Ramp Exercise Research Articles

A flattening systolic blood pressure response at the end of ramp exercise testing is not associated with all-cause mortality

Abstract Purpose Systolic blood pressure (SBP) is expected to rise linearly during ramp exercise, but sometimes plateaus before the end of exercise. We aimed to examine the predictive value of a plateauing SBP response at the end of a cycle exercise test. Methods We analyzed 9,001 consecutive patients aged ≥18 years with maximal cycle ergometer ramp tests, after excluding subjects with valvulopathy, pacemaker, arrhythmia during the test, or body mass index (BMI) >40kg/m², as well as tests with resting SBP <80mmHg or >200mmHg, exercise SBP <100 mmHg, <2 SBP measurements during the second half of the test or a test duration <4 minutes. The data were cross-linked with nationwide registries for mortality and in- and outpatient hospital diagnoses. The difference in SBP between the two last SBP measurements was standardized to the difference in Watts between the same time points, categorized as i) an SBP decrease (drop), ii) an SBP increase of <2.5 mmHg per 10 Watts increase (flat), iii) an SBP increase of 2.5-15 mmHg/10 Watts (intermediate), and iv) an SBP increase >15 mmHg/10 Watts representing the 97.5th percentile (steep). Hazards ratios (HR, [95% confidence interval, CI]) for all-cause mortality were calculated, stratified for exercise capacity (peak Watt % of predicted) with the intermediate SBP response as reference. Adjustments were made for age, sex, BMI, resting SBP, baseline diagnosis of ischemic heart disease, heart failure, chronic obstructive pulmonary disease, and the use of beta-blockers or anti-hypertensive medication. Results Decreasing, flat, intermediate, and steep SBP responses at the end of exercise were present in 1.1%, 25.6%, 70.8% and 2.5% of patients respectively (Table 1). During median follow-up 8.6 years (interquartile range 5.9–11.6 years) there were 844 deaths. When compared to an intermediate SBP response, a flat SBP response was not associated with all-cause mortality in any of the exercise capacity strata: lowest tertile of Wmax%pred unadjusted HR 0.88 (95% CI 0.69–1.11), middle tertile HR 0.91 (95% CI 0.66–1.24), and highest tertile HR 0.95 (95% CI 0.64–1.41), with HRs remaining non-significant after adjustment for covariates (Table 2). Conclusion In patients referred for exercise testing, a flattening SBP response at the end of exercise was not associated with increased all-cause mortality risk compared to an intermediate SBP response, consistent across the different exercise capacity strata.

A modified step-ramp-step protocol to prescribe constant-speed exercise in treadmill running.

This study investigated whether a running-adapted version of the cycling-based "step-ramp-step" (SRS) protocol would improve prediction of O2 in treadmill exercise compared to the traditional prescriptive approach. Fourteen healthy individuals (6 females; 25 ± 6years; 66.1 ± 12.7kg) performed a treadmill-based SRS protocol including a ramp-incremental test to task failure followed by two constant-speed bouts within the moderate-(MODstep-below estimated lactate threshold; θLT), and heavy-intensity domains (HVYstep-between θLT and respiratory compensation point; RCP). Using the uncorrected O2-to-speed relationship from the ramp exercise, three constant-speed bouts were performed at 40-50% between: baseline and θLT (CSEMOD); θLT and RCP (CSEHVY); and RCP and peak (CSESEV). For CSEMOD, CSEHVY, and CSESEV measured end-exercise O2 was compared to predicted O2 based on the: (i) "SRS-corrected" O2-to-speed relationship (where MODstep and HVYstep were used to adjust the O2 relative to speed); and (ii) linear "uncorrected" data. Average treadmill speeds for CSEMOD and CSEHVY were 7.8 ± 0.8 and 11.0 ± 1.4km·h-1, respectively, eliciting end-exercise O2 of 1979 ± 390 and 2574 ± 540mL·min-1. End-exercise O2 values were not different compared to SRS-predicted O2 at CSEMOD (mean difference: 5 ± 166mL·min-1; p = 0.912) and CSEHVY (20 ± 128mL·min-1; p = 0.568). The linear "uncorrected" estimates were not different for CSEMOD (-91 ± 172mL·min-1; p = 0.068) but lower for CSEHVY (-195 ± 146mL·min-1; p < 0.001). For CSESEV (running speed: 13.8 ± 1.7km·h-1), the end-exercise O2 was not different from peak O2 achieved during the ramp (3027 ± 682 vs. 2979 ± 655mL·min-1; p = 0.231). In healthy individuals, the SRS protocol more accurately predicts speeds for a target O2 compared to traditional approaches.

High-intensity interval training improves respiratory and cardiovascular adjustments before and after initiation of exercise.

Purpose: High-intensity interval training (HIIT) may induce training-specific physiological adaptations such as improved respiratory and cardiovascular adjustments before and after the onset of high-intensity exercise, leading to improved exercise performance during high-intensity exercise. The present study investigated the effects of HIIT on time-dependent cardiorespiratory adjustment during maximal exercise and before and after initiation of high-intensity exercise, as well as on maximal exercise performance. Methods: 21 healthy male college students were randomly assigned to HIIT group (n = 11) or control group (n = 10). HIIT group performed training on a cycle ergometer once a week for 8 weeks. The training consisted of three bouts of exercise at 95% maximal work rate (WRmax) until exhaustion. Before and after the HIIT program, dynamic cardiorespiratory function was investigated by ramp and step exercise tests, and HIIT-induced cardiac morphological changes were assessed using echocardiography. Results: HIIT significantly improved not only maximal oxygen uptake and minute ventilation, but also maximal heart rate (HR), systolic blood pressure (SBP), and time to exhaustion in both exercise tests (p < 0.05). Time-dependent increases in minute ventilation (VE) and HR before and at the start of exercise were significantly enhanced after HIIT. During high-intensity exercise, there was a strong correlation between percent change (from before to after HIIT program) in time to exhaustion and percent change in HRmax (r = 0.932, p < 0.001). Furthermore, HIIT-induced cardiac morphological changes such as ventricular wall hypertrophy was observed (p < 0.001). Conclusion: We have demonstrated that HIIT at 95% WRmax induces training-specific adaptations such as improved cardiorespiratory adjustments, not only during maximal exercise but also before and after the onset of high-intensity exercise, improvement of exercise performance mainly associated with circulatory systems.

Effects of 5-Week Oral Acetazolamide on Incremental Cycling Exercise in Pulmonary Arterial and Chronic Thromboembolic Pulmonary Hypertension: A Randomized Placebo-Controlled, Double-Blinded, Crossover Trial

Introduction: Acetazolamide (AZA) improves nocturnal and daytime blood oxygenation in patients with pulmonary vascular disease (PVD), defined as pulmonary arterial and distal chronic thromboembolic pulmonary hypertension (CTEPH), and may improve exercise performance. Methods: We investigated the effect of 5 weeks of AZA (250 mg bid) versus placebo on maximal load during incremental cycling ramp exercise in patients with PVD studied in a randomized controlled, double-blind, crossover design, separated by > 2 weeks of washout. Results: Twenty-five patients (12 pulmonary arterial hypertension, 13 CTEPH, 40% women, age 62 ± 15 years) completed the trial according to the protocol. Maximum load was similar after 5 weeks of AZA versus placebo (113 ± 9 vs. 117 ± 9 watts [W]), mean difference −4 W (95% CI: −9 to 1, p = 0.138). With AZA, maximum (max)-exercise partial pressure of O₂ (PaO₂) was significantly higher by 1.1 kPa (95% CI: 0.5–1.8, p = 0.003), while arterial pH and partial pressure of CO₂ were significantly lower. Gas exchange threshold was reached at a higher load with AZA (108 ± 8 W vs. 97 ± 8 W) and was therefore delayed by 11 W (95% CI: 3–19, p = 0.013), while the ventilatory equivalent for O₂ and CO₂ were significantly higher at both the max-exercise and gas exchange threshold with AZA versus placebo. Conclusion: AZA for 5 weeks did not significantly change maximum exercise capacity in patients with PVD despite a significant increase in PaO₂. The beneficial effects of increased blood oxygenation may have been diminished by increased ventilation due to AZA-induced metabolic acidosis and increased dyspnea.

Long-Term Alterations in Pulmonary V˙O2 and Muscle Deoxygenation On-Kinetics During Heavy-Intensity Exercise in Competitive Youth Cyclists: A Cohort Study.

The aim of this investigation was to assess alterations of pulmonary oxygen uptake (V˙O2) and muscle deoxygenation on-kinetics during heavy-intensity cycling in youth cyclists over a period of 15months. Eleven cyclists (initial age, 14.3 [1.6]y; peak V˙O2, 62.2 [4.5]mL·min-1·kg-1) visited the laboratory twice on 3 occasions within 15months. Participants performed an incremental ramp exercise test and a constant workrate test within the heavy-intensity domain during the first visitand second visit, respectively. Subsequently, parameter estimates of the V˙O2 and muscle deoxygenation on-kinetics were determined with mono-exponential models. The V˙O2 phase II time constant decreased from occasion 1 (34 [4]s) to occasion 2 (30 [4]s, P = .005) and 3 (28 [4]s, P = .010). However, no significant alteration was observed between occasions 2 and 3 (P = .565). The V˙O2 slow component amplitude either expressed in absolute values (ie,L·min-1) or relative to end exercise V˙O2 (ie,%) showed no significant changes throughout the study (P = .972 and .996). Furthermore, the muscle deoxygenation on-kinetic mean response time showed no significant changes throughout the study (18 [8], 18 [3], and 16 [5]s for occasions 1, 2, and 3, respectively; P = .279). These results indicate proportional enhancements of local muscle oxygen distribution and utilization, which both contributed to the speeding of the V˙O2 on-kinetics herein.

Mathematical modeling of exercise fatigability in the severe domain: A unifying integrative framework in isokinetic condition

Muscle fatigue is the decay in the ability of muscles to generate force, and results from neural and metabolic perturbations. This article presents an integrative mathematical model that describes the decrease in maximal force capacity (i.e. fatigue) over exercises performed at intensities above the critical force Fc (i.e. severe domain). The model unifies the previous Critical Power Model and All-Out Model and can be applied to any exercise described by a changing force F over time. The assumptions of the model are (i) isokinetic conditions, an intensity domain of Fc<F, (ii) constant individual parameters of Fc, and τ, (iii) fatigability proportional to the accumulation of impulse JAC above the critical force Fc. The present study adjusted the parameters to fit previous experimental observations from three types of exercises: constant intensity, all-out, and increasing ramp exercise. This integrative model establishes a connection between the previous individual models and provides an excellent description of exercise fatigability in the severe domain. With this new integrative model, the maximal force production of the muscle can be predicted over time during both maximal and submaximal exercises.

Abstract 17415: Oxygen Uptake Kinetics at the Onset of Incremental Ramp Exercise During Cardiopulmonary Exercise Testing in Patients Undergoing Evaluation of Dyspnea on Exertion

Background: A high metabolic cost of initiating exercise, defined by workload equivalents of unloaded cycle ergometry exercise, has been described in obese patients with HFpEF. Implications of high BMI and exaggerated metabolic cost of exercise initiation on responses to incremental ramp exercise have not been defined. We hypothesized that exaggerated metabolic cost of exercise initiation would result in delayed metabolic response to incremental ramp exercise. Methods: Patients underwent invasive cardiopulmonary exercise testing (CPET) on a cycle ergometer, including rest, unloaded exercise, and maximum incremental ramp exercise. Mean response time (MRT) was defined as 67% of the time to reach steady state VO 2 during unloaded exercise. On-ramp VO 2 kinetics were defined by the amount of time that it took for VO 2 to permanently increase by 5% (t 5% ), 10% (t 10% ), and 15% (t 15% ) above steady state after initiation of incremental ramp exercise. These values were adjusted for ramp and related to demographic and CPET measures by multivariate linear regression. Results: 200 patients referred for evaluation of exertional dyspnea and suspected HFpEF (age 55 ± 16 years, 45% female, BMI of 30 ± 6 kg/m 2 , 52% HTN, 17% DM) demonstrated variability in their on-ramp VO 2 uptake kinetics after reaching steady state during unloaded exercise. Delayed VO 2 kinetic responsiveness to incremental ramp exercise, as measured by t 5% , t 10% , and t 15%, was not related to age but was directly related to BMI, internal work, and prolonged MRT for VO 2 upon exercise initiation. Conclusion: In this initial description of VO 2 uptake kinetic patterns during the transition from unloaded to incremental ramp exercise, increased BMI, slow exercise onset VO 2 kinetics, and heightened metabolic cost of exercise initiation are all related to delayed VO 2 on-ramp kinetics. Delayed on-ramp O 2 kinetics merit further evaluation in relation to functional limitations in dyspneic patients referred for suspicion of HFpEF.

Agreement between left and right middle cerebral artery blood velocity responses to incremental and constant work-rate exercise in healthy males and females

Objective. To quantify the agreement between left and right middle cerebral artery blood velocity (MCAv) responses to incremental and constant work-rate exercise in adults. Approach Seventeen healthy adults (23.8 ± 2.4 years, 9 females) completed a ramp incremental test to exhaustion on a cycle ergometer, three 6-minute transitions at a moderate-intensity, and three at a heavy-intensity, all on separate days. Bilateral MCAv was measured throughout using transcranial Doppler ultrasonography, with left and right MCAv data analysed separately. Data were analysed at baseline, gas exchange threshold, respiratory compensation point and exhaustion during ramp incremental exercise. MCAv responses to constant work-rate exercise were analysed using a mono-exponential model, to determine time- and amplitude-based kinetic response parameters. Main Results Left and right MCAv responses to incremental and constant work-rate exercise were significantly, strongly and positively correlated (r ≥ 0.61, P < 0.01). Coefficient of variation (left versus right) ranged from 7.3%–20.7%, 6.4%–26.2% and 5.9%–22.5% for ramp, moderate and heavy-intensity exercise, respectively. The relative change in MCAv from baseline was higher in the right compared to left MCAv during ramp, moderate and heavy-intensity exercise (all P < 0.05), but the effect sizes were small (d ≤ 0.4). Small mean left–right differences were present during ramp incremental exercise at all time-points (<6 cm s−1; <4%), and for all kinetic parameters during moderate and heavy-intensity exercise (<3 cm s−1, <3%, <4 s). Significance These findings demonstrate similarities between left and right MCAv responses to incremental and constant-work rate exercise in adults on a group-level, but also highlight individual variation in the agreement between left and right MCAv exercise responses.

ACE-I/D Allele Modulates Improvements of Cardiorespiratory Function and Muscle Performance with Interval-Type Exercise.

Background: The prominent insertion/deletion polymorphism in the gene for the major modulator of tissue perfusion, angiotensin-converting enzyme (ACE-I/D) is associated with variability in adjustments in cardiac and skeletal muscle performance with standard forms of endurance and strength type training. Here, we tested whether the ACE-I/D genotype would be associated with variability in the effects of interval-type training on peak and aerobic performance of peripheral muscle and cardio-vasculature and post-exercise recovery. Methods: Nine healthy subjects (39.0 ± 14.7 years of age; 64.6 ± 16.1 kg, 173.6 ± 9.9) completed eight weeks of interval training on a soft robotic device based on repeated sets of a pedaling exercise at a matched intensity relative to their peak aerobic power output. Prior to and post-training, peak anaerobic and aerobic power output was assessed, mechanical work and metabolic stress (oxygen saturation and hemoglobin concentrations of Musculus vastus lateralis (VAS) and Musculus gastrocnemius (GAS), blood lactate and factors setting cardiac output such as heart rate, systolic and diastolic blood pressure were monitored during ramp-incremental exercise and interval exercise with the calculation of areas under the curve (AUC), which were put in relation to the produced muscle work. Genotyping was performed based on I- and D-allele-specific polymerase chain reactions on genomic DNA from mucosal swaps. The significance of interaction effects between training and ACE I-allele on absolute and work-related values was assessed with repeated measures ANOVA. Results: Subjects delivered 87% more muscle work/power, 106% more cardiac output, and muscles experienced ~72% more of a deficit in oxygen saturation and a ~35% higher passage of total hemoglobin during single interval exercise after the eight weeks of training. Interval training affected aspects of skeletal muscle metabolism and performance, whose variability was associated with the ACE I-allele. This concerned the economically favorable alterations in the work-related AUC for the deficit of SmO2 in the VAS and GAS muscles during the ramp exercise for the I-allele carriers and opposing deteriorations in non-carriers. Conversely, oxygen saturation in the VAS and GAS at rest and during interval exercise was selectively improved after training for the non-carriers of the I-allele when the AUC of tHb per work during interval exercise deteriorated in the carriers. Training also improved aerobic peak power output by 4% in the carriers but not the non-carriers (p = 0.772) of the ACE I-allele while reducing negative peak power (-27.0%) to a lesser extent in the ACE I-allele carriers than the non-carriers. Variability in cardiac parameters (i.e., the AUC of heart rate and glucose during ramp exercise, was similar to the time to recovery of maximal tHb in both muscles after cessation of ramp exercise, only associated with the ACE I-allele but not training per se. Diastolic blood pressure and cardiac output during recovery from exhaustive ramp exercise demonstrated a trend for training-associated differences in association with the ACE I-allele. Discussion: The exercise-type dependent manifestation of antidromic adjustments in leg muscle perfusion and associated local aerobic metabolism between carriers and non-carriers of the ACE I-allele with the interval-training highlight that non-carriers of the I-allele do not present an essential handicap to improve perfusion-related aerobic muscle metabolism but that the manifestation of responsiveness depends on the produced work. Conclusions: The deployed interval-type of exercise produced ACE I-allele-related differences in the alterations of negative anaerobic performance and perfusion-related aerobic muscle metabolism, which manifestation is exercise specific. The training-invariant ACE I-allele-associated differences in heart rate and blood glucose concentration emphasize that the repeated impact of the interval stimulus, despite a near doubling of the initial metabolic load, was insufficient to overturn ACE-related genetic influences on cardiovascular function.

Age- and sex-stratified normal values for circulatory and ventilatory power during ramp exercise derived from a healthy Japanese population.

Circulatory power (CP) and ventilatory power (VP), obtained by cardiopulmonary exercise testing (CPX), have been suggested to be excellent prognostic markers for heart failure. However, the normal values of these parameters in healthy Japanese populations remain unknown; thus, we aimed to investigate these values in such a population. A total of 391 healthy Japanese participants, 20-78years of age, underwent CPX with a cycle ergometer with ramp protocols. Systolic blood pressure (SBP), heart rate, oxygen uptake ([Formula: see text]O2) at peak exercise, and the slope of minute ventilation ([Formula: see text]E) versus carbon dioxide ([Formula: see text]CO2) ([Formula: see text]E vs. [Formula: see text]CO2 slope) were measured. CP was calculated by multiplying the peak [Formula: see text]O2 and SBP values, and VP was calculated by dividing the peak SBP value by the [Formula: see text]E versus [Formula: see text]CO2 slope. For males and females, the average CP values were 6119 ± 1280 (mean ± standard deviation) and 4775 ± 914mmHg·mL/min/kg, respectively (p < 0.001). The average VP values for males and females were 8.0 ± 1.3 and 6.9 ± 1.3mmHg (p < 0.001). CP decreased with age in both sexes. VP increased with age in females, with no significant change in males. We calculated the normal values for CP and VP in a healthy Japanese population. The results can contribute to the evaluation of patients' CPX results as a reference.

Can We Accurately Predict Critical Power and W' from a Single Ramp Incremental Exercise Test?

The purpose of this study was to examine the suitability of a single ramp incremental test to predict critical power (CP) and W' . We hypothesized that CP would correspond to the corrected power output (PO) at the respiratory compensation point (RCP) and W' would be calculable from the work done above RCP. One hundred fifty-three healthy young people (26 ± 4 yr, 51.4 ± 7.6 mL·min -1 ·kg -1 ) performed a maximal ramp test (20, 25, or 30 W·min -1 ), followed by three to five constant load trials to determine CP and W' . CP and W' were estimated using a "best individual fit" approach, selecting the mathematical model with the smallest total error. The RCP was identified by means of gas exchange analysis and then translated into its appropriate PO by applying a correction strategy in order to account for the gap in the V̇O 2 /PO relationship between ramp and constant load exercise. We evaluated the agreement between CP and the PO at RCP, and between W' and the total work done above CP ( W'RAMP > CP ) and above RCP ( W'RAMP > RCP ) during the ramp test. The CP was significantly higher than the PO at RCP (Δ = 8 ± 16 W, P < 0.001). W'RAMP > CP was significantly lower than W' (Δ = 1.9 ± 3.3 kJ, P < 0.001), whereas W'RAMP > RCP and W' did not differ from each other (Δ = -0.6 ± 5.8 kJ, P = 0.21). Despite the fact that CP and RCP occurred in close proximity, the estimation of W' from ramp exercise may be problematic given the likelihood of underestimation and considering the large variability. Therefore, we do not recommend the interchangeable use of CP and W' values derived from constant load versus ramp exercise, in particular, when the goal is to obtain accurate estimates or to predict performance capacity.

The effect of acute heat exposure on the determination of exercise thresholds from ramp and step incremental exercise.

The aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities. Eleven physically active male participants performed four incremental exercise tests, two RAMP (30W·min-1) and two STEP (40W·3min-1), both in 18°C (TEMP) and 36°C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LTIND) and fixed value lactate concentrations (LTFIX). A decrease in mean power output (PO) was observed in HOT at LT (-6.2 ± 1.9%), more specific LTIND (-5.4 ± 1.4%) and LTFIX (-7.5 ± 2.4%), compared to TEMP, however not at RT (-1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from -53W to +26W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8bpm). This study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes.

Association of Gene Variants for Mechanical and Metabolic Muscle Quality with Cardiorespiratory and Muscular Variables Related to Performance in Skiing Athletes.

Background: Skiing is a popular outdoor sport posing different requirements on musculoskeletal and cardiorespiratory function to excel in competition. The extent to which genotypic features contribute to the development of performance with years of ski-specific training remains to be elucidated. We therefore tested whether prominent polymorphisms in genes for angiotensin converting enzyme (ACE-I/D, rs1799752), tenascin-C (TNC, rs2104772), actinin-3 (ACTN3, rs1815739) and PTK2 (rs7460 and rs7843014) are associated with the differentiation of cellular hallmarks of muscle metabolism and contraction in high level skiers. Material & Methods: Forty-three skiers of a world-leading national ski team performed exhaustive cardiopulmonary exercise testing as well as isokinetic strength testing for single contractions, whereby 230 cardiopulmonary measurements were performed in the period from 2015–2018. A total of 168 and 62 data measurements were from the Alpine and Nordic skiing squads, respectively. Ninety-five and one hundred thirty-five measurements, respectively, were from male and female athletes. The average (±SD) age was 21.5 ± 3.0 years, height 174.0 ± 8.7 cm, and weight 71.0 ± 10.9 kg for the analysed skiers. Furthermore, all skiers were analysed concerning their genotype ACE-I/D, Tenascin C, ACTN3, PTK2. Results: The genotype distribution deviated from Hardy–Weinberg equilibrium for the ACTN3 genotype, where rs1815739-TT genotypes (corresponding to the nonsense mutation) were overrepresented in world-class skiers, indicating a slow muscle fibre phenotype. Furthermore, the heterozygous rs2104772-AT genotypes of TNC also demonstrated the best scaled peak power output values during ramp exercise to exhaustion. The highest values under maximum performance for heart rate were associated with the rs1799752-II and rs1815739-CC genotypes. The lowest values for peak power of single contractions were achieved for rs1815739-CC, rs1799752-II and rs7843014-CT genotypes. The skiing discipline demonstrated a main influence on cardiorespiratory parameters but did not further interact with genotype-associated variability in performance. Discussion: Classically, it is pointed out that muscles of, for example, alpine skiers do not possess a distinct fibre type composition, but that skiers tend to have a preponderance of slow-twitch fibres. Consequently, our findings of an overrepresentation of ACTN3-TT genotypes in a highly selective sample of elite world class skiers support the potential superiority of a slow fibre type distribution. Conclusions: We suggest that one competitive advantage that results from a slow, typically fatigue-resistant fibre type distribution might be that performance during intense training days is better preserved, whereby simply a higher technical training volume can be performed, yielding to a competitive advantage.

COMPLICATIONS OF CARDIOPULMONARY EXERCISE TESTING

COMPLICATIONS OF CARDIOPULMONARY EXERCISE TESTING

Real-time metabolic monitoring under exhaustive exercise and evaluation of ventilatory threshold by breathomics: Independent validation of evidence and advances.

Breath analysis was coupled with ergo-spirometry for non-invasive profiling of physio-metabolic status under exhaustive exercise. Real-time mass-spectrometry based continuous analysis of exhaled metabolites along with breath-resolved spirometry and heart rate monitoring were executed while 14 healthy adults performed ergometric ramp exercise protocol until exhaustion. Arterial blood lactate level was analyzed at defined time points. Respiratory-cardiac parameters and exhalation of several blood-borne volatiles changed continuously with the course of exercise and increasing workloads. Exhaled volatiles mirrored ventilatory and/or hemodynamic effects and depended on the origin and/or physicochemical properties of the substances. At the maximum workload, endogenous isoprene, methanethiol, dimethylsulfide, acetaldehyde, butanal, butyric acid and acetone concentrations decreased significantly by 74, 25, 35, 46, 21, 2 and 2%, respectively. Observed trends in exogenous cyclohexadiene and acetonitrile mimicked isoprene profile due to their similar solubility and volatility. Assignment of anaerobic threshold was possible via breath acetone. Breathomics enabled instant profiling of physio-metabolic effects and anaerobic thresholds during exercise. Profiles of exhaled volatiles indicated effects from muscular vasoconstriction, compartmental distribution of perfusion, extra-alveolar gas-exchange and energy homeostasis. Sulfur containing compounds and butyric acid turned out to be interesting for investigations of combined diet and exercise programs. Reproducible metabolic breath patterns have enhanced scopes of breathomics in sports science/medicine.

Effects of Sex, Training, and Maturity Status on the Cardiopulmonary and Muscle Deoxygenation Responses during Incremental Ramp Exercise.

Whilst participation in regular exercise and sport has generally increased over recent decades globally, fundamental questions remain regarding the influence of growth, maturation, and sex on the magnitude of training response throughout adolescence. Trained (108 participants, 43 girls; age: 14.3 ± 1.8 years) and untrained (108 participants, 43 girls; age: 14.7 ± 1.7 years) adolescents completed an incremental ramp test to exhaustion during which breath by gas exchange, beat-by-beat heart rate (HR), stroke volume (SV) and cardiac output () and muscle deoxygenation were assessed. Device-based physical activity was also assessed over seven consecutive days. Boys, irrespective of training status, had a significantly higher absolute (2.65 ± 0.70 L min−1 vs. 2.01 ± 0.45 L min−1, p < 0.01) and allometrically scaled (183.8 ± 31.4 mL·kg−b min−1 vs. 146.5 ± 28.5 mL·kg−b min−1, p < 0.01) peak oxygen uptake () than girls. There were no sex differences in peak HR, SV or but boys had a higher muscle deoxygenation plateau when expressed against absolute work rate and (p < 0.05). Muscle deoxygenation appears to be more important in determining the sex differences in peak in youth. Future research should examine the effects of sex on the response to different training methodologies in youth.

Comparing the Respiratory Compensation Point With Muscle Oxygen Saturation in Locomotor and Non-locomotor Muscles Using Wearable NIRS Spectroscopy During Whole-Body Exercise

The relationship between the muscle deoxygenation breakpoint (Deoxy-BP) measured with near-infrared spectroscopy (NIRS), and the respiratory compensation point (RCP) has been well established. This relationship has also been reported using wearable NIRS, however not in locomotor and non-locomotor muscles simultaneously during whole-body cycling exercise. Our aim was to measure muscle oxygen saturation (SmO2) using wearable NIRS sensors, and to compare the Deoxy-BPs at each muscle with RCP during a ramp cycling exercise test. Twenty-two trained female and male cyclists completed a ramp exercise test to task intolerance on a cycling ergometer, at a ramp rate of 1 W every 2 s (30 W/min). SmO2 was recorded at the subjects’ right vastus lateralis (VL) and right lateral deltoid. SmO2 and the Deoxy-BPs were assessed using a piecewise double-linear regression model. Ventilation (V̇E) and gas exchange were recorded, and RCP was determined from V̇E and gas exchange using a V-slope method and confirmed by two physiologists. The SmO2 profiles of both muscles and gas exchange responses are reported as V̇O2, power output (W), and time of occurrence (TO). SmO2 profiles at both muscles displayed a near-plateau or breakpoint response near the RCP. No differences were detected between the mean RCP and mean Deoxy-BP from either the locomotor or non-locomotor muscles; however, a high degree of individual variability was observed in the timing and order of occurrence of the specific breakpoints. These findings add insight into the relationships between ventilatory, locomotor, and non-locomotor muscle physiological breakpoints. While identifying a similar relationship between these breakpoints, individual variability was high; hence, caution is advised when using wearable NIRS to estimate RCP in an incremental ramp test.

Repeatability and reproducibility of changes in thoracoabdominal compartmental volumes and breathing pattern during low-, moderate- and heavy-intensity exercise.

To determine how repeatable thoracoabdominal compartmental contributions to tidal volume (VT) are across different intensities of exercise, and to examine if the pattern of breathing for a given minute ventilation (V̇E) is reproducible between constant-load and ramp exercise tests. Ten healthy adults (age: 27 ± 6yr, peak oxygen uptake: 42 ± 5mLmin-1kg-1) completed a 25W·min-1 ramp cycling test to exhaustion and two repetitions of a step cycling test on separate days. VT, breathing rate (BR), and V̇E were assessed using a bi-directional turbine, and thoracic and abdominal contributions to VT were measured using respiratory inductance plethysmography. Repeatability (step vs. step) and reproducibility (step vs. ramp) of responses were assessed using the intra-class correlation coefficient (ICC). The relative compartment contributions to VT during step exercise were highly repeatable for low (ICC = 0.87, p = 0.003), moderate (ICC = 0.89, p = 0.002) and heavy (ICC = 0.93, p = 0.001) exercise. Inter-individual differences in response to higher intensity exercise were observed, as two participants had significant relationships between VT and their percent compartmental contributions to VT, but five others did not. No differences were identified between ramp and step exercise tests for VT (main effect: p = 0.61) or BR (main effect: p = 0.77) at matched V̇E for each intensity, and the pattern of breathing was reproducible for each intensity. These findings suggest the way young healthy adults breathe for a given V̇E is repeatable day-to-day and reproducible between different exercise protocols.

Dietary Nitrate Supplementation Does Not Alter Exercise Efficiency at High Altitude - Further Results From the Xtreme Alps Study.

IntroductionNitrate supplementation in the form of beetroot juice (BRJ) ingestion has been shown to improve exercise tolerance during acute hypoxia, but its effect on exercise physiology remains unstudied during sustained terrestrial high altitude exposure. We hypothesized that performing exercise at high altitude would lower circulating nitrate and nitrite levels and that BRJ ingestion would reverse this phenomenon while concomitantly improving key determinants of aerobic exercise performance.MethodsTwenty seven healthy volunteers (21 male) underwent a series of exercise tests at sea level (SL, London, 75 m) and again after 5–8 days at high altitude (HA, Capanna Regina Margherita or “Margherita Hut,” 4,559 m). Using a double-blind protocol, participants were randomized to consume a beetroot/fruit juice beverage (three doses per day) with high levels of nitrate (∼0.18 mmol/kg/day) or a nitrate-depleted placebo (∼11.5 μmoles/kg/day) control drink, from 3 days prior to the exercise trials until completion. Submaximal constant work rate cycle tests were performed to determine exercise efficiency and a maximal incremental ramp exercise test was undertaken to measure aerobic capacity, using breath-by-breath pulmonary gas exchange measurements throughout. Concentrations of nitrate, nitrite and nitrosation products were quantified in plasma samples collected at 5 timepoints during the constant work rate tests. Linear mixed modeling was used to analyze data.ResultsAt both SL and HA, plasma nitrate concentrations were elevated in the nitrate supplementation group compared to placebo (P < 0.001) but did not change throughout increasing exercise work rate. Delta exercise efficiency was not altered by altitude exposure (P = 0.072) or nitrate supplementation (P = 0.836). V̇O2peak decreased by 24% at high altitude (P < 0.001) and was lower in the nitrate-supplemented group at both sea level and high altitude compared to placebo (P = 0.041). Dietary nitrate supplementation did not alter other peak exercise variables or oxygen consumption at anaerobic threshold. Circulating nitrite and S-nitrosothiol levels unexpectedly rose in a few individuals right after cessation of exercise at high altitude.ConclusionWhilst regularly consumed during an 8 days expedition to terrestrial high altitude, nitrate supplementation did not alter exercise efficiency and other exercise physiological variables, except decreasing V̇O2peak. These results and those of others question the practical utility of BRJ consumption during prolonged altitude exposure.

Abstract 13282: Oxygen Uptake and Cardiac Output Exhibit Delayed Recovery After Maximum Incremental Ramp Exercise in Patients With Exercise Pulmonary Hypertension

Introduction: In individuals with dyspnea on exertion (DOE) and suspected exercise pulmonary hypertension (exPH), oxygen uptake (VO 2 ), cardiac output (CO), peripheral oxygen extraction (Ca-vO 2 ), and mean pulmonary artery pressure (mPAP) have been well characterized during incremental exercise but less is known about the kinetics of post-exercise recovery patterns. Hypothesis: Exercise recovery cardiac output kinetics are slowed in patients with exPH. Methods: Upright maximum incremental ramp cycle ergometry cardiopulmonary exercise testing with invasive hemodynamic monitoring and serial blood gas measurements during exercise and recovery was performed in 50 consecutive patients referred for evaluation of DOE of unclear etiology. VO 2 , arterial and venous oxygen content (Ca-vO 2 ), Fick cardiac output, and mPAP were analyzed from rest, peak exercise, and 2 minutes post-exercise. ExPH was defined in a consistent manner with recent consensus statements (ΔmPAP/ΔCO &gt;3.0 mmHg/L/min) from rest to peak exercise. Results: Among 50 patients with DOE, [62% female, Age 61.7±11.8, BMI 30.7±8.2] 2-min post-exercise VO 2 was -56±11%, CO: -22±19%, Ca-vO 2 :-42±15% compared to peak exercise values. The % fall in CO at 2min was significantly lower in the 26 patients with exPH compared to the 24 patients without exPH (Table). The average mPAP remained elevated at 2 min post-exercise (&gt;20mmHg) in exPH despite normal average resting values. Conclusions: Patients with exPH demonstrate slowed CO recovery kinetics in conjunction with persistent PAP elevation 2-min post-exercise. Persistent elevation in blood flow through the pulmonary circuit at a time conducive to non-invasive assessment of PAP (i.e. by echocardiography) may lend itself to non-invasive detection of exercise-PH in patients undergoing evaluation of dyspnea on exertion.