Effect of the VO2 time-averaging interval on the reproducibility of VO2max in healthy athletic subjects

Data Processing Strategies to Determine Maximum Oxygen Uptake: A Systematic Scoping Review and Experimental Comparison with Guidelines for Reporting

BACKGROUND

Gas exchange data from maximum oxygen uptake ([Formula: see text]) testing typically require post-processing. Different processing strategies may lead to varying [Formula: see text] values affecting their interpretation. However, the exact processing strategies used in the literature have yet to be systematically investigated. Previous research investigated differences across methods at the group level only.

METHODS

Out of a random sample, we investigated 242 recently published articles that measured [Formula: see text] during ramp tests. Reported data processing methods and their rationale were extracted. We compared the most common processing strategies on a data set of 72 standardized exercise tests in trained athletes.

RESULTS

Half of the included studies did not report their data processing strategy and almost all articles failed to provide a rationale for the particular strategy chosen. Most studies use binned time averages to determine [Formula: see text], with a minority using moving time or moving breath averages. The processing strategies found in the literature can lead to mean differences in [Formula: see text] of more than 5% (range 0-7%) with considerable variation at the individual level.

CONCLUSIONS

We advise researchers to change their processing strategy and use moving averages or digital filters instead of binned averages. Researchers should report their data processing strategy used to determine [Formula: see text]. We provide a reporting checklist of seven items that can function as a template for reporting.

Influence of different data-averaging methods on mean values of selected variables derived from preoperative cardiopulmonary exercise testing in patients scheduled for colorectal surgery

INTRODUCTION

Patients with a low cardiorespiratory fitness (CRF) undergoing colorectal cancer surgery have a high risk for postoperative complications. Cardiopulmonary exercise testing (CPET) to assess CRF is the gold standard for preoperative risk assessment. To aid interpretation of raw breath-by-breath data, different methods of data-averaging can be applied. This study aimed to investigate the influence of different data-averaging intervals on CPET variables used for preoperative risk assessment, as well as to evaluate whether different data-averaging intervals influence preoperative risk assessment.

METHODS

A total of 21 preoperative CPETs were interpreted by two exercise physiologists using stationary time-based data-averaging intervals of 10, 20, and 30 seconds and rolling average intervals of 3 and 7 breaths. Mean values of CPET variables between different data averaging intervals were compared using repeated measures ANOVA. The variables of interest were oxygen uptake at peak exercise (VO2peak), oxygen uptake at the ventilatory anaerobic threshold (VO2VAT), oxygen uptake efficiency slope (OUES), the ventilatory equivalent for carbon dioxide at the ventilatory anaerobic threshold (VE/VCO2VAT), and the slope of the relationship between the minute ventilation and carbon dioxide production (VE/VCO2-slope).

RESULTS

Between data-averaging intervals, no statistically significant differences were found in the mean values of CPET variables except for the ventilatory equivalent for carbon dioxide at the ventilatory anaerobic threshold (P = 0.001). No statistically significant differences were found in the proportion of patients classified as high or low risk regardless of the used data-averaging interval.

CONCLUSION

There appears to be no significant or clinically relevant influence of the evaluated data-averaging intervals on the mean values of CPET outcomes used for preoperative risk assessment. Clinicians may choose a data-averaging interval that is appropriate for optimal interpretation and data visualization of the preoperative CPET. Nevertheless, caution should be taken as the chosen data-averaging interval might lead to substantial within-patient variation for individual patients.

CLINICAL TRIAL REGISTRATION

Prospectively registered at ClinicalTrials.gov (NCT05353127).

Appetite and energy intake following a bout of circuit resistance training in chronic hemiparetic stroke patients: a preliminary randomized controlled trial

PURPOSE

The main aim of this study was to investigate the effects of circuit resistance training (CRT) on post-exercise appetite and energy intake in chronic hemiparetic stroke patients. A secondary aim was to evaluate the reproducibility of these effects.

METHODS

Seven participants met the eligibility criteria and, in a randomized order, participated in a non-exercise control session (CTL) and two bouts of CRT. The CRT involved 10 exercises with 3 sets of 15-repetition maximum per exercise, performed using a vertical loading approach, with each set interspersed with 45s of walking. Expired gases were carried out   to calculate the net energy cost of the exercise and the relative energy intake post-CTL/CRT. Hunger, fullness, desire to eat, and energy intake were assessed at baseline and for 12 h after CTL and CRT.

RESULTS

Compared to CTL, hunger, desire to eat (P < .001), and relative energy intake (P < .05) were significantly lower after CRT, whereas the perception of fullness was significantly higher (P < .001). Significant differences between CTL and CRT were observed only for the first 9 h of the post-exercise period for hunger, fullness, and desire to eat (P < .05). No significant differences in appetite or relative energy intake were observed between the two bouts of CRT.

CONCLUSIONS

A bout of CRT elicited decreased post-exercise appetite and relative energy intake in chronic hemiparetic stroke patients. Decreased appetite perceptions lasted for around 9 h and were reproducible.

Real Assessment of Maximum Oxygen Uptake as a Verification After an Incremental Test Versus Without a Test

The study was conducted to compare peak oxygen uptake (VO_2peak) measured with the incremental graded test (GXT) (VO_2peak) and two tests to verify maximum oxygen uptake, performed 15 min after the incremental test (VO_2peak1) and on a separate day (VO_2peak2). The aim was to determine which of the verification tests is more accurate and, more generally, to validate the VO_2max obtained in the incremental graded test on cycle ergometer. The study involved 23 participants with varying levels of physical activity. Analysis of variance showed no statistically significant differences for repeated measurements (F = 2.28, p = 0.118, η² = 0.12). Bland–Altman analysis revealed a small bias of the VO_2peak1 results compared to the VO_2peak (0.4 ml⋅min^–1⋅kg^–1) and VO_2peak2 results compared to the VO_2peak (−0.76 ml⋅min^–1⋅kg^–1). In isolated cases, it was observed that VO_2peak1 and VO_2peak2 differed by more than 5% from VO_2peak. Considering the above, it can be stated that among young people, there are no statistically significant differences between the values of VO_2peak measured in the following tests. However, in individual cases, the need to verify the maximum oxygen uptake is stated, but performing a second verification test on a separate day has no additional benefit.

The Effects of Acute Aerobic Exercise on Blood Pressure, Arterial Function, and Heart Rate Variability in Men Living With HIV

PURPOSE

This study aims to investigate the effects of acute cycling on blood pressure (BP), arterial function, and heart rate variability (HRV) in men living with HIV (MLHIV) using combined antiretroviral therapy (cART).

METHODS

Twelve MLHIV (48.7 ± 9.2 years; 25.2 ± 2.8 kg m-2) and 13 healthy controls (41.2 ± 9.9 years; 26.3 ± 2.9 kg m-2) performed a cycling bout (ES) (intensity: 50% oxygen uptake reserve; duration: time to achieve 150 kcal-MLHIV: 24.1 ± 5.5 vs. controls: 23.1 ± 3.0 min; p = 0.45), and a 20-min non-exercise session (NES).

RESULTS

At rest (p < 0.05), MLHIV presented higher brachial systolic/diastolic BP (SBP/DBP: 123.2 ± 14.2/76.8 ± 6.3 vs. 114.3 ± 5.1/71.6 ± 2.6 mmHg) and central BP (cSBP/cDBP: 108.3 ± 9.3/76.5 ± 6.5 vs. 101.6 ± 4.9/71.3 ± 4.4 mmHg) vs. controls but lower absolute maximal oxygen uptake (2.1 ± 0.5 vs. 2.5 ± 0.3 L min-1) and HRV indices reflecting overall/vagal modulation (SDNN: 24.8 ± 7.1 vs. 42.9 ± 21.3 ms; rMSSD: 20.5 ± 8.5 vs. 38.1 ± 22.8 ms; pNN50: 3.6 ± 4.2 vs. 13.6 ± 11.3%). DBP postexercise lowered in controls vs. MLHIV (∼4 mmHg, p < 0.001; ES: 0.6). Moreover, controls vs. MLHIV had greater reductions (p < 0.05) in augmentation index (-13.6 ± 13.7 vs. -3.1 ± 7.2% min-1; ES: 2.4), and HRV indices up to 5 min (rMSSD: -111.8 ± 32.1 vs. -75.9 ± 22.2 ms min-1; ES: 3.8; pNN50: -76.3 ± 28.3 vs. -19.0 ± 13.7% min-1; ES: 4.4). Within-group (ES vs. NES; p < 0.05) reductions occurred in controls for SBP (∼10 mmHg, 2 h), DBP (∼6 mmHg, 20, 30, and 70 min), cSBP (∼9 mmHg, 30 min), cDBP (∼7 mmHg, 30 and 70 min), augmentation index (∼10%, 30 min), and pNN50 (∼20%; up to 2 h), while in MLHIV only cSBP (∼6 mmHg, 70 min) and cDBP (∼4 mmHg, 30 min) decreased. Similar increases (up to 5 min) in heart rate (∼22 bpm) and decreases in SDNN (∼18 ms) and rMSSD (∼20 ms) occurred in both groups.

CONCLUSION

MLHIV under cART exhibited attenuated postexercise hypotension vs. healthy controls, which seemed to relate with impairments in vascular function.

A New Fitness Test of Estimating VO2max in Well-Trained Rowing Athletes

Background

This study was designed to investigate the validity of maximal oxygen consumption (VO_2max) estimation through the Firstbeat fitness test (FFT) method when using submaximal rowing and running programs for well-trained athletes.

Methods

Well-trained flatwater rowers (n = 45, 19.8 ± 3.0 years, 184 ± 8.7 cm, 76 ± 12.9 kg, and 58.7 ± 6.0 mL⋅kg^–1⋅min^–1) and paddlers (n = 45, 19.0 ± 2.5 years, 180 ± 7.7 cm, 74 ± 9.4 kg, and 59.9 ± 4.8 mL⋅kg^–1⋅min^–1) completed the FFT and maximal graded exercise test (GXT) programs of rowing and running, respectively. The estimated VO_2max was calculated using the FFT system, and the measured VO_2max was obtained from the GXT programs. Differences between the estimated and measured VO_2max values were analyzed to assess the accuracy and agreement of the predictions. Equations from the previous study were also used to predict the VO_2max in the submaximal programs to compare the accuracy of prediction with the FFT method.

Results

The FFT method was in good agreement with the measured VO_2max in both groups based on the intraclass correlation coefficients (>0.8). Additionally, the FFT method had considerable accuracy in VO_2max estimation as the mean absolute percentage error (≤5.0%) and mean absolute error (<3.0 mL⋅kg^–1⋅min^–1) were fairly low. Furthermore, the FFT method seemed more accurate in the estimation of VO_2max than previously reported equations, especially in the rowing test program.

Conclusion

This study revealed that the FFT method provides a considerably accurate estimation of VO_2max in well-trained athletes.

Is a verification phase useful for confirming maximal oxygen uptake in apparently healthy adults? A systematic review and meta-analysis

BACKGROUND

The 'verification phase' has emerged as a supplementary procedure to traditional maximal oxygen uptake (VO2max) criteria to confirm that the highest possible VO2 has been attained during a cardiopulmonary exercise test (CPET).

OBJECTIVE

To compare the highest VO2 responses observed in different verification phase procedures with their preceding CPET for confirmation that VO2max was likely attained.

METHODS

MEDLINE (accessed through PubMed), Web of Science, SPORTDiscus, and Cochrane (accessed through Wiley) were searched for relevant studies that involved apparently healthy adults, VO2max determination by indirect calorimetry, and a CPET on a cycle ergometer or treadmill that incorporated an appended verification phase. RevMan 5.3 software was used to analyze the pooled effect of the CPET and verification phase on the highest mean VO2. Meta-analysis effect size calculations incorporated random-effects assumptions due to the diversity of experimental protocols employed. I2 was calculated to determine the heterogeneity of VO2 responses, and a funnel plot was used to check the risk of bias, within the mean VO2 responses from the primary studies. Subgroup analyses were used to test the moderator effects of sex, cardiorespiratory fitness, exercise modality, CPET protocol, and verification phase protocol.

RESULTS

Eighty studies were included in the systematic review (total sample of 1,680 participants; 473 women; age 19-68 yr.; VO2max 3.3 ± 1.4 L/min or 46.9 ± 12.1 mL·kg-1·min-1). The highest mean VO2 values attained in the CPET and verification phase were similar in the 54 studies that were meta-analyzed (mean difference = 0.03 [95% CI = -0.01 to 0.06] L/min, P = 0.15). Furthermore, the difference between the CPET and verification phase was not affected by any of the potential moderators such as verification phase intensity (P = 0.11), type of recovery utilized (P = 0.36), VO2max verification criterion adoption (P = 0.29), same or alternate day verification procedure (P = 0.21), verification-phase duration (P = 0.35), or even according to sex, cardiorespiratory fitness level, exercise modality, and CPET protocol (P = 0.18 to P = 0.71). The funnel plot indicated that there was no significant publication bias.

CONCLUSIONS

The verification phase seems a robust procedure to confirm that the highest possible VO2 has been attained during a ramp or continuous step-incremented CPET. However, given the high concordance between the highest mean VO2 achieved in the CPET and verification phase, findings from the current study would question its necessity in all testing circumstances.

PROSPERO REGISTRATION ID

CRD42019123540.

Influence of Different Treadmill Inclinations on V̇o2max and Ventilatory Thresholds During Maximal Ramp Protocols

ABSTRACT

Silva, SC, Monteiro, WD, Cunha, FA, and Farinatti, P. Influence of different treadmill inclinations on V̇o2max and ventilatory thresholds during maximal ramp protocols. J Strength Cond Res 35(1): 233-239, 2021-Ramp protocols for cardiopulmonary exercise testing (CPET) lack precise recommendations, including optimal treadmill inclination. This study investigated the impact of treadmill grades applied in ramp CPETs on maximal oxygen uptake (V̇o2max), ventilatory thresholds (VT1/VT2), and V̇o2 vs. workload relationship. Twenty-one healthy men (age 33 ± 8 years; height 176.6 ± 5.8 cm; body mass 80.4 ± 8.7 kg; and V̇o2max 44.9 ± 5.7 ml·kg-1·min-1) and 12 women (age 29 ± 7 years; height 163.3 ± 6.7 cm; body mass 56.6 ± 6.3 kg; and V̇o2max 39.4 ± 4.9 ml·kg-1·min-1) underwent ramp CPETs with similar speed increments and different treadmill grades: CPET0%, CPET2%, CPET3.5%, and CPET5.5%. The V̇o2max was similar across protocols (42.8-43.2 ml·kg-1·min-1, p = 0.76), albeit duration of CPETs shortened when treadmill inclination increased (CPET0% 12.7 minutes; CPET2% 9.1 minutes; CPET3.5% 8.0 minutes; and CPET5.5% 6.6 minutes; p < 0.01). The %V̇o2max corresponding to VT1 was slightly lower in CPET0% (63.6%) and higher in CPET5.5% (75.8%) vs. CPET2% (67.8%) and CPET3.5% (69.5%; p < 0.05), whereas VT2 was not affected by treadmill inclination (95.1-95.8% V̇o2max; p > 0.05). V̇o2max and ventilatory thresholds were similar in CPETs performed with different treadmill inclinations and similar initial/final speeds. However, linear regressions between workload and V̇o2 were closer to the identity line in CPETs performed with smaller (CPET0% and CPET2%) than with greater (CPET3.5% and CPET5.5%) inclinations. These data suggest that in healthy young adults, ramp CPETs performed with inclinations of 0-2% degree should be preferred over protocols with greater inclinations.

Prediction of VO2max based on a 3-kilometer running test for water sports athletes

BACKGROUND

No studies have reported the 3-kilometer running test (3KRT) intending to predict VO2max for water sports athletes. Therefore, the purpose of this study was to develop a new model to predict the maximal aerobic capacity (VO2max) for water sports athletes based on 3KRT.

METHODS

One hundred and two water sports athletes completed two sessions of experiments consisting of a maximal graded exercise test (GXT) and a 3KRT. Multiple linear regression was applied to predict VO2max value based on the performance and physiological responses of 3KRT, along with participants' anthropometric and demographic variables. The predicted residual error sum of square (PRESS) and error terms (constant error and total error) were calculated to further evaluate the predictive accuracy.

RESULTS

Two significant prediction models based on elapsed exercise time (T3KRT), post-exercise heart rate (PHR3KRT), body mass, and gender were proposed. One model including PHR3KRT was identified (VO2max=120.77-0.028×T3KRT [second]-0.11×PHR3KRT [bpm]-0.334×body mass [kg]+8.70×gender [1: male, 0: female]), with an adjusted R2 of 0.723. Another model excluding PHR3KRT was also identified (VO2max=103.65-0.034×T3KRT [second]-0.317×Body mass [kg] + 7.89×gender [1: male, 0: female]), with an adjusted R2 of 0.713. Both models were further validated by the result of PRESS statistics.

CONCLUSIONS

This endurance 3-kilometer running test accurately predicted VO2max value for water sports athletes (rowers, canoeists, and kayakers), and the model excluding PHR3KRT would be easier to use.

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.

Cardiopulmonary exercise testing and cardiopulmonary morbidity in patients undergoing major head and neck surgery

Cardiopulmonary exercise testing (CPET) is used as a risk stratification tool for patients undergoing major surgery. In this study, we investigated the role of CPET in predicting day five cardiopulmonary morbidity in patients undergoing head and neck surgery. This observational cohort study included 230 adults. We recorded preoperative CPET variables and day five postoperative cardiopulmonary morbidity. Full data from 187 patients were analysed; 43 patients either had incomplete data sets or declined surgery/CPET. One hundred and nineteen patients (63.6%) developed cardiopulmonary morbidity at day five. Increased preoperative heart rate and duration of surgery were independently associated with day five cardiopulmonary morbidity. Those with such morbidity also had lower peak V̇O₂ 11.4 (IQR 8.4-18.0) vs 16.0 (IQR 14.0-19.7) ml.kg^-1.min^-1, P<0.0001 and V̇O₂ at AT 10.6 (IQR 9.1-13.1) vs 11.5 (IQR 10.5-13.0) ml.kg^-1.min^-1, p=0.03. Logistic regression model containing peak V̇O₂ and duration of surgery demonstrated that increased peak V̇O2 was associated with a reduction in the likelihood of cardiopulmonary complications OR 0.92 (95%CI 0.87 to 0.96), p=0.001. The area under the receiver operating characteristic curve for this model was 0.75(95%CI 0.68 to 0.82), p<0.0001, 64% sensitivity, 81% specificity. CPET can help to predict day five cardiopulmonary morbidity in the patients undergoing head and neck surgery. A model containing peak V̇O₂ allowed identification of those with such complications.

Game Running Performance and Fitness in Women’s Futsal

The study aimed to verify possible associations between game-play running performance and outcomes derived from fitness (running) tests in female futsal players. Sixteen women professional elite futsal players from a 1st division league team (19.2±2 years-old, 4.3±2.1 years of experience) participated. Firstly, a graded incremental treadmill test was adopted to determine maximal oxygen uptake (VO2max). Following 72 h of laboratory protocol, players were asked to perform a repeated-sprint test on a court (8×40 m with two 180° change-of-directions). Twenty-four hours after, players participated in a one-off friendly game (two 20-min half-times). A computerized automatic image recognition software (DVIDEOW; 30 Hz) allowed to determine game running performance variables. Fatigue index and best time in the court test and VO2max and its attached speed derived from laboratory-based test showed significant moderate-to-moderately high correlations (r=− 0.59–0.76; p<0.05) with some game running performance outputs, notably related to high-intensity running. In conclusion, the present study provided initial evidence on associations between two fitness tests and one-off game running performance in female futsal. Information derived from the work potentially help conditioning professionals working with female futsal athletes gain awareness about some properties of common testing tools.

The effect of acute exercise on environmentally induced symptoms of dry eye

The purpose of this study was to investigate the effects of acute exercise on environmentally induced symptoms of dry eye. Twelve participants without dry eye disease volunteered to complete three experimental visits in a randomized order; (1) control condition seated for 1 h at a relative humidity (RH) of 40% (CONT), (2) dry condition seated for 1 h at a RH of 20% (DRY), and (3) exercise condition seated for 40 min followed by 20 min of cycling exercise at a RH of 20% (EXER). Tear volume, tear matrix metalloproteinase 9 (MMP-9), perception of dry eye symptoms (frequency and severity), core temperature, and ocular surface temperature (OST) were measured at the end of each exposure. The perception of dry eye frequency and MMP-9 concentration were significantly higher in DRY compared to CONT (P < 0.012), with no differences in EXER compared to CONT. The results suggest that an acute bout of exercise may attenuate symptoms of environmentally induced dry eye, and warrant further research.

Acute Effect of Aerobic and Strength Exercise on Heart Rate Variability and Baroreflex Sensitivity in Men With Autonomic Dysfunction

de Paula, T, Neves, MF, da Silva Itaborahy, A, Monteiro, W, Farinatti, P, and Cunha, FA. Recovery pattern of cardiac autonomic control after aerobic and strength exercises in overweight prehypertensive men. J Strength Cond Res 33(10): 2743-2752, 2019-The extent to which postexercise cardiac autonomic control depends on exercise modality remains unclear, particularly among individuals with autonomic dysfunction (cardiac autonomic dysfunction [CADysf]). This study compared heart rate variability (HRV) and baroreflex sensitivity (BRS) responses to acute aerobic exercise (AE) and strength exercise (SE) in men with CADysf. Twenty men were assigned into control (n = 10: 33.8 ± 3.0 years; 23.7 ± 1.5 kg·m) and CADysf (n = 10: 36.2 ± 9.8 years; 28.4 ± 2.6 kg·m) groups. Cardiac autonomic dysfunction underwent AE, SE, and a nonexercise control day (control session [CTL]) in a randomized, counter-balanced order. Heart rate variability and BRS were assessed in a supine position during 25 minutes of recovery after AE, SE, and CTL. Both HRV indices (p ≤ 0.05; effect size [Cohen's d]: >1.4) and BRS at rest were significantly lower in CADysf than those in controls (p < 0.01; effect size [Cohen's d]: ≥1.36). In CADysf, postexercise increases in heart rate, sympathetic activity (low-frequency [LF] band), and sympathovagal balance (LF:high-frequency [HF] ratio), as well as decreases in R-R interval, parasympathetic activity (HF band), and BRS were observed in AE (p ≤ 0.05; effect size [Cohen's d]: ≥1.31) and SE (p ≤ 0.05; effect size [Cohen's d]: ≥0.79) vs. CTL, but changes were larger after AE than SE (p ≤ 0.05; effect size [Cohen's d]: ≥0.73). In conclusion, both AE and SE elicited postexercise changes in HRV and BRS among CADysf men, primarily reflected by lowered vagal modulation, increased sympathovagal balance, and a delayed BRS recovery pattern. However, those changes seem to be more likely to occur after AE than SE.

Variability in exercise physiology: Can capturing intra-individual variation help better understand true inter-individual responses?

Exploring individual responses to exercise training is a growing area of interest. Understanding reasons behind true observed inter-individual responses may help personalise exercise training to maximise the benefits received. While numerous factors have been explored, an often underappreciated consideration in the sport and exercise science field is the influence intra-individual variation, both in a single measurement and in response to an intervention, may have on training outcomes. Several study designs and statistical approaches are available to incorporate intra-individual variation into interventions and accordingly provide information on whether 'true' inter-individual responses are present or if they are an artefact of intra-individual variation. However, such approaches are sparingly applied. Moreover, intra-individual variation may also be important when true inter-individual response differences are present. In this perspective piece, the concept of intra-individual variation is described before briefly summarising study designs and statistical practices to account for intra-individual variation. We then outline two examples of physiological practices (stratified randomisation and prescribing exercise programmes upon training parameters) to demonstrate why sport and exercise scientists should acknowledge intra-individual variation prior to the implementation of an intervention, which potentially offers an additional explanation behind observed true inter-individual responses to training. Repeated testing pre-implementation of exercise training would conceptually provide more confident estimates of training parameters, which if utilised in a study design will help attenuate biases that may dictate inter-individual differences. Moreover, the incorporation of intra-individual differences will facilitate insights into alternative factors that may predict and/or explain true observed individual responses to an exercise training programme.

Impact of data averaging strategies on V̇O2max assessment: Mathematical modeling and reliability

BACKGROUND

No consensus exists on how to average data to optimize V ˙ O_2max assessment. Although the V ˙ O_2max value is reduced with larger averaging blocks, no mathematical procedure is available to account for the effect of the length of the averaging block on V ˙ O_2max. AIMS: To determine the effect that the number of breaths or seconds included in the averaging block has on the V ˙ O_2max value and its reproducibility and to develop correction equations to standardize V ˙ O_2max values obtained with different averaging strategies.

METHODS

Eighty-four subjects performed duplicate incremental tests to exhaustion (IE) in the cycle ergometer and/or treadmill using two metabolic carts (Vyntus and Vmax N29). Rolling breath averages and fixed time averages were calculated from breath-by-breath data from 6 to 60 breaths or seconds.

RESULTS

V ˙ O_2max decayed from 6 to 60 breath averages by 10% in low fit ( V ˙ O_2max  < 40 mL kg^-1  min^-1 ) and 6.7% in trained subjects. The V ˙ O_2max averaged from a similar number of breaths or seconds was highly concordant (CCC > 0.97). There was a linear-log relationship between the number of breaths or seconds in the averaging block and V ˙ O_2max (R²  > 0.99, P < 0.001), and specific equations were developed to standardize V ˙ O_2max values to a fixed number of breaths or seconds. Reproducibility was higher in trained than low-fit subjects and not influenced by the averaging strategy, exercise mode, maximal respiratory rate, or IE protocol.

CONCLUSIONS

The V ˙ O_2max decreases following a linear-log function with the number of breaths or seconds included in the averaging block and can be corrected with specific equations as those developed here.

Validity and Reliability of an On-Court Fitness Test for Assessing and Monitoring Aerobic Fitness in Squash

James, C, Tenllado Vallejo, F, Kantebeen, M, and Farra, S. Validity and reliability of an on-court fitness test for assessing and monitoring aerobic fitness in squash. J Strength Cond Res 33(5): 1400-1407, 2019-Current on-court assessments of aerobic fitness in squash are not designed to yield a wealth of physiological data. Moreover, tests may require complex computer equipment or involve simulated racket strokes, which are difficult to standardize at high intensities. This study investigated the validity and reliability of a squash-specific fitness test which can yield both a standalone performance score, as well as pertinent physiological markers such as V[Combining Dot Above]O2max, the lactate turnpoint and oxygen cost, in a sport-specific environment. Eight national squash players completed 3 tests in a counterbalanced order: an incremental laboratory treadmill test (LAB) and 2 on-court fitness tests (STs) that involved repeated shuttle runs at increasing speeds. V[Combining Dot Above]O2max during ST was agreeable with LAB (typical error [TE] = 3.3 ml·kg·min, r = 0.79). The mean bias between LAB and ST was 2.5 ml·kg·min. There were no differences in maximum heart rate, postexercise blood lactate concentration, or end of test rating of perceived exertion between LAB and ST (p > 0.05). The ST was highly reliable, with 74 (10) laps completed in ST1 and 75 (12) laps in ST2 (mean bias = 1 lap, TE = 3 laps, r = 0.97). Physiological markers were also reliable, including V[Combining Dot Above]O2max, (TE = 1.5 ml·kg·min, r = 0.95), the lap number at 4 mMol (TE = 4 laps, r = 0.77), and average V[Combining Dot Above]O2 across the first 4 stages (TE = 0.94 ml·kg·min, r = 0.95). We observed good agreement between LAB and ST for assessing V[Combining Dot Above]O2max and between both on-court trials for assessing test performance and selected physiological markers. Consequently, we recommend this test for monitoring training adaptations and prescribing individualized training in elite squash players.

Total haemoglobin mass, but not haemoglobin concentration, is associated with preoperative cardiopulmonary exercise testing-derived oxygen-consumption variables

Background

Cardiopulmonary exercise testing (CPET) measures peak exertional oxygen consumption ( V˙O2peak ) and that at the anaerobic threshold ( V˙O2 at AT, i.e. the point at which anaerobic metabolism contributes substantially to overall metabolism). Lower values are associated with excess postoperative morbidity and mortality. A reduced haemoglobin concentration ([Hb]) results from a reduction in total haemoglobin mass (tHb-mass) or an increase in plasma volume. Thus, tHb-mass might be a more useful measure of oxygen-carrying capacity and might correlate better with CPET-derived fitness measures in preoperative patients than does circulating [Hb].

Methods

Before major elective surgery, CPET was performed, and both tHb-mass (optimized carbon monoxide rebreathing method) and circulating [Hb] were determined.

Results

In 42 patients (83% male), [Hb] was unrelated to V˙O2 at AT and V˙O2peak ( r =0.02, P =0.89 and r =0.04, P =0.80, respectively) and explained none of the variance in either measure. In contrast, tHb-mass was related to both ( r =0.661, P <0.0001 and r =0.483, P =0.001 for V˙O2 at AT and V˙O2peak , respectively). The tHb-mass explained 44% of variance in V˙O2 at AT ( P <0.0001) and 23% in V˙O2peak ( P =0.001).

Conclusions

In contrast to [Hb], tHb-mass is an important determinant of physical fitness before major elective surgery. Further studies should determine whether low tHb-mass is predictive of poor outcome and whether targeted increases in tHb-mass might thus improve outcome.

Concurrent exercise circuit protocol performed in public fitness facilities meets the American College of Sports Medicine guidelines for energy cost and metabolic intensity among older adults in Rio de Janeiro City

The current study investigated whether a single bout of concurrent exercise (Ex Rx) at Third Age Academies (TAAs) in Rio de Janeiro City meets the American College of Sports Medicine (ACSM) guidelines for energy cost and metabolic intensity in older adults. Nine subjects (5 males and 4 females, 63-80 years of age) visited the laboratory for clinical screening and for anthropometrical, resting, and maximal oxygen uptake assessments. Thereafter, subjects performed an Ex Rx circuit consisting of a single circuit alternating aerobic and resistance exercises with outdoor exercise equipment using body mass as the load (total of 9 exercises, 1-2 sets of 15 repetitions). Expired gases were collected via a metabolic cart during exercise bouts. The mean observed energy cost value of 169.1 kcal was slightly greater than the minimum value of 150 kcal reported in the ACSM guidelines (p = 0.018). Like energy cost, all the intensity markers adopted to analyze the physiological strain induced by the Ex Rx circuit significantly exceeded their reference values for moderate intensity (reference values: 3.2 METs (mean observed value = 4.6 METs, p = 0.002); 40% of oxygen uptake reserve (mean observed value = 51.5%, p = 0.040); 40% of heart rate reserve (mean observed value = 64.1%, p < 0.001)), according to the ACSM guidelines. In conclusion, a single bout of Ex Rx circuit performed at TAAs in Rio de Janeiro City was able to induce a physiological strain (i.e., energy cost and intensity) compatible with ACSM recommendations for eliciting health benefits among older adults.

Continuous and Accumulated Bouts of Cycling Matched by Intensity and Energy Expenditure Elicit Similar Acute Blood Pressure Reductions in Prehypertensive Men

Fonseca, GF, Farinatti, PTV, Midgley, AW, Ferreira, A, de Paula, T, Monteiro, WD, and Cunha, FA. Continuous and accumulated bouts of cycling matched by intensity and energy expenditure elicit similar acute blood pressure reductions in prehypertensive men. J Strength Cond Res 32(3): 857-866, 2018-This study investigated differences in postexercise hypotension (PEH) after continuous vs. accumulated isocaloric bouts of cycling. Ten prehypertensive men, aged 23-34 years, performed 2 bouts of cycling at 75% oxygen uptake reserve, with total energy expenditures of 400 kcal per bout. One exercise bout was performed continuously (CONTIN) and the other as 2 smaller bouts each expending 200 kcal (INTER1 and INTER2). Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and cardiac autonomic control were monitored in a supine position for 10 minutes before and 60 minutes after each exercise bout, and during a control session. Compared with control, blood pressure was significantly reduced after CONTIN (SBP: [INCREMENT] - 3.4 mm Hg, p < 0.001; MAP: [INCREMENT] - 2.5 mm Hg, p = 0.001), INTER1 (SBP: [INCREMENT] - 2.2 mm Hg, p = 0.045), and INTER2 (SBP: [INCREMENT] - 4.4 mm Hg, p < 0.001; DBP: [INCREMENT] - 2.7 mm Hg, p = 0.045; MAP: [INCREMENT] - 3.3 mm Hg, p = 0.001). The PEH was similar in CONTIN and INTER2, whereas INTER2 elicited greater PEH than INTER1 (SBP and MAP: [INCREMENT] - 2.0 and [INCREMENT] - 1.8 mm Hg, respectively, p ≤ 0.05). Increases in sympathovagal balance from baseline were inversely related to changes in SBP and DBP after CONTIN and INTER2 (r = -0.64 to -0.71; p = 0.021-0.047). These findings indicate that similar amounts of PEH are observed when exercise is performed as a single 400-kcal exercise bout or 2 × 200-kcal bouts and that the exercise recovery pattern of cardiac autonomic activity may be important in eliciting PEH.

Optimizing a Treadmill Ramp Protocol to Evaluate Aerobic Capacity of Hemiparetic Poststroke Patients

Bernardes, WL, Montenegro, RA, Monteiro, WD, de Almeida Freire, R, Massaferri, R, and Farinatti, P. Optimizing a treadmill ramp protocol to evaluate aerobic capacity of hemiparetic poststroke patients. J Strength Cond Res 32(3): 876-884, 2018-A correct assessment of cardiopulmonary capacity is important for aerobic training within motor rehabilitation of poststroke hemiparetic patients (PSHPs). However, specific cardiopulmonary exercise testing (CPET) for these patients are scarce. We proposed adaptations in a protocol originally developed for PSHPs by Ovando et al. (CPET1). We hypothesized that our adapted protocol (CPET2) would improve the original test, by preventing early fatigue and increasing patients' peak performance. Eleven PSHPs (52 ± 14 years, 10 men) performed both protocols. CPET2 integrated changes in final speed (100-120% vs. 140% maximal speed in 10-m walking test), treadmill inclination (final inclination of 5 vs. 10%), and estimated test duration (10 vs. 8 minutes) to smooth the rate of workload increment of CPET1. Peak oxygen uptake (V[Combining Dot Above]O2peak) (20.3 ± 6.1 vs. 18.6 ± 5.0 ml·kg·min; p = 0.04), V[Combining Dot Above]O2 at gas exchange transition (V[Combining Dot Above]O2-GET) (11.5 ± 2.9 vs. 9.8 ± 2.0 ml·kg·min; p = 0.04), and time to exhaustion (10 ± 3 vs. 6 ± 2 minutes; p < 0.001) were higher in CPET2 than in CPET1. Slopes and intercepts of regressions describing relationships between V[Combining Dot Above]O2 vs. workload, heart rate vs. workload, and V[Combining Dot Above]O2 vs. heart rate were similar between CPETs. However, standard errors of estimates obtained for regressions between heart rate vs. workload (3.0 ± 1.3 vs. 3.8 ± 1.0 b·min; p = 0.004) and V[Combining Dot Above]O2 vs. heart rate (6.0 ± 2.1 vs. 4.8 ± 2.4 ml·kg·min; p = 0.05) were lower in CPET2 than in CPET1. In conclusion, the present adaptations in Ovando's CPET protocol increased exercise tolerance of PSHPs, eliciting higher V[Combining Dot Above]O2peak and V[Combining Dot Above]O2-GET, preventing earlier fatigue, and providing better physiological relationships along submaximal workloads.

Changes in fat oxidation in response to various regimes of high intensity interval training (HIIT)

Increased whole-body fat oxidation (FOx) has been consistently demonstrated in response to moderate intensity continuous exercise training. Completion of high intensity interval training (HIIT) and its more intense form, sprint interval training (SIT), has also been reported to increase FOx in different populations. An explanation for this increase in FOx is primarily peripheral adaptations via improvements in mitochondrial content and function. However, studies examining changes in FOx are less common in response to HIIT or SIT than those determining increases in maximal oxygen uptake which is concerning, considering that FOx has been identified as a predictor of weight gain and glycemic control. In this review, we explored physiological and methodological issues underpinning existing literature concerning changes in FOx in response to HIIT and SIT. Our results show that completion of interval training increases FOx in approximately 50% of studies, with the frequency of increased FOx higher in response to studies using HIIT compared to SIT. Significant increases in β-HAD, citrate synthase, fatty acid binding protein, or FAT/CD36 are likely responsible for the greater FOx seen in these studies. We encourage scientists to adopt strict methodological procedures to attenuate day-to-day variability in FOx, which is dramatic, and develop standardized procedures for assessing FOx, which may improve detection of changes in FOx in response to HIIT.

Relationship Between Percentages of Heart Rate Reserve and Oxygen Uptake Reserve During Cycling and Running: A Validation Study

Guimarães, GC, Farinatti, PTV, Midgley, AW, Vasconcellos, F, Vigário, P, and Cunha, FA. Relationship between percentages of heart rate reserve and oxygen uptake reserve during cycling and running: a validation study. J Strength Cond Res 33(7): 1954-1962, 2019-This study investigated the relationship between percentages of heart rate reserve (%HRR) and oxygen uptake reserve (%VO2R) during a cardiopulmonary exercise test (CPET) and discrete bouts of isocaloric cycling and treadmill running. Thirty men visited the laboratory 3 times for anthropometrical and resting VO2 assessments, and perform cycling and running CPETs. Ten men visited the laboratory twice more to investigate the validity of the %HRR-%VO2R relationships during isocaloric bouts of cycling and running at 75% VO2R with energy expenditures of 400 kcals. The %HRR was significantly higher than the %VO2R during both CPETs at all exercise intensities (p < 0.001). During isocaloric exercise bouts, mean %HRR-%VO2R differences of 6.5% and 7.0% were observed for cycling and running, respectively (p = 0.007-p < 0.001). The %HRR and %VO2R increased over time (p < 0.001), the rate of which was influenced by exercise modality (p < 0.001). On average, heart rate was 5 (p = 0.007) and 8 (p < 0.001) b·min higher than predicted from the second energy expenditure quartile for cycling and running, respectively; however, observed VO2 was lower than predicted during all quartiles for cycling, and the first quartile for running. Consequently, time to achieve the target energy expenditure was greater than predicted (p < 0.01). In conclusion, the %HRR-%VO2R relationship observed during CPET data did not accurately transpose to prolonged isocaloric bouts of cycling and running. In addition, power outputs and speeds defined by the American College of Sports Medicine equations for cycling and running, respectively, overestimated VO2 and energy expenditure.

Physiological strain to prolonged exercise bouts at the walk-run transition speeds depends on locomotion mode in healthy untrained men

This study compared the physiological strain induced by prolonged walking and running performed at the walk-run transition speed (WRTS) in healthy untrained men. Twenty volunteers (age: 28 ± 5.01 years; height: 174.0 ± 0.3 cm; body mass: 74.5 ± 0.6 kg) underwent the following: (a) ramp-incremental maximal cardiopulmonary exercise test (CPET); (b) specific protocol to detect the WRTS; and (c) two 30-min walking and running bouts at WRTS (mean ± SD: 6.9 ± 0.06 km/h). Expired gases were collected during exercise bouts via the metabolic cart. A significant effect of locomotion mode (F = 4.8, P < 0.001) was observed with running resulting in higher cardiorespiratory responses than walking at the WRTS (oxygen uptake: mean difference = 0.26 L/min; pulmonary ventilation: mean difference = 5.53 L/min; carbon dioxide output: mean difference = 0.32 L/min; heart rate: mean difference = 13 beats/min; total energy expenditure: mean difference = 59 kcal). The rating of perceived exertion was similar across locomotion modes (mean difference = 0.3; P = 0.490). In conclusion, running promoted greater cardiorespiratory responses than walking at the WRTS in untrained healthy men. These data might have practical impact on aerobic training performed at intensities corresponding to WRTS.

Comparison between parameters from maximal cycle ergometer test first without respiratory gas analysis and thereafter with respiratory gas analysis among healthy prepubertal children

It is important to distinguish true and clinically relevant changes and methodological noise from measure to measure. In the clinical practice, maximal cycle ergometer tests are typically performed first without respiratory gas analysis and thereafter, if needed, with respiratory gas analysis. Therefore, we report a comparison of parameters from maximal cycle ergometer exercise tests that were done first without respiratory gas analysis and thereafter with it in 38 prepubertal and healthy children (20 girls, 18 boys). The Bland-Altman method was used to assess agreement in maximal workload (WMAX), heart rate (HR), and systolic blood pressure (SBP) between rest and maximum. Girls achieved higher WMAX in the exercise tests with respiratory gas analysis compared with exercise tests without respiratory gas analysis (p = 0.016), whereas WMAX was similar in the tests among boys. Maximal HR (proportional offset, -1%; coefficients of variation, 3.3%) and highest SBP (proportional offset, 3%; coefficients of variation, 10.6%) were similar in the tests among children. Precision and agreement for HR improved and precision for SBP worsened with increasing exercise intensity. Heteroscedasticity was not observed for WMAX, HR, or SBP. We conclude that maximal cycle ergometer tests without and with respiratory gas analysis can be used consecutively because measurement of respiratory gases did not impair performance or have a significant effect on the maximality of the exercise tests. Our results suggest that similar references can be used for children who accept or refuse using a mask during a maximal exercise test.

Reproducibility of incremental maximal cycle ergometer tests in healthy recreationally active subjects

PURPOSE

Testing of the ventilatory threshold (VT) and maximal oxygen uptake (VO₂ peak) is relevant for the evaluation of a range of training studies, clinical trials and cross-sectional studies. Due to a possible learning effect, a familiarization test is often performed to increase test reproducibility. However, limited research has investigated this learning effect and reproducibility of maximal exercise testing. The most appropriate ways to determine VT and VO₂ peak are not clear, and this study evaluated two approaches (V-slope and a combined method) for the determination of VT and five time-averaging intervals (60, 30, 15, 10 and 5 s) for the determination of VO₂ peak to compare test results and reproducibility.

METHODS

Thirteen recreational triathletes completed three identical incremental maximal cycle ergometer tests. The initial workload was 75 and 100 watt (W) for women and men, respectively, and the workload was increased by 4 W/10 s thereafter. No familiarization test was performed.

RESULTS

VO₂ peak increased significantly as the time-averaging interval became shorter (e.g. 5-s interval 48·7 versus 60-s interval 44·8 ml O₂  kg^-1  min^-1 ; overall P<0·001). All test results were similar for the three test rounds, indicating that repeated testing was not associated with any learning effect. The different VT measuring methods (CV 7·6 versus 7·7%, P = 0·58) and VO₂ peak time-averaging intervals (CV 3·7-4·4%, P = 0·99) did not influence test reliability.

CONCLUSIONS

The reproducibility of VT and VO₂ peak was not affected by measuring methods and time-averaging intervals. However, the time-averaging intervals significantly affect the absolute VO₂ peak values. Furthermore, no learning effect of maximal cycle ergometer testing was observed.

Postexercise hypotension after maximal short-term incremental exercise depends on exercise modality

This study investigated postexercise hypotension (PEH) after maximal cardiopulmonary exercise testing (CPET) performed using different exercise modalities. Twenty healthy men (aged 23 ± 3 years) performed 3 maximal CPETs (cycling, walking, and running), separated by 72 h in a randomized, counter-balanced order. Systolic (SBP) and diastolic blood pressure (DBP), heart rate, cardiac output, systemic vascular resistance (SVR), autonomic function (spontaneous baroreflex sensitivity (BRS) and heart rate variability (HRV)), and energy expenditure (EE) were assessed during a 60-min nonexercise control session and for 60 min immediately after each CPET. Total exercise volume (EE during CPET plus 60 min recovery) was significantly higher in running versus cycling and walking CPETs (P ≤ 0.001). Compared with control, only SBP after running CPET was significantly reduced (Δ = −6 ± 8 mm Hg; P < 0.001). Heart rate and cardiac output were significantly increased (P < 0.001) and SVR significantly decreased (P < 0.001) postexercise. BRS and HRV decreased after all CPETs (P < 0.001), whereas sympatho-vagal balance (low- and high-frequency (LF:HF) ratio) increased significantly after all exercise conditions, especially after running CPET (P < 0.001). Changes in SVR, BRS, sympathetic activity (low-frequency component of HRV), and LF:HF ratio were negatively correlated to variations in SBP (range −0.69 to −0.91; P < 0.001) and DBP (range −0.58 to −0.93; P ≤ 0.002). These findings suggest that exercise mode or the total exercise volume are major determinants of PEH magnitude in healthy men. Because of the running CPET, the PEH was primarily related to a decrease in SVR and to an increase in sympatho-vagal balance, which might be a reflex response to peripheral vasodilatation after exercise.

Parasympathetic reactivation after maximal CPET depends on exercise modality and resting vagal activity in healthy men

Purpose

The main purpose of this study was to investigate parasympathetic reactivation of the heart [evaluated through heart rate recovery (HRR) and HR variability (HRV)] after maximal cardiopulmonary exercise testing (CPET) using three different exercise modalities.

Methods

Twenty healthy men, aged 17 to 28 yr, performed three maximal CPETs (cycling, walking, and running) separated by 72 h and in a randomized, counter-balanced order. HRR was determined from the absolute differences between HR_peak and HR at 1–3 min after exercise. The root mean square of successive R-R differences calculated for consecutive 30-s windows (rMSSD_30s) was calculated to assess the parasympathetic reactivation after maximal CPET.

Results

Lower HR_peak, VO_2peak and energy expenditure were observed after the cycling CPET than the walking and running CPETs (P < 0.001). Both HRR and rMSSD_30s were significantly greater during recovery from the cycling CPET compared to the walking and running CPETs (P < 0.001). Furthermore, Δ rMSSD (i.e. resting minus postexercise rMSSD every 30 s into the recovery period) was positively related to the resting high-frequency component (HF), rMSSD, and standard deviation of all normal R-R intervals (SDNN) (r_s = 0.89 to 0.98; P < 0.001), and negatively related to the resting low-frequency component (LF) and sympathovagal balance (LF:HF ratio) after all exercise conditions (r_s = −0.73 to −0.79 and −0.86 to −0.90, respectively; P < 0.001).

Conclusions

These findings support that parasympathetic reactivation after maximal CPET (as assessed by HRR and rMSSD_30s) depends on exercise modality and cardiac autonomic control at rest.

Increased cardiac output elicits higher V̇O2max in response to self-paced exercise

Recently, a self-paced protocol demonstrated higher maximal oxygen uptake versus the traditional ramp protocol. The primary aim of the current study was to further explore potential differences in maximal oxygen uptake between the ramp and self-paced protocols using simultaneous measurement of cardiac output. Active men and women of various fitness levels (N = 30, mean age = 26.0 ± 5.0 years) completed 3 graded exercise tests separated by a minimum of 48 h. Participants initially completed progressive ramp exercise to exhaustion to determine maximal oxygen uptake followed by a verification test to confirm maximal oxygen uptake attainment. Over the next 2 sessions, they performed a self-paced and an additional ramp protocol. During exercise, gas exchange data were obtained using indirect calorimetry, and thoracic impedance was utilized to estimate hemodynamic function (stroke volume and cardiac output). One-way ANOVA with repeated measures was used to determine differences in maximal oxygen uptake and cardiac output between ramp and self-paced testing. Results demonstrated lower (p < 0.001) maximal oxygen uptake via the ramp (47.2 ± 10.2 mL·kg(-1)·min(-1)) versus the self-paced (50.2 ± 9.6 mL·kg(-1)·min(-1)) protocol, with no interaction (p = 0.06) seen for fitness level. Maximal heart rate and cardiac output (p = 0.02) were higher in the self-paced protocol versus ramp exercise. In conclusion, data show that the traditional ramp protocol may underestimate maximal oxygen uptake compared with a newly developed self-paced protocol, with a greater cardiac output potentially responsible for this outcome.

Ventilatory anaerobic thresholds of individuals recovering from traumatic brain injury compared with noninjured controls

OBJECTIVE

The purpose of this study was to compare the peak aerobic capacities and ventilatory anaerobic thresholds (VAT) of individuals with a traumatic brain injury (TBI) to age- and gender-matched controls.

METHODS

Nineteen participants that previously suffered a mild to moderate TBI and 19 apparently healthy controls volunteered as subjects. Traumatic brain injury and healthy controls were matched for age and gender and were similar in weight and body mass index. Volunteers performed a maximal graded treadmill test to volitional failure where oxygen consumption ((Equation is included in full-text article.)O2), carbon dioxide production ((Equation is included in full-text article.)CO2, ventilation ((Equation is included in full-text article.)E, and heart rate were measured continuously. From metabolic and ventilatory data, VAT was measured using a previously described method. VAT and peak exercise responses of participants with a TBI were compared with healthy controls.

RESULTS

The (Equation is included in full-text article.)O2, and (Equation is included in full-text article.)CO2 at VAT and peak exercise were lower for TBI compared with healthy controls. (Equation is included in full-text article.)E was also lower for TBI at VAT and peak exercise. Heart rate was lower for TBI at VAT; however, TBI had similar heart rate to healthy controls at peak exercise.

CONCLUSIONS

The VAT and peak exercise capacities of participants with a TBI were below the metabolic demands of many routine daily activities. The data suggest that therapeutic interventions for individuals with a TBI should include targeted exercise prescriptions to improve cardiorespiratory fitness.

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.

Pursue or shoot? Effects of exercise-induced fatigue on the transition from running to rifle shooting in a pursuit task

To investigate to what degree exercise-induced fatigue influences behavioural choices, participants' transition from running to rifle shooting in a pursue-and-shoot task was assessed. Participants ran on a treadmill and chased a target in a virtual environment and were free to choose when to stop the treadmill and shoot at the target. Fatigue increased progressively throughout the 20-minute test. Results indicated that shooting accuracy was not affected by fatigue. However, the distance to the target at which participants decided to shoot showed a U-shaped relationship with fatigue, R(2) = 0.884, p = 0.013. At low fatigue levels (ratings of perceived exertion [RPE] < 6.5), the distance to the target at which participants shot decreased, whereas at higher fatigue levels (RPE > 6.5) shooting distance increased again. At high levels of fatigue, participants stopped running sooner, aimed at the target longer and shot less often. Findings indicate that physiological parameters influence not only perception but also actual transitions between different actions.

Association between preoperative haemoglobin concentration and cardiopulmonary exercise variables: a multicentre study

Background

Preoperative anaemia and low exertional oxygen uptake are both associated with greater postoperative morbidity and mortality. This study reports the association among haemoglobin concentration ([Hb]), peak oxygen uptake (V˙O2 peak) and anaerobic threshold (AT) in elective surgical patients.

Methods

Between 1999 and 2011, preoperative [Hb] and cardiopulmonary exercise tests were recorded in 1,777 preoperative patients in four hospitals. The associations between [Hb], V˙O2 peak and AT were analysed by linear regression and covariance.

Results

In 436 (24.5%) patients, [Hb] was <12 g dl^-1 and, in 83 of these, <10 g dl^-1. Both AT and V˙O2 peak rose modestly with increasing [Hb] (r² = 0.24, P <0.0001 and r² = 0.30, P <0.0001, respectively). After covariate adjustment, an increase in [Hb] of one standard deviation was associated with a 6.7 to 9.7% increase in V˙O2 peak, and a rise of 4.4 to 6.0% in AT. Haemoglobin concentration accounted for 9% and 6% of the variation in V˙O2 peak and AT respectively.

Conclusions

To a modest extent, lower haemoglobin concentrations are independently associated with lower oxygen uptake during preoperative cardiopulmonary exercise testing. It is unknown whether this association is causative.

Running on a lower-body positive pressure treadmill: VO2max, respiratory response, and vertical ground reaction force

PURPOSE

This study investigated maximal oxygen consumption (VO2max) and time to exhaustion while running on a lower-body positive pressure treadmill (LBPPT) at normal body weight (BW) as well as how BW support affects respiratory responses, ground reaction forces, and stride characteristics.

METHOD

Twelve runners performed VO2max tests on a regular treadmill and an LBPPT. Furthermore, they performed steady-state running (10km/hr, 14 km/hr, and 18 km/hr) and high-speed running (20km/hr and 22 km/hr) at four different BWs on the LBPPT. VO2, heart rate, ventilation, and breathing frequency as well as vertical ground reaction force (vGRF) and stride characteristics were measured.

RESULTS

VO2max could be obtained on both treadmills, although time to exhaustion was 34.5% longer on the LBPPT. VO2, ventilation, and heart rate decreased linearly with increasing BW support at steady-state running, while breathing rate remained unaffected by increasing BW support. Ground reaction force was markedly reduced with increasing BW support. The contact time decreased and flight time increased with increasing BW support. The step frequency decreased and step length increased to some extent with increasing BW support.

CONCLUSIONS

VO2max can be achieved on an LBPPT at 100% BW with an incline-running protocol. The LBPPT is a suitable training device for athletes and allows training at high running speeds and high aerobic stimuli with the benefit of low vGRF and a near-normal movement pattern, although manipulation of gravitational weight causes some adaptations in locomotion.

Preoperative exercise capacity in adult inflammatory bowel disease sufferers, determined by cardiopulmonary exercise testing

BACKGROUND AND AIMS

Aerobic exercise capacity appears impaired in children with inflammatory bowel disease (IBD). Whether this holds true in adults with IBD is not known. Using cardiopulmonary exercise testing (CPET), we assessed anaerobic threshold (AT) in such patients comparing data with reference values and other elective surgical patients. We also sought to confirm whether the presence of a fistula further reduced AT.

METHODS

CPET was performed between November 2007 and December 2010 on patients awaiting abdominopelvic surgery. Gender-specific normal reference values were used for comparison. Unadjusted comparison between two groups was made using Mann-Whitney U test and by unpaired t test. Data were adjusted by analysis of covariance, using age and sex as covariates. Differences between patients' observed values and reference values were tested using paired t tests.

RESULTS

Four hundred and fourteen patients (234 male) were studied (mean ± SD age, 56.6 ± 16.4 years; weight, 74.2 ± 15.6 kg). Adjusted AT values in Crohn's disease (CD) were lower than colorectal cancer (11.4 ± 3.4 vs 13.2 ± 3.5 ml.kg(-1).min(-1), p = 0.03) and for all other colorectal disease groups combined (12.6 ± 3.5 ml.kg(-1).min(-1), p = 0.03). AT of Ulcerative colitis (UC) and CD patients together were reduced compared to population reference values (p < 0.05).

CONCLUSION

After adjusting for age and sex, CD patients had a reduced AT compared to patients with colorectal cancer and other colorectal disease groups combined. The pathogenesis of this low AT remains to be defined and warrants further investigation.

Determination of Best Criteria to Determine Final and Initial Speeds within Ramp Exercise Testing Protocols

This study compared strategies to define final and initial speeds for designing ramp protocols. V_O2max was directly assessed in 117 subjects (29 ± 8 yrs) and estimated by three nonexercise models: (1) Veterans Specific Activity Questionnaire (VSAQ); (2) Rating of Perceived Capacity (RPC); (3) Questionnaire of Cardiorespiratory Fitness (CRF). Thirty seven subjects (30 ± 9 yrs) performed three additional tests with initial speeds corresponding to 50% of estimated V_O2max and 50% and 60% of measured V_O2max. Significant differences (P < 0.001) were found between V_O2max measured (41.5 ± 6.6 mL·kg⁻¹·min⁻¹) and estimated by VSAQ (36.6 ± 6.6 mL·kg⁻¹·min⁻¹) and CRF (45.0 ± 5.3 mL·kg⁻¹·min⁻¹), but not RPC (41.3 ± 6.2 mL·kg⁻¹·min⁻¹). The CRF had the highest ICC, the lowest SEE, and better limits of agreement with V_O2max compared to the other instruments. Initial speeds from 50%–60% V_O2max estimated by CRF or measured produced similar V_O2max (40.7 ± 5.9; 40.0 ± 5.6; 40.3 ± 5.5 mL·kg⁻¹·min⁻¹ resp., P = 0.14). The closest relationship to identity line was found in tests beginning at 50% V_O2max estimated by CRF. In conclusion, CRF was the best option to estimate V_O2max and therefore to define the final speed for ramp protocols. The measured V_O2max was independent of initial speeds, but speeds higher than 50% V_O2max produced poorer submaximal relationships between workload and V_O2.

Do the speeds defined by the American College of Sports Medicine metabolic equation for running produce target energy expenditures during isocaloric exercise bouts?

The accuracy of the American College of Sports Medicine (ACSM) equations for producing predicted values of heart rate reserve (HRR) and oxygen uptake reserve (VO2R) and consequently, target energy expenditure (EE) during exercise are yet to be established. This study investigated whether speeds defined by the ACSM metabolic equation for running correctly estimate the EEs during isocaloric exercise bouts. Twenty-eight men performed a ramp-incremental maximal exercise test to determine HRmax and VO2max. Two continuous exercise bouts at 60 and 80% VO2R and target EE of 400 kcal were then performed. In the 60% VO2R exercise the observed VO2R and EE were lower than predicted only during the first time quartile of the bout (t = 6.5, p < 0.001), whereas at 80% VO2R it was lower during the first (t = 15.3, p < 0.001), second (t = 5.4, p < 0.001) and third (t = 3.1, p = 0.025) quartiles. The observed HR was lower than predicted in the first time quartile of the 60% [Formula: see text] (t = 5.6, p < 0.001) and 80% VO2R bouts (t = 10.7, p < 0.001), whereas no significant differences occurred for any other time quartiles (p ≥ 0.23). In conclusion, the running speed defined by the ACSM metabolic equation overestimated VO2R and EE within exercise performed at 60 and 80% VO2R especially in higher intensities.

No effect of upper body compression garments in elite flat-water kayakers

While the effect of lower body compression garments on performance and physiological responses are well documented, no studies have examined the effect of upper body compression garments (UBCG) on upper-body dominant exercise. This study examined the effects of wearing UBCG on performance and physiological responses during simulated flat-water kayaking. Five male (mean values±s: 21.8±2.8 years; 83.5±9.2 kg; 63.0±5.5 ml·kg(-1)·min(-1)) and two female (mean values±s: 25.0±4.2 years; 71.4±2.7 kg; 51.0±4.8 ml·kg(-1)·min(-1)) elite flat-water kayakers completed a six-step incremental test followed by a four-minute maximal performance test (4minPT) in both UBCG and control (no shirt or sports training bra) conditions in a randomized counter-balanced order. Heart rate and oxygen consumption ([Formula: see text]O2) as well as performance measures (power, distance covered, stroke rate) were recorded during the tests, and blood lactate was measured immediately after each incremental step and three minutes following the 4minPT. Near-infrared spectroscopy-derived measures of blood flow and oxygenation of the flexor carpi radialis were monitored continuously for all tests. No significant differences between the UBCG and control conditions were evident for any performance, cardiorespiratory or oxygenation measure across the incremental step test and 4minPT. It was concluded that wearing UBCG did not provide any significant physiological or performance benefits during simulated flat-water kayaking.

Standardized peak exercise perception score: validation of a new index of effort perception

PURPOSE

Standardized peak exercise perception score (SPEPS) is an index representing patient effort perception defined as SPEPS = Borg/METs, where Borg is the Borg CR-10 at maximal exercise intensity and METs is maximal metabolic equivalents. The purpose of the study was to assess the validity of SPEPS in different patient groups and to examine its applicability for evaluation of exercise training outcomes.

METHODS

Patients (n = 17) with chronic heart failure (CHF, New York Heart Association [NYHA] II and III functional class; ejection fraction= 31 +/- 14%), 16 patients with chronic obstructive pulmonary disease (COPD, forced expiratory volume in 1 second - FEV(1)%= 51 +/- 14%), and 16 age- and body mass index-matched controls formed the primary study group. An additional 22 ambulatory patients with stable CHF (NYHA II-III) were randomized to training and nontraining groups to test the effect of 8 weeks' exercise training on SPEPS.

RESULTS

Patients showed reduced exercise capacity (V(O)(2), mL*kg(-1)* min(-1)) = 18.8 +/- 3.8 (CHF) vs 21.1 +/- 5.1 (COPD) vs 29.9 +/- 5.2 (control), corresponding to SPEPS values: 1.15 +/- 0.36 (CHF) vs 0.82 +/- 0.26 (COPD) vs 0.55 +/- 0.22 (control); P < .001. The reduction in SPEPS was the largest compared with the other tested parameters after training and correlated strongly with change in Minnesota Living with Heart Failure Questionnaire (rho= 0.75, P < .001).

CONCLUSION

SPEPS is a reliable new index for discriminating perceived exertion at the end of exercise test in different groups of patients, presenting both construct and concurrent validity. It is a potent parameter for evaluation of the outcomes in training programs.