Dynamic Adjustment Of Beat-by-beat Cardiac Output And Vo2 Kinetics During Moderate Intensity Exercise Transitions

2019 ◽  
Vol 51 (Supplement) ◽  
pp. 257-258
Author(s):  
Erin Calaine Inglis ◽  
Danilo Iannetta ◽  
Juan M. Murias
Keyword(s):  
Cardiac Output ◽  
Moderate Intensity ◽  
Dynamic Adjustment ◽  
Moderate Intensity Exercise ◽  
Vo2 Kinetics ◽  
Exercise Transitions

Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults

2012 ◽  
Vol 302 (10) ◽  
pp. R1158-R1166 ◽  
Author(s):  
Gabriela De Roia ◽  
Silvia Pogliaghi ◽  
Alessandra Adami ◽  
Christina Papadopoulou ◽  
Carlo Capelli
Keyword(s):  
Older Adults ◽  
Cardiac Output ◽  
Oxidative Metabolism ◽  
Functional Decline ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Healthy Older Adults ◽  
Speed Of Adjustment ◽  
Priming Exercise ◽  
Kinetics Of

Aging is associated with a functional decline of the oxidative metabolism due to progressive limitations of both O2 delivery and utilization. Priming exercise (PE) increases the speed of adjustment of oxidative metabolism during successive moderate-intensity transitions. We tested the hypothesis that such improvement is due to a better matching of O2 delivery to utilization within the working muscles. In 21 healthy older adults (65.7 ± 5 yr), we measured contemporaneously noninvasive indexes of the overall speed of adjustment of the oxidative metabolism (i.e., pulmonary V̇o2 kinetics), of the bulk O2 delivery (i.e., cardiac output), and of the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) during moderate-intensity step transitions, either with (ModB) or without (ModA) prior PE. The local matching of O2 delivery to utilization was evaluated by the ΔHHb/ΔV̇o2 ratio index. The overall speed of adjustment of the V̇o2 kinetics was significantly increased in ModB compared with ModA ( P < 0.05). On the contrary, the kinetics of cardiac output was unaffected by PE. At the muscle level, ModB was associated with a significant reduction of the “overshoot” in the ΔHHb/ΔV̇o2 ratio compared with ModA ( P < 0.05), suggesting an improved O2 delivery. Our data are compatible with the hypothesis that, in older adults, PE, prior to moderate-intensity exercise, beneficially affects the speed of adjustment of oxidative metabolism due to an acute improvement of the local matching of O2 delivery to utilization.

scholarly journals Cardiac output during exercise by the open circuit acetylene washin method: comparison with direct Fick

2000 ◽  
Vol 88 (5) ◽  
pp. 1650-1658 ◽  
Author(s):  
B. D. Johnson ◽  
K. C. Beck ◽  
D. N. Proctor ◽  
J. Miller ◽  
N. M. Dietz ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Method Comparison ◽  
Arterial Oxygen Tension ◽  
Open Circuit ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Arterial Oxygen ◽  
Computational Techniques ◽  
Moderate Intensity Exercise ◽  
End Tidal

An open-circuit (OpCirc) acetylene uptake cardiac output (Q˙t) method was modified for use during exercise. Two computational techniques were used. OpCirc1 was based on the integrated uptake vs. end-tidal change in acetylene, and OpCirc2 was based on an iterative finite difference modeling method. Six subjects [28–44 yr, peak oxygen consumption (V˙o 2) = 120% predicted] performed cycle ergometry exercise to compareQ˙t using OpCirc and direct Fick methods. An incremental protocol was repeated twice, separated by a 10-min rest, and subsequently subjects exercised at 85–90% of their peak work rate. Coefficient of variation of the OpCirc methods and Fick were highest at rest (OpCirc1, 7%, OpCirc2, 12%, Fick, 10%) but were lower at moderate to high exercise intensities (OpCirc1, 3%, OpCirc2, 3%, Fick, 5%). OpCirc1 and OpCirc2 Q˙t correlated highly with Fick Q˙t( R 2 = 0.90 and 0.89, respectively). There were minimal differences between OpCirc1 and OpCirc2 compared with Fick up to moderate-intensity exercise (<70% peakV˙o 2); however, both techniques tended to underestimate Fick at >70% peakV˙o 2. These differences became significant for OpCirc1 only. Part of the differences between Fick and OpCirc methods at the higher exercise intensities are likely related to inhomogeneities in ventilation and perfusion matching ( R 2 = 0.36 for Fick − OpCirc1 vs. alveolar-to-arterial oxygen tension difference). In conclusion, both OpCirc methods provided reproducible, reliable measurements ofQ˙t during mild to moderate exercise. However, only OpCirc2 appeared to approximate FickQ˙t at the higher work intensities.

The Effect of Hyperoxia on Slowed VO2 Kinetics In the Upper Region of Moderate-Intensity Exercise

2008 ◽  
Vol 40 (Supplement) ◽  
pp. S115
Author(s):  
Lisa M. K. Chin ◽  
P Jonathan Pace ◽  
Caitlin Symonette ◽  
Harry B. Rossiter ◽  
Donald H. Paterson ◽  
...  
Keyword(s):  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Vo2 Kinetics

Influence of phase I duration on phase II V̇o2 kinetics parameter estimates in older and young adults

2011 ◽  
Vol 301 (1) ◽  
pp. R218-R224 ◽  
Author(s):  
Juan M. Murias ◽  
Matthew D. Spencer ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Young Adults ◽  
Phase I ◽  
Phase Ii ◽  
Moderate Intensity ◽  
Parameter Estimates ◽  
Moderate Intensity Exercise ◽  
Kinetics Parameters ◽  
Exercise Transitions ◽  
The Individual ◽  
Kinetics Parameter

Older adults (O) may have a longer phase I pulmonary O2 uptake kinetics (V̇o2p) than young adults (Y); this may affect parameter estimates of phase II V̇o2p. Therefore, we sought to: 1) experimentally estimate the duration of phase I V̇o2p (EE phase I) in O and Y subjects during moderate-intensity exercise transitions; 2) examine the effects of selected phase I durations (i.e., different start times for modeling phase II) on parameter estimates of the phase II V̇o2p response; and 3) thereby determine whether slower phase II kinetics in O subjects represent a physiological difference or a by-product of fitting strategy. V̇o2p was measured breath-by-breath in 19 O (68 ± 6 yr; mean ± SD) and 19 Y (24 ± 5 yr) using a volume turbine and mass spectrometer. Phase I V̇o2p was longer in O (31 ± 4 s) than Y (20 ± 7 s) ( P < 0.05). In O, phase II τV̇o2p was larger ( P < 0.05) when fitting started at 15 s (49 ± 12 s) compared with fits starting at the individual EE phase I (43 ± 12 s), 25 s (42 ± 10 s), 35 s (42 ± 12 s), and 45 s (45 ± 15 s). In Y, τV̇o2p was not affected by the time at which phase II V̇o2p fitting started (τV̇o2p = 31 ± 7 s, 29 ± 9 s, 30 ± 10 s, 32 ± 11 s, and 30 ± 8 s for fittings starting at 15 s, 25 s, 35 s, 45 s, and EE phase I, respectively). Fitting from EE phase I, 25 s, or 35 s resulted in the smallest CI τV̇o2p in both O and Y. Thus, fitting phase II V̇o2p from (but not constrained to) 25 s or 35 s provides consistent estimates of V̇o2p kinetics parameters in Y and O, despite the longer phase I V̇o2p in O.

Muscle phosphocreatine kinetics in children and adults at the onset and offset of moderate-intensity exercise

2008 ◽  
Vol 105 (2) ◽  
pp. 446-456 ◽  
Author(s):  
Alan R. Barker ◽  
Joanne R. Welsman ◽  
Jonathan Fulford ◽  
Deborah Welford ◽  
Neil Armstrong
Keyword(s):  
Oxidative Phosphorylation ◽  
Moderate Intensity ◽  
Resonance Spectroscopy ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Moderate Intensity Exercise ◽  
Integral Role ◽  
Constant Work Rate ◽  
Exercise Transitions ◽  
Previous Demonstration ◽  
Kinetics Of

The splitting of muscle phosphocreatine (PCr) plays an integral role in the regulation of muscle O2 utilization during a “step” change in metabolic rate. This study tested the hypothesis that the kinetics of muscle PCr would be faster in children compared with adults both at the onset and offset of moderate-intensity exercise, in concert with the previous demonstration of faster phase II pulmonary O2 uptake kinetics in children. Eighteen peri-pubertal children (8 boys, 10 girls) and 16 adults (8 men, 8 women) completed repeated constant work-rate exercise transitions corresponding to 80% of the Pi/PCr intracellular threshold. The changes in quadriceps [PCr], [Pi], [ADP], and pH were determined every 6 s using 31P-magnetic resonance spectroscopy. No significant ( P > 0.05) age- or sex-related differences were found in the PCr kinetic time constant at the onset (boys, 21 ± 4 s; girls, 24 ± 5 s; men, 26 ± 9 s; women, 24 ± 7 s) or offset (boys, 26 ± 5 s; girls, 29 ± 7 s; men, 23 ± 9 s; women 29 ± 7 s) of exercise. Likewise, the estimated theoretical maximal rate of oxidative phosphorylation (Qmax) was independent of age and sex (boys, 1.39 ± 0.20 mM/s; girls, 1.32 ± 0.32 mM/s; men, 2.36 ± 1.18 mM/s; women, 1.51 ± 0.53 mM/s). These results are consistent with the notion that the putative phosphate-linked regulation of muscle O2 utilization is fully mature in peri-pubertal children, which may be attributable to a comparable capacity for mitochondrial oxidative phosphorylation in child and adult muscle.

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