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Exercise testing in chronic lung disease
Published in R. C. Richard Davison, Paul M. Smith, James Hopker, Michael J. Price, Florentina Hettinga, Garry Tew, Lindsay Bottoms, Sport and Exercise Physiology Testing Guidelines: Volume II – Exercise and Clinical Testing, 2022
Oliver J. Price, Karl Sylvester, Joanna Shakespeare, Mark A. Faghy
Interpretation begins by evaluating V̇O2max and the anaerobic threshold. In lung disease, it is unlikely that a true V̇O2max will be achieved, and thus the ‘peak’ V̇O2 is often reported with a value <85% or below the lower limit of normal (LLN) suggesting exercise limitation. Exercise efficiency is expressed as the slope of the relationship between V̇O2 and work rate and is linear (10.3 ml.min−1.W−1) in healthy individuals. A decreased slope (<8.3 ml.min−1.W−1) indicates inadequate oxygen delivery to the exercising skeletal muscle or reduced oxygen uptake by the mitochondria, such as in a metabolic myopathy. In lung disease, the anaerobic threshold can fall to <40% predicted V̇O2 with values of 40–50% typically seen in deconditioned individuals. As expected, lung disease typically results in ventila-tory rather than cardiovascular limitation at peak exercise and thus parameters such as the ventilatory equivalents for carbon dioxide (V̇E/V̇CO2) and oxygen (V̇E/V̇CO2) and end-tidal carbon dioxide levels (PET CO2) can be evaluated to determine gas exchange abnormalities (for a detailed schematic of CPET test interpretation, see Figure 5.5.1).
Integrated Cardiovascular Responses
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Anaerobic metabolism occurs when 47%–64% of max is reached because the O2 supply cannot keep up with the increasing demands of the exercising muscles and there is an increase in blood lactate levels and lactate–pyruvate ratios. In terms of exercise physiology, at workloads below the anaerobic threshold, blood lactate levels remain low, slow-twitch (type I) muscle fibres with high oxidative capacity are used, and exercise can be sustained for prolonged periods, limited by substrate availability. At workloads above the anaerobic threshold, blood lactate levels increase, fast-twitch (type II) muscle fibres with low oxidative capacity are used, and exercise duration shortens progressively with increasing load. Lactic acid is buffered by bicarbonate (catalysed by carbonic anhydrase), producing excess nonmetabolic CO2 that is added to the metabolic CO2 production. The resultant increase in CO2 production is detected by the central and peripheral chemoreceptors which mediate an increase in ventilation. The (oxygen consumption/uptake) at the onset of blood lactate accumulation is called ventilatory anaerobic threshold or lactate threshold.
Diabetes Mellitus and Ischemic Heart Disease
Published in E.I. Sokolov, Obesity and Diabetes Mellitus, 2020
Physiological studies in recent years showed that there is a definite metabolic level in a human organism below which the content of lactic acid in the blood does not grow, but it does grow considerably above this level [333, 388, 389, 434]. This level is designated as the anaerobic threshold, and it appears at such a consumption of oxygen beginning from which anaerobic metabolism is supplemented with aerobic metabolism. Physiologists consider that the anaerobic threshold is the level of oxygen consumption under a physical load whose exceeding is accompanied by insufficiency of the aerobic mechanisms of energy formation and the inclusion into the process of energy supply without fail of an anaerobic mechanism with the development of metabolic acidosis.
Response of endothelial function and oxidative stress after supervised aerobic exercise training in formerly preeclamptic women
Published in Health Care for Women International, 2023
Wenjiang Sun, Bin Liu, Huan Zheng
Every participant underwent an incremental CPET on a bicycle ergometer. To stabilize respiratory exchange, the participant was asked to remain still on the ergometer for at least 3 min before starting to exercise. CPET was performed according to a symptom-limited Bruce’s protocol, with continuous electrocardiographic monitoring. SBP, DBP and HR values were measured and recorded at rest, at the end of each stress stage, at peak stress and at recovery. The test was stopped for any of the following reasons: a rating of perceived exertion > 17 (Borg scale); achievement of > 90% of age-predicted maximum HR; if the participant was too fatigued to continue the test safely; SBP > 200 mmHg; typical chest discomfort; severe arrhythmias; more than 1 mm of horizontal or down sloping ST segment depression. Respiratory gas exchange measurements were obtained breath-by-breath using computerized metabolic monitoring (Innocor 7.0, Innovision Cor., Denmark). VO2peak was recorded as the mean value of VO2 during the last 20 s of the test and expressed in mL x kg−1 x min−1. Powermax was the maximal workload during exercise. The ventilatory anaerobic threshold (AT) was assessed mathematically and VO2 at AT (VO2AT) was recorded. The whole process was supervised by a cardiologist and a nurse.
The effect of Preoperative threshold inspiratory muscle training in adults undergoing cardiac surgery on postoperative hospital stay: a systematic review
Published in Physiotherapy Theory and Practice, 2023
Adele Cook, Laura Smith, Callum Anderson, Nicole Ewing, Ashley Gammack, Mark Pecover, Nicole Sime, Helen F. Galley
Five studies (Chen et al., 2019; Hulzebos et al., 2006a, 2006b; Savci et al., 2011; Valkenet et al., 2017) increased the inspiratory load incrementally. Chen et al. (2019) and both studies by Hulzebos et al. (2006a); Hulzebos et al. (2006b) based the decision to increase the load on the rate of perceived exertion of participants, using the Borg CR-10 Scale (Borg, 1982). The Borg Scale is based on the intensity of exertion perceived by the individual, correlating with physiological parameters such as heart rate and blood lactate levels (Borg, 1982). In the two studies in which this scale was used, inspiratory load was increased when the rate of perceived exertion was less than five. It is thought that scores close to five can be used to quantify the anaerobic threshold during exercise (Zamunér et al., 2011).
Comparative effects of a cardiovascular rehabilitation program on functional capacity in patients with chronic chagasic cardiomyopathy with or without heart failure
Published in Disability and Rehabilitation, 2023
Aline Maria Nunes Viana, Marcelo Carvalho Vieira, Flavia Mazzoli-Rocha, Rudson Santos Silva, Aline Xavier Frota, Henrique Silveira Costa, Juliana Pereira Borges, Gilberto Marcelo Sperandio da Silva, Paula Simplício da Silva, Alejandro Marcel Hasslocher-Moreno, Roberto Magalhães Saraiva, Andrea Silvestre de Sousa, Fernanda de Souza Nogueira Sardinha Mendes, Mauro Felippe Felix Mediano
Patients were consecutively enrolled in an exercise-based CR program that comprised exercise training, daily clinical evaluation, nutritional counseling, and pharmaceutical care interventions. The exercise training was performed three times a week, 60 min per session, divided into 30 min of aerobic exercises on a treadmill or cycle ergometer (according to the availability of equipment during the sessions), 20 min of strength exercises for the major muscle groups (major pectoralis, latissimus dorsi, deltoid, quadriceps femoris, gluteus maximus, and calf) and 10 min of flexibility and balance exercises, without break between the different exercise modalities [7,9]. The intensity of aerobic exercise was prescribed according to the anaerobic threshold obtained in the initial CPET, from 90% to 100% in the first month of training and from 100% to 110% in the following months. For those patients whose anaerobic threshold was not identified during the CPET, training intensity was prescribed according to Hellerstein’s formula (heart rate (HR)=(102 + maximum metabolic equivalents achieved)/1.41)), with the target HR ranging from 70% of maximum HR obtained in the CPET to Hellerstein’s formula percentage in the first month, and from Hellerstein’s formula percentage to 85% of maximum HR in the following months. The exercise training workloads were adjusted after every CPET. Training sessions were supervised by trained professionals and occurred in the morning.