scholarly journals Assessing Maximal Exercise Capacity: Peak Work or Peak Oxygen Consumption?

2013 ◽  
Vol 59 (1) ◽  
pp. 90-96 ◽  
Author(s):  
D. A. Kaminsky ◽  
A. Knyazhitskiy ◽  
A. Sadeghi ◽  
C. G. Irvin
Keyword(s):  
Oxygen Consumption ◽  
Exercise Capacity ◽  
Maximal Exercise ◽  
Peak Oxygen Consumption ◽  
Maximal Exercise Capacity

Maximal exercise capacity and oxygen consumption of lambs with an aortopulmonary left-to-right shunt

1990 ◽  
Vol 69 (4) ◽  
pp. 1479-1485 ◽  
Author(s):  
J. W. Gratama ◽  
J. J. Meuzelaar ◽  
M. Dalinghaus ◽  
J. H. Koers ◽  
A. J. Werre ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Exercise Capacity ◽  
Maximal Exercise ◽  
Left Ventricular ◽  
Peak Oxygen Consumption ◽  
Systemic Blood ◽  
Systemic Blood Flow ◽  
Ventricular Performance ◽  
Left Ventricular Output ◽  
Maximal Exercise Capacity

We determined maximal exercise capacity and measured hemodynamics in 10 6-wk-old lambs with an aortopulmonary left-to-right shunt [S, 57 +/- 11%, (SD)] and in 9 control lambs (C) during a graded treadmill test 8 days after surgery. Maximal exercise capacity (3.7 +/- 0.2 km/h and 10 +/- 5% inclination vs. 4.0 +/- 0.9 km/h and 15 +/- 0% inclination, P less than 0.02) and peak oxygen consumption (25 +/- 7 vs. 34 +/- 8 ml O2.min-1.kg-1, P less than 0.02) were both lower in the shunt than in the control lambs. This was due to a lower maximal systemic blood flow in the shunt lambs (271 +/- 38 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.01). Despite their high maximal left ventricular output, which was higher than in the control lambs (448 +/- 87 vs. 359 +/- 71 ml.min-1.kg-1, P less than 0.05), the left-to-right shunt could not be compensated for during maximal exercise because of a decreased reserve in heart rate (S: 183 +/- 22 to 277 +/- 38 beats/min; C: 136 +/- 25 to 287 +/- 29 beats/min) and in left ventricular stroke volume (S: 1.8 +/- 0.3 to 1.6 +/- 0.4 ml/kg; C: 1.0 +/- 0.3 to 1.3 +/- 0.2 ml/kg). We conclude that exercise capacity of shunt lambs is lower than that of control lambs, despite a good left ventricular performance, because a part of the reserves for increasing the left ventricular output is already utilized at rest.

GABAergic modulation of ventilation and peak oxygen consumption in obese Zucker rats

2001 ◽  
Vol 90 (5) ◽  
pp. 1707-1713 ◽  
Author(s):  
Shin-Da Lee ◽  
Hitoshi Nakano ◽  
Gaspar A. Farkas
Keyword(s):  
Exercise Capacity ◽  
Maximal Exercise ◽  
Peak Oxygen Consumption ◽  
Zucker Rats ◽  
Inhibitory Neurotransmitter ◽  
Endogenous Gaba ◽  
Obese Rats ◽  
Obese Zucker Rats ◽  
Gabaergic Modulation ◽  
Maximal Exercise Capacity

Obesity is often associated with a reduced ventilatory response and a decreased maximal exercise capacity. GABA is a major inhibitory neurotransmitter in the mammalian central nervous system. Altered GABAergic mechanisms have been detected in obese Zucker rats and implicated in their hyperphagic response. Whether altered GABAergic mechanisms also contribute to regulate ventilation and influence exercise capacity in obese Zucker rats is unknown and formed the basis of the present study. Eight lean [317 ± 18 (SD) g] and eight obese (450 ± 27 g) Zucker rats were studied at 12 wk of age. Ventilation at rest and ventilation during hypoxic (10% O2) and hypercapnic (4% CO2) challenges were measured by the barometric method. Peak O2 consumption (V˙o 2 peak) in response to a progressive treadmill test to exhaustion was measured in a metabolic treadmill. Ventilation and V˙o 2 peak were assessed after administration of equal volumes of DMSO (vehicle) and the GABAA receptor antagonist bicuculline (1 mg/kg). In lean animals, bicuculline administration had no effect on ventilation andV˙o 2 peak. In obese rats, bicuculline administration significantly ( P < 0.05) increased resting ventilation (465 ± 53 and 542 ± 72 ml · kg−1 · min−1 for control and bicuculline, respectively), ventilation during exposure to hypoxia (899 ± 148 and 1,038 ± 83 ml · kg−1 · min−1 for control and bicuculline, respectively), andV˙o 2 peak (62 ± 3.7 and 67 ± 3.5 ml · kg−0.75 · min−1 for control and bicuculline, respectively). However, in obese Zucker rats, ventilation in response to hypercapnia did not change after bicuculline administration (608 ± 96 vs. 580 ± 69 ml · kg−1 · min−1). Our findings indicate that endogenous GABA depresses ventilation and limits exercise performance in obese Zucker rats.

scholarly journals A Low-Carbohydrate Ketogenic Diet and Treadmill Training Enhanced Fatty Acid Oxidation Capacity but Did Not Enhance Maximal Exercise Capacity in Mice

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 611
Author(s):  
Sihui Ma ◽  
Jiao Yang ◽  
Takaki Tominaga ◽  
Chunhong Liu ◽  
Katsuhiko Suzuki
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Exercise Capacity ◽  
Ketogenic Diet ◽  
Maximal Exercise ◽  
Treadmill Running ◽  
Acid Oxidation ◽  
Oxidation Capacity ◽  
Low Carbohydrate ◽  
Maximal Exercise Capacity

The low-carbohydrate ketogenic diet (LCKD) is a dietary approach characterized by the intake of high amounts of fat, a balanced amount of protein, and low carbohydrates, which is insufficient for metabolic demands. Previous studies have shown that an LCKD alone may contribute to fatty acid oxidation capacity, along with endurance. In the present study, we combined a 10-week LCKD with an 8-week forced treadmill running program to determine whether training in conjunction with LCKD enhanced fatty acid oxidation capacity, as well as whether the maximal exercise capacity would be affected by an LCKD or training in a mice model. We found that the lipid pool and fatty acid oxidation capacity were both enhanced following the 10-week LCKD. Further, key fatty acid oxidation related genes were upregulated. In contrast, the 8-week training regimen had no effect on fatty acid and ketone body oxidation. Key genes involved in carbohydrate utilization were downregulated in the LCKD groups. However, the improved fatty acid oxidation capacity did not translate into an enhanced maximal exercise capacity. In summary, while favoring the fatty acid oxidation system, an LCKD, alone or combined with training, had no beneficial effects in our intensive exercise-evaluation model. Therefore, an LCKD may be promising to improve endurance in low- to moderate-intensity exercise, and may not be an optimal choice for those partaking in high-intensity exercise.

Development of the A‐STEP: A new incremental maximal exercise capacity step test in cystic fibrosis

2021 ◽  
Author(s):  
Lisa M. Wilson ◽  
Matthew J. Ellis ◽  
Rebecca L. Lane ◽  
John W. Wilson ◽  
Dominic T. Keating ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Exercise Capacity ◽  
Maximal Exercise ◽  
Step Test ◽  
Maximal Exercise Capacity

scholarly journals Limited Maximal Exercise Capacity in Patients With Chronic Heart Failure

2010 ◽  
Vol 55 (18) ◽  
pp. 1945-1954 ◽  
Author(s):  
Fabio Esposito ◽  
Odile Mathieu-Costello ◽  
Ralph Shabetai ◽  
Peter D. Wagner ◽  
Russell S. Richardson
Keyword(s):  
Heart Failure ◽  
Chronic Heart Failure ◽  
Exercise Capacity ◽  
Maximal Exercise ◽  
Maximal Exercise Capacity

Role of ventilatory response to exercise in determining exercise capacity in COPD

1995 ◽  
Vol 79 (6) ◽  
pp. 1870-1877 ◽  
Author(s):  
O. Bauerle ◽  
M. Younes
Keyword(s):  
Body Mass Index ◽  
Oxygen Consumption ◽  
Exercise Capacity ◽  
Body Mass ◽  
Ventilatory Response ◽  
Inspiratory Flow ◽  
Peak Oxygen Consumption ◽  
Chronic Obstructive ◽  
Inspiratory Capacity ◽  
Response To Exercise

The progression of chronic obstructive pulmonary disease (COPD) is generally associated with decreased exercise capacity. Differences in forced expired volume in 1 s (FEV1) among patients account for only a fraction of the variability in maximal oxygen consumption (VO2max). We hypothesized that variability in ventilatory response to exercise and in inspiratory mechanics and body mass index contributes importantly to variability in VO2max in this disease. We analyzed the files of 53 patients with established diagnosis of COPD who underwent a recent symptom-limited exercise test. We used inspiratory capacity and maximum inspiratory flow as measures of variability in inspiratory mechanics. The minute ventilation (VE) at the subject's VO2max was divided by the predicted in a normal subject at the same VO2 to obtain a ratio (VE,max/VE,pred). The ventilatory response during exercise provided the best correlation with peak VO2 (r = 0.62). FEV1 and inspiratory capacity also correlated with peak oxygen consumption but not as well as the ventilatory response (r = 0.49 and r = 0.46, respectively). Maximum inspiratory flow and body mass index showed only weak positive correlations (r = 0.23, not significant). The stepwise analysis generated the following equation: VO2max (%predicted) = (77.26 x VE,pred/VE,max) + [0.45 x FEV1 (%predicted)] - 23.66; r = 0.76, P < 0.001. We conclude that variability in the ventilatory response during exercise is one of the main determinants of variability in exercise capacity in COPD patients.

scholarly journals Impacts of Respiratory Muscle Training on Respiratory Functions, Maximal Exercise Capacity, Functional Performance, and Quality of Life in School-Aged Children with Postoperative Congenital Diaphragmatic Hernia

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Samah A. Moawd ◽  
Alshimaa R. Azab ◽  
Zizi M. Ibrahim ◽  
Anju Verma ◽  
Walid Kamal Abdelbasset
Keyword(s):  
Quality Of Life ◽  
Exercise Capacity ◽  
Respiratory Muscle ◽  
Maximal Exercise ◽  
Functional Performance ◽  
Respiratory Muscle Training ◽  
Muscle Training ◽  
School Aged Children ◽  
Maximal Exercise Capacity

Objectives. Congenital diaphragmatic hernia (CDH) is a birth defect affecting the respiratory functions, functional performance, and quality of life (QOL) in school-aged children. Rarely have studies been conducted to evaluate the impacts of respiratory muscle training on school-aged children with postoperative CDH. The current study was designed to evaluate the impacts of respiratory muscle training on respiratory function, maximal exercise capacity, functional performance, and QOL in these children. Methods. This study is a randomized control study. 40 children with CDH (age: 9-11 years) were assigned randomly into two groups. The first group conducted an incentive spirometer exercise combined with inspiratory muscle training (study group, n=20), whereas the second group conducted only incentive spirometer exercise (control group, n=20), thrice weekly for twelve consecutive weeks. Respiratory functions, maximal exercise capacity, functional performance, and pediatric quality of life inventory (PedsQL) were assessed before and after the treatment program. Results. Regarding the posttreatment analysis, the study group showed significant improvements in all outcome measures (FVC%, p<0.001; FEV1%, p=0.002; VO2max, p=0.008; VE/VCO2 slope, p=0.002; 6-MWT, p<0.001; and PedsQL, p<0.001), whereas the control group did not show significant changes (p>0.05). Conclusion. Respiratory muscle training may improve respiratory functions, maximal exercise capacities, functional performance, and QOL in children with postoperative CDH. Clinical commendations have to be considered to include respiratory muscle training in pulmonary rehabilitation programs in children with a history of CDH.

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