Effects of Helium and 40% O2 on Graded Exercise With Self-Contained Breathing Apparatus

2003 ◽  
Vol 28 (6) ◽  
pp. 910-926 ◽  
Author(s):  
Neil D. Eves ◽  
Stewart R. Petersen ◽  
Richard L. Jones
Keyword(s):  
Exercise Performance ◽  
Maximal Exercise ◽  
Ventilatory Threshold ◽  
Arterial Oxygen ◽  
Peak Exercise ◽  
Helium Mixtures ◽  
Breathing Resistance ◽  
Breathing Apparatus ◽  
Graded Exercise ◽  
Ventilatory Limitation

Maximal exercise performance is decreased when breathing from a self-contained breathing apparatus (SCBA), owing to a ventilatory limitation imposed by the increased expiratory resistance. To test the hypothesis that decreasing the density of the breathing gas would improve maximal exercise performance, we studied 15 men during four graded exercise tests with the SCBA. Participants breathed a different gas mixture during each test: normoxia (NOX; 21% O2, 79% N2), hyperoxia (HOX; 40% O2, 60% N2), normoxic helium (HE-OX; 21% O2, 79% He), and hyperoxic helium (HE-HOX; 40% O2, 60% He). Compared to NOX, power output at the ventilatory threshold and at maximal exercise significantly increased with both hyperoxic mixtures. Minute ventilation was increased at peak exercise with both helium mixtures, and maximal aerobic power ([Formula: see text]) was significantly increased by 12.9 ± 5.6%, 10.2 ± 6.3%, and 21.8 ± 5.6% with HOX, HE-OX, and HE-HOX, respectively. At peak exercise, the expired breathing resistance imposed by the SCBA was significantly decreased with both helium mixtures, and perceived respiratory distress was lower with HE-HOX. The results show that HE-OX improved maximal exercise performance by minimizing the ventilation limitation. The performance-enhancing effect of HOX may be explained by increased arterial oxygen content. Moreover, HE-HOX appeared to combine the effects of helium and hyperoxia on [Formula: see text]Key words:[Formula: see text] breathing resistance, ventilatory limitation, heliox, firefighting

Ventilatory Threshold and Peak Exercise Response in Athletes with CP during Treadmill and Cycle Ergometry

1994 ◽  
Vol 11 (3) ◽  
pp. 329-334
Author(s):  
Gregory B. Dwyer ◽  
Anthony D. Mahon
Keyword(s):  
Cerebral Palsy ◽  
Ventilatory Threshold ◽  
Cycle Ergometer ◽  
Cycle Ergometry ◽  
Peak Exercise ◽  
Exercise Tests ◽  
Men 2 ◽  
Graded Exercise ◽  
Exercise Response ◽  
Track Athletes

Little is known about the responses to graded exercise in athletes with cerebral palsy (CP). This study compared the ventilatory threshold (VT) and peak VO2 among athletes with CP during treadmill and cycle ergometry exercise. Six (4 men, 2 women) track athletes with CP volunteered to participate in the study. Graded exercise tests on a treadmill and cycle ergometer were performed on separate days to assess VT and peak VO2. Paired t tests were used to compare the two exercise modes. The VT, expressed as a percentage of peak VO2, was significantly higher on the cycle ergometer than on the treadmill. The absolute VO2 at the VT was similar during both testing modes, and peak VO2 was significantly higher on the treadmill than on the cycle ergometer. Similar to responses seen in able-bodied individuals, the VO2 at VT was similar during both modes of exercise, while the peak VO2 was 10% lower on the cycle than on the treadmill. Cycle ergometer peak VO2 in these athletes was higher than previous reports of individuals with CP for the cycle ergometer.

The Influence of Exercise Test Protocol on Perceived Exertion at Submaximal Exercise Intensities in Children

2003 ◽  
Vol 28 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Anthony D. Mahon ◽  
David M. Plank ◽  
Molly J. Hipp
Keyword(s):  
Exercise Test ◽  
Perceived Exertion ◽  
Ventilatory Threshold ◽  
Peak Exercise ◽  
Ratings Of Perceived Exertion ◽  
Test Protocol ◽  
Exercise Tests ◽  
Sensory Signal ◽  
Cardiorespiratory Responses ◽  
Graded Exercise

This study examined ratings of perceived exertion (RPE) using Borg's 6-20 scale at 50 W, 80 W, and ventilatory threshold (VT) in 10-year-old children (n = 15) during two different graded exercise tests. Power output was increased by 10 W•min−1 in one protocol and by 30 W•3 min−1 in the other. The cardiorespiratory responses at VT and peak exercise were similar between protocols. At 50 W and 80 W the cardiorespiratory responses were generally lower (P < 0.05) in the 10-W trial. However, RPE was 11.5 ± 2.9 and 12.1 ± 3.2 at 50 W and 15.1 ± 2.7 and 15.3 ± 2.8 at 80 W in the 10-W and 30-W trials, respectively (P > 0.05). The RPE at VT was 13.9 ± 2.4 in the 10-W trial and 12.4 ± 2.4 in the 30-W trial (P < 0.05). In that variations in submaximal RPE did not coincide with variations in central mediators of exertion, locals cues of exertion may have provided the dominate sensory signal. Key words: ventilatory threshold, cardiorespiratory measures, exercise test, peak VO2, cycle ergometry, RPE

Evidence that a central governor regulates exercise performance during acute hypoxia and hyperoxia

2001 ◽  
Vol 204 (18) ◽  
pp. 3225-3234 ◽  
Author(s):  
Timothy D. Noakes ◽  
Juha E. Peltonen ◽  
Heikki K. Rusko
Keyword(s):  
Skeletal Muscle ◽  
Exercise Performance ◽  
Chronic Hypoxia ◽  
Maximal Exercise ◽  
Cardiovascular Function ◽  
Arterial Oxygen ◽  
Peripheral Fatigue ◽  
Electromyographic Activity ◽  
Cardiorespiratory Function ◽  
Sensitive Organ

SUMMARY An enduring hypothesis in exercise physiology holds that a limiting cardiorespiratory function determines maximal exercise performance as a result of specific metabolic changes in the exercising skeletal muscle, so-called peripheral fatigue. The origins of this classical hypothesis can be traced to work undertaken by Nobel Laureate A. V. Hill and his colleagues in London between 1923 and 1925. According to their classical model, peripheral fatigue occurs only after the onset of heart fatigue or failure. Thus, correctly interpreted, the Hill hypothesis predicts that it is the heart, not the skeletal muscle, that is at risk of anaerobiosis or ischaemia during maximal exercise. To prevent myocardial damage during maximal exercise, Hill proposed the existence of a ‘governor’ in either the heart or brain to limit heart work when myocardial ischaemia developed. Cardiorespiratory function during maximal exercise at different altitudes or at different oxygen fractions of inspired air provides a definitive test for the presence of a governor and its function. If skeletal muscle anaerobiosis is the protected variable then, under conditions in which arterial oxygen content is reduced, maximal exercise should terminate with peak cardiovascular function to ensure maximum delivery of oxygen to the active muscle. In contrast, if the function of the heart or some other oxygen-sensitive organ is to be protected, then peak cardiovascular function will be higher during hyperoxia and reduced during hypoxia compared with normoxia. This paper reviews the evidence that peak cardiovascular function is reduced during maximal exercise in both acute and chronic hypoxia with no evidence for any primary alterations in myocardial function. Since peak skeletal muscle electromyographic activity is also reduced during hypoxia, these data support a model in which a central, neural governor constrains the cardiac output by regulating the mass of skeletal muscle that can be activated during maximal exercise in both acute and chronic hypoxia.

The Slope Method for Prescribing Exercise with Ratings of Perceived Exertion (RPE)

1996 ◽  
Vol 83 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Christopher C. Dunbar ◽  
Diego A. Bursztyn
Keyword(s):  
Perceived Exertion ◽  
Maximal Exercise ◽  
Peak Exercise ◽  
Ratings Of Perceived Exertion ◽  
Simple Method ◽  
Graded Exercise Test ◽  
Slope Method ◽  
Graded Exercise ◽  
The Mean ◽  
Using Data

The Borg Ratings of Perceived Exertion scale (RPE) has been shown to be a valuable tool for prescribing exercise; however, use of RPE-based exercise prescriptions in field settings has often been problematic because RPE data derived from maximal exercise testing are needed. We describe a simple method for obtaining target RPEs for exercise training from submaximal exercise data. Target RPEs for 50%, 60%, 70%, and 85% VO2peak exercise intensities obtained using the new method did not differ significantly from those obtained using data from a maximal graded exercise test. The mean difference was less than one RPE unit and was not significant (p<.05). Therefore, the Slope Method appears to be valid for developing RPE-based exercise prescriptions.

Ventilatory Threshold and V̇O2 Plateau at Maximal Exercise in 8- to 11-Year-Old Children

1993 ◽  
Vol 5 (4) ◽  
pp. 332-338 ◽  
Author(s):  
Anthony D. Mahon ◽  
Melinda L. Marsh
Keyword(s):  
Exercise Test ◽  
Maximal Exercise ◽  
Ventilatory Threshold ◽  
Age Group ◽  
Maximal Exercise Test ◽  
Graded Exercise Test ◽  
Graded Exercise ◽  
The Mean

This study examined the occurrence of a V̇O2 plateau at maximal exercise, and whether ventilatory threshold (VT) differend between children who do and children who do not achieve a V̇O2 plateau at maximal exercise. After performing a graded exercise test on a treadmill to assess VT and V̇O2max, the children were divided into a plateau group (n = 14) and a nonplateau group (n = 12). There were no differences with respect to the V̇O2 at VT (36.7 ± 3.4 vs. 37.9 ± 5.4 ml · kg−1 · min−1) and V̇O2max (51.6 ± 5.4 vs. 54.6 ± 3.6 ml · kg−1 · min−1) in the plateau and nonpiateau groups, respectively. The mean HR, RER, and RPE at maximal exercise were also similar between groups. These results indicate that VT and V̇O2max are similar in children regardless of the occurrence of a V̇O2 plateau at maximal exercise. Furthermore, a plateau in V̇O2 during a maximal exercise test is not mandatory for assessment of V̇O2max in this age group.

“You can leave your mask on”: effects on cardiopulmonary parameters of different airway protection masks at rest and during maximal exercise

2021 ◽  
pp. 2004473
Author(s):  
Massimo Mapelli ◽  
Elisabetta Salvioni ◽  
Fabiana De Martino ◽  
Irene Mattavelli ◽  
Paola Gugliandolo ◽  
...  
Keyword(s):  
Respiratory Rate ◽  
Maximal Exercise ◽  
Pulmonary Function Tests ◽  
Peak Exercise ◽  
Slight Reduction ◽  
Airway Protection ◽  
Borg Scale ◽  
Exercise Tests ◽  
Significant Difference ◽  
Ventilatory Limitation

BackgroundDuring the COVID-19 pandemic, the use of protection masks is essential to reduce contagions. However, public opinion reports an associated subjective shortness of breath. We evaluated cardiorespiratory parameters at rest and during maximal exertion to highlight any differences with the use of protection masks.MethodsTwelve healthy subjects underwent three cardiopulmonary exercise tests: without wearing protection mask, with surgical and with FFP2 mask. Dyspnea was assessed by Borg Scale. Standard pulmonary function tests were also performed.ResultsAll the subjects (40.8±12.4 years; 6 males) completed the protocol with no adverse event. At spirometry, from no mask to surgical to FFP2, a progressive reduction of FEV1 and FVC was observed (3.94±0.91 l, 3.23±0.81 l, 2.94±0.98 l and 4.70±1.21 l, 3.77±1.02 l, 3.52±1.21 l, respectively, p<0.001). Rest ventilation, O2 uptake (V̇O2) and CO2 production (VCO2) were progressively lower with a reduction of respiratory rate. At peak exercise, subjects revealed a progressively higher Borg scale when wearing surgical and FFP2. Accordingly, at peak exercise, V̇O2 (31.0±23.4, 27.5±6.9, 28.2±8.8 ml/kg/min, p=0.001), ventilation (92±26, 76±22, 72±21 l, p=0.003), respiratory rate (42±8, 38±5, 37±4, p=0.04) and tidal volume (2.28±0.72, 2.05±0.60, 1.96±0.65 l, p=0.001) were gradually lower. We did not observed a significant difference in oxygen saturation.ConclusionsProtection masks are associated with significant but modest worsening of spirometry and cardiorespiratory parameters at rest and peak exercise. The effect is driven by a ventilation reduction due to an increased airflow resistance. However, since exercise ventilatory limitation is far from being reached, their use is safe even during maximal exercise, with a slight reduction in performance.

Pulmonary transit of agitated contrast is associated with enhanced pulmonary vascular reserve and right ventricular function during exercise

2010 ◽  
Vol 109 (5) ◽  
pp. 1307-1317 ◽  
Author(s):  
André La Gerche ◽  
Andrew I. MacIsaac ◽  
Andrew T. Burns ◽  
Don J. Mooney ◽  
Warrick J. Inder ◽  
...  
Keyword(s):  
Right Ventricular ◽  
Maximal Exercise ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Systolic Pressure ◽  
Arterial Oxygen ◽  
Pulmonary Artery Systolic Pressure ◽  
Peak Exercise ◽  
Similar Proportion ◽  
Vascular Reserve

Pulmonary transit of agitated contrast (PTAC) occurs to variable extents during exercise. We tested the hypothesis that the onset of PTAC signifies flow through larger-caliber vessels, resulting in improved pulmonary vascular reserve during exercise. Forty athletes and fifteen nonathletes performed maximal exercise with continuous echocardiographic Doppler measures [cardiac output (CO), pulmonary artery systolic pressure (PASP), and myocardial velocities] and invasive blood pressure (BP). Arterial gases and B-type natriuretic peptide (BNP) were measured at baseline and peak exercise. Pulmonary vascular resistance (PVR) was determined as the regression of PASP/CO and was compared according to athletic and PTAC status. At peak exercise, athletes had greater CO (16.0 ± 2.9 vs. 12.4 ± 3.2 l/min, P < 0.001) and higher PASP (60.8 ± 12.6 vs. 47.0 ± 6.5 mmHg, P < 0.001), but PVR was similar to nonathletes ( P = 0.71). High PTAC (defined by contrast filling of the left ventricle) occurred in a similar proportion of athletes and nonathletes (18/40 vs. 10/15, P = 0.35) and was associated with higher peak-exercise CO (16.1 ± 3.4 vs. 13.9 ± 2.9 l/min, P = 0.010), lower PASP (52.3 ± 9.8 vs. 62.6 ± 13.7 mmHg, P = 0.003), and 37% lower PVR ( P < 0.0001) relative to low PTAC. Right ventricular (RV) myocardial velocities increased more and BNP increased less in high vs. low PTAC subjects. On multivariate analysis, maximal oxygen consumption (V̇o2max) ( P = 0.009) and maximal exercise output ( P = 0.049) were greater in high PTAC subjects. An exercise-induced decrease in arterial oxygen saturation (98.0 ± 0.4 vs. 96.7 ± 1.4%, P < 0.0001) was not influenced by PTAC status ( P = 0.96). Increased PTAC during exercise is a marker of pulmonary vascular reserve reflected by greater flow, reduced PVR, and enhanced RV function.

Augmented Hyperventilation Via Normoxic Helium Breathing Does Not Prevent Exercise-Induced Hypoxemia

1996 ◽  
Vol 21 (4) ◽  
pp. 264-270 ◽  
Author(s):  
Michael J. Buono ◽  
Richard Maly
Keyword(s):  
Oxygen Saturation ◽  
Maximal Exercise ◽  
Arterial Oxygen Saturation ◽  
Ambient Air ◽  
Cycle Ergometer ◽  
Endurance Athletes ◽  
Arterial Oxygen ◽  
Volitional Exhaustion ◽  
Graded Exercise ◽  
Exercise Induced

The purpose of this study was to determine if augmented hyperventilation produced via normoxic helium breathing would reduce exercise-induced hypoxemia (EIH). Seven highly trained endurance athletes with a mean maximum oxygen uptake of 65 ml∙kg−1∙min−1, performed two cycle ergometer tests to volitional exhaustion. During one of the tests the subjects breathed ambient air, while during the other they breathed normoxic helium (21% O2, 79% He). Mean maximum expired ventilation significantly (p <.05) increased from 139 L∙min−1 during the ambient trial to 168 L∙min−1 while breathing normoxic helium. Mean arterial oxygen saturation obtained at maximum exercise, however, was not significantly different for the two trials (ambient = 90%, helium = 89%). These results suggest that significantly augmenting exercise hyperventilation by 21% essentially had no effect on EIH in endurance athletes. Thus, the data do not support the hypothesis that inadequate hyperventilation is an important mechanism for arterial oxygen desaturation during graded exercise to exhaustion in highly trained individuals. Key words: arterial oxygen saturation, endurance athletes, maximal exercise

scholarly journals Physiological determinants of the increase in oxygen consumption during exercise in individuals with stroke

2019 ◽  
Author(s):  
Kazuaki Oyake ◽  
Yasuto Baba ◽  
Nao Ito ◽  
Yuki Suda ◽  
Jun Murayama ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Tidal Volume ◽  
Cardiorespiratory Fitness ◽  
Ventilatory Threshold ◽  
Peak Exercise ◽  
Cardiorespiratory Response ◽  
Graded Exercise ◽  
Response To Exercise ◽  
Oxygen Difference

AbstractBackgroundUnderstanding the physiological limitations of the increase in oxygen consumption (V̇O2) during exercise is essential to improve cardiorespiratory fitness in individuals with stroke. However, the physiological determinants of the increase in V̇O2 during exercise have not been examined using multivariate analysis in individuals with stroke. This study aimed to identify the physiological determinants of the increase in V̇O2 during a graded exercise in terms of the respiratory function, cardiac function, and ability of skeletal muscles to extract oxygen.MethodsEighteen individuals with stroke (60.1 ± 9.4 years of age, 67.1 ± 30.8 days poststroke) underwent a graded exercise test for the assessment of cardiorespiratory response to exercise. The increase in V̇O2 from rest to ventilatory threshold and that from rest to peak exercise were measured as a dependent variable. The increases in respiratory rate, tidal volume, heart rate, stroke volume, and arterial-venous oxygen difference from rest to ventilatory threshold and those from rest to peak exercise were measured as independent variables.ResultsFrom rest to ventilatory threshold, the increases in heart rate (β = 0.546) and arterial-venous oxygen difference (β = 0.398) were significant determinants of the increase in V̇O2 (adjusted R2 = 0.703, p < 0.001). From rest to peak exercise, the increases in tidal volume (β = 0.611) and heart rate (β = 0.353) were significant determinants of the increase in V̇O2 (adjusted R2 = 0.702, p < 0.001).ConclusionV̇O2 is well-known to increase nearly linearly with increasing heart rate; however, our results suggest that arterial-venous oxygen difference and tidal volume are also significant physiological determinants of the increase in V̇O2 from rest to ventilatory threshold and that from rest to peak exercise, respectively. Our findings could potentially contribute to the development of appropriate therapies to improve cardiorespiratory fitness in individuals with stroke.

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