Os objetivos deste estudo foram comparar os níveis de inibição pré-sináptica (IPS) durante a iniciação do passo entre indivíduos com doença de Parkinson (DP) com bloqueio motor (BM), sem-BM (S-BM) e indivíduos saudáveis pareados pela idade (ISPI) e, possíveis correlações entre os níveis de IPS com as variáveis comportamentais (amplitude e tempo do ajuste postural antecipatório [APA]) e os escores do New Freezing of Gait Questionnaire (NFOG-Q). A amostra foi composta por 22 indivíduos com BM e 12 S-BM (estágio 3 da DP avaliados no estado on da medicação). Dezesseis ISPI também foram incluídos no estudo. Todos atenderam os critérios de inclusão. Os indivíduos foram avaliados em dois dias. No primeiro dia, todos responderam uma anamnese e o Mini Exame do Estado Mental. Para os indivíduos com DP foi aplicada a escala de estadiamento da DP e a parte III da Escala Unificada de Avaliação da DP (UPDRS) e somente os indivíduos com BM foram avaliados com o NFOG-Q. No segundo dia, todos os indivíduos realizaram a tarefa iniciação do passo na plataforma de força AMTI para avaliação da amplitude e do tempo do APA com ou sem a evocação do reflexo-H na condição teste ou condicionado. O estimulador portátil Nicolet® Viking Quest da CareFusion foi utilizado para evocar o reflexo-H teste e condicionado. O estímulo elétrico foi evocado quando a amplitude do APA ultrapassasse 10 a 20% da linha de base. Todos indivíduos realizaram a tarefa iniciação do passo em 3 condições: 1) sem estímulo; 2) estímulo teste estimulação no nervo tibial; e 3) estímulo condicionado estimulação do nervo fibular antes (intervalo de 100 ms) da estimulação do nervo tibial. Nas três condições, os indivíduos foram instruídos a realizarem 15 passos, logo, 15 estímulos nas condições 2 e 3 de maneira aleatória. A ANOVA one way mostrou diferenças significantes nos valores de IPS entre os três grupos, onde os ISPI apresentaram valores maiores de IPS do que os outros dois grupos e, indivíduos S-BM apresentaram valores maiores IPS comparado aos indivíduos com BM (P<0,001), porém, todos os indivíduos deste último grupo apresentaram facilitação. Adicionalmente, amplitudes maiores e tempos menores do APA foram observados somente para os ISPI (P<0,05), além disso, não foram observadas diferenças entre essas variáveis para os dois grupos de DP (P>0,05). Em relação às correlações, especialmente para os indivíduos com BM, observamos que valores maiores de facilitação estão: fortemente associados com os escores maiores do NFOG-Q (r = -74; P<0,0001); moderadamente associados com as amplitudes menores do APA (r = 0,54; P<0,004); e fracamente associados com os tempos maiores do APA (r = -0,42; P<0,244). Por fim, houve uma forte associação entre as amplitude menores do APA e escores maiores do NFOG-Q (r = -,075; P<0,0001). Em conclusão, indivíduos com BM apresentam facilitação (ausência de IPS) durante a iniciação do passo e associada com deficiências na amplitude e tempo do APA e a severidade do BM. Isso indica que a medula espinhal tem participação na iniciação do passo e pode ser fortemente influenciada por alterações sensório-motoras / The aims of this study were to compare the presynaptic inhibition levels (PSI) in the step initiation between subjects with Parkinson\'s disease (PD) with freezing of gait (FoG), non-FOG (non-FoG), and age-matched healthy controls (HC) and, possible correlations between the PSI levels with the behavioral variables and the New Freezing of Gait Questionnaire (NFOG-Q) scores. Twenty individuals with FoG, 12 individuals with non-FoG (stage 3 of PD assessed in the clinically defined on state), and 16 HC met the inclusion criteria. Subjects visited the laboratory for two days. On the first day, all of the subjects answered the anamnesis and the Mini-Mental State Examination. However, only in the subjects with PD were assessed the severity of disease and the motor symptoms (Unified Parkinson´s Disease Rating Scale part III [UPDRS-III], but the FoG severity was assessed only in the subjects with FoG. On the second day, all of the subjects performed the step initiation on the force platform (AMTI) to assess amplitude and time of anticipatory postural adjustment with or without evoking H-reflex in the test or conditioned condition. The constant-current stimulator (Nicolet® Viking Quest portable EMG apparatus, CareFusion) was used to evoke the H-reflex. The electrical stimulus was evoked when the APA amplitude exceeded 10 to 20% of the baseline. All of the subjects performed the step initiation in 3 conditions: 1) without stimulation of the nerve; 2) test stimulus stimulation of the tibial nerve; and 3) conditioning stimulus - stimulation of the fibular nerve before (100 ms interval) stimulation of the tibial nerve. At three conditions, subjects were instructed to perform 15 steps, thus, 15 stimuli at conditions 2 and 3 in a random order. The ANOVA one way showed significant differences in the PSI values between the three groups, where the ISPI presented higher values of PSI than the other two groups, and S-BM individuals had higher PSI values compared to individuals with BM (P<0.001), however all of the individuals with FoG presented facilitation. In addition, larger amplitudes and smaller times of APA were observed only for ISPI (P<0.05); in addition, no differences were observed between these variables for the two PD groups (P>0.05). In relation to correlations, especially for individuals with FoG, we observed that greater values of facilitation are: strongly associated with the higher NFOG-Q scores (r = -0.74; P<0.0001); moderately associated with the smaller APA amplitudes (r = 0.54; P<0.004); and weakly associated with higher APA times (r = -0.42, P<0.244). Finally, there was a strong association between the smaller APA amplitudes and higher NFOG-Q scores (r = -0.75, P<0.0001). In conclusion, individuals with FoG presented facilitation (absence of PSI) in the step initiation which was associated with deficits in amplitude and time of APA and FoG severity. This indicates that the spinal cord has participation in the step initiation that can be strongly influenced by the abnormal sensory motor

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.

Despite years of research, females continue to have a higher incidence of non-contact ACL injuries. One of the major findings of this research is that males and females perform certain tasks, such as, cutting, landing, and single-leg squatting, differently. In particular, females tend to move the knee into a more valgus position; a motion putting the ACL at risk for injury. Yet the underlying spinal control mechanisms modulating this motion are unknown. Additionally, the mechanisms regulating the ability to rapidly initiate and produce maximal torque are also unknown. Therefore, the purpose was to: 1) determine if the sexes modulate spinal control differently, 2) examine the contributions of spinal control mechanisms to valgus knee motion, and 3) identify contributions of spinal control to the ability to rapidly produce force. The spinal control variables were the first derivative of the Hoffmann (H)-reflex, the first derivative of extrinsic pre-synaptic inhibition (EPI), the first derivative of intrinsic pre-synaptic inhibition (IPI), recurrent inhibition (RI), and V-waves. To assess the neuromuscular system’s ability to rapidly activate, rate of torque development (RTD) and electromechanical delay (EMD) were measured. Lastly, valgus motion was determined by the frontal plane projection angle (FPPA). The results reveal males and females do modulate spinal control differently; specifically males had an increased RTD, which is the slope of the torque-time curve, and increased RI, which is a post-synaptic regulator of torque output. However, the spinal control mechanisms did not significantly contribute to FPPA at the knee. EMD which is the time lag from muscle activity to torque production was significantly predicted by the spinal control mechanisms. Specifically, EPI, a modulator of afferent inflow from peripheral and descending sources, IPI, a regulator of Ia afferent inflow, and sex significantly contributed to EMD. Lastly, the spinal control mechanisms significantly contributed to RTD. Specifically, IPI, sex, and V-waves, a measure of supraspinal drive, all significantly contributed to RTD. / Graduation date: 2009

To assess acute performance-related effects of foam rolling, this study investigated the immediate effects of a standard foam rolling protocol on explosive strength of the plantarflexors and alpha motor neuron excitability in the soleus. Explosive strength was measured via vertical jump height (JUMP) and the Reactive Strength Index (RSI) obtained from a single leg drop jump. Alpha motor neuron excitability was measured by H reflex amplitude as H wave to M wave ratio (HM) obtained from the soleus muscle. JUMP and RSI measures were analyzed from nineteen subjects (12 male, 7 female) HM data were analyzed from 15 subjects (9 male, 6 female). Subjects attended one day of practice and instruction for the single leg drop jump and one day for data collection. One leg was randomly assigned to be the test leg (FL) and the other as the control (NL). The reported dominant leg and gender were also recorded for each subject. Subjects performed two single leg drop jumps per leg from a box height of 30 cm and then 10 soleus H reflexes were obtained. The intervention, which followed standard professional guidelines, consisted of 2.5 minutes of foam rolling for the FL and rest for the NL, followed by a 5 minute warm up on a cycle ergometer. The best jump and the average HM ratio were chosen for analysis. For each variable a post/pre ratio was calculated for statistical analysis. A 2x2x2 factor ANOVA with repeated measures on both factors was used for each variable. Analysis revealed no statistically significant differences for any of the variables, either as main effects or any of the interaction effects. Subjects trended towards a slightly larger post-intervention decrease in JUMP and RSI for the FL than the NL but this was not significant. It was concluded that a 2.5 minute intervention of foam rolling had no acute effect on explosive strength of the plantarflexors or alpha motor neuron excitability of the soleus. / text

<p>Циљ рада: Циљ истраживања је да се утврди разлика у акутним ефектима статичког (СИ) и динамичког истезања (ДИ), у комбинацији са специфичним кошаркашким загревањем (СКЗ), на флексибилност, експлозивну снагу ногу, брзину, агилност и неуромишићну адаптацију кошаркаша јуниорског узраста.</p><p>Методе: Истраживање у оквиру ове докторске тезе су чинила два одвојена експеримента, један спроведен у теренским условима, и други спроведен у лабораторијским. Оба су била &bdquo;cross-over&ldquo; дизајна. У теренском експерименту је учествовало 46 кошаркаша (узраста 17&plusmn;0,83 година), док је у лабораторијском учествовало 12 (узраста 17,7&plusmn;0,49 година). У теренском експерименту су тестиране четири моторичке способности. За процену флексибилности коришћен је тест досезања у седећем претклону, експлозивна снага ногу је процењивана уз помоћ вертикалног скока са контактне плоче, брзина трчањем на 20 метара, док је Т тест коришћен за процену агилности. У лабораторијском експерименту је као мера неурофизиолошке адаптације коришћена промена ексцитабилности &alpha;-мотонеурона, која је представљена као однос Хофмановог (Х) рефлекса и М таласа (Х/М). За њихово одређивање се користио Medelec ST-10 стимулатор (Medelec, Old Woking, UK). Површинске електромиографске електроде су биле постављене на унутрашњој глави m.gastrocnemius-a одскочне ноге, применом тзв. &bdquo;belly-tendon&ldquo; монтаже. Као третмани, у оба експеримента су коришћени протокол статичког и протокол динамичког истезања, уз комбинацију са специфичним кошаркашким загревањем. Мерења су се у оба експеримента изводила у 3 временске тачке и то пре протокола истезања, одмах након протокола истезања (а пре специфичног кошаркашког загревања) и одмах након специфичног кошаркашког загревања.</p><p>Резултати: Резултати истраживања показују да постоје одређене разлике акутних ефеката комбинација протокола СИ+СКЗ и ДИ+СКЗ. Комбинација протокола СИ+СКЗ је повољније утицала на експлозивну снагу ногу и на агилност кошаркаша јуниорског узраста. Ефекти обе комбинације протокола су били готово идентични на флексибилност, а разлика је изостала и у ефектима на брзину, иако је пре СКЗ био&nbsp;уочљив негативан ефекат СИ. Однос Х/М се значајно разликовао одмах након истезања, када је СИ значајно оборило однос, али су се те разлике изгубиле након примене СКЗ.</p><p>Закључак: Посматрајући ефекте комбинације протокола СИ+СКЗ и ДИ+СКЗ на моторичке способности и неуромишићну адаптацију кошаркаша јуниорског узраста, може се закључити да је примена СИ+СКЗ препоручљивија у свакодневном тренингу и такмичењу.</p> / <p>Cilj rada: Cilj istraživanja je da se utvrdi razlika u akutnim efektima statičkog (SI) i dinamičkog istezanja (DI), u kombinaciji sa specifičnim košarkaškim zagrevanjem (SKZ), na fleksibilnost, eksplozivnu snagu nogu, brzinu, agilnost i neuromišićnu adaptaciju košarkaša juniorskog uzrasta.</p><p>Metode: Istraživanje u okviru ove doktorske teze su činila dva odvojena eksperimenta, jedan sproveden u terenskim uslovima, i drugi sproveden u laboratorijskim. Oba su bila &bdquo;cross-over&ldquo; dizajna. U terenskom eksperimentu je učestvovalo 46 košarkaša (uzrasta 17&plusmn;0,83 godina), dok je u laboratorijskom učestvovalo 12 (uzrasta 17,7&plusmn;0,49 godina). U terenskom eksperimentu su testirane četiri motoričke sposobnosti. Za procenu fleksibilnosti korišćen je test dosezanja u sedećem pretklonu, eksplozivna snaga nogu je procenjivana uz pomoć vertikalnog skoka sa kontaktne ploče, brzina trčanjem na 20 metara, dok je T test korišćen za procenu agilnosti. U laboratorijskom eksperimentu je kao mera neurofiziološke adaptacije korišćena promena ekscitabilnosti &alpha;-motoneurona, koja je predstavljena kao odnos Hofmanovog (H) refleksa i M talasa (H/M). Za njihovo određivanje se koristio Medelec ST-10 stimulator (Medelec, Old Woking, UK). Površinske elektromiografske elektrode su bile postavljene na unutrašnjoj glavi m.gastrocnemius-a odskočne noge, primenom tzv. &bdquo;belly-tendon&ldquo; montaže. Kao tretmani, u oba eksperimenta su korišćeni protokol statičkog i protokol dinamičkog istezanja, uz kombinaciju sa specifičnim košarkaškim zagrevanjem. Merenja su se u oba eksperimenta izvodila u 3 vremenske tačke i to pre protokola istezanja, odmah nakon protokola istezanja (a pre specifičnog košarkaškog zagrevanja) i odmah nakon specifičnog košarkaškog zagrevanja.</p><p>Rezultati: Rezultati istraživanja pokazuju da postoje određene razlike akutnih efekata kombinacija protokola SI+SKZ i DI+SKZ. Kombinacija protokola SI+SKZ je povoljnije uticala na eksplozivnu snagu nogu i na agilnost košarkaša juniorskog uzrasta. Efekti obe kombinacije protokola su bili gotovo identični na fleksibilnost, a razlika je izostala i u efektima na brzinu, iako je pre SKZ bio&nbsp;uočljiv negativan efekat SI. Odnos H/M se značajno razlikovao odmah nakon istezanja, kada je SI značajno oborilo odnos, ali su se te razlike izgubile nakon primene SKZ.</p><p>Zaključak: Posmatrajući efekte kombinacije protokola SI+SKZ i DI+SKZ na motoričke sposobnosti i neuromišićnu adaptaciju košarkaša juniorskog uzrasta, može se zaključiti da je primena SI+SKZ preporučljivija u svakodnevnom treningu i takmičenju.</p> / <p>Objective: The aim of this study was to determine the difference of acute effects of static stretching (SS) and dynamic stretching (DS), in combination with specific basketball warm-up (SBWU), on flexibility, explosive leg strength, speed, agility and neuromuscular adaptation of basketball players U18.</p><p>Methods: This study consisted of two separated experiments, first in field conditions, and second conducted in laboratory. Both had &bdquo;cross-over&ldquo; design. Forty-six basketball players (age: 17&plusmn;0,83 years) participated in field experiment, while twelve participated in laboratory experiment (age 17,7&plusmn;0,49 years). In field experiment, four motor abilities were tested. Seat and rech test was used for the evaluation of flexibility, explosive leg strength was evaluated by vertical jump from contact plate, speed by 20m run, and T test was used for agility testing. In laboratory experiment, the excitability of &alpha;-motoneuron was taken for the evaluation of neuromuscular adaptation. It is presented as a ratio of the maximal amplitudes of Hoffman (H) reflex and M wave (H/M). For their determining we used Medelec ST-10 stimulator (Medelec, Old Woking, UK). Surface electromyographic (EMG) electrodes were placed over the m.gastrocnemius medialis, and Achilles tendon, in a &bdquo;belly-tendon&ldquo; montage. In both experiments, SS protocol and DS protocol, in the combination with SBWU, were used as a treatment. Measures were taken in 3 time points: before the stretching, immediately after stretching (and before SBWU) and immediately after the SBWU.</p><p>Results: Results of this study showed that there are certain differences in acute effects of combination of protocols SS+SBWU and DS+SBWU. Combination of protocols SS+SBWU had more positive influence on explosive leg strength and agility of U18 basketball players. The effects of both protocols were almost the same on flexibility, and there was no noticeable difference in effects on speed, although before SBWU there was significant negative of SS. Immediately after the stretching there was significant difference in H/M ratio, it was significantly lower after the SS, but after the application of SBWU, differences disappeared.<br />&nbsp;<br />Conlcusion: Regarding the effects of SS+SBWU and DS+SBWU protocols on motor abilities and neuromuscular adaptation of U18 basketball players, it could be concluded that the use of SS+SBWU is more preferrable in everyday practice and competition.</p>