A aprendizagem motora é um processo desencadeado pelo treino, que envolve inúmeras mudanças sinápticas que, inicialmente, são temporárias e depois, com a continuidade do estímulo, consolidam-se definitivamente. Como tal processo não pode ser mensurado diretamente in vivo, as medidas tomadas como evidências da sua consolidação são comportamentais, ou seja, medidas de alteração de desempenho desencadeadas pelo treino. Um maior conhecimento a respeito dos fatores que interferem no processo de aprendizagem motora é de extrema importância para todas as ciências que estudam os efeitos do treino motor, tais como Pedagogia, Educação Física, Terapia Ocupacional, Fisioterapia, entre outras, à medida que permitem a implantação de abordagens mais específicas. Dentre vários fatores importantes, esse estudo elegeu a idade, já que, atualmente, não é claro como diferenciar o treino para crianças em diferentes faixas etárias. A indagação a respeito dos possíveis efeitos da idade sobre o processo sustenta-se no fato que o cérebro humano, ao nascimento, não se encontra completamente desenvolvido, o que só será alcançado, aproximadamente, duas décadas depois. Assim, sendo o processo de aprendizagem dependente de várias estruturas cerebrais, funcionando de forma complexa e sincrônica, é plausível supor que crianças em diferentes estágios maturacionais do Sistema Nervoso, sob as mesmas condições de treino, alcancem diferentes desempenhos. Dessa forma, o objetivo desse trabalho foi, por meio da análise do desempenho de uma nova tarefa, investigar possíveis diferenças no processo de aprendizagem motora entre crianças saudáveis de 6 e 10 anos. Para isso, foi comparado o desempenho motor em uma tarefa de oposição de dedos da mão, em duas diferentes seqüências, uma treinada por meio de 4 blocos de 600 movimentos e outra tomada como controle, entre um grupo de 16 crianças com idade de seis anos (6,5+0,2) e outro composto por dez crianças com idade entre 9 e 10 anos (9,6+0.50). O desempenho para ambas as seqüências foi tomado em 6 diferentes momentos: antes, 2 minutos, 4, 7, 14 e 28 dias depois da sessão de treino e então, analisado estatisticamente por meio da ANOVA para medidas repetidas. Os resultados obtidos durante o treino mostraram que, em termos de velocidade de oposição de dedos, as crianças menores apresentavam, inicialmente, uma lentidão que desapareceu após as primeiras 600 repetições. Já a análise do desempenho dos mesmos movimentos dentro de uma seqüência específica mostrou o comportamento oposto: as crianças menores, inicialmente, apresentavam o mesmo desempenho em comparação às mais velhas, mas, após o primeiro bloco de treino, essas últimas tornaram-se progressivamente mais eficientes no aproveitamento do treinamento. A análise dos resultados obtidos com a seqüência tomada como controle mostrou que as crianças menores apresentaram dificuldade em generalizar a aprendizagem para a seqüência reversa. Tomados em conjunto, esses resultados indicam diferenças no aproveitamento do treino entre crianças de 6 e 10 anos, discutidas nesse estudo como associadas principalmente a diferenças nas funções cognitivas envolvidas na construção da habilidade, coerentes com as diferenças maturacionais do Sistema Nervoso esperadas entre essas idades. / Motor learning is a process triggered by training, which involves numerous synaptic changes that are initially temporary, and further, with the stimulus continuity, consolidate definitively. As such process cannot be measured directly in vivo, the measures taken as evidences of their consolidation are behavioral, that is, they are performance change measures triggered by training. A greater knowledge on the factors that interfere on the motor learning process is extremely important for all the sciences that investigate the effects of motor training, such as Pedagogy, Physical Education, Occupational Therapy, Physiotherapy, among others, as they enable the implementation of more specific approaches. Among several important factors, this investigation has elected age, since today it is not clear how to differentiate training for children at different age ranges. The question about the possible effects of age on the process is supported by the fact that the human brain, upon birth, is not completely developed, and this development will only be reached approximately two decades later. Thus, as the learning process depends on several brain structures, which operate in a complex and synchronized way, it is plausible assuming that children at different maturity stages of the Nervous System, and under the same training conditions, achieve different performances. Thus, this work aimed at investigating eventual differences in the motor learning process, by analyzing the performance of a new task, among healthy children from 6 to 10 years old. To do that, the motor performance was compared for a task of hand\'s fingers opposition, in two different sequences, one trained by means of 4 blocks with 600 motions, and the other taken as control, in a group of 16 (sixteen) six-year old children (6.5+0.2), and another one comprised by 10 (ten) 9-10-year old children (9.6+0.50). The performance for both sequences was taken in 6 different times: before, 2 minutes, 4, 7, 14 and 28 days after the training sessions, and then statistically analyzed via ANOVA for repeated measures. The results achieved during the training evidenced that, in terms of finger opposition speed, smaller children initially presented a slowness, which disappeared after the first 600 repetitions. By its turn, the performance for the same motions within a specific sequence showed the opposite behavior: smaller children initially presented the same performance when compared to the older ones, but after the first training block, the latter ones became more and more efficient in terms of training results. The analysis of the results achieved with the sequence taken for control purposes showed that smaller children presented difficulty in generalizing the learning for the reverse sequence. When considered as a set, these results indicate differences in the training results between 6- and 10-year old children, discussed in this investigation as especially associated to differences in the cognitive functions involved in skill construction, coherent with the maturity differences of the Nervous System, expected between these ages.

Attentional focus research has reliably demonstrated that an external (beyond the body) focus is superior in terms of skill performance, retention and transfer relative to an internal conscious focus on movement mechanics. This thesis extends current knowledge by evaluating the impact of external focus distance on the performance of continuous skills in an applied context. Specifically, two external focus points of different distances were compared to an undirected attention condition. Three separate studies were conducted using different kayak sprinting disciplines; two of these took place in benign environments using relatively closed skills whilst the third was carried out in an open skill context. In all cases a within-participants experimental design was employed with an independent variable of conscious focus and a dependent variable of performance time. In Study 1, using competent, experienced kayakers (n = 20) in a surf ski sprinting task, the distal external condition significantly outperformed both the undirected focus and proximal external conditions (p < .001 in both cases). The undirected focus condition was significantly faster than the proximal external focus condition (p = .003). The effect size was large (ηp2 = .55). Study 2 examined the same attentional points using youth racers in K1 sprint kayaks (n = 16). The undirected focus condition was significantly faster than the proximal external condition (p = .028); the effect size was large (ηp2 = .23). In Study 3 experienced kayakers (n = 27) were tested in a wild water racing task against the same experimental conditions. The distal external focus condition significantly surpassed both the proximal external condition and the undirected focus condition (p < .001 in both cases). The effect size was large (ηp2 = .53). The studies in this thesis show that the distance of a specified external focus is important and can have a significant influence on performance. In contrast to previous work the proximal external focus did not provide a performance advantage relative to an undirected focus condition; in studies 1 and 2 it was actually detrimental. A distal external focus was beneficial compared to both other conditions in two studies and insignificantly different to the undirected focus trial in Study 2. This thesis brings together work on focus distance and skill type in three applied and non-contrived sporting contexts. The main practical implication of this research is that distance of focus should be considered by learners and coaches with a view to optimising conscious attention. A distal external focus appears to be particularly useful in targeting attention on a pertinent point whilst simultaneously excluding cognitive competition, distractions and unnecessary attentional switching which could undermine skilled performance.

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When subjects are presented with distorted visual feedback of their hand during a goal-directed movement (i.e. subjects view a cursor representing their hand that is rotated from their hand’s actual position while reaching in a virtual reality environment), they typically adapt their movements so that the cursor is brought to the target, thus reducing reaching errors. In addition to motor adaptation, it has recently been shown that reaching with distorted visual feedback of the hand results in sensory changes, such that proprioceptive estimates of hand position are shifted in the direction of the visual feedback (Cressman and Henriques 2009). The current study looked to establish how quickly these sensory changes arise while training to reach with distorted visual feedback of the hand. Additionally, by comparing sensory to motor changes across time, we looked to determine the relationship between their underlying processes. Subjects trained to reach to a single visual target while seeing a cursor that was aligned with their actual hand position (50 trials: aligned reach training), or rotated 30° clockwise (CW) relative to their actual hand position (150 trials: rotated reach training). Reach errors and proprioceptive estimates of felt hand position were assessed following the aligned reach training trials and at 7 different times during the rotated reach training trials by having subjects reach to the target without visual feedback, and provide estimates of the position of their hand relative to a visual reference marker respectively. Results revealed a slow change in proprioceptive estimates over the course of reach training with the rotated cursor relative to estimates after the aligned reach training, and in fact, significant sensory changes were not observed until after 70 trials. In contrast, reach adaptation showed a much steeper increase and significant adaptation after a limited number of reach training trials with a rotated cursor. These different time courses suggest that proprioceptive recalibration and reach adaptation arise due to separate neural processes.

It is well established that an effective way to schedule knowledge of results (KR) during practice to facilitate motor learning is to allow the learner to control their KR delivery, termed self-controlled KR, rather than imposing the same schedule on the learner without choice, termed yoked KR. The learning advantages of self-controlled KR schedules have been attributed to motivational influences and/or information-processing activities with numerous researchers favouring the motivational perspective in recent years. However, many findings currently exist that are difficult to reconcile using a (purely) motivational influences explanation. For this dissertation, three experiments were conducted that aimed to better understand the learning advantages of self-controlled KR schedules from an information-processing perspective. Chapter 2 of this dissertation provides further evidence that the learning benefits of self-controlled KR schedules depend on the option of completing the decision to receive KR after a motor response. The option of making the KR decision after a trial, rather than before a trial was suggested to allow the learner to request KR only when a comparison between estimated and actual error would maximize the informational value of the KR received. This in turn would be expected to strengthen one’s error detection capabilities. This was supported by retention and transfer data where a more accurate ability to estimate one’s performance in the absence of KR was found in the two self-controlled groups that were able to make a KR decision after a trial. In addition, open-ended questions regarding the strategies used for requesting KR during practice were administered at the midpoint and end of practice. An inductive thematic analysis (Chapter 3) of the self-reported KR strategies generated five themes and it was noted that strategy use changes as a function of practice. That is, the dominant strategy used during the first half of practice was different from that used during the second half of practice. Based on the results presented in Chapters 2 and 3, Chapter 4 provides evidence that the KR-delay interval is a critical time period for reaping the learning benefits of self-controlled KR schedules. Specifically, having participants engage in an interpolated activity during the KR-delay interval eliminated the effectiveness of self-controlled KR schedules for motor learning. It is argued that the interpolated activity interfered with the processing of response-produced feedback upon movement completion that are critical for determining whether receiving KR on a given trial would provide a meaningful learning experience. Lastly, Chapter 5 provides evidence that suggests the primary motor cortex (M1) may not have a significant role in the learning advantages of self-controlled KR schedules. However, a caveat of this conclusion is that the learning benefits of practicing with a self-controlled KR schedule were negligible. Taken together, the results presented in this dissertation suggest that informational factors associated with the processing of response-produced feedback and KR for the development of one’s error-detection capabilities, rather than motivational influences are more critical for the learning advantages of self-controlled KR schedules.

Proprioception is recalibrated following reaches with misaligned visual feedback of the hand, such that one’s sense of felt hand position is shifted in the direction of the visual feedback provided (Cressman & Henriques 2009). In the current experiment, we examined the ability of proprioceptive recalibration to be retained over an extended period of time (i.e. 4 days), and the benefits of additional training on retention in the form of recall and savings (i.e. faster re-learning on subsequent testing days). Twenty-four participants trained to reach to a target while seeing a cursor that was rotated 30° clockwise relative to their hand on an initial day of testing. Half of the participants then completed additional reach training trials on 4 subsequent testing days (Training group), whereas the second half of participants did not complete additional training (Non-Training group). Participants provided estimates of their felt hand position on all 5 testing days to establish retention of proprioceptive recalibration. Results revealed that proprioceptive recalibration was recalled 24 hours after initial training and that there was no benefit of additional training. Retention in the form of savings was observed on all days for the Training group and on Day 5 in the Non-Training group. These results reveal that proprioceptive recalibration does not benefit from additional training but is retained in the form of recall and savings. Taken together, results from the two groups of participants showed that the sensory system’s ability to change over time appeared to saturate early on, within two days of training. Moreover, the different time scales (i.e. 1 day for recall versus 4 days for savings), suggested that distinct processes may underlie recall and savings of proprioceptive recalibration.

Neuromuscular fatigue, even that caused by light submaximal exercise, impairs motor performance and alters motor planning. This impairment is evident in muscle reaction time, force production capacity and joint position sense as well as in more complex tasks such as postural stability. When an individual is fatigued their postural sway increases and they are less able to recover from unexpected postural perturbations. Although a large number of work-related falls are caused by fatigue every year, the mechanisms behind the instability are not well understood. Since postural control does not require a large amount of muscular strength it is unclear whether the post-fatigue changes in posture are due to impairment within the muscle fibers or are a central modification of the motor plan used to execute the movement task. In order to better understand neuromuscular fatigue researchers have labeled fatigue occurring within the muscles ‘peripheral fatigue’ and that occurring within the central nervous system ‘central fatigue’. At the onset of a muscular contraction peripheral and central fatigue develop simultaneously, making it difficult to clearly articulate the role that they each play in the decreased motor performance found post-fatigue. Techniques such as transcranial magnetic and electrical nerve stimulation quantify the contribution of central fatigue to the decreased maximal force production but the impact on motor planning is still not well understood. Therefore, the primary aim of this doctoral dissertation was to isolate central fatigue from peripheral muscle fatigue and to compare the influence that it may have on dynamic postural control to the changes caused by general fatigue of the local postural muscles. This overarching research goal was accomplished through five separate studies. The first study in this dissertation determined that at least seven postural trials needed to be performed to ensure that the participants had fully adapted to the postural task before the fatigue protocol was implemented. Experiment 2 characterized the fatigue produced by bilateral, isometric ankle muscle contractions and examined the recovery of the central and peripheral changes throughout a ten-minute post-fatigue recovery period. The results demonstrated that the alternating maximal ankle plantar and dorsiflexor contractions created central and peripheral fatigue. Central fatigue recovered within the first two minutes post-fatigue while peripheral fatigue lasted throughout the ten-minute post-fatigue period. Experiment 3 analyzed the impact of this ankle muscle fatigue protocol on the postural response to a continual, externally driven, sinusoidal oscillation of the support platform. In this study the fatigued participants were able to stabilize their center of mass displacement using two different anticipatory postural responses to the backwards perturbation whereas all of the participants used the same anticipatory response to the forwards perturbation. All three postural responses became progressively more conservative throughout the ten-minute post-fatigue period, despite the rapid recovery of the ankle force production capacity. The final two studies characterized the fatigue produced during a continuous, isometric forearm contraction and assessed the impact on ankle motor performance (Experiment 4) and on postural control (Experiment 5). Peripheral fatigue created in the forearm muscles during this contraction remained throughout the post-fatigue testing session. Central fatigue and a decreased maximal force production capacity were quantified in both the forearm and ankle plantarflexor muscles immediately after the forearm contraction, indicating that central fatigue created during the forearm exercise crossed over to the distal and unrelated ankle plantarflexor muscles. The influence of the central fatigue created during the forearm contraction affected the anticipatory postural response in a similar way to the fatigue created by the ankle fatigue protocol. The post-fatigue modification of the postural response dissipated as the central fatigue recovered. Taken together, these five studies extend the current understanding of how exercise induced neuromuscular fatigue modifies the central nervous system’s control of complex motor tasks.

This study used the word processor as a tool for written output to examine the effects of an experiential 'Write to Read' program on typing performance, decoding strategies and successive processing in learning disordered children with motor dysfunction. A case history approach was taken in view of the small number of subjects available, and in order to adequately describe each individual's unique and complex cognitive motor profile. Subjects involved in the study were three male students in a Junior Learning Assistance Class in a Lower Mainland British Columbia school district elementary school. Each of the students had a history of poor motor performance, poor handwriting and delayed reading ability. The three subjects were involved in an eight week intervention program which taught keyboarding and word processing techniques using the 'Write to Read' program, a systematic method of training the motor skills required. It was hypothesized that, if the learning disabled student with poor motor skills could use the word processor as an adjunct to handwriting, the improved legibility would facilitate consistent decoding by the student of his own work, reinforcing acquisition of early reading skills. Within the case history format, a theoretical frame of reference based on the simultaneous - successive information processing model was chosen and a limited time series design measured the effects of the intervention on successive processing as determined by a block sequencing task (Das, Kirby and Jarman, 1980). The data was collected for each student and graphed for visual inspection, graphic analysis and statistical analysis. One subject showed a stable and significant intervention effect, and no stable trends or significant results for successive processing were found in the other two subjects. Rates of word processing output increased over the course of the study and the number of errors declined. All subjects made progress in measures of decoding and word analysis. Implications for future research and professional practice were described. / Education, Faculty of / Educational and Counselling Psychology, and Special Education (ECPS), Department of / Graduate

Swimmers depend on accessory breathing muscles for adequate ventilation. Pectoralis minor is an accessory breathing muscle. The daily repetition of gleno-humeral flexion and medial rotation results in adaptive shortening of Pectoralis, a common phenomenon in competitive swimmers. If Pectoralis minor is shortened the scapula is in an anteriorly tipped position. This anteriorly tipped position will affect scapula kinematics as well as the strength of Pectoralis minor to function as an accessory breathing muscle. One of the risk factors contributing to shoulder dysfunction in competitive swimmers is an altered scapular position. The study aimed to determine if lateral costal breathing dissociation exercises in conjunction with scapular retraining exercises had an effect on the position of the scapula in competitive swimmers. A comparative parallel group longitudinal design was used in this study. During a six week supervised intervention period the intervention group (n=28) and control group (n=30) did retraining of the scapula stabilisers and stretching of Pectoralis minor. The intervention group did breathing dissociation exercises to facilitate lateral costal breathing. No specific breathing exercises were facilitated within the control group. Pectoralis minor length and thoracic expansion had been measured. The function of the scapula stabilisers was evaluated. The resting as well as dynamic scapula positions were evaluated. Evaluations were done at baseline, six weeks and five months post intervention. Treatment groups were compared with respect to change from baseline to six weeks and baseline to five months in PMI, FVC and thoracic expansion utilizing analysis of covariance (ANCOVA) with covariates baseline reading. The intervention group showed an increase in the Pectoralis minor Index (PMI) of 0.5 (left & right) and the control group reflected an increase of 0.5 (left) and 0.7 (right). The intervention group reflected continuous improvement in PMI and the control group showed deterioration. In addition to the PMI upper thoracic, expansion decreased and lower thoracic expansion increased in the intervention group. The control group showed a decrease in upper and lower thoracic expansion. Groups were compared with respect to change from baseline to six weeks and five months respectively for categorical parameters, muscle function and scapula position (resting and dynamic) using Fisher’s exact test. After six weeks the intervention group showed significantly (p<0.04) less winging of the distal third of the scapula on the left side when compared to the control group. After five months the scapula showed significantly less tipping (p<0.02) during gleno-humeral flexion, on the left side. The McNemar test for symmetry had been applied to determine if any within group changes occurred. Within the intervention group ten of the thirteen markers used to determine the resting position of the scapula, reflected significant improvement compared to the six markers in the control group. Only the intervention group reflected remarkable improvement in function of the lower fibres of Trapezius muscle. Serratus anterior and middle fibres of Trapezius muscles showed significance within group improvement in function for both groups. The scapula showed significantly less dysrhythmia within the intervention group on the left and right sides (p< 0.0209) when compared to the control group. After five months the resting scapula position reflected deterioration for both groups. Dysrhythmia and winging of the scapula deteriorated from six weeks to five months for both groups. The muscle function of the lower fibres of Trapezius showed significance within group changes for both groups from six weeks to five months. The ability to contract Serratus anterior and the middle fibres of Trapezius agonistically was maintained from six weeks to five months. However the eccentric control and ability to contract the muscle without fatigue within the Serratus anterior and middle fibres of Trapezius showed deterioration from six weeks to five months for both groups. Conclusion: The increase in PMI and increase in lower thoracic expansion for the intervention group could favour swimmers to breathe more effectively. An increase in Pectoralis minor length resulted in a more posteriorly tipped scapula. This better positioned scapula promotes optimum function of the lower fibres of Trapezius. Contracting from a stable scapula, Pectoralis minor can fulfil its function as an accessory breathing muscle more effectively. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Physiotherapy / PhD / Unrestricted

Em habilidades como o nadar tem se creditado o sucesso à consistência do comportamento, negligenciando o papel da flexibilidade. Nesse sentido, com o objetivo de investigar o efeito da modificação da tarefa na braçada do nado crawl em indivíduos em níveis de habilidades distintos, partiu-se da visão de complementaridade entre consistência e flexibilidade do comportamento motor habilidoso. Crianças (42), com média de 8,7 anos de idade, com domínio do nado crawl, participaram do experimento. Usando o instrumento de análise do nível de proficiência do nado crawl, dois grupos, de 15 sujeitos cada, em níveis de habilidades distintos foram formados. Medidas de aspectos invariantes e variantes foram utilizadas para analisar as braçadas na tarefa de deslocar-se 30 metros em três velocidades. Segundo os resultados, os nadadores mantiveram a organização temporal da braçada (OTB) nas três condições experimentais; o grupo mais habilidoso (+H) apresentou a OTB mais estável; e, as alterações de desempenho foram efetuadas, exclusivamente a partir de ajustes dos aspectos variantes das braçadas. Em função dos resultados conclui-se que a aquisição do nadar, vista como um processo contínuo, envolve a formação de representações mentais que asseguram tanto a consistência (aspectos invariantes) como a flexibilidade (aspectos variantes) da braçada e, que sua complexidade está associada ao nível de habilidade dos nadadores. / In skills, as swimming, there has been credit to the success of the consistency of behaviour neglecting the role of flexibility. In this way with the objective of investigating the effect of the modification of the task in the front crawl stroke in individuals with distinct levels of skill we launched from the point that consistency and flexibility complement each other in the skilful motor behaviour. Children (42), with an average age of 8.7 with the skill of swimming crawl participated in the experiment. Using the analysis instrument of proficiency level of the crawl style, two groups of 15 subjects each, with distinct levels of ability were formed. Measures of variant and invariant aspects were used to analyze the stroke of drifting 30 meters in three velocities. According to the results the swimmers maintained the temporal organization of the stroke (TOS) in three experimental conditions; the more skilful group presented the more stable TOS; and the alterations of the performance were made exclusively from the adjustments of the variant aspects of the strokes. Due to the results it was concluded that the acquisition of swimming seen as a continuous process, involves the formation of mental representations that assure not only consistency (invariant aspects) but also the flexibility (variaant aspects) of the stroke and that its complexity is associated to the level of skill in the swimmers.