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1.
Artificial Pancreas Systems and Physical Activity in Patients with Type 1 Diabetes: Challenges, Adopted Approaches, and Future Perspectives.
Tagougui, S, Taleb, N, Molvau, J, Nguyen, É, Raffray, M, Rabasa-Lhoret, R
Journal of diabetes science and technology. 2019;(6):1077-1090
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Abstract
Physical activity is important for patients living with type 1 diabetes (T1D) but limited by the challenges associated with physical activity induced glucose variability. Optimizing glycemic control without increasing the risk of hypoglycemia is still a hurdle despite many advances in insulin formulations, delivery methods, and continuous glucose monitoring systems. In this respect, the artificial pancreas (AP) system is a promising therapeutic option for a safer practice of physical activity in the context of T1D. It is important that healthcare professionals as well as patients acquire the necessary knowledge about how the AP system works, its limits, and how glucose control is regulated during physical activity. This review aims to examine the current state of knowledge on exercise-related glucose variations especially hypoglycemic risk in T1D and to discuss their effects on the use and development of AP systems. Though effective and highly promising, these systems warrant further research for an optimized use around exercise.
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The Effect of Exercise on Glucoregulatory Hormones: A Countermeasure to Human Aging: Insights from a Comprehensive Review of the Literature.
Sellami, M, Bragazzi, NL, Slimani, M, Hayes, L, Jabbour, G, De Giorgio, A, Dugué, B
International journal of environmental research and public health. 2019;(10)
Abstract
Hormones are secreted in a circadian rhythm, but also follow larger-scale timetables, such as monthly (hormones of the menstrual cycle), seasonal (i.e., winter, summer), and, ultimately, lifespan-related patterns. Several contexts modulate their secretion, such as genetics, lifestyle, environment, diet, and exercise. They play significant roles in human physiology, influencing growth of muscle, bone, and regulating metabolism. Exercise training alters hormone secretion, depending on the frequency, duration, intensity, and mode of training which has an impact on the magnitude of the secretion. However, there remains ambiguity over the effects of exercise training on certain hormones such as glucoregulatory hormones in aging adults. With advancing age, there are many alterations with the endocrine system, which may ultimately alter human physiology. Some recent studies have reported an anti-aging effect of exercise training on the endocrine system and especially cortisol, growth hormone and insulin. As such, this review examines the effects of endurance, interval, resistance and combined training on hormones (i.e., at rest and after) exercise in older individuals. We summarize the influence of age on glucoregulatory hormones, the influence of exercise training, and where possible, examine masters' athletes' endocrinological profile.
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The Physiological Roles of Carnosine and β-Alanine in Exercising Human Skeletal Muscle.
Matthews, JJ, Artioli, GG, Turner, MD, Sale, C
Medicine and science in sports and exercise. 2019;(10):2098-2108
Abstract
Carnosine (β-alanyl-L-histidine) plays an important role in exercise performance and skeletal muscle homeostasis. Dietary supplementation with the rate-limiting precursor β-alanine leads to an increase in skeletal muscle carnosine content, which further potentiates its effects. There is significant interest in carnosine and β-alanine across athletic and clinical populations. Traditionally, attention has been given to performance outcomes with less focus on the underlying mechanism(s). Putative physiological roles in human skeletal muscle include acting as an intracellular pH buffer, modulating energy metabolism, regulating Ca handling and myofilament sensitivity, and scavenging of reactive species. Emerging evidence shows that carnosine could also act as a cytoplasmic Ca-H exchanger and form stable conjugates with exercise-induced reactive aldehydes. The enigmatic nature of carnosine means there is still much to learn regarding its actions and applications in exercise, health, and disease. In this review, we examine the research relating to each physiological role attributed to carnosine, and its precursor β-alanine, in exercising human skeletal muscle.
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Is Endurance Exercise Safe? The Myth of Pheidippides.
Rutlen, C, Rutlen, DL
Southern medical journal. 2019;(4):210-214
Abstract
With the increase in participation in endurance events in the general population, patient concern may arise as to whether endurance exercise is safe. Acute but not chronic increases in blood urea nitrogen, creatinine, and urine albumin occur in endurance exercise. Iron-deficiency anemia may be observed in female athletes. Upper respiratory illness is increased in elite athletes but decreased in intense recreational athletes. No convincing evidence of developing osteoarthritis exists. Common gastrointestinal symptoms occur and isolated reports of gastrointestinal bleeding exist. Nevi are increased and the minimal erythematous dose is decreased. Exercising in the presence of air pollution has negative pulmonary effects, but overall, benefit exists. Numerous reports pertain to the cardiovascular system. The risk of cardiac arrest increases during exercise, troponin is elevated after exercise, and a predisposition for atrial fibrillation exists. Ventricular myocardial scar formation as assessed by gadolinium enhancement on magnetic resonance imaging is inconsistently observed, and increased coronary plaque of a more stable variety is reported. Left ventricular compliance is chronically increased and no decrease in longevity is found. Although some concerns exist, endurance exercise is safe.
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Examining Childhood Obesity From Infancy: The Relationship Between Tummy Time, Infant BMI-z, Weight Gain, and Motor Development-An Exploratory Study.
Koren, A, Kahn-D'angelo, L, Reece, SM, Gore, R
Journal of pediatric health care : official publication of National Association of Pediatric Nurse Associates & Practitioners. 2019;(1):80-91
Abstract
INTRODUCTION This exploratory study investigated the infant time spent in tummy time (TT) in relation to body mass index z score (BMI-z), weight gain, and motor development in infants from birth to 4 months. METHOD Mothers and their infants were telephone surveyed at 2 and 4 months. Mother demographics; TT; feeding practices; and infant length, and height, and development were collected each time. RESULTS Results from Cochran-Mantel-Haenszel and single logistic regression showed a significant association between development, level of BMI-z, and time spent in TT at 2 months of age (p < .0001). The threshold model showed there was a decline in BMI-z at 4 months as daily time in TT increases past the threshold value of approximately 12 minutes per day. Mother education and TT at 2 months were significant predictors of BMI-z at 4 months. DISCUSSION Study outcomes suggest that infant positioning and time in TT promote infant motor development and may moderate rapid infant weight gain.
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The renal molecular clock: broken by aging and restored by exercise.
Schmitt, EE, Johnson, EC, Yusifova, M, Bruns, DR
American journal of physiology. Renal physiology. 2019;(5):F1087-F1093
Abstract
The mammalian circadian clock governs physiological, endocrine, and metabolic responses coordinated in a 24-h rhythmic pattern by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The SCN also dictates circadian rhythms in peripheral tissues like the kidney. The kidney has several important physiological functions, including removing waste and filtering the blood and regulating fluid volume, blood osmolarity, blood pressure, and Ca2+ metabolism, all of which are under tight control of the molecular/circadian clock. Normal aging has a profound influence on renal function, central and peripheral circadian rhythms, and the sleep-wake cycle. Disrupted circadian rhythms in the kidney as a result of increased age likely contribute to adverse health outcomes such as nocturia, hypertension, and increased risk for stroke, cardiovascular disease, and end organ failure. Regular physical activity improves circadian misalignment in both young and old mammals, although the precise mechanisms for this protection remain poorly described. Recent advances in the heart and skeletal muscle literature suggest that regular endurance exercise entrains peripheral clocks, and we propose that similar beneficial adaptations occur in the kidney through regulation of renal blood flow and fluid balance.
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Erectile dysfunction, physical activity and physical exercise: Recommendations for clinical practice.
Duca, Y, Calogero, AE, Cannarella, R, Giacone, F, Mongioi, LM, Condorelli, RA, La Vignera, S
Andrologia. 2019;(5):e13264
Abstract
Erectile dysfunction could be an early sign of endothelial dysfunction and, therefore, of cardiovascular disease, with which it shares many risk factors. Among reversible risk factors, physical inactivity is one of the most important. Regular physical exercise has been shown to improve erectile function through different mechanisms involving glucose and lipid metabolism, regulation of arterial pressure, production of nitric oxide and hormonal modulation. Furthermore, exercise shows a synergistic effect with the drugs commonly used in the treatment of impotence. Since many patients with erectile dysfunction may have underlying cardiovascular disease, the evaluation of individual cardiovascular risk is mandatory before prescribing physical exercise. When exercise is not contraindicated, the most appropriate protocol must be chosen, considering the individual characteristics of the patient. Both aerobic and anaerobic/resistance protocols have proven effective. However, meta-analytic studies show that aerobic exercise with moderate-to-vigorous intensity is the most effective in improving erection. Testosterone is an important modulator of physical performance, and its blood levels must always be evaluated in patients with erectile dysfunction.
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Effects of dietary sports supplements on metabolite accumulation, vasodilation and cellular swelling in relation to muscle hypertrophy: A focus on "secondary" physiological determinants.
Cholewa, J, Trexler, E, Lima-Soares, F, de Araújo Pessôa, K, Sousa-Silva, R, Santos, AM, Zhi, X, Nicastro, H, Cabido, CET, de Freitas, MC, et al
Nutrition (Burbank, Los Angeles County, Calif.). 2019;:241-251
Abstract
Increased blood flow via vasodilation, metabolite production, and venous pooling contribute to the hyperemia and cellular swelling experienced during resistance training. It has been suggested that these effects play a role in hypertrophic adaptations. Over the past 2 decades, sport supplement products have been marketed to promote exercise hyperemia and intracellular fluid storage, thereby enhancing hypertrophy via acute swelling of myocytes. The three main classes of supplements hypothesized to promote exercise-induced hyperemia include vasodilators, such as nitric oxide precursor supplements; anaerobic energy system ergogenic aids that increase metabolite production, such as β-alanine and creatine; and organic osmolytes, such as creatine and betaine. Previous studies indicated that these dietary supplements are able to improve muscle performance and thus enhance muscle hypertrophy; however, recent evidences also point to these three classes of supplements affecting "secondary" physiological determinants of muscle mass accretion such as vasodilation, metabolite accumulation, and muscle cellular swelling. Although we recognize that the literature is relatively scarce regarding these topics, a better comprehension and discussion of these determinants can lead to increased knowledge and might guide further research regarding the proposed mechanisms of action of the identified compounds. In this case, increased knowledge may contribute to the development of improved efficacy, new products, or direct new research to specifically investigate those secondary effects. The aim of this review was to bring into focus new perspectives associated with secondary physiological effects induced by supplementation and to determine their relevance.
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Exercise for the prevention of osteoporosis in postmenopausal women: an evidence-based guide to the optimal prescription.
Daly, RM, Dalla Via, J, Duckham, RL, Fraser, SF, Helge, EW
Brazilian journal of physical therapy. 2019;(2):170-180
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Abstract
BACKGROUND Osteoporosis and related fragility fractures are a global public health problem in which pharmaceutical agents targeting bone mineral density (BMD) are the first line of treatment. However, pharmaceuticals have no effect on improving other key fracture risk factors, including low muscle strength, power and functional capacity, all of which are associated with an increased risk for falls and fracture, independent of BMD. Targeted exercise training is the only strategy that can simultaneously improve multiple skeletal and fall-related risk factors, but it must be appropriately prescribed and tailored to the desired outcome(s) and the specified target group. OBJECTIVES In this review, we provide an overview of the general principles of training and specific loading characteristics underlying current exercise guidelines for the prevention of osteoporosis, and an update on the latest scientific evidence with regard to the type and dose of exercise shown to positively influence bone mass, structure and strength and reduce fracture risk in postmenopausal women.
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The impact of keto-adaptation on exercise performance and the role of metabolic-regulating cytokines.
Sherrier, M, Li, H
The American journal of clinical nutrition. 2019;(3):562-573
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Abstract
The ketogenic diet (KD) is a normocaloric diet composed of high-fat, low-carbohydrate, and adequate protein that induces fasting-like effects and results in the production of ketone bodies. Initially used widely for children with refractory epilepsy, the KD gained popularity due to its beneficial effects on weight loss, diabetes, and cancer. In recent years, there has been a resurgence in interest surrounding the KD and exercise performance. This review provides new insights into the adaptation period necessary for enhancement in skeletal muscle fat and ketone oxidation after sustained nutritional ketosis. In addition, this review highlights metabolically active growth factors and cytokines, which may function as important regulators of keto-adaptation in the setting of exercise and the KD.