyond the equipment's accuracy.

End criteria for reaching maximal oxygen uptake must be strict and adjusted to sex and age: a cross-sectional study

Objective

To describe different end criteria for reaching maximal oxygen uptake (VO_2max) during a continuous graded exercise test on the treadmill, and to explore the manner by which different end criteria have an impact on the magnitude of the VO_2max result.

Methods

A sample of 861 individuals (390 women) aged 20–85 years performed an exercise test on a treadmill until exhaustion. Gas exchange, heart rate, blood lactate concentration and Borg Scale_6–20 rating were measured, and the impact of different end criteria on VO_2max was studied;VO₂ leveling off, maximal heart rate (HR_max), different levels of respiratory exchange ratio (RER), and postexercise blood lactate concentration.

Results

Eight hundred and four healthy participants (93%) fulfilled the exercise test until voluntary exhaustion. There were no sex-related differences in HR_max, RER, or Borg Scale rating, whereas blood lactate concentration was 18% lower in women (P<0.001). Forty-two percent of the participants achieved a plateau in VO₂; these individuals had 5% higher ventilation (P = 0.033), 4% higher RER (P<0.001), and 5% higher blood lactate concentration (P = 0.047) compared with participants who did not reach a VO₂ plateau. When using RER ≥1.15 or blood lactate concentration ≥8.0 mmol•L^–1, VO_2max was 4% (P = 0.012) and 10% greater (P<0.001), respectively. A blood lactate concentration ≥8.0 mmol•L^–1 excluded 63% of the participants in the 50–85-year-old cohort.

Conclusions

A range of typical end criteria are presented in a random sample of subjects aged 20–85 years. The choice of end criteria will have an impact on the number of the participants as well as the VO_2max outcome. Suggestions for new recommendations are given.

Exercise therapy, cardiorespiratory fitness and their effect on brain volumes: a randomised controlled trial in patients with schizophrenia and healthy controls

The objective of this study was to examine exercise effects on global brain volume, hippocampal volume, and cortical thickness in schizophrenia patients and healthy controls. Irrespective of diagnosis and intervention, associations between brain changes and cardiorespiratory fitness improvement were examined. Sixty-three schizophrenia patients and fifty-five healthy controls participated in this randomised controlled trial. Global brain volumes, hippocampal volume, and cortical thickness were estimated from 3-Tesla MRI scans. Cardiorespiratory fitness was assessed with a cardiopulmonary ergometer test. Subjects were assigned exercise therapy or occupational therapy (patients) and exercise therapy or life-as-usual (healthy controls) for six months 2h weekly. Exercise therapy effects were analysed for subjects who were compliant at least 50% of sessions offered. Significantly smaller baseline cerebral (grey) matter, and larger third ventricle volumes, and thinner cortex in most areas of the brain were found in patients versus controls. Exercise therapy did not affect global brain and hippocampal volume or cortical thickness in patients and controls. Cardiorespiratory fitness improvement was related to increased cerebral matter volume and lateral and third ventricle volume decrease in patients and to thickening in the left hemisphere in large areas of the frontal, temporal and cingulate cortex irrespective of diagnosis. One to 2h of exercise therapy did not elicit significant brain volume changes in patients or controls. However, cardiorespiratory fitness improvement attenuated brain volume changes in schizophrenia patients and increased thickness in large areas of the left cortex in both schizophrenia patients and healthy controls.

The effects of exercise modality on the incidence of plateau at VO2max

The purpose of this study was to determine the effect of exercise modality on the incidence of plateau at VO2max. Twelve recreationally active men (age, 21·7 ± 2·3 year; mass, 74·8 ± 6·5 kg; height, 177·6 ± 5·6 cm) completed four incremental tests to volitional exhaustion, of which two were completed on a treadmill (TRE) and two were completed using a cycle ergometer (CYC). The work rate employed for CYC was 1 W·2 s(-1) from an initial loading of 100 W with cadence being maintained at 60 rpm. For TRE, the workload (gradient) increased at a rate of 0·5% · 30 s(-1) while maintaining a constant running speed of 10 kph. Throughout all the trials, VO2 was determined on a breath-by-breath basis using a precalibrated metabolic cart. The criteria adopted for determination of a plateau was a Δ VO2 over the final two consecutive 30-s sampling periods of ≤50 ml · min(-1). Averaging across the two trials per each exercise modality showed a significant difference for plateau incidence between CYC (8%) and TRE (58%) (P = 0·017). This was aligned with a significant difference in the slope of the regression line during the final 60 s of the VO2max test, CYC (99·9 ± 49·7 ml · min(-1)) and TRE (49·6 ± 42·6 ml · min(-1)) (P = 0·017). Repeat measures ANOVA of these data suggests that plateau incidence rates at VO2max differ between treadmill- and cycle ergometry-based exercises. Future studies need to address whether these response rates are replicated in well-trained athletes.

Influência do protocolo ergométrico na ocorrência de diferentes critérios de esforço máximo

INTRODUÇÃO E OBJETIVO: Neste estudo investigamos a influência de diferentes protocolos ergométricos na ocorrência dos critérios de esforço máximo. MÉTODOS: Nove sujeitos fisicamente ativos (23 ± 4 anos, 177 ± 10cm, e 77,1 ± 16kg) realizaram três testes de esforço (PR1 - 15W·min-1, PR2 - 50W·3 min-1, e PR3 - 50W·5 min-1) no cicloergômetro. O consumo de oxigênio foi medido em circuito aberto e integrado a cada 20s. Adotaram-se como critérios de esforço máximo: o platô no consumo de oxigênio < 150 mL·min-1; frequência cardíaca máxima (FCmáx) > 95% prevista pela idade; lactato > 8,0 mM; e RER > 1,1. RESULTADOS: O VO2máx não apresentou diferenças entre os protocolos (2,68 ± 1,0; 2,58 ± 1,0 e 2,99 ± 1,3L·min-1 para PR1, PR2 e PR3, p = 0,72). A maior ocorrência do platô foi observada em PR1 (cinco sujeitos). O critério da frequência cardíaca máxima foi satisfeito em três sujeitos em PR3, e o critério do lactato em seis sujeitos, no mesmo protocolo (PR3). O RER > 1,1 foi observado em seis sujeitos em PR1. CONCLUSÃO: Concluímos que a ocorrência de diferentes critérios de esforço máximo é influenciada pela escolha do protocolo ergométrico, não indicando, contudo, valores distintos de VO2máx

The slope of the oxygen pulse curve does not depend on the maximal heart rate in elite soccer players

INTRODUCTION

It is unknown whether an extremely high heart rate can affect oxygen pulse profile during progressive maximal exercise in healthy subjects.

OBJECTIVE

Our aim was to compare relative oxygen pulse (adjusted for body weight) curves in athletes at their maximal heart rate during treadmill cardiopulmonary exercise testing.

METHODS

A total of 180 elite soccer players were categorized in quartiles according to their maximum heart rate values (n = 45). Oxygen consumption, maximum heart rate and relative oxygen pulse curves in the extreme quartiles, Q1 and Q4, were compared at intervals corresponding to 10% of the total duration of a cardiopulmonary exercise testing.

RESULTS

Oxygen consumption was similar among all subjects during cardiopulmonary exercise testing; however subjects in Q1 started to exhibit lower maximum heart rate values when 20% of the test was complete. Conversely, the relative oxygen pulse was higher in this group when cardiopulmonary exercise testing was 40% complete (p<.01). Although the slopes of the lines were similar (p = .25), the regression intercepts differed (p<.01) between Q1 and Q4. During the last two minutes of testing, a flat or decreasing oxygen pulse was identified in 20% of the soccer players, and this trend was similar between subjects in Q1 and Q4.

CONCLUSION

Relative oxygen pulse curve slopes, which serve as an indirect and non-invasive surrogate for stroke volume, suggest that the stroke volume is similar in young and aerobically fit subjects regardless of the maximum heart rate reached.