276 research outputs found
ALTITUDE AND FOOTBALL: WHAT ARE NEW METHODS AND OPPORTUNITIES TO MAXIMIZE PLAYERS' FITNESS?
International audiencePlaying football competition at terrestrial altitude is not an isolated phenomenon. For instance, eight of the last 19 football FIFA World Cup tournaments were hosted by countries located at low-to-moderate altitude. While football-required fitness and technical qualities are affected by the development of neuromuscular fatigue at sea level, hypoxia-induced decrease in convective oxygen transport further hinders the aerobic capacity but also the ability to perform consecutive sprints, eventually impacting the outcome of a game. This results from the decrease in partial pressure of oxygen which reduces maximal aerobic power. The later, in turn, increases the relative intensity of any given absolute level of work, potentially delaying recovery of high-energy phosphates between high-intensity intermittent efforts. Despite reduction in air resistance (caused by the decrease in air density) could facilitate high-velocity running, it can also alter drag and lift, thereby impairing sensorimotor skills. Conversely, altitude/hypoxic training could help footballers preparing for competition at altitude, but also at sea level. Traditional altitude training camps involve chronic exposure to low-to-moderate terrestrial or simulated altitudes (14%) for improving oxygen-carrying capacity. While "live high-train high" or "live high-train low" paradigms are actually implemented by many elite club or national team football squads, the benefits they may have on (repeated-) sprint performance are still debated. The development of hypoxic technologies has led to the emergence of "live low-train high" methods, in isolation (i.e., the "repeated-sprint training in hypoxia" and "resistance training in hypoxia") or in combination with hypoxic/altitude residence (i.e., "live high-train low and high"). Today, the panorama of altitude/hypoxic training methods is wider than ever and includes also practices such as "blood flow restriction" or "ischemic preconditioning", which demonstrate encouraging preliminary results. The aims of this chapter are twofold: First, to summarize the effects of acute altitude/hypoxia exposure on football-specific qualities measured in the laboratory and/or during games at terrestrial altitude. Second, to discuss the potential benefits of each altitude/hypoxic training method in respect to sport-specific physiological and fitness development and/or in-game performance
Physiological requirements in triathlon
This article aims to present the current knowledge on physiological requirements in Olympic distance and Ironman triathlon. Showing the data available from a âtraditional point of viewâ (aerobic power, anaerobic threshold, heart rate, running economy) and from a âcontemporaryâ point of view (VÌ O2 kinetics), it emphasises where we are currently and the areas that remain unknown
Look to the starsâIs there anything that public health and rehabilitation can learn from elite sports?
CONTACT TIME AND FOOT STRIKE ANGLES ESTIMATION USING FOOT WORN INERTIAL SENSORS IN RUNNING
The purpose of this study was to evaluate the performance of new algorithms based on foot-worn inertial measurement units (IMUs), to detect foot contact time and foot strike angles in running. Treadmill instrumented with force plate and camera-based motion capture system were use as reference system. For 35 participants running on treadmill with different speeds, contact time and foot strike angle values obtained from IMUs were compared with those measured by force plate and motion cameras, respectively, with a relative error (mean ± SD) of -10.5 ± 2.2% and 3.9 ± 5.3°. This error could be further reduced using a corrective model based on the runnerâs speed and foot strike angle
Coopérer en éducation physique : Le Jigsaw, une méthode prometteuse ?
Cet article porte sur lâutilisation de la mĂ©thode dâapprentissage coopĂ©ratif, le Jigsaw en Ă©ducation physique et sportive. En sâappuyant sur les apports des recherches antĂ©rieures, lâobjectif de cet article est dâĂ©tayer en quoi la mĂ©thode Jigsaw peut ĂȘtre une approche intĂ©ressante en Ă©ducation physique et sportive. Ă ce jour, seulement cinq Ă©tudes ont portĂ© sur son utilisation en Ă©ducation physique et sportive. Pourtant au regard des 57 Ă©tudes existantes analysĂ©es, cette approche semble prometteuse Ă mettre en place en Ă©ducation physique et sportive. Les travaux antĂ©rieurs montrent des rĂ©sultats positifs sur lâengagement et lâapprentissage des Ă©lĂšves, ainsi que les perceptions des Ă©lĂšves et enseignants qui ont vĂ©cu des expĂ©riences Jigsaw dans le milieu Ă©ducatif. Des progrĂšs sont Ă rĂ©aliser pour mettre en place ce type de mĂ©thode en Ă©ducation physique et sportive et dans les autres disciplines notamment en amĂ©liorant la formation des enseignants dans ce domaine.The present paper focuses on the use of Jigsaw, a cooperative learning method, in Physical Education. Based on the findings of previous researches, the purpose of this paper is to discuss if and how the Jigsaw method could be valuable in Physical Education. To date, only five studies have focused on its use in Physical Education. However, considering the numerous existing studies analyzed in education (N = 57), this approach seems appropriate to be implemented in Physical Education. The literature review in education has shown positive results of Jigsaw on studentsâ engagement and learning, as well as on studentsâ and teachersâ perceptions. Progress needs to be made to implement this type of method in physical education and in other school subjects, notably by increasing teacher training in this area
Constant low-to-moderate mechanical asymmetries during 800-m track running
IntroductionModifications in asymmetry in response to self-paced efforts have not been thoroughly documented, particularly regarding horizontally-derived ground reaction force variables. We determined the magnitude and range of gait asymmetries during 800â
m track running.MethodsEighteen physical education students completed an 800â
m self-paced run on a 200â
m indoor track. During the run, vertical and horizontal ground reaction forces were measured at a sampling frequency of 500â
Hz using a 5â
m-long force platform system, with data collected once per lap. The following mechanical variables were determined for two consecutive steps: contact time and duration of braking/push-off phases along with vertical/braking/push-off peak forces and impulses. The group mean asymmetry scores were evaluated using the âsymmetry angleâ (SA) formula, where scores of 0% and 100% correspond to perfect symmetry and perfect asymmetry, respectively.ResultsThere was no influence of distance interval on SA scores for any of the nine biomechanical variables (Pââ„â0.095). The SA scores were âŒ1%â2% for contact time (1.3â±â0.5%), peak vertical forces (1.8â±â0.9%), and vertical impulse (1.7â±â1.0%). The SA scores were âŒ3%â8% for duration of braking (3.6â±â1.1%) and push-off (3.2â±â1.4%) phases, peak braking (5.0â±â2.1%) and push-off (6.9â±â3.1%) forces as well as braking (7.6â±â2.3%) and push-off (7.7â±â3.3%) impulses. The running velocity progressively decreased at 300â
m and 500â
m compared to that at 100â
m but levelled off at 700â
m (Pâ<â0.001).DiscussionThere were no modifications in gait asymmetries, as measured at 200-m distance intervals during 800-m track running in physical education students. The 800â
m self-paced run did not impose greater mechanical constraints on one side of the body. Experimental procedures for characterizing the gait pattern during 800â
m track running could be simplified by collecting leg mechanical data from only one side
Sphingolipids and impaired hypoxic stress responses in Huntington disease.
Huntington disease (HD) is a debilitating, currently incurable disease. Protein aggregation and metabolic deficits are pathological hallmarks but their link to neurodegeneration and symptoms remains debated. Here, we summarize alterations in the levels of different sphingolipids in an attempt to characterize sphingolipid patterns specific to HD, an additional molecular hallmark of the disease. Based on the crucial role of sphingolipids in maintaining cellular homeostasis, the dynamic regulation of sphingolipids upon insults and their involvement in cellular stress responses, we hypothesize that maladaptations or blunted adaptations, especially following cellular stress due to reduced oxygen supply (hypoxia) contribute to the development of pathology in HD. We review how sphingolipids shape cellular energy metabolism and control proteostasis and suggest how these functions may fail in HD and in combination with additional insults. Finally, we evaluate the potential of improving cellular resilience in HD by conditioning approaches (improving the efficiency of cellular stress responses) and the role of sphingolipids therein. Sphingolipid metabolism is crucial for cellular homeostasis and for adaptations following cellular stress, including hypoxia. Inadequate cellular management of hypoxic stress likely contributes to HD progression, and sphingolipids are potential mediators. Targeting sphingolipids and the hypoxic stress response are novel treatment strategies for HD
Cardio-Respiratory Characterization of the Autonomic Balance
The autonomic balance is often measured using the low frequency~(LF) and high frequency~(HF) powers of the heart beat-to-beat intervals. However, these indices do not adequately integrate the influence of respiration and have been widely criticized. We studied the autonomic balance with measures from the heart beat-to-beat intervals taking into account the respiratory activity. Using cardiac and respiratory data acquired simultaneously from healthy volunteers in supine and orthostatic positions, we found that the investigated measures convey changes in the autonomic balance in a physiologically meaningful manner in contrast to the classic LF and HF indices
Prooxidant/Antioxidant Balance in Hypoxia: A Cross-Over Study on Normobaric vs. Hypobaric âLive High-Train Lowâ
âLive High-Train Lowâ (LHTL) training can alter oxidative status of athletes. This study compared prooxidant/antioxidant balance responses following two LHTL protocols of the same duration and at the same living altitude of 2250 m in either normobaric (NH) or hypobaric (HH) hypoxia. Twenty-four well-trained triathletes underwent the following two 18-day LHTL protocols in a cross-over and randomized manner: Living altitude (PIO2 = 111.9 ± 0.6 vs. 111.6 ± 0.6 mmHg in NH and HH, respectively); training ânaturalâ altitude (~1000â1100 m) and training loads were precisely matched between both LHTL protocols. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP) and nitrotyrosine] and antioxidant markers [ferric-reducing antioxidant power (FRAP), superoxide dismutase (SOD) and catalase], NO metabolism end-products (NOx) and uric acid (UA) were determined before (Pre) and after (Post) the LHTL. Cumulative hypoxic exposure was lower during the NH (229 ± 6 hrs.) compared to the HH (310 ± 4 hrs.; P<0.01) protocol. Following the LHTL, the concentration of AOPP decreased (-27%; P<0.01) and nitrotyrosine increased (+67%; P<0.05) in HH only. FRAP was decreased (-27%; P<0.05) after the NH while was SOD and UA were only increased following the HH (SOD: +54%; P<0.01 and UA: +15%; P<0.01). Catalase activity was increased in the NH only (+20%; P<0.05). These data suggest that 18-days of LHTL performed in either NH or HH differentially affect oxidative status of athletes. Higher oxidative stress levels following the HH LHTL might be explained by the higher overall hypoxic dose and different physiological responses between the NH and HH.The study was funded by grants from the MinistĂšre des Sports, de la Jeunesse, de lâEducation Populaire et de la Vie Associative (MSJEPVA; France; to L.S. and G.P.M.), Institut National du Sport, de lâExpertise et de la Performance (INSEP; France; to L.S. and G.P.M.) and Institut Universitaire de France (IUF; France; to V.P.)
Similar Hemoglobin Mass Response in Hypobaric and Normobaric Hypoxia in Athletes
Purpose: To compare hemoglobin mass (Hbmass) changes during an 18-day live high-train low (LHTL) altitude training camp in normobaric hypoxia (NH) and hypobaric hypoxia (HH). Methods: Twenty-eight well-trained male triathletes were split into three groups (NH: n = 10, HH: n = 11, control (CON): n = 7) and participated in an 18-day LHTL camp. NH and HH slept at 2250 m while CON slept and all groups trained at altitudes 0.08) and remained unchanged in CON (+0.2%, P = 0.89). Conclusion: HH and NH evoked similar Hbmass increases for the same hypoxic dose and after 18-day LHTL. The wide variability in individual Hbmass responses in HH and NH emphasize the importance of individual Hbmass evaluation of altitude training.This study was financially supported by the Federal Office of Sport (FOSPO; Switzerland) and by the MinistĂšre des Sports, de la Jeunesse, de lâEducation Populaire et de la Vie Associative (MSJEPVA)/Institut National du Sport, de lâExpertise et de la Performance (INSEP, France)
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