Gas Exchange Responses to Constant Work-Rate Exercise in Patients with Glycogenosis Type V and VII

2004 ◽  
Vol 169 (11) ◽  
pp. 1238-1244 ◽  
Author(s):  
Hean-Yee Ong ◽  
Conor S. O'Dochartaigh ◽  
Sharon Lovell ◽  
Victor H. Patterson ◽  
Karlman Wasserman ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Work Rate ◽  
Constant Work Rate ◽  
Glycogenosis Type ◽  
Type V

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.

scholarly journals Gas exchange responses to constant work rate exercise in chronic cardiac failure.

Heart ◽  
1994 ◽  
Vol 72 (2) ◽  
pp. 150-155 ◽  
Author(s):  
M Riley ◽  
J Porszasz ◽  
C F Stanford ◽  
D P Nicholls
Keyword(s):  
Gas Exchange ◽  
Cardiac Failure ◽  
Work Rate ◽  
Chronic Cardiac Failure ◽  
Constant Work Rate

Measurement of the maximum oxygen uptake V̇o2max: V̇o2peak is no longer acceptable

2017 ◽  
Vol 122 (4) ◽  
pp. 997-1002 ◽  
Author(s):  
David C. Poole ◽  
Andrew M. Jones
Keyword(s):  
Gas Exchange ◽  
Exercise Test ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Work Rate ◽  
Experimental Investigations ◽  
Maximal Heart Rate ◽  
Constant Work Rate ◽  
Rate Test ◽  
Oxidative Function

The maximum rate of O2 uptake (i.e., V̇o2max), as measured during large muscle mass exercise such as cycling or running, is widely considered to be the gold standard measurement of integrated cardiopulmonary-muscle oxidative function. The development of rapid-response gas analyzers, enabling measurement of breath-by-breath pulmonary gas exchange, has facilitated replacement of the discontinuous progressive maximal exercise test (that produced an unambiguous V̇o2-work rate plateau definitive for V̇o2max) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investigations and enables measurement of the gas exchange threshold, exercise efficiency, and V̇o2 kinetics, a V̇o2-work rate plateau is not an obligatory outcome. This shortcoming has led to investigators resorting to so-called secondary criteria such as respiratory exchange ratio, maximal heart rate, and/or maximal blood lactate concentration, the acceptable values of which may be selected arbitrarily and result in grossly inaccurate V̇o2max estimation. Whereas this may not be an overriding concern in young, healthy subjects with experience of performing exercise to volitional exhaustion, exercise test naïve subjects, patient populations, and less motivated subjects may stop exercising before their V̇o2max is reached. When V̇o2max is a or the criterion outcome of the investigation, this represents a major experimental design issue. This CORP presents the rationale for incorporation of a second, constant work rate test performed at ~110% of the work rate achieved on the initial ramp test to resolve the classic V̇o2-work rate plateau that is the unambiguous validation of V̇o2max. The broad utility of this procedure has been established for children, adults of varying fitness, obese individuals, and patient populations.

scholarly journals Control of ventilation during exercise in patients with central venous-to-systemic arterial shunts

1988 ◽  
Vol 64 (1) ◽  
pp. 234-242 ◽  
Author(s):  
K. E. Sietsema ◽  
D. M. Cooper ◽  
J. K. Perloff ◽  
J. S. Child ◽  
M. H. Rosove ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Minute Ventilation ◽  
Venous Blood ◽  
Work Rate ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Arterial Circulation ◽  
Arterial Blood ◽  
Constant Work Rate ◽  
End Tidal

The diversion of systemic venous blood into the arterial circulation in patients with intracardiac right-to-left shunts represents a pathophysiological condition in which there are alterations in some of the potential stimuli for the exercise hyperpnea. We therefore studied 18 adult patients with congenital (16) or noncongenital (2) right-to-left shunts and a group of normal control subjects during constant work rate and progressive work rate exercise to assess the effects of these alterations on the dynamics of exercise ventilation and gas exchange. Minute ventilation (VE) was significantly higher in the patients than in the controls, both at rest (10.7 +/- 2.4 vs. 7.5 +/- 1.2 l/min, respectively) and during constant-load exercise (24.9 +/- 4.8 vs. 12.7 +/- 2.61 l/min, respectively). When beginning constant work rate exercise from rest, the ventilatory response of the patients followed a pattern that was distinct from that of the normal subjects. At the onset of exercise, the patients' end-tidal PCO2 decreased, end-tidal PO2 increased, and gas exchange ratio increased, indicating that pulmonary blood was hyperventilated relative to the resting state. However, arterial blood gases, in six patients in which they were measured, revealed that despite the large VE response to exercise, arterial pH and PCO2 were not significantly different from resting values when sampled during the first 2 min of moderate-intensity exercise. Arterial PCO2 changed by an average of only 1.4 Torr after 4.5-6 min of exercise. Thus the exercise-induced alveolar and pulmonary capillary hypocapnia was of an appropriate degree to compensate for the shunting of CO2-rich venous blood into the systemic arterial circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative Measurement Properties of Constant Work-Rate Cycling and Endurance Shuttle Walking in Patients with COPD: Data from the TORRACTO Study

Pneumologie ◽  
2018 ◽  
Vol 72 (S 01) ◽  
pp. S90-S90
Author(s):  
K Siemon ◽  
F Maltais ◽  
DE O'Donnell ◽  
A Hamilton ◽  
Y Zhao ◽  
...  
Keyword(s):  
Work Rate ◽  
Measurement Properties ◽  
Comparative Measurement ◽  
Constant Work Rate

Muscle fatigue and exhaustion during dynamic leg exercise in normoxia and hypobaric hypoxia

1996 ◽  
Vol 81 (5) ◽  
pp. 1891-1900 ◽  
Author(s):  
Charles S. Fulco ◽  
Steven F. Lewis ◽  
Peter N. Frykman ◽  
Robert Boushel ◽  
Sinclair Smith ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Hypobaric Hypoxia ◽  
Knee Extension ◽  
Work Rate ◽  
Dynamic Exercise ◽  
Time To Exhaustion ◽  
Electromyographic Activity ◽  
Constant Work Rate ◽  
Generating Capacity ◽  
Leg Exercise

Fulco, Charles S., Steven F. Lewis, Peter N. Frykman, Robert Boushel, Sinclair Smith, Everett A. Harman, Allen Cymerman, and Kent B. Pandolf. Muscle fatigue and exhaustion during dynamic leg exercise in normoxia and hypobaric hypoxia. J. Appl. Physiol. 81(5): 1891–1900, 1996.—Using an exercise device that integrates maximal voluntary static contraction (MVC) of knee extensor muscles with dynamic knee extension, we compared progressive muscle fatigue, i.e., rate of decline in force-generating capacity, in normoxia (758 Torr) and hypobaric hypoxia (464 Torr). Eight healthy men performed exhaustive constant work rate knee extension (21 ± 3 W, 79 ± 2 and 87 ± 2% of 1-leg knee extension O2 peak uptake for normoxia and hypobaria, respectively) from knee angles of 90–150° at a rate of 1 Hz. MVC (90° knee angle) was performed before dynamic exercise and during ≤5-s pauses every 2 min of dynamic exercise. MVC force was 578 ± 29 N in normoxia and 569 ± 29 N in hypobaria before exercise and fell, at exhaustion, to similar levels (265 ± 10 and 284 ± 20 N for normoxia and hypobaria, respectively; P > 0.05) that were higher ( P < 0.01) than peak force of constant work rate knee extension (98 ± 10 N, 18 ± 3% of MVC). Time to exhaustion was 56% shorter for hypobaria than for normoxia (19 ± 5 vs. 43 ± 7 min, respectively; P < 0.01), and rate of right leg MVC fall was nearly twofold greater for hypobaria than for normoxia (mean slope = −22.3 vs. −11.9 N/min, respectively; P < 0.05). With increasing duration of dynamic exercise for normoxia and hypobaria, integrated electromyographic activity during MVC fell progressively with MVC force, implying attenuated maximal muscle excitation. Exhaustion, per se, was postulated to relate more closely to impaired shortening velocity than to failure of force-generating capacity.

Muscle metabolic responses to exercise above and below the “critical power” assessed using 31P-MRS

2008 ◽  
Vol 294 (2) ◽  
pp. R585-R593 ◽  
Author(s):  
Andrew M. Jones ◽  
Daryl P. Wilkerson ◽  
Fred DiMenna ◽  
Jonathan Fulford ◽  
David C. Poole
Keyword(s):  
Critical Power ◽  
Quadriceps Muscle ◽  
High Energy ◽  
Knee Extension ◽  
Work Rate ◽  
Metabolic Responses ◽  
Time To Exhaustion ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Constant Work Rate

We tested the hypothesis that the asymptote of the hyperbolic relationship between work rate and time to exhaustion during muscular exercise, the “critical power” (CP), represents the highest constant work rate that can be sustained without a progressive loss of homeostasis [as assessed using 31P magnetic resonance spectroscopy (MRS) measurements of muscle metabolites]. Six healthy male subjects initially completed single-leg knee-extension exercise at three to four different constant work rates to the limit of tolerance (range 3–18 min) for estimation of the CP (mean ± SD, 20 ± 2 W). Subsequently, the subjects exercised at work rates 10% below CP (<CP) for 20 min and 10% above CP (>CP) for as long as possible, while the metabolic responses in the contracting quadriceps muscle, i.e., phosphorylcreatine concentration ([PCr]), Pi concentration ([Pi]), and pH, were estimated using 31P-MRS. All subjects completed 20 min of <CP exercise without duress, whereas the limit of tolerance during >CP exercise was 14.7 ± 7.1 min. During <CP exercise, stable values for [PCr], [Pi], and pH were attained within 3 min after the onset of exercise, and there were no further significant changes in these variables (end-exercise values = 68 ± 11% of baseline [PCr], 314 ± 216% of baseline [Pi], and pH 7.01 ± 0.03). During >CP exercise, however, [PCr] continued to fall to the point of exhaustion and [Pi] and pH changed precipitously to values that are typically observed at the termination of high-intensity exhaustive exercise (end-exercise values = 26 ± 16% of baseline [PCr], 564 ± 167% of baseline [Pi], and pH 6.87 ± 0.10, all P < 0.05 vs. <CP exercise). These data support the hypothesis that the CP represents the highest constant work rate that can be sustained without a progressive depletion of muscle high-energy phosphates and a rapid accumulation of metabolites (i.e., H+ concentration and [Pi]), which have been associated with the fatigue process.

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