Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Ischaemic heart disease is a major contributor to global morbidity and mortality rates. Manoeuvres such as ischaemic preconditioning confer cardioprotection against ischaemia/reperfusion (I/R) injury by activating several intracellular signalling pathways. These pathways have been defined solely in terms of the kinases involved, despite the realization in recent years that protein phosphatase activity also contributes significantly to the attributes of the propagated signal. Protein phosphatase 2A (PP2A) is a heteromultimeric enzyme involved in an array of phosphatase reactions. We hypothesized that PP2A is an important participant in the myocardial response to I/R by regulating intracellular signalling. This project aimed to (i) characterize PP2A during myocardial I/R; (ii) determine the importance of its contribution to the cellular response to I/R; and (iii) investigate its role in the signalling pathways mediated by PKB/Akt, GSK-3β, ERK p42/p44 and p38 MAPK. Two models were used to characterize PP2A during I/R: (i) H9c2 cells exposed to simulated ischaemia (SI) buffer in conjunction with hypoxia (0.5% O2) for a maximum of 2 hours, followed by reoxygenation in standard growth medium for up to 30 minutes; and (ii) isolated working rat hearts exposed to a maximum of 20 minutes global ischaemia and 10 minutes reperfusion. In both models samples were collected at several time points during I/R for Western blotting analysis. PP2A-C (the catalytic subunit) accumulated in the nucleus during early ischaemia, but later redistributed to the cytosol. At the end of ischaemia there was an elevation of PP2A-C relative to PP2A-A in the unfractionated whole cell preparation concomitant with an increase in the inhibitory phosphorylation of PP2A-C. The impact of PP2A activity was evaluated by either inhibiting PP2A using okadaic acid (OA, 10 nM) or activating it by administering FTY720 (1 μM) in an isolated working rat heart model exposed to either 35 minutes of regional ischaemia (RI) with infarct size (IFS) as primary end-point, or 20 minutes global ischaemia (GI) with functional recovery as end-point. The results showed that the pre-ischaemic administration of OA or FTY720 reduced or exacerbated IFS respectively, indicating that PP2A activation during I/R favours cell death. OA and FTY720 were also employed to assess the contribution of PP2A to intracellular signalling in an isolated working rat heart exposed to I/R. Samples were collected at several timepoints and analyzed using Western Blotting. Pre-ischaemic administration of OA enhanced the phosphorylation of PKB/Akt, ERK p42/p44 and GSK-3β at the onset of reperfusion, while FTY720 given before ischaemia reduced the phosphorylation of GSK-3β, p38 MAPK and PKB/Akt at the end of ischaemia and onset of reperfusion. In summary, PP2A is part of an early nuclear-based response to ischaemia, while long-term ischaemia induces an increase in PP2A-C. A portion of this PP2A-C is stored in an inactive form, while an active portion acts as a regulator of the pro-survival signalling components PKB/Akt, GSK- 3β and ERK p42/p44 at the end of ischaemia and the onset of reperfusion. PP2A is therefore an important component of the myocardial response to I/R by regulating pro-survival signalling. / AFRIKAANSE OPSOMMING: Iskemiese hartsiekte is een van die belangrikste komponente wat bydra tot globale morbiditeit en mortaliteit. Ingrepe soos iskemiese prekondisionering aktiveer veelvoudige intrasellulêre seintransduksiepaaie om kardiobeskerming teen iskemie/herperfusie (I/H)-besering te ontlok. Die kinases betrokke in hierdie seintransduksiepaaie is reeds deeglik nagevors, terwyl die potensiële belang van die proteïenfosfatases in seintransduksie tot onlangs misken is. Ons hipotese was dat Proteïenfosfatase 2A (PP2A), wat in ‘n wye verskeidenheid fosfatase reaksies betrokke is, ‘n belangrike rolspeler in die miokardiale reaksie op I/H-besering is, deur deelname aan die regulering van intrasellulêre seintransduksie. Hierdie projek het ten doel gehad om (i) PP2A te karakteriseer tydens miokardiale I/H; (ii) die belang van PP2A in die sellulêre reaksie op I/H-besering te bepaal; en (iii) PP2A se rol in die seintransduksiepaaie, gemedieer deur PKB/Akt, GSK-3β, ERK p42/p44 en p38 MAPK, te evalueer. Twee modelle is aangewend om PP2A tydens I/H te karakteriseer: (i) H9c2-selle blootgestel aan ‘n simuleerde iskemiebuffer tesame met hipoksie (0.5% O2) vir ‘n maksimum van 2 uur gevolg deur heroksiginasie in standaardgroeimedium vir verskillende tydsperiodes tot ‘n maksimum van 30 minute; en (ii) geïsoleerde, werkende rotharte blootgestel aan ‘n maksimum van 20 minute globale iskemie en 10 minute herperfusie. In beide modelle is monsters op verskillende tye versamel vir Western-kladanalise. Tydens vroeë iskemie het PP2A-C in die kern toegeneem, waarna dit met verloop van tyd na die sitosol herversprei het. Teen die einde van iskemie was daar ‘n toename in die vlakke van PP2A-C relatief tot PP2A-A in ongefraksioneerde weefselhomogenate, tesame met ‘n toename in die inhibitoriese fosforilering van PP2A-C. Die belang van PP2A-aktiwiteit is ondersoek deur die effek te bepaal van die inhibisie of aktivering daarvan op infarktgrootte (IFS) en funksionele herstel in ‘n geïsoleerde werkende rothartmodel, blootgestel aan onderskeidelik 35 minute streeksiskemie (RI) of 20 minute globale iskemie. Preiskemiese toediening van die PP2A-inhibitor okadaïensuur (OA, 10 nM), of aktiveerder FTY720 (1 μm) het infarktgrootte respektiewelik beperk of vergroot. PP2A-aktivering tydens I/H is dus nadelig. OA en FTY720 is ook aangewend om die bydrae van PP2A tot I/H-verwante, intrasellulêre seintransduksie in die geïsoleerde, werkende rothart te bepaal. Monsters is op verskeie tydintervalle versamel en ontleed deur gebruik te maak van die Western-kladtegniek. Preiskemiese toediening van OA het die fosforilering van PKB/Akt, ERK p42/p44 en GSK-3β by die aanvang van herperfusie bevoordeel, terwyl pre-iskemiese toediening van FTY720, die fosforilering van GSK-3β, p38 MAPK en PKB/Akt aan die einde van iskemie en die begin van herperfusie verminder het. Ter opsomming: PP2A is deel van ‘n vroeë gelokaliseerde kerngebaseerde reaksie op iskemie, terwyl langdurige iskemie ‘n toename in PP2A-C relatief tot PP2A-A induseer. ‘n Deel van hierdie PP2A-C is onaktief, terwyl die res funksioneer in die regulering van die seintransduksiekomponente PKB/Akt, GSK-3β en ERK p42/p44 wat oorlewing fasiliteer met die aanvang van herperfusie. PP2A is dus ‘n belangrike komponent in die miokardiale reaksie op I/H deurdat dit tot die beheer van seintransduksiepaaie bydra.

Dissertation (PhD)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Activation of the NO-cGMP pathway is associated with myocardial protection against ischaemia/reperfusion injury. However, high-cholesterol diets alter function of this pathway and these alterations have been implicated in both ischaemic/reperfusion injury and the development of ischaemic heart disease. Little is known about the effects of supplements such as Red Palm Oil (RPO) on the myocardial NO-cGMP-signalling pathway. RPO consists of saturated, mono-unsaturated and poly-unsaturated fatty acids and is rich in antioxidants such as β-carotene and Vitamin E (tocopherols and tocotrienols). The aims of this study were: 1) to determine whether dietary RPO-supplemention protects against ischaemia/reperfusion injury in rats fed a standard rat chow (control) and cholesterol-enriched diets and 2) if so, to investigate possible mechanisms for this protection. Male Long-Evans rats were fed a standard rat chow or a standard rat chow plus cholesterol and/or RPO-supplementation for 6 weeks. Myocardial functional recovery was measured and hearts were freeze-clamped for determination of myocardial phospholipid, cAMP/cGMP concentrations, total myocardial nitric oxide concentrations, lipid hydroperoxide production and superoxide dismutase- and nitric oxide synthase activity in isolated rat hearts subjected to 25 minutes of normothermic total global ischaemia. In addition, the degree of phosphorylation of extracellular signal-regulated kinase (ERK), p38, c-Jun N-terminal protein kinase (JNK) and protein kinase B (PKB/Akt) was investigated. Furthermore, the effect of RPO-supplementation on caspase-3 activation and poly (ADP-ribose) polymerase (PARP)-cleavage in hearts subjected to ischaemia and reperfusion was also investigated. Our data show that dietary RPO-supplementation protects the hearts of rats on a standard rat chow (control) and hypercholesterolaemic diet against ischaemia/reperfusion injury as reflected by improved aortic output recovery. Increased intracellular cardiomyocyte NO concentrations as observed in control hearts supplemented with RPO after 120 minutes hypoxia may contribute to the elevated cGMP concentration and may confer some of the cardioprotection to the ischaemic/reperfused heart. Although improved functional recovery with RPO-supplementation of a high-cholesterol diet was also associated with an increase in intracellular cardiomyocyte NO production after hypoxia compared to the non-hypoxic conditions, it could not be linked to increased NO-cGMP signalling. These data are in agreement with other studies, which showed that high-cholesterol diet impairs NO-cGMP signalling and confirms our hypothesis that elevated cGMP concentrations may not be the only mechanism of protection. We have also shown that RPOsupplementation caused increased phosphorylation of p38 and PKB, reduced phosphorylation of JNK and attenuation of PARP cleavage, which may contribute to the protection of the cell against apoptosis. Based on our results we propose that the myocardial protection offered by RPO-supplementation of rats on a normal and hypercholesterolaemic diet may be associated with either its antioxidant characteristics and/or changes in the fatty acid composition of the myocardium during ischaemia/reperfusion. Furthermore, we demonstrated for the first time that RPO-supplementation protects the isolated perfused working rat heart during reperfusion from ischaemia/reperfusion-induced injury through a MAPK-dependent pathway. / AFRIKAANSE OPSOMMING: Aktivering van die NO-cGMP sein transduksie pad word geassosieer met miokardiale beskerming teen isgemie/herperfusie skade. Hoë cholesterol diëte verander egter die funksie van die pad en hierdie veranderings speel ‘n rol in beide isgemie/herperfusie besering en die ontwikkeling van isgemiese hartsiekte. Daar is egter min inligting beskikbaar oor die uitwerking van aanvullings soos rooi palm olie (RPO) op die miokardiale NO-cGMP sein transduksie pad. RPO bevat versadigde, mono-onversadigde en poli-onversadigde vetsure en is ryk aan anti-oksidante nl. β-karotene en vitamien E (tokoferole en tokotriënole). Die doelwitte van hierdie studie was: 1) om vas te stel of ‘n RPO-aanvulling beskerming bied teen isgemie/herperfusie besering in rotte wat gevoed is met ‘n standaard rotmengsel (kontrole) en cholesterol-verrykte dieet en 2) indien wel, om moontlike meganismes van beskerming te ondersoek. Long-Evans manlike rotte is vir 6 weke gevoer met ‘n standaard rotmengsel of ‘n standaard rotmengsel plus cholesterol en/of RPO-aanvulling. Miokardiale funksionele herstel is gemeet en harte is gevriesklamp vir die bepaling van miokardiale fosfolipied, cAMP/cGMP, totale stikstofoksied, lipied hidroperoksied, superoksied dismutase en stikstofoksied sintase in geïsoleerde rotharte wat vir 25 minute onderwerp was aan normotermiese totale globale isgemie. Hiermee saam is die graad van fosforilering van ekstrasellulêre sein gereguleerde kinase (ERK), p38 mitogeen-geaktiveerde proteïen kinase (p38 MAPK), c-Jun-N-terminale proteïenkinase (JNK) en proteïen kinase B (PKB/Akt) ondersoek, asook kaspase-3 aktivering en poli (ADP-ribose) polimerase (PARP) kliewing in harte blootgestel aan isgemie en herperfusie. Ons resultate toon dat RPO-aanvulling van rotte op ‘n normale en hipercholesterolemiese dieet die hart beskerm soos getoon deur verbeterde herstel van aortiese uitset. Verhoogde intrasellulêre miokardiale NO vlakke in kontrole harte met ‘n RPO-aanvulling wat blootgestel was aan 120 minute hipoksie, mag bygedra het tot die verhoogde cGMP vlakke en beskerming van die hart tydens isgemie en herperfusie. Alhoewel verbeterde funksionele herstel met RPO-aanvulling van ‘n hoë cholesterol dieet ook geassosieer is met ‘n toename in intrasellulêre miokardiale NO produksie ná hipoksiese toestande, kon dit nie verbind word met verhoogde aktivering van die NOcGMP sein transduksie pad nie. Hierdie resultate stem ooreen met ander studies wat aangetoon het dat hoë-cholesterol diëte die NO-cGMP seinpad onderdruk. Hierdie bevinding bevestig ons hipotese dat verhoogde cGMP vlakke moontlik nie die enigste beskermingsmeganisme is nie. Ons resultate het ook gewys dat RPO-aanvulling fosforilering van p38 en PKB/Akt verhoog, fosforilering van JNK verminder en PARP kliewing onderdruk. Dit dui op beskerming van die sel teen apoptose. Ons resultate dui aan dat die miokardiale beskerming wat RPO-dieet aanvulling bied moontlik geassosieer kan word met sy anti-oksidant eienskap en/of veranderinge in die vetsuur samestelling van die miokardium tydens isgemie/herperfusie. Ons het ook vir die eerste keer bewys dat RPO-aanvulling die geïsoleerde geperfuseerde werkende rothart gedurende herperfusie beskerm teen isgemie/herperfusie besering deur die aktivering en/of deaktivering van die MAPK afhanklike pad.

Title: Posterior chain muscle endurance and arm paddling peak power in amateur female surfers Objectives: Thesis is dedicated to female surfing, particularly paddling, as this is an undiscovered area of research. Very few studies have been carried out, which would focus on muscle activity in surfing. None of the studies focused on posterior chain or muscle activity of female surfers while paddling. Not only that the level of competitive surfing is increasing rapidly, as it will be part of Olympic Games in Tokyo in 2020, but the recreational surfers are also becoming more literate about surf science and willing to improve their surfing performance by dry land surf specific trainings. Surfing industry represents a worldwide business, where big companies offer sponsorship, which is reasonable motivation for young athletes (M. Mendez-Villanueva & Bishop, 2005). As the number of recreational and competitive female surfers is raising as well, the level of competitive female surfing is increasing (Booth, 2001) and professional female surfers are becoming equal in regards to getting the same amount of prize money in competitions, more research should be dedicated to female surfing. The aim of this thesis was to study association between posterior chain endurance and other variables such as frequency of...

Syftet med denna studie har varit att studera psykosociala faktorers påverkan på skaderisken hos ungdomslandslagsspelare i fotboll. Tvångsmässig passion är en central faktor som studerats i relation till skada. Även faktorerna antal träningstimmar per vecka, antal spelade matcher, stress, själförtroende och motivation har studerats i relation till skada. En kvantitativ design har använts där 300 svenska ungdomslandslagsspelare i fotboll ingått som undersökningsdeltagare. Använda mätinstrument i undersökningen har varit PANAS, PSS, Grit-scale, PCLDS, Passion Scale, SCI samt SMS. Resultaten visade att män ådrar sig fler allvarliga skador (minst 4 veckors frånvaro) än kvinnor. Vidare visade resultaten att flergångsskadade spelare har en signifikant högre tvångsmässig passion än andra spelare. Resultaten diskuteras i förhållanden till uppsatsens teoretiska ramverk samt resultat från tidigare forskning. Förslag för framtida forskning inom området ges. / The purpose of this study was to study psychosocial factors influence on injury risk among youth national team soccer players. Obsessive passion has been a key factor that has been studied in relation to injury. Also the factors number of training hours per week, number of matches played, stress, self confidence and motivation has been studied in relation to injury. A quantitative design was used in which 300 Swedish youth national team soccer players have concluded as study participants. Used instruments in this survey has been PANAS, PSS, Grit-scale, PCLDS, Passion Scale, SCI and SMS.. The results showed that men incur more serious injuries then women. Furthermore, results showed that players with more than one injury during the season had higher obsessive passion then other players. The results are discussed in relation to the theoretical framework and the results from previous research. Proposal for future research in the field are provided.

Caregivers injure their backs more than workers in any other industry. Efforts to reduce injuries have been on-going for decades with limited results. Mechanical lift devices have been incorporated into clinical practice over the past 30 years to reduce the risk of injury from patient lifting. Yet injury rates remain high. The use of mechanical lifts may be partly to blame. While these devices assist with lifting patients, they also introduce new activities that result in caregivers experiencing unsafe loading on the spine. We measured loads on the lower back during manoeuvres of the two most common lift types (overhead and floor) as well as during sling insertion. A new device called SlingSerterTM was evaluated for use in the clinical environment. We also investigated spine shrinkage as a measurement tool for estimating cumulative load. Caregivers worked alone and in pairs for both lift maneuvering and sling insertion activities. Overhead lift use resulted in much lower loads than floor lift use. We conclude caregivers can safely operate overhead lifts alone, while floor lift use remained unsafe even with two caregivers. Less-experienced caregivers had higher loads than more-experienced counterparts when using floor lifts. There was no corresponding effect of experience with overhead lift use and we found this to be a further benefit of overhead lifts over floor lifts. Most caregivers exceeded the safe limit for spine compression during sling insertion, though a single caregiver was at no higher risk of injury than two caregivers working together. Clinicians who tested SlingSerterTM agreed the device would be useful in clinical practice, particularly with bariatric patients and other special patient populations that are difficult to roll or turn. Finally, we investigated a novel method for estimating cumulative load based on spine shrinkage. There is growing recognition that excess cumulative load may be responsible for back injury. We found the variability in spine shrinkage was too large to estimate cumulative load directly. However, the technique may still be useful for determining the relative importance of the load from different activities to the cumulative total.

Professional orchestral string musicians represent a population at risk for performance-related musculoskeletal disorders (PRMD). Research literature suggests the influence of stress in the incidence of work-related and performance-related musculoskeletal disorders. The purpose of this study was to qualitatively investigate the role of holistic health (physical, mental, emotional, spiritual, and social) and stress management in the prevention of PRMDs in professional orchestral string musicians. Five musicians representing different instruments, genders, and PRMD histories were recruited and sorted from a single professional orchestra in Canada. This study combined quantitative data - in the form of basic demographic information and a Health and Well-being Assessment - with qualitative interview data. This combined data provided a focused, in-depth view of typical instances in the professional orchestral string population. The musicians reported a variety of occupational and non-occupational risk factors, as well as a range of intrinsic risk factors. They also reported a variety of PRMD prevention strategies and lifestyle behaviours. The musicians in this study provide evidence that stress may play a mediating role in PRMDs and that the management of biomechanical and psychosocial stressors through holistic health practices may positively influence the incidence, severity, and treatment of PRMDs in orchestral string musicians. This dissertation recommends that increased awareness and education in holistic health practices be encouraged for the purpose of improved PRMD prevention in professional orchestral string musicians.

Caregivers injure their backs more than workers in any other industry. Efforts to reduce injuries have been on-going for decades with limited results. Mechanical lift devices have been incorporated into clinical practice over the past 30 years to reduce the risk of injury from patient lifting. Yet injury rates remain high. The use of mechanical lifts may be partly to blame. While these devices assist with lifting patients, they also introduce new activities that result in caregivers experiencing unsafe loading on the spine. We measured loads on the lower back during manoeuvres of the two most common lift types (overhead and floor) as well as during sling insertion. A new device called SlingSerterTM was evaluated for use in the clinical environment. We also investigated spine shrinkage as a measurement tool for estimating cumulative load. Caregivers worked alone and in pairs for both lift maneuvering and sling insertion activities. Overhead lift use resulted in much lower loads than floor lift use. We conclude caregivers can safely operate overhead lifts alone, while floor lift use remained unsafe even with two caregivers. Less-experienced caregivers had higher loads than more-experienced counterparts when using floor lifts. There was no corresponding effect of experience with overhead lift use and we found this to be a further benefit of overhead lifts over floor lifts. Most caregivers exceeded the safe limit for spine compression during sling insertion, though a single caregiver was at no higher risk of injury than two caregivers working together. Clinicians who tested SlingSerterTM agreed the device would be useful in clinical practice, particularly with bariatric patients and other special patient populations that are difficult to roll or turn. Finally, we investigated a novel method for estimating cumulative load based on spine shrinkage. There is growing recognition that excess cumulative load may be responsible for back injury. We found the variability in spine shrinkage was too large to estimate cumulative load directly. However, the technique may still be useful for determining the relative importance of the load from different activities to the cumulative total.

Professional orchestral string musicians represent a population at risk for performance-related musculoskeletal disorders (PRMD). Research literature suggests the influence of stress in the incidence of work-related and performance-related musculoskeletal disorders. The purpose of this study was to qualitatively investigate the role of holistic health (physical, mental, emotional, spiritual, and social) and stress management in the prevention of PRMDs in professional orchestral string musicians. Five musicians representing different instruments, genders, and PRMD histories were recruited and sorted from a single professional orchestra in Canada. This study combined quantitative data - in the form of basic demographic information and a Health and Well-being Assessment - with qualitative interview data. This combined data provided a focused, in-depth view of typical instances in the professional orchestral string population. The musicians reported a variety of occupational and non-occupational risk factors, as well as a range of intrinsic risk factors. They also reported a variety of PRMD prevention strategies and lifestyle behaviours. The musicians in this study provide evidence that stress may play a mediating role in PRMDs and that the management of biomechanical and psychosocial stressors through holistic health practices may positively influence the incidence, severity, and treatment of PRMDs in orchestral string musicians. This dissertation recommends that increased awareness and education in holistic health practices be encouraged for the purpose of improved PRMD prevention in professional orchestral string musicians.

Aquesta tesi és una aproximació teòrica i empírica a la metodologia actualitzada per a l'entrenament de la propiocepció. La part teòrica desenvolupa l'estat de la qüestió en l'estudi de la propiocepció des de diferents perspectives, de les particularitats de la columna vertebral lumbar i de les característiques de la propiocepció en aquesta zona del raquis. Ens resumeix els aspectes més importants de la teoria de l'entrenament i les necessitats de l'entrenament propioceptiu lumbar en la natació competitiva. La part empírica pretén ser un punt de partida en la investigació experimental de la metodologia més adequada per a l'entrenament de la propiocepció conscient. Es realitza un disseny específic per a la millora del control de la CV lumbar en la tècnica de natació subaquàtica, en el qual es tracta d'intercedir sobre l'amplitud de moviment lumbar en el pla sagital i sobre la precisió en el seu posicionament dins del mateix pla. S'aplica, s'avalua i es comparen els efectes de l'administració d’uns exercicis durant 75 sessions, en un període de 2-3 mesos naturals, amb dues metodologies d'execució diferenciades: Amb ulls tapats centrant l'atenció sobre la zona lumbar i sense cap condició diferent a la de complir la tècnica d'execució del moviment. Els resultats de l'estudi experimental demostren que el mètode que millora les variables relacionades amb la propiocepció és el que proposa la realització dels exercicis amb els ulls tancats i centrant l'atenció sobre la zona lumbar, mentre que amb els ulls oberts empitjoren aquestes variables respecte al grup control. Ambdós mètodes provoquen millores significatives de l'amplitud de moviment lumbar en el pla treballat. En línies generals tot el procés revela la necessitat d'actualitzar el tractament conceptual i metodològic de la propiocepció, posant un exemple d'intervenció en la natació competitiva que orienta sobre les bases per a la seva aplicació en altres esports. / Esta tesis es una aproximación teórica y empírica a la metodología actualizada para el entrenamiento de la propiocepción. La parte teórica desarrolla el estado de la cuestión en el estudio de la propiocepción desde diferentes perspectivas, de las particularidades de la columna vertebral lumbar y de las características de la propiocepción en ésta zona del raquis. Nos resume los aspectos más importantes de la teoría del entrenamiento y las necesidades del entrenamiento propioceptivo lumbar en la natación competitiva. La parte empírica pretende ser un punto de partida en la investigación experimental de la metodología más adecuada para el entrenamiento de la propiocepción consciente. Se realiza un diseño específico para la mejora del control de la CV lumbar en la técnica de natación subacuática, en el que se trata de interceder sobre la amplitud de movimiento lumbar en el plano sagital y sobre la precisión en su posicionamiento dentro del mismo plano. Se aplica, se evalúa y se comparan los efectos de la administración de unos ejercicios durante 75 sesiones, en un período de 2-3 meses naturales, con dos metodologías de ejecución diferenciadas: Con ojos cerrados centrando la atención sobre la zona lumbar y con los ojos abiertos sin ninguna condición diferente a la de cumplir la técnica de ejecución del movimiento. Los resultados del estudio experimental demuestran que el método que mejora las variables relacionadas con la propiocepción es el que propone la realización de los ejercicios con los ojos cerrados, mientras que con los ojos abiertos empeoran estas variables con respecto al grupo control. Ambos métodos provocan mejoras significativas de la amplitud de movimiento lumbar en el plano trabajado. Todo el proceso revela la necesidad de actualizar el tratamiento conceptual y metodológico de la propiocepción a partir de una intervención en la natación, y orienta sobre las bases para su aplicación en otros deportes. / This thesis is a theoretical and empirical approach to the updated methodology for proprioception training. The theoretical part develops the state of affairs in the study of proprioception from different perspectives, the particulars of the lumbar spine and the characteristics of proprioception in this area of the spine. It’s summarized the most important aspects of training theory and the needs of lumbar proprioceptive training in competitive swimming. The empirical part is intended as a starting point for experimental research on the most appropriate methodology for the conscious proprioception training. It performs a specific design for improved lumbar spine control on underwater swimming technique, which tries to intercede on lumbar range of motion in the sagittal plane and positioning accuracy within the same plane. It applies, evaluates and compares the effects of exercises’ administration during 75 sessions over 2 to 3 calendar months, with two different methods of execution: First one blindfolded and focusing on the lower back and second one with eyes opened and no different condition to fulfill the technical execution. The results show that the method improves proprioception-related variables is proposed conducting the exercises with eyes closed focusing on the lower back, while with eyes opened this variables get worse towards the control group. Both methods lead to significant improvements in lumbar range of motion in the worked plane. Thus, the process reveals the need to update the conceptual and methodological treatment of proprioception after an intervention in swimming, and guides about the basis for its application in other sports.

Introduction: In January 2005, a nationwide mandatory bicycle helmet law for children under the age of 15 was introduced in Sweden. In the current study, the effect of this law was evaluated by analyzing national trends in hospital admissions due to bicycle-related head injuries during the period 1998-2011. Methods: An interrupted time-series design with segmented regression analysis was used to evaluate the intervention effect on head injuries as a percentage of all injuries (%HI) among cyclists in age- and sex-specific groups. Effect was measured as a change in level and/or slope of the trend at the time of legislation. Results: A total of 35261 cyclists (0-54 years) were hospitalized due to a bicycle injury during the study period. Linear regression analyses of the entire study period (not segmented) showed significant year-to-year decreases in the %HI of 1.3-1.7% in all age and sex-specific groups (p < .0001). Results from the segmented regression analysis showed that, at the time of legislation, a significant drop in level occurred among males under 15 years (-4.5% [95% CI: -7.7% to -1.3%], p = .01) and a significant change in slope occurred among females aged 30-54 years (-1.6% [95% CI: -2.9% to -0.2%], p = .025). Conclusions: The law seems to have had an effect on males in the target population (<15 years). Although no significant changes were observed among females in this group as an immediate result of the law, the difference in %HI between genders was minimal at the end of the study period due to the steeper general decline among females. / Inledning: I Sverige infördes en cykelhjälmslag för barn under 15 år den första januari 2005. Syftet med denna studie var att studera effekten av denna lag genom att analysera nationella trender i andelen huvudskador bland svenska cyklister under tidsperioden 1998-2011. Metod: Segmenterad regressionsanalys applicerades på tidsseriedata (interrupted time-series design) för att utvärdera om ett trendbrott när det gäller andelen cykelrelaterade huvudskador sammanföll med lagens införande i olika köns- och åldersspecifika grupper. Effekt mättes som en skillnad i regressionslinjens riktning och nivå. Resultat: Inom åldersgruppen 0-54 år vårdades totalt 35261 cyklister under studieperioden. Linjära regressionsanalyser (ej segmenterade) visade att mellan 1998-2011 minskade andelen huvudskador årligen minskade med 1,3–1,7 % i samtliga studerade köns- och åldersspecifika grupper. Den segmenterade regressionsanalysen visade att samtidigt som cykelhjälmslagen infördes skedde en signifikant skillnad i regressionslinjens nivå bland pojkar under 15 år (-4,5 % [95 % CI: -7,7 % till -1,3 %], p = 0,01) och en signifikant skillnad i regressionslinjens riktning bland kvinnor i åldersgruppen 30-54 år (-1,6 % [95 % CI: -2,9 % till -0,2 %], p = 0,025). Slutsats: Den svenska cykelhjälmslagen verkar ha haft en betydande inverkan på trenden i cykelrelaterade huvudskador bland pojkar under 15 år. Även om något liknande fenomen inte framstod bland flickor i interventionsgruppen bör det noteras att skillnaden i andelen huvudskador mellan könen i slutet av studieperioden var minimal.