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1.
Physiological and Tactical On-court Demands of Water Polo.
Botonis, PG, Toubekis, AG, Platanou, TI
Journal of strength and conditioning research. 2019;(11):3188-3199
Abstract
Botonis, PG, Toubekis, AG, and Platanou, TI. Physiological and tactical on-court demands of water polo. J Strength Cond Res 33(11): 3188-3199, 2019-The purpose of the present review is to provide a quantification of the specific game's activities performed by elite water polo players and a comprehensive overview of the physiological requirements reflecting physical and tactical on-court demands in water polo. Game analysis demonstrates that various swimming movements occur throughout a match play, although approximately 50% of these are recorded in horizontal body position. The various offensive and defensive tactical actions transiently modify the playing intensity, which overall corresponds to the players' lactate threshold. Even play corresponds to 60% of total game actions, whereas the respective percentage of power-play and counterattacks may exceed 30%. The ability to perform high-intensity activities with short recovery periods is critical for water polo players. Elite water polo players present a high level of aerobic power and endurance as indicated by their maximal oxygen uptake and speed at the lactate threshold. Depending on the positional roles, outfield players are characterized as centers or peripherals. The overall physiological load seems to be similar between players at various positions, despite that centers execute more dynamic body contacts, whereas peripherals more swimming bouts. Despite limitations concerning the experimental setting, the current findings indicate that the incidence of fatigue deteriorates playing intensity and performance. Nonetheless, data from the reviewed studies should be cautiously interpreted because in some of the studies, players' substitutions were not allowed. A high conditioning level is essential for water polo, as it is associated with superior technical and tactical efficacy and lower decline of physical or technical performance within the game.
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2.
Monitoring training load and fatigue in soccer players with physiological markers.
Djaoui, L, Haddad, M, Chamari, K, Dellal, A
Physiology & behavior. 2017;:86-94
Abstract
The quantification and monitoring of training load (TL) has been the topic of many scientific works in the last fifteen years. TL monitoring helps coaches to individually prescribe, follow-up, analyse, adjust and programme training sessions. In particular, the aim of the present review was to provide a critical literature report regarding different physiological markers of TL monitoring, particularly in soccer, as the load is specific to individual sports. Therefore, the interests and limitations of heart rate (HR), HR variability (HRV) and biochemical variables (blood, urinary and hormonal variations) were analysed, with a special focus on daily measures (before, during and after training) and monitoring throughout a whole season. It appears that the most relevant markers were the resting HR before training, HR reserve during training, HRV during rest days, blood lactate, and blood and salivary immunological status in follow-ups throughout the season. Urinary markers indicative of the players' hydration status also deserve attention. However, these objective markers should be considered with a subjective marker of TL such as the rating of perceived exertion to give a more precise quantification of TL and its perception. Future research could be directed towards urinary marker analysis and the analysis of specific markers of TL, which could be related to injury occurrence and to performance during competition.
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3.
Effects of beta-alanine supplementation on performance and muscle fatigue in athletes and non-athletes of different sports: a systematic review.
Berti Zanella, P, Donner Alves, F, Guerini de Souza, C
The Journal of sports medicine and physical fitness. 2017;(9):1132-1141
Abstract
INTRODUCTION Beta-alanine (BA) is a non-essential amino acid that can be synthesized in the liver and obtained from diet, particularly from white and red meat. Increased availability of BA via dietary supplement, may improve performance of athletes. The aim of this study was to conduct a review of the use of BA supplementation as an ergogenic aid to improve performance and fatigue resistance in athletes and non-athletes. EVIDENCE ACQUISITION In this systematic review, a search in PubMed and Bireme databases was performed for the terms "beta-alanine," "beta-alanine and exercise," "carnosine" or "carnosine and exercise" in the titles or abstracts. We included randomized, clinical trials published between 2005 and 2015. EVIDENCE SYNTHESIS Twenty-three studies were selected. Most of them included physically active individuals. The mean intervention period was 5.2±1.8 weeks, and mean BA dose was 4.8±1.3 g/day. The main outcome measures were blood lactate, pH, perceived exertion, power and physical working capacity at fatigue threshold. After BA supplementation, no statistically significant difference was observed in total work, exercise performance time, oxygen consumption and time to exhaustion. CONCLUSIONS BA supplementation seems to improve perceived exertion and biochemical parameters related to muscle fatigue and less evidence was found for improvement in performance.
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4.
Fatigue associated with prolonged graded running.
Giandolini, M, Vernillo, G, Samozino, P, Horvais, N, Edwards, WB, Morin, JB, Millet, GY
European journal of applied physiology. 2016;(10):1859-73
Abstract
Scientific experiments on running mainly consider level running. However, the magnitude and etiology of fatigue depend on the exercise under consideration, particularly the predominant type of contraction, which differs between level, uphill, and downhill running. The purpose of this review is to comprehensively summarize the neurophysiological and biomechanical changes due to fatigue in graded running. When comparing prolonged hilly running (i.e., a combination of uphill and downhill running) to level running, it is found that (1) the general shape of the neuromuscular fatigue-exercise duration curve as well as the etiology of fatigue in knee extensor and plantar flexor muscles are similar and (2) the biomechanical consequences are also relatively comparable, suggesting that duration rather than elevation changes affects neuromuscular function and running patterns. However, 'pure' uphill or downhill running has several fatigue-related intrinsic features compared with the level running. Downhill running induces severe lower limb tissue damage, indirectly evidenced by massive increases in plasma creatine kinase/myoglobin concentration or inflammatory markers. In addition, low-frequency fatigue (i.e., excitation-contraction coupling failure) is systematically observed after downhill running, although it has also been found in high-intensity uphill running for different reasons. Indeed, low-frequency fatigue in downhill running is attributed to mechanical stress at the interface sarcoplasmic reticulum/T-tubule, while the inorganic phosphate accumulation probably plays a central role in intense uphill running. Other fatigue-related specificities of graded running such as strategies to minimize the deleterious effects of downhill running on muscle function, the difference of energy cost versus heat storage or muscle activity changes in downhill, level, and uphill running are also discussed.
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5.
The Effect of Vigorous- Versus Moderate-Intensity Aerobic Exercise on Insulin Action.
McGarrah, RW, Slentz, CA, Kraus, WE
Current cardiology reports. 2016;(12):117
Abstract
Due to the beneficial effects on a wide range of modern medical conditions, most professional societies recommend regular aerobic exercise as part of a healthy lifestyle. Many of the exercise-related health benefits exhibit a dose-response relationship: Up to a point, more exercise is more beneficial. However, recent studies have suggested that different exercise intensities may provide distinct health benefits, independent of energy expenditure (i.e., exercise dose). One of these benefits, primarily mediated by the skeletal muscle, is exercise-related changes in insulin action and glucose homeostasis. Glucose uptake in the exercising muscle occurs through insulin-independent mechanisms whose downstream signaling events ultimately converge with insulin-signaling pathways, a fact that may explain why exercise and insulin have additive effect on skeletal muscle glucose uptake. Although the existing evidence is somewhat conflicting, well-controlled randomized studies suggest that, when controlled for total energy expenditure, moderate-intensity aerobic exercise improves insulin sensitivity more than vigorous-intensity aerobic exercise. The mechanisms underlying this difference are largely unknown. One possible explanation involves enhanced metabolism of fatty acid stores in the skeletal muscle by moderate-intensity exercise, which may directly improve insulin sensitivity. Overall, new technologic and physiologic investigative tools are beginning to shed light on the biology. Further understanding of these mechanisms will lead to better understanding of the clinical implications of a healthy lifestyle and may ultimately offer new therapeutic targets for common medical conditions such as insulin resistance and diabetes.
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6.
Exertional rhabdomyolysis after spinning: case series and review of the literature.
Ramme, AJ, Vira, S, Alaia, MJ, VAN DE Leuv, J, Rothberg, RC
The Journal of sports medicine and physical fitness. 2016;(6):789-93
Abstract
Spinning is a popular indoor stationary cycling program that uses group classes as a motivational tool. Exertional rhabdomyolysis (ER) is frequently reported in athletes and military recruits; however, infrequently it has been reported after spinning class. ER is diagnosed by clinical history, physical exam, and laboratory values. Hydration, electrolyte management, and pain control are key components to treatment of this condition. Severe cases can be complicated by acute renal failure, compartment syndrome, arrhythmia, and disseminated intravascular coagulation. We describe three cases of admission due to rhabdomyolysis after spinning. The diagnosis, admission criteria, and medical treatment of ER are presented in the context of a literature review. A retrospective review of three cases with review of the current literature. The medical and laboratory records of three patient cases were reviewed. A search of the PubMed database was used to perform a comprehensive review of exertional rhabdomyolysis. Our institution's IRB reviewed this study. We report three cases of exertional rhabdomyolysis after spinning and describe the diagnostic workup and medical management of these patients. The diagnosis of ER is made by clinical history, physical exam, and laboratory values. The disease spectrum ranges from mild to severe with the potential of serious complications in some patients. We demonstrate three cases of ER in deconditioned individuals who presented to the emergency department for evaluation. Careful medical management and patient monitoring resulted in improved patient symptomatology and eventual return to physical activity.
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7.
Modulating exercise-induced hormesis: Does less equal more?
Peake, JM, Markworth, JF, Nosaka, K, Raastad, T, Wadley, GD, Coffey, VG
Journal of applied physiology (Bethesda, Md. : 1985). 2015;(3):172-89
Abstract
Hormesis encompasses the notion that low levels of stress stimulate or upregulate existing cellular and molecular pathways that improve the capacity of cells and organisms to withstand greater stress. This notion underlies much of what we know about how exercise conditions the body and induces long-term adaptations. During exercise, the body is exposed to various forms of stress, including thermal, metabolic, hypoxic, oxidative, and mechanical stress. These stressors activate biochemical messengers, which in turn activate various signaling pathways that regulate gene expression and adaptive responses. Historically, antioxidant supplements, nonsteroidal anti-inflammatory drugs, and cryotherapy have been favored to attenuate or counteract exercise-induced oxidative stress and inflammation. However, reactive oxygen species and inflammatory mediators are key signaling molecules in muscle, and such strategies may mitigate adaptations to exercise. Conversely, withholding dietary carbohydrate and restricting muscle blood flow during exercise may augment adaptations to exercise. In this review article, we combine, integrate, and apply knowledge about the fundamental mechanisms of exercise adaptation. We also critically evaluate the rationale for using interventions that target these mechanisms under the overarching concept of hormesis. There is currently insufficient evidence to establish whether these treatments exert dose-dependent effects on muscle adaptation. However, there appears to be some dissociation between the biochemical/molecular effects and functional/performance outcomes of some of these treatments. Although several of these treatments influence common kinases, transcription factors, and proteins, it remains to be determined if these interventions complement or negate each other, and whether such effects are strong enough to influence adaptations to exercise.
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8.
Influence of body mass loss on changes in heart rate during exercise in the heat: a systematic review.
Adams, WM, Ferraro, EM, Huggins, RA, Casa, DJ
Journal of strength and conditioning research. 2014;(8):2380-9
Abstract
The purpose of this review was to compare the changes in heart rate (HR) for every 1% change in body mass loss (ΔBML) in individuals while exercising in the heat. PubMed, SPORTDiscus, ERIC, CINAHL, and Scopus were searched from the earliest entry to February 2013 using the search terms dehydration, heart rate, and exercise in various combinations. Original research articles that met the following criteria were included: (a) valid measure of HR, (b) exercise in the heat (>26.5° C [79.7 °F]), (c) the level of dehydration reached at least 2%, (d) a between-group comparison (a euhydrated group or a graded dehydration protocol) was evident, and (e) for rehydration protocols, only oral rehydration was considered for inclusion. Twenty articles were included in the final analysis. Mean values and SDs for HR and percentage of body mass loss immediately after exercise were used for this review. The mean change in HR for every 1% ΔBML was 3 b·min-1. In trials where subjects arrived euhydrated and hypohydrated, the mean change in HR for every 1% ΔBML was 3 and 3 b·min-1, respectively. Fixed intensity and variable intensity trials exhibited a mean HR change of 4 and 1 b·min-1, respectively. Exercising in the heat while hypohydrated (≥2%) resulted in an increased HR after exercise. This increase in HR for every 1% ΔBML exacerbates cardiovascular strain in exercising individuals, thus causing decrements in performance. It should be encouraged that individuals should maintain an adequate level of hydration to maximize performance, especially in the heat.
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9.
Prediction of maximal or peak oxygen uptake from ratings of perceived exertion.
Coquart, JB, Garcin, M, Parfitt, G, Tourny-Chollet, C, Eston, RG
Sports medicine (Auckland, N.Z.). 2014;(5):563-78
Abstract
Maximal or peak oxygen uptake (V˙O2 max and V˙O2 peak , respectively) are commonly measured during graded exercise tests (GXTs) to assess cardiorespiratory fitness (CRF), to prescribe exercise intensity and/or to evaluate the effects of training. However, direct measurement of CRF requires a GXT to volitional exhaustion, which may not always be well accepted by athletes or which should be avoided in some clinical populations. Consequently, numerous studies have proposed various sub-maximal exercise tests to predict V˙O2 max or V˙O2 peak . Because of the strong link between ratings of perceived exertion (RPE) and oxygen uptake (V˙O2), it has been proposed that the individual relationship between RPE and V˙O2 (RPE:V˙O2) can be used to predict V˙O2 max (or V˙O2 peak) from data measured during submaximal exercise tests. To predict V˙O2 max or V˙O2 peak from these linear regressions, two procedures may be identified: an estimation procedure or a production procedure. The estimation procedure is a passive process in which the individual is typically asked to rate how hard an exercise bout feels according to the RPE scale during each stage of a submaximal GXT. The production procedure is an active process in which the individual is asked to self-regulate and maintain an exercise intensity corresponding to a prescribed RPE. This procedure is referred to as a perceptually regulated exercise test (PRET). Recently, prediction of V˙O2max or V˙O2 peak from RPE:V˙O2 measured during both GXT and PRET has received growing interest. A number of studies have tested the validity, reliability and sensitivity of predicted V˙O2 max or V˙O2 peak from RPE:V˙O2 extrapolated to the theoretical V˙O2 max at RPE20 (or RPE19). This review summarizes studies that have used this predictive method during submaximal estimation or production procedures in various populations (i.e., sedentary individuals, athletes and pathological populations). The accuracy of the methods is discussed according to the RPE:V˙O2 range used to plot the linear regression (e.g., RPE9–13 versus RPE9–15 versus RPE9–17 during PRET), as well as the perceptual endpoint used for the extrapolation (i.e., RPE19 and RPE20). The V˙O2 max or V˙O2 peak predictions from RPE:V˙O2 are also compared with heart rate-related predictive methods. This review suggests that V˙O2 max (or V˙O2 peak ) may be predicted from RPE:V˙O2 extrapolated to the theoretical V˙O2 max (or V˙O2 peak) at RPE20 (or RPE19). However, it is generally preferable to (1) extrapolate RPE:V ˙ O 2 to RPE19 (rather than RPE20); (2) use wider RPE ranges (e.g. RPE ≤ 17 or RPE9–17) in order to increase the accuracy of the predictions; and (3) use RPE ≤ 15 or RPE9–15 in order to reduce the risk of cardiovascular complications in clinical populations.
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10.
High-intensity intermittent exercise: methodological and physiological aspects.
Tschakert, G, Hofmann, P
International journal of sports physiology and performance. 2013;(6):600-10
Abstract
High-intensity intermittent exercise (HIIE) has been applied in competitive sports for more than 100 years. In the last decades, interval studies revealed a multitude of beneficial effects in various subjects despite a large variety of exercise prescriptions. Therefore, one could assume that an accurate prescription of HIIE is not relevant. However, the manipulation of HIIE variables (peak workload and peak-workload duration, mean workload, intensity and duration of recovery, number of intervals) directly affects the acute physiological responses during exercise leading to specific medium- and long-term training adaptations. The diversity of intermittent-exercise regimens applied in different studies may suggest that the acute physiological mechanisms during HIIE forced by particular exercise prescriptions are not clear in detail or not taken into consideration. A standardized and consistent approach to the prescription and classification of HIIE is still missing. An optimal and individual setting of the HIIE variables requires the consideration of the physiological responses elicited by the HIIE regimen. In this regard, particularly the intensities and durations of the peak-workload phases are highly relevant since these variables are primarily responsible for the metabolic processes during HIIE in the working muscle (eg, lactate metabolism). In addition, the way of prescribing exercise intensity also markedly influences acute metabolic and cardiorespiratory responses. Turn-point or threshold models are suggested to be more appropriate and accurate to prescribe HIIE intensity than using percentages of maximal heart rate or maximal oxygen uptake.