Effects of the self-contained breathing apparatus on left-ventricular function at rest and during graded exercise

2009 ◽  
Vol 34 (4) ◽  
pp. 625-631 ◽  
Author(s):  
Jonathan R. Mayne ◽  
Mark J. Haykowsky ◽  
Michael D. Nelson ◽  
Timothy C. Hartley ◽  
Scott J. Butcher ◽  
...  
Keyword(s):  
Free Breathing ◽  
Esophageal Pressure ◽  
Left Ventricular ◽  
The Self ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Lv Function ◽  
Moderate Intensity Exercise ◽  
Similar Reduction ◽  
Breathing Apparatus

The purpose of this study was to examine the effects of the self-contained breathing apparatus (SCBA) on left-ventricular (LV) function at rest and during mild- to moderate-intensity exercise, using 2-dimensional echocardiography. Twenty-three healthy male volunteers exercised on a stair-climber at work rates equivalent to 50%, 60%, 70%, and 80% of peak oxygen consumption. Esophageal pressure LV diastolic and systolic cavity areas, and myocardial areas were acquired during the final minute of each stage of exercise. As expected, the esophageal pressure response during SCBA breathing revealed significantly lower (more negative) inspiratory pressures and higher (more positive) expiratory pressures and, consequently, higher pressure swings, than free breathing (FB). End-diastolic cavity area (EDCA) and end-systolic cavity area (ESCA) were lower with the SCBA than with FB. LV contractility was higher (p < 0.05) with the SCBA, which can partially be explained by decreases in end-systolic wall stress. Therefore, the SCBA was found to decrease LV preload during moderate-intensity exercise, but did not negatively affect stroke area because of a similar reduction in ESCA.

Effects of exercise training on LV performance and mortality in a murine model of dilated cardiomyopathy

2000 ◽  
Vol 279 (1) ◽  
pp. H210-H215 ◽  
Author(s):  
Kirk T. Spencer ◽  
Keith Collins ◽  
Claudia Korcarz ◽  
Richard Fentzke ◽  
Roberto M. Lang ◽  
...  
Keyword(s):  
Exercise Training ◽  
Dilated Cardiomyopathy ◽  
Murine Model ◽  
Cardiac Myocyte ◽  
Camp Response Element Binding ◽  
Left Ventricular ◽  
Dominant Negative ◽  
Moderate Intensity ◽  
Lv Function ◽  
Moderate Intensity Exercise

Dilated cardiomyopathy (DC) is a leading cause of cardiovascular morbidity, and nonpharmacological therapies, such as exercise training, have been suggested. The effects of exercise on left ventricular (LV) function and mortality remain controversial. Using a recently described murine model of DC, which involves a dominant-negative form of the cAMP response element binding protein (CREB) transcription factor (CREBA133) under the control of the cardiac myocyte-specific α-myosin heavy chain promoter, we sought to assess the effects of moderate-intensity exercise training on LV performance and mortality. Thirty-two transgenic mice were subjected to exercise training and compared with sedentary controls. There was progressive enlargement in LV dimensions in both the sedentary and exercise-trained mice. LV performance was progressively impaired, and exercise training did not prevent this decline. The sedentary CREBA133 mice displayed a significantly increased rate of death, and exercise training did not prevent or delay this excess mortality. The CREBA133 murine model of inherited DC demonstrated progressive ventricular dilatation and dysfunction with increased mortality, which was not altered with 12 wk of moderate-intensity exercise training.

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.

Substrate metabolism when subjects are fed carbohydrate during exercise

1999 ◽  
Vol 276 (5) ◽  
pp. E828-E835 ◽  
Author(s):  
Jeffrey F. Horowitz ◽  
Ricardo Mora-Rodriguez ◽  
Lauri O. Byerley ◽  
Edward F. Coyle
Keyword(s):  
Plasma Insulin ◽  
Fat Oxidation ◽  
Insulin Concentration ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Plasma Insulin Concentration ◽  
Carbohydrate Ingestion ◽  
Low Intensity ◽  
Low Intensity Exercise

This study determined the effect of carbohydrate ingestion during exercise on the lipolytic rate, glucose disappearance from plasma (Rd Glc), and fat oxidation. Six moderately trained men cycled for 2 h on four separate occasions. During two trials, they were fed a high-glycemic carbohydrate meal during exercise at 30 min (0.8 g/kg), 60 min (0.4 g/kg), and 90 min (0.4 g/kg); once during low-intensity exercise [25% peak oxygen consumption (V˙o 2 peak)] and once during moderate-intensity exercise (68%V˙o 2 peak). During two additional trials, the subjects remained fasted (12–14 h) throughout exercise at each intensity. After 55 min of low-intensity exercise in fed subjects, hyperglycemia (30% increase) and a threefold elevation in plasma insulin concentration ( P < 0.05) were associated with a 22% suppression of lipolysis compared with when subjects were fasted (5.2 ± 0.5 vs. 6.7 ± 1.2 μmol ⋅ kg−1 ⋅ min−1, P < 0.05), but fat oxidation was not different from fasted levels at this time. Fat oxidation when subjects were fed carbohydrate was not reduced below fasting levels until 80–90 min of exercise, and lipolysis was in excess of fat oxidation at this time. The reduction in fat oxidation corresponded in time with the increase in Rd Glc. During moderate-intensity exercise, the very small elevation in plasma insulin concentration (∼3 μU/ml; P < 0.05) during the second hour of exercise when subjects were fed vs. when they were fasted slightly attenuated lipolysis ( P < 0.05) but did not increase Rd Glc or suppress fat oxidation. These findings indicate that despite a suppression of lipolysis after carbohydrate ingestion during exercise, the lipolytic rate remained in excess and thus did not limit fat oxidation. Under these conditions, a reduction in fat oxidation was associated in time with an increase in glucose uptake.

Left atrial phasic function interacts to support left ventricular filling during exercise in healthy athletes

2015 ◽  
Vol 119 (4) ◽  
pp. 328-333 ◽  
Author(s):  
Steve Wright ◽  
Zion Sasson ◽  
Taylor Gray ◽  
Anjala Chelvanathan ◽  
Sam Esfandiari ◽  
...  
Keyword(s):  
Left Atrial ◽  
Left Ventricular ◽  
Moderate Intensity ◽  
Diastolic Filling ◽  
Moderate Exercise ◽  
Moderate Intensity Exercise ◽  
Longitudinal Contraction ◽  
Maximal Volume ◽  
Conduit Flow ◽  
Filling Time

We studied the contribution of phasic left atrial (LA) function to left ventricular (LV) filling during exercise. We hypothesized that reduced LV filling time at moderate-intensity exercise limits LA passive emptying and increases LA active emptying. Twenty endurance-trained males (55 ± 6 yr) were studied at rest and during light- (∼100 beats/min) and moderate-intensity (∼130 beats/min) exercise. Two-dimensional and Doppler echocardiography were used to assess phasic volumes and diastolic function. LV end-diastolic volume increased from rest to light exercise (54 ± 6 to 58 ± 5 ml/m2, P < 0.01) and from light to moderate exercise (58 ± 5 to 62 ± 6 ml/m2, P < 0.01). LA maximal volume increased from rest to light exercise (26 ± 4 to 30 ± 5 ml/m2, P < 0.01) related to atrioventricular plane displacement ( r = 0.55, P < 0.005), without further change at moderate exercise. LA passive emptying increased at light exercise (9 ± 2 to 13 ± 3 ml/m2, P < 0.01) and then returned to baseline at moderate exercise, whereas LA active emptying increased appreciably only at moderate exercise (6 ± 2 to 14 ± 3 ml/m2, P < 0.01). Thus, the total atrial emptying volume did not increase beyond light exercise, and the increase in LV filling at moderate exercise could be attributed primarily to an increase in the conduit flow volume (19 ± 3 to 25 ± 5 ml/m2, P < 0.01). LA filling increases during exercise in relation to augmented LV longitudinal contraction. Conduit flow increases progressively with exercise in athletes, although this is driven by LV properties rather than intrinsic LA function. The pump function of the LA augments only at moderate exercise due to a reduced diastolic filling time and the Frank-Starling mechanism.

scholarly journals Effect of Moderate-Intensity Exercise Training on Peak Oxygen Consumption in Patients With Hypertrophic Cardiomyopathy

JAMA ◽  
2017 ◽  
Vol 317 (13) ◽  
pp. 1349 ◽  
Author(s):  
Sara Saberi ◽  
Matthew Wheeler ◽  
Jennifer Bragg-Gresham ◽  
Whitney Hornsby ◽  
Prachi P. Agarwal ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Hypertrophic Cardiomyopathy ◽  
Exercise Training ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

scholarly journals Oxygen Cost of Recreational Horse-Riding in Females

2015 ◽  
Vol 12 (6) ◽  
pp. 808-813 ◽  
Author(s):  
Louisa Beale ◽  
Neil S Maxwell ◽  
Oliver R Gibson ◽  
Rosemary Twomey ◽  
Becky Taylor ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Cycle Ergometer ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Oxygen Cost ◽  
Metabolic Demand ◽  
Moderate Intensity Exercise ◽  
The Public ◽  
Horse Riding ◽  
Ergometer Exercise

Background:The purpose of this study was to characterize the physiological demands of a riding session comprising different types of recreational horse riding in females.Methods:Sixteen female recreational riders (aged 17 to 54 years) completed an incremental cycle ergometer exercise test to determine peak oxygen consumption (VO2peak) and a 45-minute riding session based upon a British Horse Society Stage 2 riding lesson (including walking, trotting, cantering and work without stirrups). Oxygen consumption (VO2), from which metabolic equivalent (MET) and energy expenditure values were derived, was measured throughout.Results:The mean VO2 requirement for trotting/cantering (18.4 ± 5.1 ml·kg-1·min-1; 52 ± 12% VO2peak; 5.3 ± 1.1 METs) was similar to walking/trotting (17.4 ± 5.1 ml·kg-1·min-1; 48 ± 13% VO2peak; 5.0 ± 1.5 METs) and significantly higher than for work without stirrups (14.2 ± 2.9 ml·kg-1·min-1; 41 ± 12% VO2peak; 4.2 ± 0.8 METs) (P = .001).Conclusion:The oxygen cost of different activities typically performed in a recreational horse riding session meets the criteria for moderate intensity exercise (3-6 METs) in females, and trotting combined with cantering imposes the highest metabolic demand. Regular riding could contribute to the achievement of the public health recommendations for physical activity in this population.

Training-induced alterations in fat and carbohydrate metabolism during exercise in elderly subjects

1998 ◽  
Vol 274 (5) ◽  
pp. E785-E790 ◽  
Author(s):  
Shahid Sial ◽  
Andrew R. Coggan ◽  
Robert C. Hickner ◽  
Samuel Klein
Keyword(s):  
Fatty Acid ◽  
Endurance Training ◽  
Average Rate ◽  
Fat Oxidation ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Elderly Subjects ◽  
Elderly Persons ◽  
Moderate Intensity Exercise ◽  
Significant Change

Compared with young adults, fat oxidation is lower in elderly persons during endurance exercise performed at either the same absolute or relative intensity. We evaluated the effect of 16 wk of endurance training on fat and glucose metabolism during 60 min of moderate intensity exercise [50% of pretraining peak oxygen consumption (V˙o2 peak)] in six elderly men and women (74 ± 2 yr). Training caused a 21% increase in meanV˙o2 peak. The average rate of fat oxidation during exercise was greater after (221 ± 28 μmol/min) than before (166 ± 17 μmol/min) training ( P = 0.002), and the average rate of carbohydrate oxidation during exercise was lower after (3,180 ± 461 μmol/min) than before (3,937 ± 483 μmol/min) training ( P = 0.003). Training did not cause a significant change in glycerol rate of appearance (Ra), free fatty acid (FFA) Ra, and FFA rate of disappearance during exercise. However, glucose Raduring exercise was lower after (1,027 ± 95 μmol/min) than before (1,157 ± 69 μmol/min) training ( P = 0.01). These results demonstrate that a 16-wk period of endurance training increases fat oxidation without a significant change in lipolysis (glycerol Ra) or FFA availability (FFA Ra) during exercise in elderly subjects. Therefore, the training-induced increase in fat oxidation during exercise is likely related to alterations in skeletal muscle fatty acid metabolism.

scholarly journals Exercise training improves systolic function in hypertensive myocardium

2011 ◽  
Vol 111 (6) ◽  
pp. 1637-1643 ◽  
Author(s):  
Joseph R. Libonati ◽  
Abdelkarim Sabri ◽  
Canhua Xiao ◽  
Scott M. MacDonnell ◽  
Brian F. Renna
Keyword(s):  
Exercise Training ◽  
Caspase 3 ◽  
Ex Vivo ◽  
Systolic Function ◽  
Systolic Dysfunction ◽  
Weight Ratio ◽  
Left Ventricular ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Phosphorylated Akt

The general purpose of this study was to test the effect of exercise training on the left ventricular (LV) pressure-volume relationship (LV/PV) and apoptotic signaling markers in normotensive and hypertensive hearts. Four-month-old female normotensive Wistar-Kyoto rats (WKY; n = 37) and spontaneously hypertensive rats (SHR; n = 38) were assigned to a sedentary (WKY-SED, n = 21; SHR-SED, n = 19) or treadmill-trained (WKY-TRD, n = 16; SHR-TRD, n = 19) group (∼60% V̇o2 peak, 60 min/day, 5 days/wk, 12 wk). Ex vivo LV/PV were established in isovolumic Langendorff-perfused hearts, and LV levels of Akt, phosphorylated Akt (AktPi), Bad, phosphorylated Bad (BadPi) c-IAP, x-IAP, calcineurin, and caspases 3, 8, and 9 were measured. Heart-to-body weight ratio was increased in SHR vs. WKY ( P < 0.05), concomitant with increased calcineurin mRNA ( P < 0.05). There was a rightward shift in the LV/PV ( P < 0.05) and a reduction in systolic elastance (Es) in SHR vs. WKY. Exercise training corrected Es in SHR ( P < 0.05) but had no effect on the LV/PV in WKY. Caspase 3 was increased in SHR-SED relative to WKY-SED, while BadPi, c-IAP, and x-IAP were significantly lower in SHR relative to WKY ( P < 0.05). Exercise training increased BadPi in both WKY and SHR but did not alter caspase 9 activity in either group. While caspase 3 activity was increased with training in WKY ( P < 0.05), it was unchanged with training in SHR. We conclude that moderate levels of regular aerobic exercise attenuate systolic dysfunction early in the compensatory phase of hypertrophy, and that a differential phenotypical response to moderate-intensity exercise exists between WKY and SHR.

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