Ramp Incremental Test Research Articles

Mechanical Assistance During Unloaded Pedaling Improves the Dynamic Range of the Metabolic Response in Obesity

PURPOSE: Obese individuals have a greater oxygen uptake (VO2) than lean individuals for a given work rate during cycling exercise due to higher resting metabolic rate and metabolic cost from lifting heavier legs against gravity. This can result in the majority of the total increase in VO2 occurring early in the exercise test, resulting in short test duration and obscuring the gas exchange details. We hypothesized that mechanical assistance of pedaling early in exercise could reduce the initial increase in VO2 of obese subjects, and increase the VO2 range. METHODS: 20 obese (O, BMI 40.2 + 6.1 kg/m2) and 10 lean otherwise normal subjects (L, BMI 24.9 + 2.2) were tested. Subjects performed 2 symptom-limited ramp incremental tests on a cycle ergometer capable of providing variable degrees of mechanical assistance to pedaling (Ergo-strength, Mitsubishi Electrical Engineering, Osaka, Japan). Ventilation and pulmonary gas exchange were measured breath by breath (Vyaire, Yorba Linda, California). During warm up, in random order, the subjects performed either unmodified cycling (UM) or mechanical assistance (MC) to pedaling. After warm up, each subject performed a progressively increasing test to exhaustion. RESULTS: The MC protocol resulted in a lower initial VO2 compared to UM in 19 of 20 O subjects and 8 of 10 L subjects, with average differences of 165 +/- 125 ml/min (p < 0.00001) and 101 ml/min +/- 94 (p < 0.008) for O and L, respectively, by paired T-tests. Peak VO2 did not differ systematically within subjects by protocols (p=NS).CONCLUSIONS: Mechanical assisted cycling during the initial phase of an incremental exercise test was effective in modulating the initial increase in VO2 with unloaded cycling, and increases the VO2 testing range in obese and normal weight subjects. This may be a significant proportion of the entire response in a patient with exercise limitation, and therefore useful in exercise testing and training. Funding: MITSUBISHI ELECTRIC ENGINEERING Co.,LTD.

Exercise Tolerance: New Insights From Single-leg Cycling Exercise

The biological factors determining the maximal exercise capacity are typically assessed during whole-body exercise (e.g. double-leg cycling), implicitly assuming that limbs contribute homogeneously to exercise tolerance. However, given the presence of limb dominance, it is possible that the dominant leg may achieve greater peak O2 uptake (V̇O2peak) and be able to sustain greater power outputs during prolonged dynamic exercise compared to the non-dominant leg. PURPOSE: To investigate peak power output (PPO), V̇O2peak, and maximal lactate steady-state (MLSS) during double-leg as well as during dominant and non-dominant and counter-weighted single-leg cycling exercise performed with the dominant and non-dominant legs. METHODS: Twelve men (30 ± 5 yrs) during 12 to 14 lab visits performed: (i) a ramp-incremental test to determine PPO, V̇O2peak, and maximal O2 extraction; and (ii) 30-min constant-load tests to determine MLSS. These tests were performed using both legs (DBL), the dominant leg only (SLd), and the non-dominant leg only (SLnd). Gas exchange variables were measured with a metabolic cart; local de-oxygenation ([HHb]) of the vastus lateralis (VL) was measured using a frequency-domain NIRS; capillary blood samples were analysed for lactate concentration ([Lac-]b). RESULTS: PPO for DBL, SLd, and SLnd was different in each condition: 329 ± 38, 181 ± 30, 168 ± 27 W, respectively (p < 0.05). V̇O2peak for DBL, SLd, and SLnd was different in each condition: 3.43 ± 0.34, 2.92 ± 0.42, 2.74 ± 0.38 L·min-1, respectively (p < 0.05). The [HHb] amplitude of the VL was greater in the dominant compared to the non-dominant leg during both DBL (18.6 ± 8.5 vs 15.4 ± 9.5 mMol) and SL (15.4 ± 9.5 vs 11.6 ± 7.7 mMol) ramp-exercise (p < 0.05). These amplitudes were highly correlated with the V̇O2peak values observed during DBL dominant and non-dominant (r = 0.86 and r=0.91, respectively), SLd (r=0.79), and SLnd (r=0.71) RI tests (p < 0.05). The PO at MLSS for DBL, SLd, and SLnd was different in each condition: 183 ± 32, 119 ± 25, and 111 ± 24 W, respectively (p < 0.05). The V̇O2, [Lac-]b, and RPE values during SLnd and SLd were similar (p > 0.05) despite this lower PO. CONCLUSIONS: These data indicate a heterogeneous exercise capacity of the exercising limbs that should be considered when evaluating exercise tolerance during double-leg exercise.

Effect of high-intensity interval training in adolescents with asthma: The eXercise for Asthma with Commando Joe's® (X4ACJ) trial

BackgroundHigher levels of cardiorespiratory fitness are associated with reduced asthma severity and increased quality of life in those with asthma. Therefore, the purpose of this study was to evaluate the effectiveness of a 6-month high-intensity interval training (HIIT) intervention in adolescents with and without asthma. MethodsA total of 616 adolescents (334 boys; 13.0 ± 1.1 years, 1.57 ± 0.10 m, 52.6 ± 12.9 kg, mean ± SD), including 155 with asthma (78 boys), were recruited as part of a randomized controlled trial from 5 schools (4 control and 1 intervention). The 221 intervention participants (116 boys; 47 asthma) completed 6 months of school-based HIIT (30 min, 3 times per week, 10–30 s bouts at >90% age-predicted maximum heart rate with equal rest). At baseline, mid-intervention, post-intervention, and 3-month follow-up, measurements for 20-m shuttle run, body mass index (BMI), lung function, Pediatric Quality of Life Inventory, Paediatric Asthma Quality of Life Questionnaire, and Asthma Control Questionnaire were collected. Additionally, 69 adolescents (39 boys (of the 36 with asthma there were 21 boys)) also completed an incremental ramp test. For analysis, each group's data (intervention and control) were divided into those with and without asthma. ResultsParticipants with asthma did not differ from their peers in any parameter of aerobic fitness, at any time-point, but were characterized by a greater BMI. The intervention elicited a significant improvement in maximal aerobic fitness but no change in sub-maximal parameters of aerobic fitness, lung function, or quality of life irrespective of asthma status. Those in the intervention group maintained their BMI, whereas BMI significantly increased in the control group throughout the 6-month period. ConclusionHIIT represents an effective tool for improving aerobic fitness and maintaining BMI in adolescents, irrespective of asthma status. HIIT was well-tolerated by those with asthma, who evidenced a similar aerobic fitness to their healthy peers and responded equally well to a HIIT program.

Validity of the Supramaximal Test to Verify Maximal Oxygen Uptake in Children and Adolescents.

Purpose: This study had 2 objectives: (1)to examine whether the validity of the supramaximal verification test for maximal oxygen uptake ( ) differs in children and adolescents when stratified for sex, body mass, and cardiorespiratory fitness and (2)to assess sensitivity and specificity of primary and secondary objective criteria from the incremental test to verify . Methods: In total, 128 children and adolescents (76 male and 52 females; age: 9.3-17.4y) performed a ramp-incremental test to exhaustion on a cycle ergometer followed by a supramaximal test to verify . Results: Supramaximal tests verified in 88% of participants. Group incremental test peak was greater than the supramaximal test (2.27 [0.65] L·min-1 and 2.17 [0.63] L·min-1; P < .001), although both were correlated (r = .94; P < .001). No differences were found in plateau attainment or supramaximal test verification between sex, body mass, or cardiorespiratory fitness groups (all Ps > .18). Supramaximal test time to exhaustion predicted supramaximal test verification (P = .04). Primary and secondary objective criteria had insufficient sensitivity (7.1%-24.1%) and specificity (50%-100%) to verify . Conclusion: The utility of supramaximal testing to verify is not affected by sex, body mass, or cardiorespiratory fitness status. Supramaximal testing should replace secondary objective criteria to verify .

A Method for the Evaluation of Anaerobic Threshold Based on Heart Rate Dynamics during Incremental Exercise Test and Recovery

A new graphical method for determining the anaerobic threshold (AT), which has been experimentally tested in testing the maximal aerobic capacity in 46 cyclic sports athletes (mean age, 20.3 ± 3.6 years; body weight, 68.3 ± 10.4 kg). The gas exchange indices, the heart rate, the time of onset (from the beginning of the test) of AT by pulmonary gas exchange ratios, the non-metabolic CO2 excess, the concentration of lactate in capillary blood, and the time of onset of AT determined by the proposed graphical method by the parameters of the pulsogram obtained during the test and 10-min recovery were determined. Two different protocols of load change—the incremental ramp test on a treadmill and the incremental step test on a bicycle ergometer—were used. Regardless of the protocol and the load type, statistical analysis revealed no significant differences between the results of AT measurements in the same athletes by the gas exchange and lactate dynamics indices, on the one hand, and by using the graphical method by the pulsogram parameters, on the other hand. In the test with a stepwise increase in load on a bicycle ergometer, as well as in the test with a smoothly increasing load on a running treadmill, the indices obtained at the AT that was determined by using the graphical method highly correlated with the indices obtained at the AT that was determined by analyzing the dynamics of pulmonary ventilation, non-metabolic CO2 excess, and lactate concentration (p < 0.05). The proposed method does not require the use of sophisticated equipment and invasive procedures and can be widely used in sports and fitness practice.

Validity of a Muscle Specific Method to Evaluate the Anaerobic Threshold in Exercised Muscles

The goal of this study was to describe and validate a muscle specific method to evaluate the anaerobic threshold in a working muscle based on the simultaneous measurement of EMG activity and the deoxyhemoglobin content (ATHHb-EMG). The study involved males with different fitness levels. During the cycling (n = 40) and ski double poling (n = 9) incremental ramp tests, blood lactate concentration, and muscle deoxyhemoglobin content and EMG activity were measured. Some participants were involved in the cycling test-retest study (n = 11). In cycling and double poling tests, close and significant correlations (r = 0.89 – 0.92, P < 0.002) were found between lactate threshold (a marker of the anaerobic threshold at the organism level) and the ATHHb-EMG (a marker of the AT at the working muscle level). The coefficient of variation of the ATHHb-EMG in the cycling test-retest was low (~3%). The muscle specific ATHHb-EMG demonstrates low variability and is appropriate to detect the fitness level and training-induced increase in aerobic performance in a working muscle. The emergence on the market of miniature EMG amplifiers and near-infrared spectrometers opens wide possibilities for using our method in laboratory studies and in field tests.

Thigh Ischemia-Reperfusion Model Does Not Accelerate Pulmonary VO 2 Kinetics at High Intensity Cycling Exercise.

Background: We aimed to investigate the effect of a priming ischemia-reperfusion (IR) model on the kinetics of pulmonary oxygen uptake (VO2) and cardiopulmonary parameters after high-intensity exercise. Our primary outcome was the overall VO2 kinetics and secondary outcomes were heart rate (HR) and O2 pulse kinetics. We hypothesized that the IR model would accelerate VO2 and cardiopulmonary kinetics during the exercise.Methods: 10 recreationally active men (25.7 ± 4.7 years; 79.3 ± 10.8 kg; 177 ± 5 cm; 44.5 ± 6.2 mL kg−1 min−1) performed a maximal incremental ramp test and four constant load sessions at the midpoint between ventilatory threshold and VO2 max on separate days: two without IR (CON) and two with IR (IR). The IR model consisted of a thigh bi-lateral occlusion for 15 min at a pressure of 250 mmHg, followed by 3 min off, before high-intensity exercise bouts.Results: There were no significant differences for any VO2 kinetics parameters (VO2 base 1.08 ± 0.08 vs. 1.12 ± 0.06 L min−1; P = 0.30; τ = 50.1 ± 7.0 vs. 47.9 ± 6.4 s; P = 0.47), as well as for HR (MRT180s 67.3 ± 6.0 vs. 71.3 ± 6.1 s; P = 0.54) and O2 pulse kinetics (MRT180s 40.9 ± 3.9 vs. 48.2 ± 5.6 s; P = 0.31) between IR and CON conditions, respectively.Conclusion: We concluded that the priming IR model used in this study had no influence on VO2, HR, and O2 pulse kinetics during high-intensity cycling exercise.

Cardiopulmonary exercise testing in children and adolescents

In cardiopulmonary exercise testing with children and adolescents, age specific protocols are used together with tools adjustable to their body dimension and development. Assessing weight, height und pubertal stage is a prerequisite for the interpretation of every test. Indications for exercise testing are airway symptoms and findings limited performance, chronic diseases, planning of trainings and scientific studies. The more tests are standardized and used on a large scale, the more normal values are available to compare individual results. However, the interindividual variability of measured values is high, depending as much from the developmental stage of the individual as from protocols, tools and the performing laboratory. Tests are mainly incremental step or ramp tests, test duration should not exceed 10–12 min

A post-exercise facilitation of executive function is independent of aerobically supported metabolic costs

A single-bout of aerobic or resistance training facilitates executive function and is a benefit thought to be specific to exercise durations greater than 20 min. We sought to determine whether an executive benefit is observed for a session as brief as 10-min, and whether distinct and participant-specific exercise intensities – and associated metabolic costs – influence the magnitude of the benefit. Participants completed exercise sessions – via cycle ergometer – at moderate (80% of lactate threshold [LT]), heavy (15% of the difference between LT and VO2 peak) and very-heavy (50% of the difference between LT and VO2 peak) intensities determined via an incremental ramp test to volitional exhaustion. Pre- and post-exercise executive function was examined via antisaccades – an executive task requiring a saccade mirror-symmetrical to a visual stimulus. Antisaccades are an ideal tool for examining post-exercise executive changes due to the resolution of eye-tracking and because the task is mediated via the same frontoparietal networks as modified following single-bout and chronic exercise. A non-executive prosaccade task (i.e., saccade to veridical target location) was also completed to determine if the putative post-exercise benefit was specific to executive function. Results showed a 20 ms reduction in pre- to post-exercise antisaccade RTs (p < .02) and was independent of exercise intensity, whereas no such change was observed for prosaccades (p = .14). Furthermore, the antisaccade benefit occurred without concomitant changes in directional errors or endpoint accuracy; that is, participants did not decrease their post-exercise RTs at the cost of increased planning and execution errors (ps > 0.34). Accordingly, we propose that an exercise duration as brief as 10-min provides a reliable benefit to executive function and is an effect observed across the continuum of moderate to very-heavy intensities.

Metabolic and performance-related consequences of exercising at and slightly above MLSS.

Exercising at the maximal lactate steady state (MLSS) results in increased but stable metabolic responses. We tested the hypothesis that even a slight increase above MLSS (10W), by altering the metabolic steady state, would reduce exercise performance capacity. Eleven trained men in our study performed: one ramp-incremental tests; two to four 30-minute constant-load cycling exercise trials to determine the PO at MLSS (MLSSp ), and ten watts above MLSS (MLSSp+10 ), which were immediately followed by a time-to-exhaustion test; and a time-to-exhaustion test with no-prior exercise. Pulmonary O2 uptake V.O2 ) and blood lactate concentration ([La- ]b ) as well as local muscle O2 extraction ([HHb]) and muscle activity (EMG) of the vastus lateralis (VL) and rectus femoris (RF) muscles were measured during the testing sessions. When exercising at MLSSp+10 , although V.O2 was stable, there was an increase in ventilatory responses and EMG activity, along with a non-stable [La- ]b response (P<0.05). The [HHb] of VL muscle achieved its apex at MLSSp with no additional increase above this intensity, whereas the [HHb] of RF progressively increased during MLSSp+10 and achieved its apex during the time-to-exhaustion trials. Time-to-exhaustion performance was decreased after exercising at MLSSp (37.3±16.4%) compared to the no-prior exercise condition, and further decreased after exercising at MLSSp+10 (64.6±6.3%) (P<0.05). In summary, exercising for 30min slightly above MLSS led to significant alterations of metabolic responses which disproportionately compromised subsequent exercise performance. Furthermore, the [HHb] signal of VL seemed to achieve a "ceiling" at the intensity of exercise associated with MLSS.

Cardiopulmonary exercise testing with supramaximal verification produces a safe and valid assessment of V̇o2max in people with cystic fibrosis: a retrospective analysis.

The validity and safety of using supramaximal verification (Smax) to confirm a maximal effort during cardiopulmonary exercise testing (CPET) in people with cystic fibrosis (CF) and/or those with severe disease has been questioned. Therefore, this study aimed to investigate these concerns in children, adolescents, and adults with mild-to-severe CF lung disease. Retrospective analysis of 17 pediatric and 28 adult participants with CF [age range: 9.2-62.9 y; forced expiratory volume in 1 s: 66.7% (range: 29.9%-102.3%); 30 men] who completed a routine ramp-incremental cycling test to determine peak oxygen uptake (V̇o2peak) was studied. Maximal oxygen uptake (V̇o2max) was subsequently confirmed by Smax at 110% of peak power output. All participants satisfied the criteria to verify a maximal effort during CPET. However, Smax-V̇o2peak exceeded ramp-V̇o2peak in 3/14 (21.4%) of pediatric and 6/28 (21.4%) adult exercise tests. A valid measurement of V̇o2max was attained in 85.7% of pediatric and 96.4% of adult exercise tests, as Smax-V̇o2peak did not exceed ramp-V̇o2peak by >9%. Adults ( n = 9) experienced a ≥5% reduction in arterial O2 saturation during CPET, 4 during both the ramp and Smax, 3 during only the ramp, and 2 during only Smax. Smax did not significantly worsen perceived breathing effort, chest tightness, throat narrowing, or exertion compared with ramp-incremental testing. Given the clinical importance of aerobic fitness in people with CF, incorporating Smax is recommended to provide a safe and valid measure of V̇o2max in children, adolescents, and adults who span the spectrum of CF disease severity. NEW & NOTEWORTHY Incorporating supramaximal verification into cardiopulmonary exercise testing protocols did not increase the frequency of adverse events or perceived discomfort versus a single-phase incremental exercise test in people with mild-to-severe cystic fibrosis. Furthermore, a valid measure of maximal oxygen uptake (V̇o2max) was obtained from 85.7% of pediatric and 96.4% of adult exercise tests, whereas peak oxygen uptake underestimated aerobic fitness in comparison with V̇o2max in 21.4% of cases (by up to 24.4%).

A "Blood Relationship" Between the Overlooked Minimum Lactate Equivalent and Maximal Lactate Steady State in Trained Runners. Back to the Old Days?

Maximal Lactate Steady State (MLSS) and Lactate Threshold (LT) are physiologically-related and fundamental concepts within the sports and exercise sciences. Literature supporting their relationship, however, is scarce. Among the recognized LTs, we were particularly interested in the disused “Minimum Lactate Equivalent” (LEmin), first described in the early 1980s. We hypothesized that velocity at LT, conceptually comprehended as in the old days (LEmin), could predict velocity at MLSS (VMLSS) more accurate than some other blood lactate-related thresholds (BLRTs) routinely used nowadays by many sport science practitioners. Thirteen male endurance-trained [VMLSS 15.0 ± 1.1 km·h−1; maximal oxygen uptake () 67.6 ± 4.1 ml·kg−1·min−1] homogeneous (coefficient of variation: ≈7%) runners conducted 1) a submaximal discontinuous incremental running test to determine several BLRTs followed by a maximal ramp incremental running test for determination, and 2) several (4–5) constant velocity running tests to determine VMLSS with a precision of 0.20 km·h−1. Determined BLRTs include LEmin and LEmin-related LEmin plus 1 (LEmin+1mM) and 1.5 mmol·L−1 (LEmin+1.5mM), along with well-established BLRTs such as conventionally-calculated LT, Dmax and fixed blood lactate concentration thresholds. LEmin did not differ from LT (P = 0.71; ES: 0.08) and was 27% lower than MLSS (P < 0.001; ES: 3.54). LEmin+1mM was not different from MLSS (P = 0.47; ES: 0.09). LEmin was the best predictor of VMLSS (r = 0.91; P < 0.001; SEE = 0.47 km·h−1), followed by LEmin+1mM (r = 0.86; P < 0.001; SEE = 0.58 km·h−1) and LEmin+1.5mM (r = 0.84; P < 0.001; SEE = 0.86 km·h−1). There was no statistical difference between MLSS and estimated MLSS using LEmin prediction formula (P = 0.99; ES: 0.001). Mean bias and limits of agreement were 0.00 ± 0.45 km·h−1 and ±0.89 km·h−1. Additionally, LEmin, LEmin+1mM and LEmin+1.5mM were the best predictors of (r = 0.72–0.79; P < 0.001). These results support LEmin, an objective submaximal overlooked and underused BLRT, to be one of the best single MLSS predictors in endurance trained runners. Our study advocates factors controlling LEmin to be shared, at least partly, with those controlling MLSS.

Blood flow occlusion-related O2 extraction "reserve" is present in different muscles of the quadriceps but greater in deeper regions after ramp-incremental test.

It was recently demonstrated that an O2 extraction reserve, as assessed by the near-infrared spectroscopy (NIRS)-derived deoxygenation signal ([HHb]), exists in the superficial region of vastus lateralis (VL) muscle during an occlusion performed at the end of a ramp-incremental test. However, it is unknown whether this reserve is present and/or different in magnitude in other portions and depths of the quadriceps muscles. We tested the hypothesis that an O2 extraction reserve would exist in other regions of this muscle but is greater in deep compared with more superficial portions. Superficial (VL-s) and deep VL (VL-d) as well as superficial rectus femoris (RF-s) were monitored by a combination of low- and high-power time-resolved (TRS) NIRS. During the occlusion immediately post-ramp-incremental test there was a significant overshoot in the [HHb] signal ( P < 0.05). However, the magnitude of this increase was greater in VL-d (93.2 ± 42.9%) compared with VL-s (55.0 ± 19.6%) and RF-s (47.8 ± 14.0%) ( P < 0.05). The present study demonstrated that an O2 extraction reserve exists in different pools of active muscle fibers of the quadriceps at the end of a ramp exercise to exhaustion. The greater magnitude in the reserve observed in the deeper portion of VL, however, suggests that this portion of muscle may present a greater surplus of oxygenated blood, which is likely due to a greater population of slow-twitch fibers. These findings add to the notion that the plateau in the [HHb] signal toward the end of a ramp-incremental exercise does not indicate the upper limit of O2 extraction. NEW & NOTEWORTHY Different portions of the quadriceps muscles exhibited an untapped O2 extraction reserve during a blood flow occlusion performed at the end of a ramp-incremental exercise. In the deeper portion of the vastus lateralis muscle, this reserve was greater compared with superficial vastus lateralis and rectus femoris. These data suggest that the O2 extraction reserve may be dependent on the vascular and/or oxidative capacities of the muscles.

Work Performed Above The Respiratory Compensation Point Is Not Equivalent To W′

The hyperbolic power-time relationship for severe-intensity cycling exercise is defined by two physiological parameters: (i) the asymptote, critical power (CP); and (ii) the curvature constant, W′. Recently, we reported that the respiratory compensation point (RCP) displays poor measurement agreement with the CP. However, it is unknown whether the amount of supra-RCP mechanical work (RCP′) performed during ramp-incremental cycling is similar to that performed above the CP (i.e., W′). PURPOSE: We sought to determine the measurement agreement between W′ and RCP′ obtained during incremental cycling of varying ramp slopes. METHODS: Twelve male cyclists completed three separate ramp-incremental cycling protocols, where the work rate increment was slow (SR, 15 W[BULLET OPERATOR]min-1), medium (MR, 30 W[BULLET OPERATOR]min-1), or fast (FR, 45 W[BULLET OPERATOR]min-1). Initially, the RCP (adjusted for mean response time) was obtained using the ventilatory equivalent for CO method. To assess RCP′, we calculated the power–time integral between the RCP and the instantaneous power output observed at exercise termination for each ramp-incremental test, separately. W′ was determined via Morton’s model for ramp-incremental exercise. The assumption that W′ and RCP′ occur at equivalent kilojoule (kJ) values was assessed by one-way repeated- measures ANOVA and by evaluating the concordance correlation coefficient (CCC) and typical error (root-mean-square error [RMSE]) for each ramp-incremental test, separately. RESULTS:RCP′ decreased with increases in the ramp-incremental slope (P < 0.05). RCP′ in SR (21.5 ± 6.5 kJ), MR (16.8 ± 5.6 kJ) and FR (13.3 ± 4.3 kJ) were not different from W′ (15.7 ± 6.9 kJ). The degree to which the relationship between W′ and RCP′ approximated the line of identity was poor for SR (CCC = -0.09 and RMSE = 11.3 kJ), MR (CCC = 0.23 and RMSE = 7.5 kJ) and FR (CCC = 0.37 and RMSE = 6.5 kJ). CONCLUSION: Our data demonstrate that RCP′ is lower when the ramp-incremental slope is increased. Furthermore, despite occurring at similar kJ values, we observed poor measurement agreement between W′ and RCP′, as evidenced by the low CCC and the large RMSE values, irrespective of the ramp-incremental protocol. Together, these findings indicate that RCP′ obtained during ramp-incremental cycling is not equivalent to W′.

Using ramp-incremental V̇O2 responses for constant-intensity exercise selection.

Despite compelling evidence to the contrary, the view that oxygen uptake (V̇O2) increases linearly with exercise intensity (e.g., power output, speed) until reaching its maximum persists within the exercise physiology literature. This viewpoint implies that the V̇O2 response at any constant intensity is predictable from a ramp-incremental exercise test. However, the V̇O2 versus task-specific exercise intensity relationship constructed from ramp-incremental versus constant-intensity exercise are not equivalent preventing the use of V̇O2 responses from 1 domain to predict those of the other. Still, this "linear" translational framework continues to be adopted as the guiding principle for aerobic exercise prescription and there remains in the sport science literature a lack of understanding of how to interpret V̇O2 responses to ramp-incremental exercise and how to use those data to assign task-specific constant-intensity exercise. The objectives of this paper are to (i) review the factors that disassociate the V̇O2 versus exercise intensity relationship between ramp-incremental and constant-intensity exercise paradigms; (ii) identify when it is appropriate (or not) to use ramp V̇O2 responses to accurately assign constant-intensity exercise; and (iii) illustrate the technical and theoretical challenges with prescribing constant-intensity exercise solely on information acquired from ramp-incremental tests. Actual V̇O2 data collected during cycling exercise and V̇O2 kinetics modelling are presented to exemplify these concepts. Possible solutions to overcome these challenges are also presented to inform on appropriate intensity selection for individual-specific aerobic exercise prescription in both research and practical settings.

The effects of taurine on repeat sprint cycling after low or high cadence exhaustive exercise in females

This study investigated the effects of taurine on repeated sprint exercise, performed after fixed incremental ramp exercise to exhaustion at isokinetic high (90r/min) or low (50r/min) cadences. In a double-blind, repeated measures design, nine females completed an incremental ramp test to volitional exhaustion, followed by 2min active recovery and 6×10s sprints on a cycle ergometer, in one of four conditions: high cadence (90r/min) + taurine (50mg/kg body mass); high cadence + placebo (3mg/kg body mass maltodextrin); low cadence (50r/min) + taurine; low cadence + placebo. Heart rate (HR) and blood lactate concentration B[La] were measured before and after the ramp test and after the sprints. Taurine lowered HR vs. placebo prior to the ramp test (P = 0.004; d = 2.1). There was an effect of condition on ramp performance (P < 0.001), with higher end-test power (d = 3.7) in taurine conditions. During repeated sprints, there was a condition×time interaction (P = 0.002), with higher peak sprint power in the placebo conditions compared to taurine (sprint 2-6; P < 0.05). B[La] was higher in taurine compared to placebo post-ramp (P = 0.004; d = 4.7). Taurine-lowered pre-exercise HR and improved incremental end-test power output, with subsequent detrimental effects on sprint performance, independent of cadence. Short endurance performance can be acutely enhanced after taurine ingestion but this effect might not be maintained across longer periods of exercise or induce the need for longer recovery periods.

Measurement of a True [Formula: see text]O2max during a Ramp Incremental Test Is Not Confirmed by a Verification Phase.

The accuracy of an exhaustive ramp incremental (RI) test to determine maximal oxygen uptake (O2max) was recently questioned and the utilization of a verification phase proposed as a gold standard. This study compared the oxygen uptake (O2) during a RI test to that obtained during a verification phase aimed to confirm attainment of O2max. Sixty-one healthy males [31 older (O) 65 ± 5 yrs; 30 younger (Y) 25 ± 4 yrs] performed a RI test (15–20 W/min for O and 25 W/min for Y). At the end of the RI test, a 5-min recovery period was followed by a verification phase of constant load cycling to fatigue at either 85% (n = 16) or 105% (n = 45) of the peak power output obtained from the RI test. The highest O2 after the RI test (39.8 ± 11.5 mL·kg−1·min−1) and the verification phase (40.1 ± 11.2 mL·kg−1·min−1) were not different (p = 0.33) and they were highly correlated (r = 0.99; p < 0.01). This response was not affected by age or intensity of the verification phase. The Bland-Altman analysis revealed a very small absolute bias (−0.25 mL·kg−1·min−1, not different from 0) and a precision of ±1.56 mL·kg−1·min−1 between measures. This study indicated that a verification phase does not highlight an under-estimation of O2max derived from a RI test, in a large and heterogeneous group of healthy younger and older men naïve to laboratory testing procedures. Moreover, only minor within-individual differences were observed between the maximal O2 elicited during the RI and the verification phase. Thus a verification phase does not add any validation of the determination of a O2max. Therefore, the recommendation that a verification phase should become a gold standard procedure, although initially appealing, is not supported by the experimental data.

Does True Inter-Individual Variability Exist in Individual Responses After Endurance Training?

Introduction: Despite the apparent existence of individual responses, it remains unknown whether the variability observed in peak oxygen consumption (VO2peak) and work rate at onset of blood lactate (OBLAWR) response following exercise training reflects true inter-individual differences. To date, few studies include a non-exercise control group to determine the impact of random/measurement error on the variability associated with VO2peak and OBLAWR responses to endurance training. Therefore, the purpose of this study was to determine whether true individual differences exist in responses to training by assessing whether the variability in VO2peak and OBLAWR responses following training exceeded the variability in a non-training control group.&#x0D; Methods: 16 recreationally active males completed two incremental ramp tests to determine VO2peak and OBLAWR. Participants were assigned into the control group (n = 7) or the training group (n = 9; endurance training: 30 minutes of 65% of work rate at VO2peak, four times per week) in a manner to counterbalance baseline VO2peak measures.&#x0D; Results: VO2peak increased significantly (p &lt; 0.05) (+338 ± 416.2 mL/min/kg) and OBLAWR (+32.1 ± 29.2 W) increased following endurance training. The SD in change scores was greater in the training group for VO2peak and OBLAWR than the parallel control group. Specifically, this resulted in large and moderately-large effect sizes at respective values of 0.6 for VO2peak and 0.5 for OBLAWR.&#x0D; Conclusion: Although these preliminary results may suggest that the variability in VO2peak and OBLAWR responses to endurance training reflect true inter-individual variability beyond random/measurement error, a definitive conclusion can be made upon the completion of the study.

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function.

In ramp-incremental cycling exercise, some individuals are capable of producing power output (PO) in excess of that produced at their limit of tolerance (LoT) whereas others cannot. This study sought to describe the 1) prevalence of a "power reserve" within a group of young men ( n = 21; mean ± SD: age 25 ± 4 yr; V̇o2max 45 ± 8 ml·kg-1·min-1); and 2) muscle fatigue characteristics of those with and without a power reserve. "Power reserve" (ΔPReserve) was determined as the difference between peak PO achieved during a ramp-incremental test to exhaustion and maximal, single-leg isokinetic dynamometer power determined within 45 s of completing the ramp-incremental test. Between-group differences in pre- vs. postexercise changes in voluntary and electrically stimulated single-leg muscle force production measures (maximal voluntary contraction torque, voluntary activation, maximal isotonic velocity and isokinetic power; 1-, 10-, 50-Hz torque; and 10/50-Hz ratio), V̇o2max, and constant-PO cycling time-to-exhaustion also were assessed. Frequency distribution analysis revealed a dichotomy in the prevalence of a power reserve within the sample resulting in two groups: 1) "No Reserve" (NRES: power reserve <5%; n = 10) and 2) "Reserve" (RES: power reserve >15%; n = 11). At the LoT, all participants had achieved V̇o2max. Muscle fatigue was evident in both groups, although the NRES group had greater reductions ( P < 0.05) in 10-Hz peak torque (PT), 10/50 Hz ratio, and maximal velocity. Time to the LoT during the constant PO test was 22 ± 16% greater ( P < 0.05) in RES (116 ± 19 s; PO = 317 ± 52 W) than in NRES (90 ± 23 s; PO = 337 ± 71 W), despite similar ramp-incremental exercise durations and V̇o2max between groups. Compared with the RES group, the NRES group accrued greater peripheral muscle fatigue at the LoT, suggesting that the mechanisms contributing to exhaustion in a ramp-incremental protocol are not uniform. NEW & NOTEWORTHY This study demonstrates that the mechanisms associated with the limit of tolerance during ramp-incremental cycling exercise differ between those who are capable of generating power output in excess of that at exercise termination vs. those who are not. Those without a "power reserve" exhibit greater peripheral muscle fatigue and reduced muscle endurance, supporting the hypothesis that exhaustion occurs at a specific level of neuromuscular fatigue. In contrast, those with a power reserve likely are limited by other mechanisms.

The plateau in the NIRS-derived [HHb] signal near the end of a ramp incremental test does not indicate the upper limit of O2 extraction in the vastus lateralis.

This study aimed to examine, at the level of the active muscles, whether the plateau in oxygen (O2) extraction normally observed near the end of a ramp incremental (RI) exercise test to exhaustion is caused by the achievement of an upper limit in O2 extraction. Eleven healthy men (27.3 ± 3.0 yr, 81.6 ± 8.1 kg, 183.9 ± 6.3 cm) performed a RI cycling test to exhaustion. O2 extraction of the vastus lateralis (VL) was measured continuously throughout the test using the near-infrared spectroscopy (NIRS)-derived deoxygenated hemoglobin [HHb] signal. A leg blood flow occlusion was performed at rest (LBFOCC1) and immediately after the RI test (LBFOCC2). The [HHb] values during the resting occlusion (108.1 ± 21.7%; LBFOCC1) and the peak values during exercise (100 ± 0%; [HHb]plateau) were significantly greater than those observed at baseline (0.84 ± 10.6% at baseline 1 and 0 ± 0% at baseline 2) (P < 0.05). No significant difference was found between LBFOCC1 and [HHb]plateau (P > 0.05) or between the baseline measurements (P > 0.05). [HHb] values at LBFOCC2 (130.5 ± 19.7%) were significantly greater than all other time points (P < 0.05). These results support the existence of an O2 extraction reserve in the VL muscle at the end of a RI cycling test and suggest that the observed plateau in the [HHb] signal toward the end of a RI test is not representative of an upper limit in O2 extraction.