Ramp Incremental Test Research Articles

Influence Of Body Position On Pulmonary Oxygen Uptake And Muscle Deoxygenation Kinetics During Cycle Exercise

Whether pulmonary oxygen uptake (VO2) kinetics are limited by O2 delivery remains contentious. Previous studies have demonstrated that the time constant of pulmonary VO2 kinetics (τVO2) is greater during supine compared to upright cycle exercise, presumably reflecting the superimposition of an O2 availability limitation. However, interpretation of these studies is compromised by their use of superficial single-site measurements using continuous-wave near-infrared spectroscopy (NIRS), which is unable to determine absolute [heme]. PURPOSE: To determine the impact of body position (i.e. upright [U] vs. supine [S]) on the kinetics of pulmonary VO2, as well as muscle deoxygenation (deoxy[heme]) kinetics and total[heme] using time-resolved (TR-)NIRS. METHODS: 7 healthy men completed an incremental ramp test to determine VO2 max and the gas exchange threshold in the supine position. 4 visits followed whereby pulmonary VO2 and deoxy[heme] kinetics and total[heme] were determined via TR-NIRS at three muscle sites (deep [VLd] and superifical [VLs] vastus lateralis and superficial rectus femoris [RFs]) in two conditions: 1) during S heavy intensity constant work rate exercise at 40%Δ (between ventilatory threshold and VO2 max); and 2) during U exercise at the same absolute work rate. RESULTS: τVO2 was increased during S compared to U (S: 42 ± 12 vs. U: 32 ± 9 s, P = 0.03). The fundamental phase τdeoxy[heme] was greater (i.e. slower) in S compared to U for each muscle site (VLd S: 19 ± 10 vs. U: 8 ± 5 s; VLs S: 16 ± 7 vs. U: 10 ± 3 s; RFs S: 20 ± 7 vs. U: 11 ± 3 s, P = 0.002) and its amplitude was greater in S compared to U for RFs only (S: 27.4 ± 12.1 vs. U: 9.1 ± 2.5 μM, P = 0.008). Total[heme] did not differ between U and S for any muscle site (all P > 0.05). CONCLUSION: The slowing of pulmonary VO2 kinetics for S versus U occurs concomitant with a depressed rate of muscle(s) deoxygenation. This finding suggests that supine exercise results in a relatively greater fall in muscle VO2 when compared to O2 delivery kinetics at least for VLd and VLs. The increased amplitude of deoxy[heme] in S for RFs suggests an increase in O2 extraction to compensate for impaired muscle perfusion in S compared to U.

Influence Of Priming Exercise On Muscle Deoxygenation Kinetics During Upright And Supine Cycle Exercise

A bout of prior heavy “priming” exercise typically reduces the time constant of fundamental phase oxygen uptake (VO2) kinetics (τVO2) in the supine position, an effect that is generally absent during upright exercise. This priming-induced speeding of pulmonary VO2 kinetics has been attributed to increased muscle oxygenation at the onset of the second bout. However, the extent to which priming-induced improvements in muscle oxy/deoxygenation status differ across distinct muscle regions, as well as between deep vs. superficial muscle and with respect to body position, remains unknown. PURPOSE: To examine the impact of priming exercise on pulmonary VO2 and muscle deoxygenation kinetics at three muscle sites (superficial rectus femoris [RFs], deep [VLd] and superficial [VLs] vastus lateralis) using time-resolved near-infrared spectroscopy during upright (U) and supine (S) exercise. METHODS: 7 healthy men completed an incremental ramp test to determine VO2 max and the gas exchange threshold in S. 4 visits followed whereby participants performed two 6-min bouts of heavy exercise separated by 6-min unloaded pedalling in two conditions: 1) during constant power exercise at 40%Δ in S; and 2) during exercise at the same absolute work rate in U. Pulmonary VO2 and muscle deoxy[heme] kinetics were determined during each test. RESULTS: τVO2 was reduced in bout 2 in S (bout 1: 42 ± 12 vs. bout 2: 31 ± 7 s, P = 0.016) but not in U (bout 1: 32 ± 9 vs. bout 2: 28 ± 5 s, P = 0.32). The fundamental phase τdeoxy[heme] was greater in bout 2 for RFs in both postures (S, bout 1: 20 ± 7 vs. bout 2: 31 ± 18 s; U, 1: 11 ± 3 vs. bout 2: 23 ± 9 s, P = 0.021), whereas it was increased in bout 2 for VLs during U only (bout 1: 10 ± 3 vs. bout 2: 15 ± 4 s, P = 0.028). The fundamental phase muscle deoxy[heme] amplitude was greater in bout 2 for RFs (P = 0.001) and VLs (P = 0.024) in both U and S. Both the fundamental phase τdeoxy[heme] and amplitude did not differ between bouts 1 and 2 for VLd in either position (both P > 0.05). CONCLUSION: Prior heavy exercise reduced τVO2 in S but not U. This was accompanied by a greater amplitude and slower rate of muscle deoxygenation in superficial but not deep muscle. The contrasting responses of deep and superficial muscle to priming exercise in both U and S suggests that these muscles rely on fundamentally different O2 transport strategies.

Hypoxia equally reduces the respiratory compensation point and the NIRS-derived [HHb] breakpoint during a ramp-incremental test in young active males.

This study investigated the effect of reduced inspired fraction of O2 (FiO2) in the correspondence between the respiratory compensation point (RCP) and the breakpoint in the near‐infrared spectroscopy‐derived deoxygenated hemoglobin signal ([HHb]bp) during a ramp‐incremental (RI) test to exhaustion. Eleven young males performed, on two separated occasions, a RI test either in normoxia (NORM, FiO2 = 20.9%) or hypoxia (HYPO, FiO2 = 16%). Oxygen uptake ( V˙O2), and [HHb] signal from the vastus lateralis muscle were continuously measured. Peak V˙O2 (2.98 ± 0.36 vs. 3.39 ± 0.26 L min−1) and PO (282 ± 29 vs. 310 ± 19 W) were lower in HYPO compared to NORM condition, respectively. The V˙O2 and PO associated with RCP and [HHb]bp were lower in HYPO (2.35 ± 0.24 and 2.34 ± 0.26 L min−1; 198 ± 37 and 197 ± 30 W, respectively) when compared to NORM (2.75 ± 0.26 and 2.75 ± 0.28 L min−1; 244 ± 29 and 241 ± 28 W, respectively) (p < .05). Within the same condition, the V˙O2 and PO associated with RCP and [HHb]bp were not different (p > .05). Bland–Altman plots mean average errors between RCP and [HHb]bp were not different from zero in HYPO (0.01 L min−1 and 1.1 W) and NORM (0.00 L min−1 and 3.6 W) conditions. The intra‐individual changes between thresholds associated with V˙O2 and PO in HYPO from NORM were strongly correlated (r = .626 and 0.752, p < .05). Therefore, breathing a lower FiO2 during a RI test resulted in proportional reduction in the RCP and the [HHb]bp in terms of V˙O2 and PO, which further supports the notion that these physiological responses may arise from similar metabolic changes reflecting a common phenomenon.

Alterations to neuromuscular properties of skeletal muscle are temporally dissociated from the oxygen uptake slow component

To assess if the alteration of neuromuscular properties of knee extensors muscles during heavy exercise co-vary with the SCV ({dot{{rm{V}}}{rm{O}}}_{2} slow component), eleven healthy male participants completed an incremental ramp test to exhaustion and five constant heavy intensity cycling bouts of 2, 6, 10, 20 and 30 minutes. Neuromuscular testing of the knee extensor muscles were completed before and after exercise. Results showed a significant decline in maximal voluntary contraction (MVC) torque only after 30 minutes of exercise (−17.01% ± 13.09%; p < 0.05) while single twitch (PT), 10 Hz (P10), and 100 Hz (P100) doublet peak torque amplitudes were reduced after 20 and 30 minutes (p < 0.05). Voluntary activation (VA) and M-wave were not affected by exercise, but significant correlation was found between the SCV and PT, MVC, VA, P10, P100, and P10/P100 ratio, respectively (p < 0.015). Therefore, because the development of the SCV occurred mainly between 2–10 minutes, during which neuromuscular properties were relatively stable, and because PT, P10 and P100 were significantly reduced only after 20-30 minutes of exercise while SCV is stable, a temporal relationship between them does not appear to exist. These results suggest that the development of fatigue due to alterations of neuromuscular properties is not an essential requirement to elicit the SCV.

A 4-week endurance training program improves tolerance to mental exertion in untrained individuals

ObjectivesThe aim of this study was to investigate whether 4 weeks of endurance training could improve tolerance to mental exertion in untrained participants. DesignLongitudinal training study. MethodsTwenty untrained young adults (14 F, 6 M; 27.6±6.2 years) completed a 4-week training protocol in a randomised and counterbalanced order. Baseline and follow-up assessment were conducted over three sessions in the week preceding and following the training period. During session 1, participants completed an incremental maximal ramp test. During sessions 2 and 3 participants completed a 15min cycling time trial preceded by either a mental exertion or control conditions. Following baseline assessments, participants were randomised into a physical training or placebo group that completed the training intervention thrice weekly over four weeks. ResultsThe physical training resulted in increase in VO2 peak relative to the placebo group (p=0.003). Linear Mixed Models utilising the control condition time trial performance as a covariate found the physical training group increased their time trial distance following the mental exertion condition to a greater extent than the placebo group (p=0.03). RPE during the time trial and perceptual measures of mental exertion did not significantly change between groups (all p>0.10) although interaction effects were observed when considering the RPE-power output relationship during the time trial. ConclusionsFour weeks of endurance training increased tolerance to mental exertion in untrained participants during a subsequent physical performance, but not during prolonged cognitive performance. This finding suggests that the ability to tolerate mental exertion is trainable in at least some contexts and highlights the far-reaching benefits of endurance training.

Evaluation of Pulse Arrival Time Model to Estimate Systolic Blood Pressure during Exercise

Pulse arrival time (PAT) is a method used to estimate systolic blood pressure (SBP), as the amount of time it takes for a pulse to travel from the heart to a peripheral location is inversely related to blood pressure. However, the validity and accuracy of this method’s blood pressure estimation has been questioned. Therefore, the purpose of this study was to evaluate the accuracy of a PAT model’s estimation of SBP over a range of exercise intensities. Six participants (5 men, 1 woman; age: 26 ± 4 yrs) completed three cycling exercise tests (25 Watt/min ramp incremental test, and moderate and heavy pseudorandom binary sequence exercise) during three separate laboratory visits. PAT was calculated as the time difference between the R‐wave of an electrocardiogram and the pulse arrival at the forehead measured with a pulse oximeter. SBP was estimated using the following equation: SBPPAT = 64.578/(PAT) – 43.957, and was compared to calibrated brachial blood pressure measured at the finger (FBP) by photoplethysmography during the exercise trials. Participant blood pressure responses were pooled, and Bland‐Altman analysis was conducted to evaluate the accuracy of estimated SBP for each exercise test. PAT model estimation of SBP had the smallest bias during heavy (−2.8 mmHg), then moderate (8.1 mmHg), and the largest bias during ramp incremental exercise (−11 mmHg), with their limits of agreement being between −56 and 50 mmHg, −29 and 45 mmHg, and −74 and 53 mmHg, respectively. Linear regression of the ramp incremental SBP response revealed that SBP estimated from the PAT does not increase by the same magnitude as the pressure measured at the finger (SBPPAT = 0.295 · SBPFBP + 106.236, r2 = 0.350, p &lt; 0.05). Overall, these findings support that SBP estimated by PAT is linearly related to brachial SBP measured at the finger; however, this PAT model is a poor estimator of absolute SBP during exercise ranging from moderate to maximal intensities.Support or Funding InformationSupported by NSERC.

Translating Ramp V˙O2 into Constant Power Output: A Novel Strategy that Minds the Gap.

This study aimed to model the dissociation in the V˙O2/power output (PO) relationship between ramp incremental (RI) and constant work rate (CWR) exercise and to develop a novel strategy that resolves this gap and enables an accurate translation of the RI V˙O2 response into a constant PO. Nine young men completed two RI tests (30 and 15 W·min) and CWR tests at seven intensities across exercise intensity domains. The V˙O2/PO relationship for RI and CWR exercise was modeled, and the dissociation was compared in terms of PO. The accuracy of three translation strategies was tested in the moderate-intensity (i.e., zone 1) and heavy-intensity (i.e., zone 2) domain. Strategy 1 comprised a simple mean response time correction, whereas strategies 2 and 3 accounted for the loss of mechanical efficiency in zone 2 by applying an extra correction that was based on, respectively, the difference between s2 - CWR and s2 - ramp and the ratio s2/s1. For all intensities, differences in PO were found between CWR and RI exercise (P < 0.001). Overall, these differences were smaller for the 15-W·min compared with the 30-W·min protocol (P = 0.012). Strategy 1 was accurate for PO selection in zone 1 (bias = 0.4 ± 7.3 W), but not in zone 2 (bias = 17.1 ± 15.9 W). Only strategy 2 was found to be accurate for both intensity zones (bias = 2.2 ± 14.2 W) (P = 0.107). This study confirmed that a simple mean response time correction works for PO selection in the moderate-intensity but not in the heavy-intensity domain. A novel strategy was tested and validated to accurately prescribe a constant PO based on the RI V˙O2 response in a population of young healthy men.

A Rapidly Incremented Tethered-Swimming Maximal Protocol for Cardiorespiratory Assessment of Swimmers.

Incremental exercise testing is the standard means of assessing cardiorespiratory capacity of endurance athletes. While the maximal rate of oxygen consumption is typically used as the criterion measurement in this regard, two metabolic breakpoints that reflect changes in the dynamics of lactate production/consumption as the work rate is increased are perhaps more relevant for endurance athletes from a functional standpoint. Exercise economy, which represents the rate of oxygen consumption relative to performance of submaximal work, is also an important parameter to measure for endurance-athlete assessment. Ramp incremental tests comprising a gradual but rapid increase in work rate until the limit of exercise tolerance is reached are useful for determining these parameters. This type of test is typically performed on a cycle ergometer or treadmill because there is a need for precision with respect to work-rate incrementation. However, athletes should be tested while performing the mode of exercise required for their sport. Consequently, swimmers are typically assessed during free-swimming incremental tests where such precision is difficult to achieve. We have recently suggested that stationary swimming against a load that is progressively increased (incremental tethered swimming) can serve as a "swim ergometer" by allowing sufficient precision to accommodate a gradual but rapid loading pattern that reveals the aforementioned metabolic breakpoints and exercise economy. However, the degree to which the peak rate of oxygen consumption achieved during such a protocol approximates the maximal rate that is measured during free swimming remains to be determined. In the present article, we explain how this rapidly incremented tethered-swimming protocol can be employed to assess the cardiorespiratory capacity of a swimmer. Specifically, we explain how assessment of a short-distance competitive swimmer using this protocol revealed that his rate of oxygen uptake was 30.3 and 34.8 mL∙min-1∙kg-1BM at his gas-exchange threshold and respiratory compensation point, respectively.

Effect of High-Intensity Training and Asthma on the V˙O2 Kinetics of Adolescents

High-intensity interval training (HIIT) represents a potent stimulus to the dynamic oxygen uptake (V˙O2) response in adults, but whether the same is evident in youth is unknown. HIIT has also been suggested to place a lower demand on the respiratory system, decreasing the likelihood of exacerbation in those with respiratory conditions, such as asthma. Sixty-nine adolescents (13.6 ± 0.9 yr; 36 asthma) took part, 35 of which (17 asthma) participated in a 30-min HIIT intervention three times a week for 6 months. Each participant completed an incremental ramp test to volitional exhaustion and three heavy-intensity constant work rate tests to determine the dynamic V˙O2, heart rate, and deoxyhemoglobin response at baseline, midintervention, postintervention and at a 3-month follow-up. There was no influence of asthma at baseline or in response to the intervention. Participants in the intervention group demonstrated a faster V˙O2 time constant (τp) after intervention (intervention: 29.2 ± 5.7 s vs control: 34.2 ± 6.5 s; P = 0.003), with these differences maintained at follow-up (intervention: 32.5 ± 5.5 s vs control: 37.3 ± 8.7 s; P = 0.008). The intervention was associated with a speeding of the concentration of deoxyhemoglobin τ (pre: 20.1 ± 4.7 s vs post: 18.2 ± 4.1 s; P = 0.05) compared with a slowing over the same time period in the control participants (pre: 17.9 ± 4.9 s vs post: 20.1 ± 4.6 s; P = 0.012). Heart rate kinetics were not altered (pre: 46.5 ± 12.2 s vs post: 47.7 ± 11.1 s; P = 0.98). These findings highlight the potential utility of school-based HIIT as a strategy to enhance the V˙O2 kinetics of youth, regardless of the presence of asthma.

A Critical Evaluation of Current Methods for Exercise Prescription in Women and Men.

Thus, the aim of this study was to compare contemporary gold-standard approaches for exercise prescription based on fixed percentages of maximum values to the well-established, but underutilized, "domain" schema of exercise intensity. One hundred individuals participated in the study (women, 46; men, 54). A cardiopulmonary ramp-incremental test was performed to assess V˙O2max, WRpeak, HRmax, and the lactate threshold (LT), and submaximal constant-work rate trials of 30-min duration to determine the maximal lactate steady-state (MLSS). The LT and MLSS were used to partition the intensity spectrum for each individual in three domains of intensity: moderate, heavy, and severe. V˙O2max in women and men was 3.06 ± 0.41 L·min and 4.10 ± 0.56 L·min, respectively. Lactate threshold and MLSS occurred at a greater %V˙O2max and %HRmax in women compared with men (P < 0.05). The large ranges in both sexes at which LT and MLSS occurred on the basis of %V˙O2max (LT, 45%-74%; MLSS, 69%-96%), %WRpeak (LT, 23%-57%; MLSS, 44%-71%), and %HRmax (LT, 60%-90%; MLSS, 75%-97%) elicited large variability in the number of individuals distributed in each domain at the fixed-percentages examined. Contemporary gold-standard methods for exercise prescription based on fixed-percentages of maximum values conform poorly to exercise intensity domains and thus do not adequately control the metabolic stimulus.

The effect of the fraction of inspired oxygen on the NIRS-derived deoxygenated hemoglobin "breakpoint" during ramp-incremental test.

During ramp-incremental (RI) exercise to exhaustion, the near-infrared spectroscopy-derived deoxygenated hemoglobin ([HHb]) signal in the vastus lateralis muscle shows a linear increase up to a point at which a plateau-like response is manifested ([HHb]bp). This study investigated if 1) the [HHb]bp is affected by different fractions of inspired O2 () [hypoxia (16%; HYPO); normoxia (21%; NORM); hyperoxia (30%; HYPER)]; and 2) an abrupt change to hyperoxic-inspired gas just before the occurrence of the [HHb]bp (HYPERSWITCH) would affect the [HHb] plateau-like response. Ten physically active male participants reported to the laboratory on four separate occasions to perform an RI test to exhaustion in NORM, HYPO, and HYPER and an RI test to exhaustion with an abrupt increase in (30%; HYPERSWITCH) 15 W before the power output (PO) associated with [HHb]bp in normoxia. PO, [HHb], tissue O2 (), and pulse O2 saturation () were recorded continuously. Peak PO was significantly lower in HYPO (290 ± 21 W) and higher in HYPER (321 ± 22 W) and HYPERSWITCH (320 ± 19 W) compared with NORM (311 ± 18 W). The PO associated with [HHb]bp was not different between NORM and HYPER (246 ± 23 vs. 247 ± 24 W), but it was lower in HYPO (198 ± 31 W) than NORM and HYPER. The PO associated with the [HHb]bp in HYPERSWITCH (240 ± 23) was not different compared with NORM. HYPER and HYPERSWITCH resulted in greater and compared with NORM. These results suggest that the [HHb]bp response is not dependent of O2 driving pressure and that other physiological mechanisms might determine its occurrence.

Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses.

To examine whether the menstrual or monophasic oral contraceptive cycle phases affect submaximal (oxygen uptake ( O2 ) kinetics, maximal lactate steady-state (MLSS)) and maximal ( O2max , time-to-exhaustion (TTE)) responses to exercise in healthy, active women. During the mid-follicular or inactive-pill phase and the mid-luteal or active-pill phase of the respectivemenstrual or oral contraceptive cycle, 15 non-oral contraceptive users (meanandstandard deviation(SD) (±): 27±6 years; 171±5cm; 65±7kg) and 15 monophasic oral contraceptive users (24±4 years; 169±10cm; 68±10kg) performed: one O2 kinetics test; one ramp-incremental test; two to three 30-minute constant-load cycling trials to determine the power output corresponding to MLSS (MLSSp ), followed by a TTE trial. The phase of the menstrual or oral contraceptive cycle did not affect the time constant of the O2 kinetics response (τ O2 ) (mid-follicular, 20±5seconds and mid-luteal, 18±3seconds; inactive-pill, 22±8seconds and active-pill, 23±6seconds), O2max (mid-follicular, 3.06±0.32Lmin-1 and mid-luteal, 3.00±0.33Lmin-1 ; inactive-pill, 2.87±0.39Lmin-1 and active-pill, 2.87±0.45Lmin-1 ), MLSSp (mid-follicular, 181±30W and mid-luteal, 182±29W; inactive-pill, 155±26W and active-pill, 155±27W), and TTE (mid-follicular, 147±42seconds and mid-luteal, 128±54seconds; inactive-pill, 146±70seconds and active-pill, 139±77seconds) (P>.05). The rate of perceived exertion (RPE) at minute 30 of the MLSSp trials was greater in the mid-follicular phase (6.2±1.5) compared with the mid-luteal phase (5.3±1.4) for non-oral contraceptive users (P=.022). The hormonal fluctuations between the menstrual and oral contraceptive cycle phases had no detectable effects on submaximal and maximal exercise performance, even when RPE differed.

Training-Induced Changes in the Respiratory Compensation Point, Deoxyhemoglobin Break Point, and Maximal Lactate Steady State: Evidence of Equivalence.

To evaluate whether the coherence in the oxygen uptake (V˙O2) associated with the respiratory compensation point (RCP), near-infrared spectroscopy-derived muscle deoxyhemoglobin ([HHb]) break point ([HHb]BP), and maximal lactate steady state (MLSS) would persist at the midpoint and endpoint of a 7-month training and racing season. Eight amateur male cyclists were tested in 3 separate phases over the course of a cycling season (PRE, MID, and POST). Testing at each phase included a ramp-incremental test to exhaustion to determine RCP and [HHb]BP. The PRE and POST phases also included constant power output rides to determine MLSS. Compared with PRE, V˙O2 at both RCP and [HHb]BP was greater at MID (delta: RCP 0.23 [0.14]L·min-1, [HHb]BP 0.33 [0.17]L·min-1) and POST (delta: RCP 0.21 [0.12], [HHb]BP 0.30 [0.14]L·min-1) (P < .05). V˙O2 at MLSS also increased from PRE to POST (delta: 0.17 [12]L·min-1) (P < .05). V˙O2 was not different at RCP, [HHb]BP, and MLSS at PRE (3.74 [0.34], 3.64 [0.40], 3.78 [0.23]L·min-1) or POST (3.96 [0.25], 3.95 [0.32], 3.94 [0.18]L·min-1) respectively, and RCP (3.98 [0.33]L·min-1) and [HHb]BP (3.97 [0.34]L·min-1) were not different at MID (P > .05). PRE-MID and PRE-POST changes in V˙O2 associated with RCP, [HHb]BP, and MLSS were strongly correlated (range: r = .85-.90) and demonstrated low mean bias (range = -.09 to .12L·min-1). At all measured time points, V˙O2 at RCP, [HHb]BP, and MLSS were not different. Irrespective of phase comparison, direction, or magnitude of V˙O2 changes, intraindividual changes between each index were strongly related, indicating that interindividual differences were reflected in the group mean response and that their interrelationships are beyond coincidental.

Influence of Warm-Up Prior to Incremental Exercise Test on Aerobic Performance in Physically Active Men

Abstract Introduction. The aim of the study was to verify the influence of warm-up before a ramp incremental exercise test with linearly increasing loads on the maximal values of physiological variables which determine performance. Material and methods. Thirteen healthy and physically active male students (age = 23.3 ± 1.5 years, body height = 179.1 ± 8.6 cm and body mass = 79.5 ± 9.1 kg) completed a cross-over comparison of two incremental exercise test interventions – an incremental exercise test with a 15-minute warm-up at an intensity of 60% of the maximal oxygen uptake obtained in the first incremental exercise test and the same test without warm-up. Results. The peak values of physiological variables were statistically significantly higher for the incremental exercise test with warm-up, the differences between tests being 2.66% for peak power output (p = 0.039, t = 2.312, ES = 0.24), 7.75% for peak oxygen uptake (p = 0.000, t = 5.225, ES = 0.56), 7.72% for peak minute ventilation (p = 0.005, t = 3.346, ES = 0.53) and 1.62% for peak heart rate (p = 0.019, t = 2.690, ES = 0.60). Conclusions. Warm-up before a ramp incremental exercise test resulted in higher values of maximal oxygen uptake, maximal minute ventilation, maximal heart rate and peak power output.

Respiratory and muscular response to acute non-metabolic fatigue during ramp incremental cycling

We tested the hypothesis that acute, non-metabolic fatigue, by reducing maximal power output and possibly increasing muscle recruitment at a given exercise intensity, will reduce indexes of exercise tolerance during incremental cycling. Ten subjects performed three ramp incremental tests respectively after static stretching (STRC), dropjumps (DJ) or control (CTRL). Fatigue was assessed as reduction in maximal power output (sprintPO) during isokinetic sprints. During the ramps we measured: oxygen consumption (VO2), power output (PO), and surface electromyography. sprintPO was reduced after STRC and DJ (p = 0.007) yet not after CTRL. During the ramps, the interventions augmented muscle excitation vs CTRL (p ≤ 0.001). Peak PO and VO2 were reduced after STRC (302 ± 39W p = 0.033, 3365 ± 465 ml/min p = 0.015) and DJ (300 ± 37W p = 0.023, 3413 ± 476 ml/min p = 0.094) vs CTRL (314 ± 41W, 3505 ± 486 ml/min). Interventions were associated with early occurrence of the ventilatory thresholds and increased VO2 vs CTRL (p = 0.029). The physiological response after acute non-metabolic fatigue suggests a link between exercise intolerance and the decreased ability to produce force.

The Effect of Short- and Long-Term Aerobic Training Years on Systemic O2 Utilization, and Muscle and Prefrontal Cortex Tissue Oxygen Extraction in Young Women

Buzza, G, Lovell, GP, Askew, CD, and Solomon, C. The effect of short- and long-term aerobic training years on systemic O2 utilization, and muscle and prefrontal cortex tissue oxygen extraction in young women. J Strength Cond Res 33(8): 2128-2137, 2019-This study aimed to determine if systemic O2 utilization (VO2) and tissue oxygen extraction (deoxyhemoglobin [HHb]) in the vastus lateralis (VL), gastrocnemius (GAST), and prefrontal cortex were different during exercise between short-term trained (STT, 6-24 months) and long-term trained (LTT, >5 years) young women while controlling for current training load. Thirteen STT and 13 LTT participants completed ramp incremental (RI) and square-wave constant load (SWCL) tests on a cycle ergometer. In LTT compared with STT: (a) VO2 was higher during the RI (p = 0.024) and SWCL (p = 0.001) tests; (b) HHb in the VL (p = 0.044) and GAST (p = 0.027) was higher in the RI test; and (c) there were significant group × intensity interactions for VO2 in the SWCL test. The additional years of aerobic training in LTT compared with STT (LTT 7.1 ± 1.9 vs. STT 1.5 ± 0.4 years) resulted in higher VO2 and HHb in the VL and GAST. These results indicate that in young women, independent of current training load, systemic VO2 and peripheral muscle O2 extraction during exercise continues to increase beyond 24 months of aerobic training.

Evaluating the NIRS-derived microvascular O2 extraction "reserve" in groups varying in sex and training status using leg blood flow occlusions.

It has been demonstrated that the plateau in the near-infrared spectroscopy (NIRS) derived deoxygenated hemoglobin and myoglobin (deoxy[Hb+Mb]) signal (i.e., deoxy[Hb+Mb]PLATEAU) towards the end of a ramp-incremental (RI) test does not represent the upper-limit in O2 extraction of the vastus lateralis (VL) muscle, given that an O2 extraction reserve has been recently observed. This study aimed to investigate whether this O2 extraction reserve was present in various populations and whether it exhibited sex- and/or training- related differences.Sixteen men- 8 untrained (27±5 years; 83±11 kg; 179±9 cm), 8 trained (27±4 years; 82±10 kg; 182±8 cm) and 9 trained women (27±2 years; 66±10 kg; 172±6 cm) performed a RI cycling test to exhaustion. The NIRS-derived deoxy[Hb+Mb] signal was measured continuously on the VL as a proxy for O2 extraction. A leg blood flow occlusion (i.e., ischemia) was performed at rest (LBFOCC 1) and immediately post the RI test (LBFOCC 2).No significant difference was found between the deoxy[Hb+Mb] amplitude during LBFOCC 1 and the deoxy[Hb+Mb]PLATEAU (p>0.05) nor between baseline (bsln) deoxy[Hb+Mb] values. deoxy[Hb+Mb] amplitude during LBFOCC 2 was significantly greater than LBFOCC 1 and at deoxy[Hb+Mb]PLATEAU (p<0.05) with group means ~30–45% higher than the deoxy[Hb+Mb]PLATEAU and LBFOCC 1 (p<0.05). No significant differences were found between groups in O2 extraction reserve, regardless of sex- or training-statusThe results of this study demonstrated the existence of an O2 extraction reserve in different populations, and that neither sex- nor training-related differences affect the amplitude of the reserve.

Effect of asthma and six-months high-intensity interval training on heart rate variability during exercise in adolescents

ABSTRACTLittle is known regarding the influence of asthma and exercise, and their interaction, on heart rate variability (HRV) in adolescents.Thirty-one adolescents with asthma (13.7±0.9 years; 21.9±3.9 kg·m−2; 19 boys, 12 girls) and thirty-three healthy adolescents (13.8±0.9 years; 20.3±3.2 kg·m−2; 16 boys, 17 girls) completed an incremental ramp test and three heavy-intensity constant-work-rate cycle tests. Thirteen adolescents (7 boys, 6 girls; 6 asthma, 7 control) completed six-months high-intensity interval training (HIIT) and were compared to age- and sex-matched controls. Standard time-domain, frequency-domain and non-linear indices of HRV were derived at baseline, three- and six-months.Asthma did not influence HRV at baseline or following HIIT. Total power, low frequency and normalised low frequency power, and sympathovagal balance increased at three-months in HIIT, subsequently declining towards baseline at six-months. Normalised high frequency power was reduced at three-months in both groups, which was sustained at six-months. No effects of HIIT were observed in the time-domain nor in the non-linear indices.HRV was not influenced by asthma, potentially because such derangements are a function of disease progression, severity or duration. HIIT may be associated with a short-term shift towards greater sympathetic predominance during exercise, perhaps caused by physiological overload and fatigue.

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.