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Genetics and exercise: an introduction
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Claude Bouchard, Henning Wackerhage
Since there are more than 1,000 proteins playing an active role in the mitochondria, mtDNA makes a critical but small contribution to mitochondrial biology. All other proteins and small molecules required for healthy mitochondria are encoded in the nuclear genome and are exported to mitochondria. The integrity of mtDNA is a great importance, as inherited or acquired anomalies in the mtDNA sequence can lead to mitochondrial dysfunction. Such dysfunctions are observed in some cases of exercise intolerance and a number of pathologies.
Oxidative Stress and Exercise Tolerance in Cystic Fibrosis
Published in James N. Cobley, Gareth W. Davison, Oxidative Eustress in Exercise Physiology, 2022
Cassandra C. Derella, Adeola A. Sanni, Ryan A. Harris
Oxidative stress is a key contributor to the pathogenesis of several diseases and is a common phenotype in people with CF. Although a moderate level of ROS is essential in keeping the optimal function and energy production in the cell, an excess accumulation can cause damage to the cells and result in the loss of pulmonary, cardiovascular, and skeletal muscle function. Exercise intolerance is also a distinguishing characteristic in CF and routine exercise testing has great clinical prognostic value. Although pulmonary dysfunction may not play a key role, the mechanisms that contribute to exercise intolerance in CF, to date, have yet to be fully elucidated. Indeed, there is evidence to support the negative role that oxidative stress has on cardiovascular and skeletal muscle function. Accordingly, elevated systemic oxidative stress may likely impact the function of many biological systems, contributing to exercise intolerance in people with CF.
Respiratory limitations to exercise
Published in John W. Dickinson, James H. Hull, Complete Guide to Respiratory Care in Athletes, 2020
Joseph F. Welch, Bruno Archiza, A. William Sheel
The structure of the lungs (e.g. large surface area and thin blood-gas barrier to maximise diffusion of gases), airways (e.g. richly innervated by β2 adrenergic receptors to improve laminar airflow) and respiratory muscles (e.g. high oxidative capacity to prevent fatigue) are well suited to their function – a concept known as symmorphosis. However, no bodily system is without limitation. A respiratory-related threat to arterial O2 content (CaO2) and convective O2 transport may exist under certain conditions of exercise in both healthy athletic humans and in those with respiratory disease. As will be described in the later chapters in this book, both upper and lower airway disorders such as exercise-induced laryngeal obstruction (EILO), asthma and exercise-induced bronchoconstriction (EIB) respectively, may impair respiratory function and lead to exercise limitation. This chapter will examine and summarise how several conditions may impact the respiratory system and lead to exercise intolerance.
Determinants of exercise capacity in children and adolescents with severe therapy-resistant asthma
Published in Journal of Asthma, 2022
Cláudia Silva Schindel, Daniele Schiwe, João Paulo Heinzmann-Filho, Mailise Fátima Gheller, Natália Evangelista Campos, Paulo Márcio Pitrez, Márcio Vinícius Fagundes Donadio
Although aerobic fitness, as an isolated factor, does not differ between mild-to-moderate asthmatics and healthy children, the interaction between habitual physical activity levels and exercise tolerance may impact asthmatic patients (12). In the present study, VO2peak and ventilatory efficiency were significantly correlated with resting HR. This finding may be of clinical and prognostic relevance because individuals with good aerobic fitness tend to have lower resting HR (42), and HR measurement is a simple and inexpensive procedure. In addition, healthy adolescents with higher levels of habitual physical activity also present lower resting HR (44). Other determinant factors that may contribute to exercise intolerance include the concern that physical exertion might trigger bronchial obstruction and obesity. In a study examining the relationships among asthma severity, level of physical activity, aerobic fitness, and body weight in asthmatic children, asthma severity was not associated with oxygen consumption, but there was a strong association of aerobic fitness with perceived competence in physical activity, weight gain, and greater medication needs (6). The elevated heart rate found in the present study, both at rest and at the AT, may indicate deconditioning, although other possible influencing factors, as anxiety levels in patients with asthma, cannot be ruled out.
Cardiopulmonary exercise testing – refining the clinical perspective by combining assessments
Published in Expert Review of Cardiovascular Therapy, 2020
Ross Arena, Justin M. Canada, Dejana Popovic, Cory R. Trankle, Marco Giuseppe Del Buono, Alexander Lucas, Antonio Abbate
During the early stages of PH, an accurate and fast diagnosis is essential for optimal treatment; however, standard resting echocardiographic measurements, such as RV size, PASP, TAPSE, and Doppler RV outflow tract abnormalities, may not be sufficient[74]. Exercise intolerance is a hallmark in these patients and thus measurements obtained during exercise provide diagnostic and prognostic information[75]. Accordingly, exercise-induced PH is defined as a PASP ≥ 60 mmHg during effort [74,75]. Moreover, CPX is able to identify PH, in those with a normal resting echocardiogram [76] while providing measures with strong prognostic value, including peak VO2, PETCO2 and the VE/VCO2 slope[48]. An interesting study demonstrated that impaired peak VO2 and the inability to increase PASP more than 30 mmHg during exercise, which reflects RV failure, portends worse prognosis [76,77].
Current practice in atrial septal defect occlusion in children and adults
Published in Expert Review of Cardiovascular Therapy, 2020
Wail Alkashkari, Saad Albugami, Ziyad M. Hijazi
Most children with an ASD present with a murmur and are asymptomatic. Occasionally infants may present with breathlessness, recurrent chest infections, and even congestive heart failure. Failure to thrive is an uncommon presentation [13]. Adults with an ASD typically have a prolonged asymptomatic course. Symptom onset is insidious, most often occurring in the third or fourth decade. Women may become symptomatic earlier specially during the physiologic demands of pregnancy or labor [6]. Most of the symptoms initially related to exertion and this is related to decrease in cardiac output due to the shunting. These symptoms may include, shortness of breath, fatigue, and exercise intolerance. Palpitations may indicate the development of atrial arrhythmias such as atrial fibrillation and this is due to atrial stretch. Ultimately, they will suffer from right-sided congestive heart failure, with peripheral edema [5]. Syncope may indicate ventricular arrhythmias but also can be related to low cardiac output, heart failure, and/or PAH. In the absence of other CHD or lung disease, cyanosis indicates the development of severe PAH and Eisenmenger syndrome. Cyanosis can occur in the presence of severe TR and/or RV failure especially during exercise. Paradoxical emboli are well-known complications and it may occur even with small defects [14].