Magister Scientiae (Physiotherapy) - MSc(Physio) / Sprinting can be described as the ability to cover a short distance in the fastest possible time. It requires enormous stability, strength and speed to achieve this goal. Any improvements in technique or speed can be the difference between winning and losing and ultimately gold or silver. Many coaches focus their training on improving the mechanics of the lower limb in order to achieve their goal. They often neglect to consider the effect the upper limb, head, neck and trunk has on the sprinters technique. This study aimed to determine the effect the muscles that assist in stabilising the head and neck namely the deep neck flexors, has on sprinting technique. A systematic review was conducted to determine the factors that influence the acquisition of the correct and most efficient sprint technique. Thereafter assessments were done to determine the prevalence of neck discomfort and how it impacts the athlete’s life by use of the Disability Neck Index. In addition, the endurance of the participant’s deep neck flexors using the Craniocervical Flexion Test and an analysis of their sprinting technique through video analysis were conducted. Variables for each assessment were coded and analysed with Chisquared tests to determine statistically significant relationships. Results show that there was to prevalence of neck pain among participants and although the participants have poor deep neck flexor endurance and an inadequate sprinting technique, no statistically significant relationships could be found between these two variables. Thus poor endurance in the deep neck flexors has no effect on sprinting technique. The results of the study was limited due to a small sample size and lack of equipment, thus further research is required in order to completely reject the possibility that the deep neck flexors effects a sprinters ability to acquire an efficient sprinting technique.

Tyrimo pagrindimas: sportininkų judėjimo gebėjimai vyksta dalyvaujant paskutiniai grandžiai pėdos lenkiamiesiems ir tiesiamiesiems raumenims (Нечаев, 2011). Didelio meistriškumo graikų-romėnų imtynininkų raumenų kraujotakos mobilizacijos ir atsigavimo ypatybės yra artimesnės ištvermės sporto šakų atstovams nei sprinto grupės sportininkų ypatybėms. (Ežerskis, 2009). Tikslas- išanalizuoti skirtingos adaptacijos fiziniams krūviams vyrų ir merginų pėdų lenkiamųjų raumenų funkcinius ypatumus. Hipotezė: pėdos lenkiamųjų raumenų ištvermė priklauso nuo maksimalios valingos jėgos dydžių, kuo didesnė jėga, tuo mažesnė ištvermė. Metodai: dinamometrija, literatūros šaltinių studija, statistinė analizė. Aptarimas ir Išvados: dvikovos sportininkių, ištvermės ir greitumo jėgos atstovų tarpusavyje kairės ir dešinės kojos jėga nesiskyrė yra proporcingų dydžių. Ištvermės sportininkų vyrų pėdos lenkiamųjų raumenų kojų jėga buvo ženkliai didesnė už dvikovos, sporto šakų, tačiau mažesnė nei greitumo jėgos atstovų. Dvikovos sporto šakų sportininkių ir ištvermės atstovų bei greitumo jėgos sportininkų MRI rodikliai skyrėsi neženkliai, tačiau jėga buvo mažesnė Nuo jėgos dydžio priklauso ištvermės trukmė. Esant didesnei jėgai ištvermės trukmė mažėja. Pagal santykio MVJ/MRI reikšmes visos priklauso stajerio tipui. Tyrimo uždaviniai: 1. Nustatyti dvikovos sporto šakų moterų ir vyrų, pėdos lenkiamųjų raumenų maksimalios valingos jėgos dydžius. 2. Nustatyti dvikovos sporto šakų moterų ir vyrų, pėdos... [toliau žr. visą tekstą] / Introduction: Atlete's movement depends on the activity of the foot flexor muscle strength and endurance. High craftsmanship Greco- Roman wrestlers muscle blood mobilization and recovery features are closer to endurance sports disciplines than sprint atlete properties. Aim: Analysis the different physical exertion adaptation of men and a girl's foot muscle flexion functional features. Hypothesis: foot flexor muscle endurance duel sport athletes are the same length as the representatives of the endurance strength but size was lager. Methods: dynamometry, literature study, a statistical analysis. Discussion and Conclusion: The duel athletes, endurance and speed power representatives each other left and right leg power is proportional not different sizes. Endurance representatives of men's foot flexor muscles leg strength was significantly higher than the duel sports, but less than the speed force representatives. Duel sport athletes and endurance representatives maximal muscle endurance characteristics differed slightly, but the force was smaller size of the force depends on endurance time. At higher power of endurance time decreases. According to the ratio of maximal voluntary contruction / maximal muscle endurance values all belong stajer type. Exploratory tasks : 1)set duel sports for men and women, foot flexion maximum voluntary muscle force figures. 2)Set duel sports for men and women, foot flexor muscle endurance for maximum muscle size. 3)Identify and analyze the duel... [to full text]

Performance of a series of eccentric contractions produces adverse effects including muscle weakness, delayed onset muscle soreness (DOMS), fluid accumulation and decreased muscle function. The repeated bout effect is a physiological adaptation observed when a single-bout of eccentric exercise protects against muscle damage from subsequent eccentric bouts. Similar to the repeated bout effect, increases in flexibility have been linked to attenuations in acute muscle damage, muscle fatigue and strength loss after eccentric exercise. Purpose: The purpose of this study was to examine the muscle physiological responses to eccentric strength training after first priming the muscles with either a period of static flexibility training or a single intense bout of eccentric exercise performed weeks earlier; and compare these to the responses from eccentric strength training when no prior intervention is administered. Methods: Twenty-five participants were randomly assigned to a flexibility (F) (n=8), a single-bout (SB) (n=9), or a control (C) (n=8) group. The design consisted of two 4-week phases; 1) priming intervention, 2) eccentric training. The priming intervention included static stretching (3x/week; 30mins/day) (F), a single-bout of eccentric exercise (SB) or no priming intervention (C). All groups proceeded to complete eccentric training of the knee flexors using isotonic contractions (%load progressively increased over training period) on a dynamometer following the priming intervention phase. Testing was completed at baseline, post-priming intervention and post-eccentric training, in conjunction with data being collected during the acute eccentric training phase (0hr, 24hr, 48hr; post-bout 1 and 4). Dependent measures included muscle thickness, isometric maximal voluntary contraction (MVC), eccentric and concentric MVC, optimal angle, active range of motion (ROM), passive ROM, maximal power, electromyography (EMG) and delayed onset muscle soreness (DOMS). Results: Acute data during the eccentric training phase revealed a significant reduction in DOMS for both the F and SB groups compared to the C following the first bout of eccentric exercise (p<0.05). The F also had reduced soreness in comparison to both the SB and C post fourth bout of eccentric exercise (p<0.05). The F group demonstrated attenuated loss in isometric strength (post fourth bout) and maximal power (post first bout) during eccentric training compared to the C group (p<0.05). However, there was no significant difference between groups across all dependent variables following the eccentric training phase. Conclusion: This is the first study to directly compare the protective effects observed with static flexibility training to that of a single-bout of eccentric exercise throughout a subsequent eccentric training regime. Although differences in muscle soreness, strength and maximal power occurred during the acute stages of eccentric training, there appeared to be no significant advantage of either protective priming method at the end of eccentric training.

Le conflit fémoro-acétabulaire (femoroacetabular impingement, FAI) est une pathologie mécanique de la hanche qui peut causer des douleurs et limitations fonctionnelles. Le but de cette thèse était d’étudier la fonction musculaire au niveau de la hanche chez des patients présentant un FAI symptomatique. La fonction musculaire de la hanche a été évaluée, dans un premier temps, chez des patients avant qu’ils ne subissent une opération. Ces patients démontraient un déficit de force qui pourrait être expliqué par de l’inhibition musculaire. Cependant, ce déficit de force n’était pas associé à une plus grande fatigabilité musculaire. Dans un deuxième temps, les altérations de force musculaire ont été évaluées chez des patients ayant subi une arthroscopie de la hanche. Après l’opération, les patients récupéraient un niveau de force normal au niveau de tous les groupes musculaires de la hanche excepté les fléchisseurs. Le cas d’un joueur de hockey sur glace ayant subi une chirurgie ouverte aux deux hanches pour traiter un FAI bilatéral a aussi été décrit. On a démontré que la déhiscence de la bandelette iléo-tibiale pouvait survenir après chirurgie, empêcher l’augmentation de force musculaire des abducteurs de la hanche, et retarder la reprise du sport. Enfin, un protocole d’évaluation du taux de développement de la force normalisé, variable permettant d’estimer l’inhibition musculaire de la hanche, a été proposé chez des sujets sains. La fiabilité et reproductibilité des résultats ont été montrées au niveau des adducteurs, rotateurs externes, et fléchisseurs de la hanche. Ces résultats montrent que ces patients ont une fonction musculaire altérée au niveau de la hanche, qui est toutefois récupéré après une opération. / Femoroacetabular impingement (FAI) is a pathomechanical process of the hip joint, which could lead to hip pain and functional disability. Aim of this thesis was to investigate hip muscle function in patients with a symptomatic FAI. Hip muscle function was first investigated before patients underwent any surgical treatment for managing FAI. It was shown that they present with reduced hip muscle strength (i.e., muscle weakness), probably due to hip muscle inhibition. Nevertheless, hip muscle weakness was not associated with exaggerated hip muscle fatigue. Hip muscle strength recovery was then evaluated in a series of patients after hip arthroscopy to treat FAI. These patients demonstrated a good recovery for all hip muscle groups, except for hip flexors. The case of a professional ice hockey player who underwent bilateral hip open surgeries for treating bilateral FAI was also documented. This report showed that iliotibial band dehiscence could occur after hip open surgery, thereby preventing hip abductor strength increase during rehabilitation and delaying the return to sport. In addition, the assessment of the rate of force development scaling factor for the hip muscles was evaluated in a group of healthy adults. This parameter seems to be promising for the evaluation of hip muscle inhibition. The testing protocol was feasible and reproducible for hip adductors, external rotators and flexors. Taken as a whole, these findings show that patients with symptomatic FAI demonstrate an impaired hip muscle function, which is however mainly resolved after surgical treatment.

L'objectif de ce travail de thèse est d'étudier d'une part les spécificités de la commande nerveuse lors de la contraction excentrique en explorant les mécanismes impliqués au niveau spinal et d'autre part d'examiner les mécanismes nerveux responsables de la plasticité du système neuromusculaire après un entraînement de force excentrique sous-maximal. A travers ce travail de thèse, nous mettons en évidence la contribution de l'inhibition récurrente à la réduction de l'activation musculaire classiquement observée lors de la contraction excentrique. Par ailleurs, nous montrons que l'inhibition récurrente est majorée lors des contractions sous-maximales indépendamment du mode de contraction. Ces résultats soulignent le rôle important de l'inhibition récurrente dans la spécificité de la commande nerveuse lors de la contraction excentrique. Nous confirmons que le pilotage nerveux de la contraction excentrique peut être modulé par l'entraînement de force excentrique même si les modulations de l'excitabilité spinale semblent dépendre des caractéristiques de l'entraînement. / The purpose of this PhD research is, on the one hand, to study the neural drive specificities during eccentric contractions by exploring the neural mechanisms involved at spinal level and, on the other hand, to examine the neural mechanisms responsible for the modulations of neuromuscular system following a strength submaximal eccentric training. Through this PhD research we highlight the contribution of recurrent inhibition by the Renshaw cell to the decrease of muscular activation typically observed during eccentric contraction. Furthermore, we show that recurrent inhibition is enhanced during submaximal contractions regardless of the contraction type. These results emphasize the important role of recurrent inhibition in the specificity of neural control during eccentric contractions. We confirm that the neural drive of the eccentric contraction may be modulated by eccentric strength training although modulations of spinal excitability seem to depend on the characteristics of training.