Askling C.M.,The Swedish School of Sport and Health Sciences |
Askling C.M.,Karolinska Institutet |
Tengvar M.,Karolinska Sjukhuset |
Thorstensson A.,The Swedish School of Sport and Health Sciences
British Journal of Sports Medicine | Year: 2013
Background Hamstring injury is the single most common injury in European professional football and, therefore, time to return and secondary prevention are of particular concern. Objective To compare the effectiveness of two rehabilitation protocols after acute hamstring injury in Swedish elite football players by evaluating time needed to return to full participation in football team-training and availability for match selection. Study design Prospective randomised comparison of two rehabilitation protocols. Methods Seventy-five football players with an acute hamstring injury, verified by MRI, were randomly assigned to one of two rehabilitation protocols. Thirtyseven players were assigned to a protocol emphasising lengthening exercises, L-protocol and 38 players to a protocol consisting of conventional exercises, C-protocol. The outcome measure was the number of days to return to full-team training and availability for match selection. Reinjuries were registered during a period of 12 months after return. Results Time to return was significantly shorter for the players in the L-protocol, mean 28 days (1SD±15, range 8-58 days), compared with the C-protocol, mean 51 days (1SD±21, range 12-94 days). Irrespective of protocol, stretching-type of hamstring injury took significantly longer time to return than sprinting-type, L-protocol: mean 43 vs 23 days and C-protocol: mean 74 vs 41 days, respectively. The L-protocol was significantly more effective than the C-protocol in both injury types. One reinjury was registered, in the C-protocol. Conclusions A rehabilitation protocol emphasising lengthening type of exercises is more effective than a protocol containing conventional exercises in promoting time to return in Swedish elite football.
Schmied C.,University of Zürich |
Borjesson M.,The Swedish School of Sport and Health Sciences
Journal of Internal Medicine | Year: 2014
A 'paradox of sport' is that in addition to the undisputed health benefits of physical activity, vigorous exertion may transiently increase the risk of acute cardiac events. In general, the risk of sudden cardiac death (SCD) approximately doubles during physical activity and is 2- to 3-fold higher in athletes compared to nonathletes. The incidence of SCD in young athletes is in fact very low, at around 1-3 per 100 000, but attracts much public attention. Variations in incidence figures may be explained by the methodology used for data collection and more importantly by differences between subpopulations of athletes. The incidence of SCD in older (≥35 years) athletes is higher and may be expected to rise, as more and older individuals take part in organized sports. SCD is often the first clinical manifestation of a potentially fatal underlying cardiovascular disorder and usually occurs in previously asymptomatic athletes. In the young (<35 years), SCD is mainly due to congenital/inherited cardiac abnormalities, whilst coronary artery disease (CAD) is the most common cause in older athletes. Cardiac screening including family/personal history, physical examination and resting electrocardiogram (ECG) may identify individuals at risk and has the potential to decrease the risk of SCD in young athletes. Screening including the ECG has a high sensitivity for underlying disease in young athletes, but the specificity needs to be improved, whereas the sensitivity of screening without the use of ECG is very low. The screening modality recommended for young athletes is of limited value in older athletes, who should receive individualized screening with cardiac stress testing for patients with high risk of underlying CAD. As cardiovascular screening will never be able to identify all athletes at risk, adequate preparedness is vital in case of a potentially fatal event at the sporting arena/facility. Firstly, we will review the magnitude of the problem of SCD in athletes of different ages, as well as the aetiology. Secondly, we will focus on how to prevent SCD in athletes of all ages, reviewing cardiovascular screening recommendations as well as emergency preparedness and arena safety. © 2013 The Association for the Publication of the Journal of Internal Medicine.
Larsson H.,The Swedish School of Sport and Health Sciences |
Karlefors I.,Umeå University
Sport, Education and Society | Year: 2015
In a significant article from 1993, Crum describes the purpose of physical education (PE) as a ‘planned introduction into movement culture’. In broad terms, this purpose is tantamount to the stated purpose of Swedish PE in national steering documents. Crum contends, however, that physical educators do not prioritise learning, which is largely due to the different ‘movement cultures’ that constitute the PE lessons. This article explores how practice unfolds in movement cultures that are included in Swedish PE and their implications for teaching and learning in the subject. Some 30 (indoor) PE lessons in eight secondary schools in four cities throughout Sweden were video recorded. At ‘first glance’ these lessons indicated the prevalence of four logics of practice: a physical training logic, a sports logic, a sport technique logic and a dance logic. However, further analysis revealed that the teachers' and students' actions were not entirely in line with a logic of practice of training the body, winning the game, learning sporting skills or learning to dance. Instead, the PE practice largely unfolded as a ‘looks-like-practice’, where the purpose of teaching was blurred, and where any ‘planned introduction into movement culture’ was difficult to identify. In the final section, the authors discuss how physical activity logics can be recontextualised in a PE setting in order to emphasise the educational contribution of PE. © 2015 The Author(s). Published by Taylor & Francis.
Larsen F.J.,The Swedish School of Sport and Health Sciences |
Weitzberg E.,The Swedish School of Sport and Health Sciences |
Lundberg J.O.,The Swedish School of Sport and Health Sciences |
Ekblom B.,The Swedish School of Sport and Health Sciences
Free Radical Biology and Medicine | Year: 2010
The anion nitrate-abundant in our diet-has recently emerged as a major pool of nitric oxide (NO) synthase-independent NO production. Nitrate is reduced stepwise in vivo to nitrite and then NO and possibly other bioactive nitrogen oxides. This reductive pathway is enhanced during low oxygen tension and acidosis. A recent study shows a reduction in oxygen consumption during submaximal exercise attributable to dietary nitrate. We went on to study the effects of dietary nitrate on various physiological and biochemical parameters during maximal exercise. Nine healthy, nonsmoking volunteers (age 30 ± 2.3 years, VO2max 3.72 ± 0.33 L/min) participated in this study, which had a randomized, double-blind crossover design. Subjects received dietary supplementation with sodium nitrate (0.1 mmol/kg/day) or placebo (NaCl) for 2 days before the test. This dose corresponds to the amount found in 100-300 g of a nitrate-rich vegetable such as spinach or beetroot. The maximal exercise tests consisted of an incremental exercise to exhaustion with combined arm and leg cranking on two separate ergometers. Dietary nitrate reduced VO2max from 3.72 ± 0.33 to 3.62 ± 0.31 L/min, P < 0.05. Despite the reduction in VO2max the time to exhaustion trended to an increase after nitrate supplementation (524 ± 31 vs 563 ± 30 s, P = 0.13). There was a correlation between the change in time to exhaustion and the change in VO2max (R2 = 0.47, P = 0.04). A moderate dietary dose of nitrate significantly reduces VO2max during maximal exercise using a large active muscle mass. This reduction occurred with a trend toward increased time to exhaustion implying that two separate mechanisms are involved: one that reduces VO2max and another that improves the energetic function of the working muscles. © 2009 Elsevier Inc. All rights reserved.
Sahlin K.,The Swedish School of Sport and Health Sciences
Amino acids | Year: 2011
The classical role of PCr is seen as a reservoir of high-energy phosphates defending cellular ATP levels under anaerobic conditions, high rates of energy transfer or rapid fluctuations in energy requirement. Although the high concentration of PCr in glycolytic fast-twitch fibers supports the role of PCr as a buffer of ATP, the primary importance of the creatine kinase (CK) reaction may in fact be to counteract large increases in ADP, which could otherwise inhibit cellular ATPase-mediated systems. A primary role for CK in the maintenance of ADP homeostasis may explain why, in many conditions, there is an inverse relationship between PCr and muscle contractility but not between ATP and muscle contractility. The high rate of ATP hydrolysis during muscle contraction combined with restricted diffusion of ADP suggests that ADP concentration increases transiently during the contraction phase (ADP spikes) and that these are synchronized with the contraction. The presence of CK, structurally bound in close vicinity to the sites of ATP utilization, will reduce the amplitude and duration of the ADP spikes through PCr-mediated phosphotransfer. When PCr is reduced, the efficiency of CK as an ATP buffer will be reduced and the changes in ADP will become more prominent. The presence of ADP spikes is supported by the finding that other processes known to be activated by ADP (i.e. AMP deamination and glycolysis) are stimulated during exercise but not during anoxia, despite the same low global energy state. Breakdown of PCr is driven by increases in ADP above that depicted by the CK equilibrium and the current method to calculate ADPfree from the CK reaction in a contracting muscle is therefore questionable.
Larsson H.,The Swedish School of Sport and Health Sciences
Sport, Education and Society | Year: 2013
This article sets out to show how physiological knowledge about sex/gender relates to power issues within sport. The sport physiology research at the Swedish School of Sport and Health Sciences (Swedish acronym: GIH) during the twentieth century is analysed in relation to the political rationality concerning gender at GIH and within the Swedish Sports Confederation during the same period. The analysis is constituted by Michel Foucault's notion of power-knowledge relations and regimes oftruth. The construction of sex/gender in the physiological research changes over time. Comparative studies on the function of 'sexual difference' during strenuous work, which, in hindsight, might be seen to restrict women's sport participation, was gradually displaced by a lack of interest in sexual difference, and later by a growing fascination with sexual difference from a 'gender perspective' in terms of women being 'different but equal' to men. This displacement goes hand in hand with a displacement of the political rationality concerning gender at GIH and within the Swedish Sports Confederation, where a pre-World War II strategy of excluding women's competitive sport participation, restricting women's physical exercise to gymnastics, was after 1945 followed by a strategy of including women. This was at first in the name of 'women's right to do sport'-where the physiological research advocated this endeavour-and later in the name of 'women's right to do sport on their own terms'. However, the research was still being conducted based on the male physiology as the norm. © 2013 Copyright Taylor and Francis Group, LLC.
Sahlin K.,The Swedish School of Sport and Health Sciences
Sports Medicine | Year: 2014
The high-energy demand during high-intensity exercise (HIE) necessitates that anaerobic processes cover an extensive part of the adenosine triphosphate (ATP) requirement. Anaerobic energy release results in depletion of phosphocreatine (PCr) and accumulation of lactic acid, which set an upper limit of anaerobic ATP production and thus HIE performance. This report focuses on the effects of training and ergogenic supplements on muscle energetics and HIE performance. Anaerobic capacity (i.e. the amount of ATP that can be produced) is determined by the muscle content of PCr, the buffer capacity and the volume of the contracting muscle mass. HIE training can increase buffer capacity and the contracting muscle mass but has no effect on the concentration of PCr. Dietary supplementation with creatine (Cr), bicarbonate, or beta-alanine has a documented ergogenic effect. Dietary supplementation with Cr increases muscle Cr and PCr and enhances performance, especially during repeated short periods of HIE. The ergogenic effect of Cr is related to an increase in temporal and spatial buffering of ATP and to increased muscle buffer capacity. Bicarbonate loading increases extracellular buffering and can improve performance during HIE by facilitating lactic acid removal from the contracting muscle. Supplementation with beta-alanine increases the content of muscle carnosine, which is an endogenous intracellular buffer. It is clear that performance during HIE can be improved by interventions that increase the capacity of anaerobic ATP production, suggesting that energetic constraints set a limit for performance during HIE. © 2014, The Author(s).
Thedin Jakobsson B.,The Swedish School of Sport and Health Sciences
Physical Education and Sport Pedagogy | Year: 2014
Background: International studies have revealed that young people engage in sports because of friends, the enjoyment of participation, and the ability to feel healthy. Furthermore, it is often argued that sports should be characterized as joyful and provide both recreational and elite investment. In Sweden, many children participate in club sports during their childhood or youth, but many drop out in their late teens. Furthermore, few children take up a sport after 12 years of age. Rather than concentrating on those who drop out of club sports, the focus of this article is on those who continue during their teenage years despite being non-elite participants.Purpose: By illuminating the experiences of non-elite participants, the overall aim is to study what makes teenagers continue to participate in club sports with a specific focus on what teenagers find meaningful and important when they participate in club sports. This is done with the help of Antonovsky's salutogenic theory and his sense of coherence (SOC) model. The discussion will focus on how club sports can be organized to encourage more teenagers to participate longer.Research design and data collection: In this study, a total of 18 semi-structured, in-depth interviews were conducted. The teenagers were between 15 and 19 years old, and they participated in eight different club sports (athletics, basketball, equestrian sports, floorball, football, handball, swimming, and ultimate frisbee). The selection of sports and clubs was done using the Swedish Sports Confederation's (RF) database. A targeted sample selection was carried out by contacting club trainers, who provided the names of teenagers suitable with respect to the research aim and questions. The interviews were systematically coded and analysed using the SOC components as analytical tools.Key findings: When analysing the results, three themes emerged. The teenagers found sports fun in terms of meaningfulness because they experienced learning and development; they found competition challenging; and they enjoyed the involvement and engagement with others. Furthermore, the young people who remained in club sports were participating in more than one competitive elite sport even if they themselves did not have elite ambitions.Conclusions: If the goal of society in general and sports clubs in particular is to get as many people as possible to be physically active and develop a lifelong interest in sports, it is conceivable that club sports should offer activities that attract people with different levels of ambition and abilities. If the findings correspond with young people's willingness to learn and develop together with others, it is conceivable that club sports as well as physical education should be organized to give all young people opportunities to learn physical activities with numerous opportunities for motor and social learning in focus. © 2012 Association for Physical Education.
Larsson H.,The Swedish School of Sport and Health Sciences
Sport, Education and Society | Year: 2014
Over the last one of two decades, researchers within the physical education (PE) and sport pedagogy research frequently use the concept 'the material body'. An initial purpose of this article is to explore what a concept of a 'material body' might mean. What other bodies are there? Who would dispute the materiality of bodies? I suggest that the use of a concept as 'the material body' suggests a hesitation before the radicalism of the linguistic turn in the sense that the concept 'discourse' does not include a material dimension. In this way 'the material body' relates to an interpretation of 'the socially (or discursively) constructed body' as void of matter. A further purpose with the article is to re-inscribe matter in the concept of 'discourse'. This is done by way of discussing what theorists like Michel Foucault and, in particular, Judith Butler, has to say about the materiality of the body. In their writings, discourse should not be limited to spoken and/or written language. Rather, discourse is understood in terms of actions and events that create meanings-that matters. One conclusion of the article is that it is important to problematise the mundane view of discourse as 'verbal interchange' because it reinforces the promise of an objective knowledge that will eventually shed light on the 'real' body and the mysteries of sexual difference, what its origins are, what causes it. Another conclusion is that the PE and sport pedagogy research should pay less attention to the body as an object (what it 'is'), and pay more attention to how the body matters, and e.g. how movements make bodies matter. © 2012 © 2012 Taylor & Francis.
Nordlund Ekblom M.M.,The Swedish School of Sport and Health Sciences
Journal of Applied Physiology | Year: 2010
The aim of this study was to investigate if, and via what mechanisms, resistance training of the plantar flexor muscles affects voluntary activation during maximal voluntary eccentric and concentric muscle actions. Twenty healthy subjects were randomized into a resistance training group (n = 9) or a passive control group (n = 11). Training consisted of 15 sessions of unilateral mainly eccentric plantar flexor exercise over a 5-wk period. During pre- and posttraining testing, dynamic plantar flexor strength was measured and voluntary activation was calculated using the twitch interpolation technique. The soleus Hoffman reflex (H-reflex) was used to assess motoneurone excitability and presynaptic inhibition of Ia afferents, whereas the soleus V-wave was used to test for changes in both presynaptic inhibition of Ia afferents and supraspinal inputs to the motoneurone pool. H-reflexes, V-waves, supramaximal M-waves, and twitches were evoked as the foot was moved at 5°/s through an angle of 90° during passive ankle rotations (passive H-relexes and M-waves) and during maximal voluntary concentric and eccentric plantar flexions [maximal voluntary contraction (MVC) H-reflexes, M-waves, and V-waves], Training induced significant improvements in plantar flexor strength and voluntary activation during both concentric and eccentric maximal voluntary actions. Soleus passive and MVC Hto-M ratios remained unchanged after training, whereas the soleus V-to-M ratio was increased during both concentric and eccentric contractions after training. No changes were found in the control group for any of the parameters. The enhanced voluntary strength could be attributed partly to an increase in voluntary activation induced by eccentric training. Since the passive and MVC H-to-M ratios remained unchanged, the increase in activation is probably not due to decreased presynaptic inhibition. The increased V-to-M ratio for both action types indicates that increased voluntary drive from supraspinal centers and/or modulation in afferents other than Ia afferents may have contributed to such an increase in voluntary activation. Copyright © 2010 the American Physiological Society.