Mechanistic basis for the gas exchange threshold in Thoroughbred horses

2002 ◽  
Vol 92 (4) ◽  
pp. 1499-1505 ◽  
Author(s):  
Paul McDonough ◽  
Casey A. Kindig ◽  
Howard H. Erickson ◽  
David C. Poole
Keyword(s):  
Gas Exchange ◽  
Ventilatory Threshold ◽  
Healthy Humans ◽  
Thoroughbred Horses ◽  
Ventilatory Equivalent ◽  
Mechanistic Basis ◽  
Cardiopulmonary Performance ◽  
The Relationship ◽  
Peak Blood ◽  
Gas Exchange Threshold

The exercising Thoroughbred horse (TB) is capable of exceptional cardiopulmonary performance. However, because the ventilatory equivalent for O2(V˙e/V˙o 2) does not increase above the gas exchange threshold (Tge), hypercapnia and hypoxemia accompany intense exercise in the TB compared with humans, in whom V˙e/V˙o 2 increases during supra-Tge work, which both removes the CO2 produced by the HCO[Formula: see text] buffering of lactic acid and prevents arterial partial pressure of CO2 (PaCO2 ) from rising. We used breath-by-breath techniques to analyze the relationship between CO2 output (V˙co 2) andV˙o 2 [V-slope lactate threshold (LT) estimation] during an incremental test to fatigue (7 to ∼15 m/s; 1 m · s−1 · min−1) in six TB. Peak blood lactate increased to 29.2 ± 1.9 mM/l. However, as neither V˙e/V˙o 2 norV˙e/V˙co 2 increased, PaCO2 increased to 56.6 ± 2.3 Torr at peakV˙o 2(V˙o 2 max). Despite the presence of a relative hypoventilation (i.e., no increase inV˙e/V˙o 2 orV˙e/V˙co 2), a distinct Tge was evidenced at 62.6 ± 2.7%V˙o 2 max. Tge occurred at a significantly higher ( P < 0.05) percentage ofV˙o 2 max than the lactate (45.1 ± 5.0%) or pH (47.4 ± 6.6%) but not the bicarbonate (65.3 ± 6.6%) threshold. In addition, PaCO2 was elevated significantly only at a workload > Tge. Thus, in marked contrast to healthy humans, pronounced V-slope (↑V˙co 2/V˙o 2) behavior occurs in TB concomitant with elevated PaCO2 and without evidence of a ventilatory threshold.

Spleen Emptying Does Not Correlate With Faster Oxygen Kinetics During a Step-Transition Supine Cycling

2021 ◽  
Author(s):  
Damir Zubac ◽  
Ante Obad ◽  
Ana Bosnjak ◽  
Mirela Zec ◽  
Vladimir Ivancev ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Power Output ◽  
Spleen Volume ◽  
Volume Changes ◽  
V̇o2 Kinetics ◽  
Oxygen Kinetics ◽  
Ultrasonic Measurements ◽  
Step Transition ◽  
The Relationship ◽  
Gas Exchange Threshold

This manuscript quantified spleen volume changes and examined the relationship between those changes and V̇O2 kinetics during supine cycling. Ten volunteers (age=22±3), completed three step-transitions from 20 W to their power output at 90% gas exchange threshold. Ultrasonic measurements of the spleen were performed each minute. The largest spleen volume reduction was 105 mL (p=.001). No associations existed between: i) spleen volumes at rest ii) spleen volume changes (%) and τV̇O2p. Larger resting spleen volume and greater emptying do not correlate with a faster τV̇O2p. Novelty: • Greater splenic contractions do not augment τV̇O2p, irrespective of spleen emptying and subsequent erythrocyte release.

scholarly journals Absolute Accelerometer-Based Intensity Prescription Compared to Physiological Variables in Pregnant and Nonpregnant Women

2020 ◽  
Vol 17 (16) ◽  
pp. 5651
Author(s):  
Philipp Birnbaumer ◽  
Pavel Dietz ◽  
Estelle Dorothy Watson ◽  
Gudani Mukoma ◽  
Alexander Müller ◽  
...  
Keyword(s):  
Ventilatory Threshold ◽  
Resting Metabolic Rate ◽  
Moderate Intensity ◽  
Cut Points ◽  
Physiological Variables ◽  
Metabolic Equivalents ◽  
Ventilatory Equivalent ◽  
Ventilatory Parameters ◽  
Accelerometer Cut Points ◽  
The Relationship

Estimation of the intensity of physical activity (PA) based on absolute accelerometer cut points (Cp) likely over- or underestimates intensity for a specific individual. The purpose of this study was to investigate the relationship between absolute moderate intensity Cp and the first ventilatory threshold (VT1). A group of 24 pregnant and 15 nonpregnant women who performed a submaximal incremental walking test with measures of ventilatory parameters and accelerations from three different accelerometers on the wrist (ActiGraph wGT3X-BT, GENEActiv, Axivity AX3) and one on the hip (Actigraph wGT3X-BT) were analyzed. Cp were determined corresponding to 3 metabolic equivalents of task (MET), using the conventional MET definition (Cp3.5) (3.5 mL/kg×min) and individual resting metabolic rate (Cpind). The ventilatory equivalent (VE/VO2) was used to determine VT1. Accelerations at VT1 were significantly higher (p < 0.01) compared to Cp3.5 and Cpind in both groups. Cp3.5 and Cpind were significantly different in nonpregnant (p < 0.01) but not in pregnant women. Walking speed at VT1 (5.7 ± 0.5/6.2 ± 0.8 km/h) was significantly lower (p < 0.01) in pregnant compared to nonpregnant women and correspondent to 3.8 ± 0.7/4.9 ± 1.4 conventional METs. Intensity at absolute Cp was lower compared to the intensity at VT1 independent of the device or placement in pregnant and nonpregnant women. Therefore, we recommend individually tailored cut points such as the VT1 to better assess the effect of the intensity of PA.

scholarly journals PO-096 Correlation between Muscle oxygen and Cardiopulmonary of young cyclists at Ventilation threshold

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
Peng Ge ◽  
Bing-hong Gao
Keyword(s):  
Heart Rate ◽  
Gas Exchange ◽  
Oxygen Saturation ◽  
Ventilatory Threshold ◽  
Vastus Lateralis ◽  
Minute Ventilation ◽  
Lower Extremities ◽  
Muscle Oxygen ◽  
Muscle Deoxygenation ◽  
The Relationship

Objective To investigate the relationship between Near-infrared spectroscopy (NIRS)-derived muscle oxygen saturation (SmO2) and Cardiopulmonary indexes at the Ventilatory threshold (VT1 and VT2) during Cardiopulmonary exercise test (CPET) ofyoung cyclists. Methods 12 young cyclists performed a maximal incremental exercise test to exhaustion on a friction-braked cycle ergometer (Monark 839E, Sweden).Heart rate (Polar RS400, Finland) and respiratory gas exchange were measured during the Resting and exercise phases using a breath-by-breath system. SmO2 of active muscles during cycling was measured by NIRS monitors (Fortiori Design LLC, USA), and three of the monitors were placed on both vastus lateralis (VLL & VLR) and left gastrocnemius lateralis (GLL) of left leg. The resting value of the SmO2 of the GLL (SmO2-GLL), the left vastus lateralis (SmO2-VLL), and the right vastus lateralis (SmO2-VLR) was recorded as a baseline.  Then after VT1 and VT2 of each subject were measured by the V-slope method during a CPET, values of muscle oxygen corresponding to the three lower limb sites at two ventilation thresholds was recorded to reflect the muscle oxygenation level at the anaerobic threshold; And the change of muscle oxygen relative to the baseline was calculated to reflect the degree of muscle deoxygenation, which is termed as deoxygenation indexes(ΔSmO2-GLL, ΔSmO2-VLL, ΔSmO2-VLR); As well, Cardiopulmonary indexes including Heart rate (HR), Minute ventilation (VE), Relative oxygen uptake (VO2R), Carbon dioxide production (VCO2) and Respiratory exchange rate (RER) at the Ventilatory threshold were measured. All Results were expressed as mean ± standard deviation. Finally, Pearson correlation analysis was used to determine the relationship between multi-site muscle oxygen saturation of lower extremities and Cardiopulmonary indexes (HR, VE, VO2R, VCO2, RER). The significance level was defined as p<0.05. Results Each subject performed their best to complete the aerobic capacity test. The average VO2peak of the 12 subjects was 42.77 ± 9.69 ml/kg/min (Male: 47.38 ± 9.41 ml/kg/min; Female: 36.31 ± 3.33 ml/kg/min). At rest, the calf and thigh SmO2 were 67.92%± 6.84% (SmO2-GLL), 61.42% ± 13.77% (SmO2-VLL), 64.83% ± 10.62% (SmO2-VLR)respectively; HR, VE, VO2, VO2R, VCO2 and RER were 112.08 ± 14.38, 25.96 ± 8.74 L / min 0.94 ± 0.32 L/min, 15.82 ± 4.30 ml/kg/min, 0.81 ± 0.24 L/min,0.88 ± 0.12 L/min, and 0.38 ± 0.07, respectively. Correlation analysis shows that when adolescent athletes reached the anaerobic threshold level, there was a significant correlation between muscle oxygen and cardiopulmonary: At the time of VT1, for Oxygenation index, SmO2 of GLL was highly negatively correlated with HR (r=-0.69,p<0.05), VE (r=-0.71, p<0.01), VO2R (r=-0.65, p<0.05), VCO2 (r=-0.66, p<0.05) and RER (r=-0.58, p<0.05); SmO2-VLL was also highly negatively correlated with VE (r=-0.70, p<0.05), VO2R (r=-0.70, p<0.05), VCO2 (r=-0.66, p<0.05); Additionally, there is also high inverse correlation between SmO2-VLR and HR (r=-0.66, p<0.05), VE (r=-0.70, p<0.05), VO2R (r=-0.66, p<0.05), VCO2 (r=-0.68, p<0.05), RER (r=-0.60, p<0.05). In terms of deoxygenation indexes, ΔSmO2-GLL was highly negatively correlated with VE (r=-0.61, p<0.05), VO2R  (r=-0.64, p<0.05) and VCO2 (r=-0.59, p<0.05); While, ΔSmO­2-VLL was highly negatively correlated with HR (r=-0.62, p<0.05), VE (r=-0.72, p<0.01),VO2R (r=-0.80, p<0.01) and VCO2(r=-0.84, p<0.01); ΔSmO2-VLR was correlated with HR (r=-0.75, p<0.01), VE (r=-0.62, p<0.05), VO2R (r=-0.58, p<0.05) and RER (r=-0.74, p<0.01), and it also shows highly negative correlation. When VT2 occurred, only SmO2 of the GLL in the oxygenation indexes was highly positively correlated with HR (r=0.65, p<0.05), there was no correlation between GLL-SmO2 and any other gas exchange indexes. In terms of muscle deoxygenation indexes, only ΔSmO2 in the thigh VLR was significantly negatively correlated with RER (r=-0.75, p<0.01). Conclusions Based on these results, there is a high correlation between NIRS-derived regional muscle oxygen saturation (Oxygenation and Deoxygenation indexes) of lower extremities and cardiopulmonary index (HR, VE, VO2R, VCO2, RER) during CPET of young cyclists at first Ventilatory threshold, however, it is still unclear whether there is a significant correlation between muscle oxygen saturation of lower extremities and other cardiopulmonary indexes when second Ventilatory threshold occurs except Heart rate or Minute ventilation.

Relationship of critical speed derived from a 10-minute submaximal treadmill test to 5-km and 10-km running performances

2021 ◽  
Author(s):  
Lucio Follador ◽  
Edilson Fernando de Borba ◽  
Sergio Gregorio da Silva
Keyword(s):  
Critical Speed ◽  
Ventilatory Threshold ◽  
Strong Relationship ◽  
Treadmill Test ◽  
Speed Test ◽  
Practical Performance ◽  
Recreational Runners ◽  
Relationship Of ◽  
The Relationship ◽  
Gas Exchange Threshold

It has been shown that the critical speed (CS) predicted from a perceptually self-regulated 10-min submaximal treadmill test (T10) is reliable and closely matches the CS estimated from conventional methods. To assess the relationship between the T10 and 5-km and 10-km running performances, 36 recreational runners (mean SD: age: 32.2 ± 6.2 years, height: 173.2 ± 7.3 cm, weight: 70.9 ± 8.8 kg, V̇O2max: 53.3 ± 6.1 mL.kg-1.min-1) performed a ramp incremental test and two T10 tests (the first as a familiarization trial). Results showed that the T10 CS (3.9 ± 0.44 m.s-1) was significantly correlated with runners’ last 6 months best performances in 5-km (20.3 ± 2.7 min; r = -0.90) and 10-km (42.7 ± 5.7 min; r = -0.91), the V̇O2max (r = 0.75), the speed associated with the gas exchange threshold (vGET: 3.38 ± 0.36 m.s-1; r = 0.76), the speed associated with the second ventilatory threshold (vVT2: 4.15 ± 0.49 m.s-1; r = 0.84), and the speed associated with the V̇O2max (vV̇O2max: 4.78 ± 0.54 m.s-1; r = 0.87). Moreover, 79% and 83% of the variance in 5-km and 10-km performances could be explained solely by the CS predicted from the T10. Results evidenced the strong relationship and practical performance relevance of the T10 CS test. Novelty: • Critical speed derived from a 10-min submaximal treadmill test (T10) is significantly correlated with 5-km and 10-km running performances • The T10 critical speed test may represent a useful tool for assessing running performance capabilities

Ventilatory threshold is related to walking tolerance in patients with intermittent claudication

VASA ◽  
2012 ◽  
Vol 41 (4) ◽  
pp. 275-281 ◽  
Author(s):  
da Rocha Chehuen ◽  
G. Cucato ◽  
P. dos Anjos Souza Barbosa ◽  
A. R. Costa ◽  
M. Ritti-Dias ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Intermittent Claudication ◽  
Lower Limb ◽  
Ventilatory Threshold ◽  
Reactive Hyperemia ◽  
Ankle Brachial Index ◽  
Metabolic Parameters ◽  
Walking Distance ◽  
The Relationship

Background: This study assessed the relationship between lower limb hemodynamics and metabolic parameters with walking tolerance in patients with intermittent claudication (IC). Patients and methods: Resting ankle-brachial index (ABI), baseline blood flow (BF), BF response to reactive hyperemia (BFRH), oxygen uptake (VO2), initial claudication distance (ICD) and total walking distance (TWD) were measured in 28 IC patients. Pearson and Spearman correlations were calculated. Results: ABI, baseline BF and BF response to RH did not correlate with ICD or TWD. VO2 at first ventilatory threshold and VO2peak were significantly and positively correlated with ICD (r = 0.41 and 0.54, respectively) and TWD (r = 0.65 and 0.71, respectively). Conclusions: VO2peak and VO2 at first ventilatory threshold, but not ABI, baseline BF and BFHR were associated with walking tolerance in IC patients. These results suggest that VO2 at first ventilatory threshold may be useful to evaluate walking tolerance and improvements in IC patients.

Influence of Selected Endomycorrhizae from the Sonoran Desert and Glomus intraradices on Growth Response and Gas Exchange of Hibiscus rosa-sinensis L. cv. Leprechaun

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 501d-501
Author(s):  
Jonathan N. Egilla ◽  
Fred T. Davies
Keyword(s):  
Gas Exchange ◽  
Sonoran Desert ◽  
Growth Response ◽  
Glomus Intraradices ◽  
Root Colonization ◽  
Gas Exchange Parameters ◽  
Hibiscus Rosa Sinensis ◽  
Low Phosphorus ◽  
The Relationship ◽  
Exchange Parameters

Six endomycorrhiza isolates from the Sonoran Desert of Mexico [Desert-14(18)1, 15(9)1, 15(15)1, Palo Fierro, Sonoran, and G. geosporum] were evaluated with a pure isolate of Glomus intraradices for their effect on the growth and gas exchange of Hibiscus rosa-sinensis L. cv. Leprechaun under low phosphorus fertility (11 mg P/L). Rooted cuttings of Hibiscus plants were inoculated with the seven mycorrhiza isolates and grown for 122 days. Gas exchange measurements were made on days 26, 88, and 122 after inoculation, and plants were harvested on day 123 for growth analysis. Plants inoculated with the seven isolates had 70% to 80% root colonization at harvest. Plants inoculated with G. intraradices had significantly higher leaf, shoot and root dry matter (DM), leaf DM/area (P ≤ 0.05) than those inoculated with any of the six isolates, and greater leaf area (LA) than Desert-15(9)1 and 15(15)1. Uninoculated plants had significantly lower leaf, shoot, root DM, leaf DM/area and LA (P ≤ 0.05) than the inoculated plants. There were no differences among the seven isolates in any of the gas exchange parameters measured [photosynthesis (A) stomatal conductance (gs), the ratio of intercellular to external CO2 (ci/ca), A to transpiration (E) ratio (A/E)]. The relationship between inoculated and uninoculated plants in these gas exchange parameters were variable on day 122 after inoculation.

Gas Exchange Threshold in Male Speed–Power versus Endurance Athletes Ages 20–90 Years

2012 ◽  
Vol 44 (12) ◽  
pp. 2415-2422 ◽  
Author(s):  
KRZYSZTOF KUSY ◽  
MAGDALENA KRÓL-ZIELIŃSKA ◽  
KATARZYNA DOMASZEWSKA ◽  
JAKUB KRYŚCIAK ◽  
TOMASZ PODGÓRSKI ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Endurance Athletes ◽  
Gas Exchange Threshold

scholarly journals A Rapidly-Incremented Tethered-Swimming Test for Defining Domain-Specific Training Zones

2017 ◽  
Vol 57 (1) ◽  
pp. 117-128
Author(s):  
Dalton M. Pessôa Filho ◽  
Leandro O.C. Siqueira ◽  
Astor R. Simionato ◽  
Mário A.C. Espada ◽  
Daniel S. Pestana ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Work Rate ◽  
Metabolic Rates ◽  
Incremental Test ◽  
Domain Specific ◽  
Respiratory Compensation ◽  
Exercise Economy ◽  
Constant Work Rate ◽  
Swimming Test ◽  
Gas Exchange Threshold

AbstractThe purpose of this study was to investigate whether a tethered-swimming incremental test comprising small increases in resistive force applied every 60 seconds could delineate the isocapnic region during rapidly-incremented exercise. Sixteen competitive swimmers (male, n = 11; female, n = 5) performed: (a) a test to determine highest force during 30 seconds of all-out tethered swimming (Favg) and the ΔF, which represented the difference between Favg and the force required to maintain body alignment (Fbase), and (b) an incremental test beginning with 60 seconds of tethered swimming against a load that exceeded Fbase by 30% of ΔF followed by increments of 5% of ΔF every 60 seconds. This incremental test was continued until the limit of tolerance with pulmonary gas exchange (rates of oxygen uptake and carbon dioxide production) and ventilatory (rate of minute ventilation) data collected breath by breath. These data were subsequently analyzed to determine whether two breakpoints defining the isocapnic region (i.e., gas exchange threshold and respiratory compensation point) were present. We also determined the peak rate of O2 uptake and exercise economy during the incremental test. The gas exchange threshold and respiratory compensation point were observed for each test such that the associated metabolic rates, which bound the heavy-intensity domain during constant-work-rate exercise, could be determined. Significant correlations (Spearman’s) were observed for exercise economy along with (a) peak rate of oxygen uptake (ρ = .562; p < 0.025), and (b) metabolic rate at gas exchange threshold (ρ = −.759; p < 0.005). A rapidly-incremented tethered-swimming test allows for determination of the metabolic rates that define zones for domain-specific constant-work-rate training.

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