Background: Running is one of the most popular branches of athletics. Running has several physiological benefits, such as a higher maximal oxygen consumption, increased muscle mass and reduced blood pressure. There have been plenty of discussions about what the most efficient running technique might be, should you use a short step length and a high step frequency or vice versa. It is generally known that you can increase your running speed by increasing your step frequency or your step length, and also both. However, maximal speed is achieved by increasing your step frequency rather than your step length. For endurance runners it is important to have a good running economy, because runners with a good running economy use less energy while running, and therefore require less oxygen than a runner with poor running economy. Previous research have not found any correlations between the length of the leg with step frequency or step length.  Aim: The aim of this study was to examine whether there are any significant correlations between the length of the leg in relation to the step frequency or the step length while running in different speeds.  Method: 15 trained males participated in this correlation study. All participants’ leg length were measured with a measuring tape. Three running trials, with the speeds of 12, 16 and 20 km/h were performed on a treadmill during 1 minute each. Between each trial the participants rested for 3 minutes. The trials were recorded with a video camera, and the participants individual step frequency, step length and heel or fore foot strike were collected. Persons coefficient of correlation test was used to analyze if there were any significant correlations between the length of the leg with step frequency and step length. Also a paired samples T test was performed to see if there was a significant increase between step frequency and step length with the speeds.  Result: There were no significant correlations (p>0,05) found between the length of the leg and the step frequency or the length of the leg and step length in any of the different speeds. The paired samples t-test showed a significant (p<0,001) increase in step frequency and step length with the different speeds.  Conclusion: In conclusion, according to the present study, there were no significant correlations found between the length of the leg with step frequency or step length, which is in consensus with previous research.  Therefore, it is not advisable to predict an individual’s step length based on their leg length. There are various factors involved in determining a person’s step length and step frequency, and this study showed that running speed is one important factor. This information may be useful for runners and their coaches to apply, so they avoid making interventions involving alternations in the runners step length based on their body dimensions, such as leg length.

Music appears to have advantageous effects during exercise as it has been shown to increase motivation, decrease ratings of perceived exertion (RPE), and improve exercise performance. The improvement of running performance in particular, is the main effect recreational runners want to focus on as many want to improve their time in road races. Running velocity, indicated by a faster time to completion is thought to improve with an increase in step frequency, step length, or a combination of these variables. Currently, there is limited research that observes methods to help increase step frequency or step length. The manipulation of music cadence may be considered an effective training method that influences step frequency. The purpose of this study was to observe the effect of music cadence on step frequency in the recreational runner. A total of 30 recreational runners (15 male, 15 female) with a mean age of 31.0 ± 5.8 (range= 20-39), a BMI of 24.0 ± 3.3 (range= 19-32), and an estimated VO2 max of 49.6 ± 5.4 (range= 41-60) participated in this study. Individually, runners completed four 1600-meter time trials on an outdoor track at maximal effort. The first trial was a familiarization trial where participants ran 1600 meters with no music. Two music conditions were then created for each runner based on their natural step frequency obtained during the familiarization trial. The first condition represented music at natural step cadence and the second condition represented music at increased step cadence. The next three 1600 meter time trials were randomized and included a control condition of no music, a natural cadence music condition at the runner's natural step frequency, and an increased cadence music condition of 10-20 beats per minute (bpm) above the natural cadence music condition. Results indicated that step frequency was significantly higher during the increased cadence music condition compared to both the natural cadence music and no music conditions (p < 0.05). Additionally, time to completion was significantly lower in the increased cadence music condition compared to both the natural cadence music and no music conditions (p < 0.05). Lastly, there was no significant difference in step length among music conditions. These results indicate that music cadence had a positive influence on running performance as it was able to increase step frequency and improve time to completion in a group of recreational runners. Therefore, for practical application, recreational runners can alter music cadence to help improve running performance.

abstract: Progressive gait disorder in Parkinson's disease (PD) is usually exhibited as reduced step/stride length and gait speed. People with PD also exhibit stooped posture, which can contribute to reduced step length and arm swing. Since gait and posture deficits in people with PD do not respond well to pharmaceutical and surgical treatments, novel rehabilitative therapies to alleviate these impairments are necessary. Many studies have confirmed that people with PD can improve their walking patterns when external cues are presented. Only a few studies have provided explicit real-time feedback on performance, but they did not report how well people with PD can follow the cues on a step-by-step basis. In a single-session study using a novel-treadmill based paradigm, our group had previously demonstrated that people with PD could follow step-length and back angle feedback and improve their gait and posture during treadmill walking. This study investigated whether a long-term (6-week, 3 sessions/week) real-time feedback training (RTFT) program can improve overground gait, upright posture, balance, and quality of life. Three subjects (mean age 70 ± 2 years) with mild to moderate PD (Hoehn and Yahr stage III or below) were enrolled and participated in the program. The RTFT sessions involved walking on a treadmill while following visual feedback of step length and posture (one at any given time) displayed on a monitor placed in front of the subject at eye-level. The target step length was set between 110-120% of the step length obtained during a baseline non-feedback walking trial and the target back angle was set at the maximum upright posture exhibited during a quiet standing task. Two subjects were found to significantly improve their posture and overground walking at post-training and these changes were retained six weeks after RTFT (follow-up) and the third subject improved his upright posture and gait rhythmicity. Furthermore, the magnitude of the improvements observed in these subjects was greater than the improvements observed in reports on other neuromotor interventions. These results provide preliminary evidence that real-time feedback training can be used as an effective rehabilitative strategy to improve gait and upright posture in people with PD. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2017

Research has shown that older adults who have experienced a previous fall are 60-70% more likely to suffer future falls. A study was conducted to investigate if stress and anxiety associated with a fear of falling contributes to the increased incidents of falls among older adults. The investigation compared physiological parameters, with biomechanical parameters of walking for twenty-eight participants in two age groups: (18-35) and (65 or older). Both age groups were evaluated while walking over dry and slippery floor surfaces. Biomechanical parameters included: step length, required coefficient of friction (RCOF), slip distance, and heel contact velocity. Physiological parameters included: stress and anxiety. Overall, the results indicated that there were differences between older and younger adult's biomechanical parameters of walking, and their physiological stress and anxiety associated with an inadvertent slip. Younger adult's normal RCOF was higher and their normal step length was longer compared to older adults. Older adult's stress level after a slip was significantly higher than younger adults. However, younger and older adult's anxiety scores were not significantly different. Furthermore, younger and older adults modified their step length differently to avoid slipping, when walking over the slippery floor surface. It was concluded that some anxiety and stress may be beneficial in reducing the occurrence of inadvertent slips and falls due to an increased awareness of one's external environment. / Master of Science

Understanding the underlying coordination mechanisms that lead to a patient’s poor walking performance is critical in developing effective rehabilitation interventions. However, most common measures of rehabilitation effectiveness do not provide information regarding underlying coordination mechanisms. The overall goal of this research was to analyze the relationship between two potential measures of walking performance (step length asymmetry and module composition) and underlying walking mechanics. Experimental analyses were used to analyze the walking mechanics of hemiparetic subjects grouped by step length asymmetry. All groups had impaired plantarflexor function and the direction of asymmetry provided information regarding the compensatory mechanism used to overcome this plantarflexor impairment. Those subjects who walked with longer paretic than nonparetic steps compensated using increased output from the nonparetic leg, while those with symmetric steps compensated using a bilateral hip strategy. These results suggest that step length asymmetry may provide information regarding underlying coordination mechanisms that can be used to guide rehabilitation efforts. Another way to assess walking performance is to directly analyze deficits in muscle coordination. Recent studies have suggested that complex muscle activity during walking may be generated using a reduced neural control strategy organized around the co-excitation of multiple muscles, or modules, which may provide a useful framework for characterizing coordination deficits. Simulation analyses using modular control were performed to understand how modules contribute to important biomechanical functions of non-impaired walking and how the generation of these functions is altered in groups of post-stroke hemiparetic subjects who commonly merged different sets of non-impaired modules. The non-impaired simulation found that six modules are needed to generate the three-dimensional tasks of walking (support, forward propulsion, mediolateral balance control and leg swing control). When the plantarflexor module was merged with the module controlling the knee extensors and hip abductors, forward propulsion and ipsilateral leg swing were impaired. When the module controlling the hamstrings was merged with the module controlling the knee extensors and hip abductors, forward propulsion, body support and mediolateral balance control were impaired. These results suggest that module analysis may provide useful information regarding the source of walking deficits and can be used to guide rehabilitation efforts. / text

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.

Falling during walking leads to millions of emergency room visits every year for all age groups and is a significant medical concern. While gait training has shown some promise for fall prevention, we know relatively little about how humans maintain stability, how we can quantify it and how we can use this knowledge to increase the success of fall prevention training. In this dissertation, I studied how human stability responds to continuous, small magnitude perturbations and to voluntary changes in gait characteristics by examining movement variability and long-term and instantaneous dynamic stability. In the first set of experiments, participants were exposed to continuous, pseudo-random external perturbations of the visual field and support surface in a Computer Assisted Rehabilitation ENvironment (CAREN). Participants exhibited increased step widths, shorter step lengths and increased step variability, orbital and short-term local instability. Despite this, mean instantaneous lateral stability remained approximately constant. In the second set of experiments, participants voluntarily adopted changes in their step widths and step lengths. Wider steps were associated with increased step width variability, decreased nonlinear stability, decreased anterior-posterior margins of stability and increased instantaneous lateral stability. Shorter steps were associated with decreased short-term and orbital stability but did not affect mean instantaneous stability. When instantaneous stability was examined between steps, as opposed to as an average over many steps, results from both studies indicated a relationship between each step’s stability and the stability of the immediately preceding step. From these studies, we now know that unpredictable, continuous perturbations during human walking applied in a given direction can be used to elicit predictable responses in motion variability and stability in that same direction. We know that the type of stability examined can influence the conclusions drawn about an individual’s stability during perturbed walking. For example, an individual’s variability may indicate increased risk of falling while he or she simultaneously demonstrates increased orbital stability and instantaneous lateral stability. A challenge faced in this area of research will be to understand how quantitative measures of stability relate to how we perceive our stability. / text

Previous research has shown that with advancing age, there are increasing incidences of slip and fall injuries. Understanding mechanisms associated with gait adjustments across a known slippery surface may help in proactively avoiding slips and falls. The primary goal of this study involved examination of gait parameters and muscle activity characteristics of the lower extremities during two different walking conditions. Research has shown that both physical and mental changes accompany the aging process in humans. Moreover, research has shown that emotions and physiological responses are related. A secondary goal of this study was to examine the relationships of fear of falling with gait parameters and muscle activity. This study consisted of exposing 14 younger and 14 older participants to controlled slippery conditions safely, while studying normal and adjusted gait characteristics (friction requirement, heel contact velocity, and step length) and muscle activity characteristics (Integrated EMG). First, a baseline measure was done to study normal gait prior to any exposure to slipping. A second measure was done following a slip from a contaminated floor surface, but before the initiation of a second slip. The results indicate that there were significant gait parameter differences between younger and older participants for both walking conditions. Results also indicate that there were differences in muscle activity between to the two age groups for the adjusted condition. Findings suggest that older individuals require an additional step to properly adjust gait for a contaminated walking surface. / Master of Science

The thesis deals with the issue of walking and standing in patients with a scoliosis. The theoretical part of this thesis summarizes current knowledge of scoliosis, its classification, etiology, pathogenesis and risk factors of the curve progression. Then the most often changes of the stand and gait stereotype and their main causes are discussed. Goal of the practical part was to identify the difference between particular parameters of gait in an experimental group of patients with scoliosis and a control group of healthy individuals. The examination was performed via the dynamic plantography method using the Zebris FDM-T System. 19 probands with scoliosis aged 8 - 19 and a control group of 19 orthopedically healthy patients in a corresponding age distribution have been selected for the study. The results did not provide any statistically significant difference on a significance level p=0,05. However, there were clear differences between the groups referring to bigger asymmetries in stance and gait stereotype in the scoliosis patients group. Since even in a scientific literature there is a difference in opinion on this issue, more research might be necessary for the exact evaluation of the influence of scoliosis on the stance and gait stereotype.

L’asymétrie de longueur de pas est une caractéristique du patron de marche fréquemment observée chez des personnes qui ont subi un accident vasculaire cérébral (AVC). Très peu d’interventions conventionnelles en réadaptation ont démontré leur efficacité sur ce paramètre de marche. Une approche novatrice utilisant un tapis roulant à double courroie (DC) a récemment présenté des effets prometteurs en réduisant, à court et long termes, l’asymétrie de longueur de pas chez des personnes post-AVC. Cependant, une meilleure compréhension des mécanismes sous-jacents aux changements induits par cette intervention est nécessaire avant que l’utilisation de cette intervention soit recommandée en clinique. Ce projet doctoral visait à améliorer les connaissances sur la contribution musculaire et les facteurs biomécaniques impliqués dans les changements immédiats (c.-à-d. les post-effets) et à long terme de l’asymétrie de la longueur de pas chez des personnes post-AVC. Les objectifs principaux étaient 1) d’analyser l’activité musculaire associée aux changements de longueur de pas après la marche sur un tapis à DC avec des vitesses de courroies inégales, 2) d’évaluer les effets d’un entraînement sur un tapis à DC sur l’asymétrie de longueur de pas et sur la capacité de marche au sol et 3) de quantifier la contribution musculaire et les stratégies sous-jacentes aux changements du patron de marche résultant de l’entraînement. L’hypothèse générale était que les muscles distaux des membres inférieurs seraient majoritairement impliqués dans les changements de longueur de pas induits par la marche sur le tapis à DC avec des vitesses de courroies inégales (ratio 2:1) chez les personnes post-AVC. L’étude transversale (article #1) a quantifié l’activité musculaire des membres inférieurs associée aux post-effets observés au niveau de la longueur de pas après six minutes de marche sur le tapis à DC (ratio 2:1) chez 16 personnes post-AVC et 10 personnes saines. Les résultats ont confirmé que les muscles distaux, c.-à-d. les fléchisseurs plantaires et dorsaux, étaient associés aux post-effets de la longueur de pas. Ces effets ont été observés, quel que soit le membre inférieur (c.-à-d. parétique ou non parétique) qui était sur la courroie rapide. La deuxième étude, a démontré que six séances d’entraînement sur le tapis à DC conduisaient à une réduction de l’asymétrie de longueur de pas et amélioraient la vitesse de marche sur le sol chez 12 personnes post-AVC (article #2). Les changements ont persisté un mois après l’entraînement. En outre, les résultats de cette étude pilote ont suggéré une bonne faisabilité de ce protocole d’entraînement dans un environnement clinique (données supplémentaires de l’article #2). Dans l’article #3, il a été démontré que l’amélioration post-entraînement de la symétrie et de la vitesse de marche était associée à une variété de stratégies et de contributions musculaires chez nos participants. Cependant, une contribution prédominante a été observée au niveau du membre inférieur entraîné sur la courroie rapide avec des tailles d’effet modérées obtenues surtout pour les changements de moment et d’activité musculaire des fléchisseurs plantaires pendant la phase d’appui de la marche. Suite à ces résultats et ceux de l’article #1, il a été suggéré que ce groupe musculaire jouait un rôle principal dans l’adaptation locomotrice et la réduction à long terme de l’asymétrie de la longueur de pas chez des personnes post-AVC. Néanmoins, des études cliniques contrôlées avec une population plus importante sont nécessaires afin de préciser la pertinence de l’entraînement sur le tapis à DC ainsi que les différentes stratégies musculaires associées aux changements de l’asymétrie de longueur du pas à long terme chez des personnes post-AVC. / Step length asymmetry is a common characteristic of post-stroke gait, but considered as particularly resistant to conventional gait interventions. A recent novel approach using a split-belt treadmill (SBT) showed promising results in short- and long-term reduction of step length asymmetry post-stroke. However, the underlying mechanisms of this intervention and its effects must be better understood before recommending its use in clinical settings. This project aimed to improve our current knowledge about muscular and biomechanical factors contributing to immediate and long-term changes in step length asymmetry in chronic stroke survivors. The main objectives were to: 1) analyze muscle activity associated with changes in step length after walking at unequal belt speeds on a SBT; 2) test the effects of repeated exposure to SBT walking on step length asymmetry and gait ability during walking over ground; and 3) investigate the muscular contributions and strategies involved in these changes. To attain these objectives, a cross-sectional analysis was conducted followed by a pilot training study. The general hypothesis was that distal lower limb muscles are the main contributors to SBT-induced changes in step length asymmetry in chronic stroke survivors using a SBT protocol where two belts were set at unequal speeds with a ratio of 2:1 for a period of time (split-belt configuration). The cross-sectional study analyzed the immediate changes in muscle activity and step length after six minutes of SBT walking in a group of 16 individuals post-stroke and in 10 healthy controls. The findings confirmed that regardless of the side (paretic or non-paretic) walking on the fast belt during split-belt configuration, changes in muscle activity of the ankle plantar- and dorsiflexors were mainly associated with changes in step length symmetry (paper #1). The pilot training study demonstrated that repeated exposure to SBT protocol reduced step length asymmetry and improved walking speed over ground in 12 individuals post-stroke (paper #2). Improvements persisted at least one month post-training. Findings also indicated that from a therapist’s viewpoint the training protocol was easy to use and practical in a clinical environment (supplementary data paper #2). Paper #3 showed that these consistent improvements in gait parameters were achieved by a variety of muscular contributions and strategies which involved both lower limbs with a predominant contribution on the side that was trained on the faster belt. Large effect sizes were found in the plantarflexor group during late stance of gait for both net joint moments and muscle activity in the training study. These results combined with the findings of paper #1 indicate that overall, step length asymmetry post-stroke can be successfully reduced with repeated exposure to the tested SBT protocol with distal lower limb muscles appearing to be strong contributors to locomotor adaptation post-stroke and long-term changes in step length asymmetry. Larger control trials are necessary to confirm the relevance of the use of SBT protocols and to further understand the role of the distal lower limb muscles in improvements in step length symmetry post-stroke.