Evaluating dynamic similarity of fixed,self-selected and anatomically scaled speeds in non-linear analysis of gait during treadmill running

ObjectivesThe aim of this study is to evaluate how speed affects non-linear measures of variability. Fixed and self-selected speeds were compared to an anatomically scaled speed calculated based on leg length to evaluate which provided a more reproducible result between subjects.MethodsSixteen subjects ran on a treadmill at a fixed, scaled and self-selected speed and at ±10% in each case. Kinematic data were collected for two minutes at 250 Hz for each trial. Sample entropy (SaEn) and maximum Lyapunov exponents (LyE) were calculated from the sagittal knee and hip joint angles to evaluate regularity of gait and local stability. These nonlinear measures were compared to evaluate the dynamic similarity of the movement in each case, and to evaluate speed as a confounding variable in non-linear analysis.ResultsAn anatomically scaled speed shows more dynamic similarity than a fixed or self-selected speed with the lowest observed coefficient of variation for each measure. This was found to be statistically significant for both nonlinear measures of the hip (SaEn p = 0.038; LyE p = 0.040). Speed was not found to be a confounding variable in non-linear analysis of running gait of a healthy population (η² < 0.05).ConclusionsChanges in speed by ±10% do not significantly affect stability and variability of gait for healthy participants, suggesting that they make adaptations to ensure optimal gait variability.Anatomically scaled speeds provide a more reliable methodology for both linear and non-linear analysis by providing a definitive protocol, suggesting it could replace self-selected or fixed speeds in future research.     

Variability in trunk and pelvic movement of transfemoral amputees using a C-leg system compared to healthy controls

ObjectiveGait variability is a measure of gait disturbance, and therefore constitutes a useful parameter for gait assessment as well as planning of therapeutic and medical interventions. To date, variability during walking has not been adequately analyzed in amputees. The aim of this examination was to evaluate trunk and pelvic movement variability in transfemoral amputees. The effect of different types of walking surfaces on variability in trunk and pelvic movement was also studied.MethodThis prospective clinical examination compares 20 transfemoral amputees (17 ♂, 42 ± 16 years; 3 ♀, 48 ± 3 years) with a group of 20 age and mass matched healthy controls regarding the extent of variability in trunk and pelvic movement. Kinematic data of trunk and pelvic movement during walking on level, uneven ground and slope was captured by eight infrared cameras (Vicon Nexus ™, Oxford, UK). Variability in trunk and pelvic movement was analyzed. Univariate ANCOVA and ANOVA with repeated measures and post hoc tests were used for statistical comparison. Fall history was retrospectively collected from medical history to assess the association between falls and variability in trunk and pelvic movement.ResultsTrunk and pelvic movement variability in amputees was significantly higher during walking on uneven ground and slope compared to healthy controls (p ≤ 0.05). Variability in trunk and pelvic movement was increased during walking on uneven ground and slope compared to even ground for both groups (p ≤ 0.05).ConclusionAmputees showed increased trunk and pelvic movement variability during walking on uneven ground and slope, indicating an affected gait pattern in comparison to healthy controls. Therefore, trunk and pelvic movement variability could be a potential marker for gait quality with diagnostic implications.     

The influence of aging on the spatial and temporal variables of gait during usual and fast speeds in older adults aged 60 to 102 years

BackgroundWith increases in life expectancy, it is important to understand the influence of aging on gait, given that this activity is related to the independence of older adults and may help in the development of health strategies that encourage successful aging in all phases of this process.Research questionTo compare gait parameters with usual and fast speeds for independent and autonomous older adults throughout the aging process (60 to 102 years old), and also to identify which of the gait variables are best for identifying differences across the different age groups.MethodsTwo hundred older adults aged between 60 and 102 years were evaluated. The sample was divided into 3 age groups: 60 to 79 years, 80 to 89 years and 90 years and over. The analyzed gait variables were: speed (meters/s), cadence (steps/min), stride time (seconds), step length (centimeters), double support (percentage of the gait cycle), swing (percentage of the gait cycle), step length variability (CoV%) and stride time variability (CoV%).ResultsGroup comparison regarding usual gait and fast gait revealed a significant difference in all gait variables. In addition, it can be seen that variables such as gait speed and step length showed greater effect sizes in intergroup comparison (usual gait: 0.48 and 0.47; fast gait: 0.36 and 0.40; respectively), possibly showing that these variables can better detect the changes observed with increasing age.ConclusionThere are differences in the gait performance of older adults from different age groups for usual and fast gait speeds, which is more evident regarding gait speed and step length variables. We recommend the use of usual gait for the identification of the effects of aging because, besides showing a higher effect size values it is more comfortable and requires less effort from older subjects.     

Expertise effects on decision-making in sport are constrained by requisite response behaviours – A meta-analysis

ObjectivesA quantitative review of the effects of requisite responses and methods of stimulus presentation for assessing decision-making expertise in sport was undertaken.DesignAn electronic literature search was conducted in the online databases: SPORTDiscus with Full Text and ISI Web Knowledge All Databases. Articles for analysis were selected according to prior defined criteria.MethodsWe considered 111 effect sizes in studies involving 882 expert and non-expert participants. Effect sizes were calculated for six common protocols for measures responses: verbalized knowledge, eye movement measures, decision time, response accuracy, movement accuracy, and movement time. Two moderator variables were also considered to assess effects of research protocols on the dependent variables: “the requisite response” and “stimulus presentation”. A random effect model was used to calculate effect sizes.ResultsAnalysis of moderator variables suggested that expertise effects were more apparent for “requisite responses” when participants were required to actually perform sporting actions and for “stimulus presentation” under in situ task constraints than for other conditions.ConclusionsFuture empirical work on expertise and decision-making needs to consider task representativeness in considering requisite responses of participants in simulating performance environment conditions. Use of representative task constraints with performers required to perform sport actions in in situ conditions appeared the most functional empirical protocols to enhance validity of data.     

Age and walking conditions differently affect domains of gait

IntroductionAnalysing gait in controlled conditions that resemble daily life walking could overcome the limitations associated with gait analysis in uncontrolled real-world conditions. Such analyses could potentially aid the identification of a walking condition that magnifies age-differences in gait. Therefore, the aim of the current study was to determine the effects of age and walking conditions on gait performance.MethodsTrunk accelerations of young (n = 27, age: 21.6) and older adults (n = 26, age: 68.9) were recorded for 3 min in four conditions: walking up and down a university hallway on a track of 10 m; walking on a specified path, including turns, in a university hallway; walking outside on a specified path on a pavement including turns; and walking on a treadmill. Factor analysis was used to reduce 27 computed gait measures to five independent gait domains. A multivariate analysis of variance was used to examine the effects of age and walking condition on these gait domains.ResultsFactor analysis yielded 5 gait domains: variability, pace, stability, time & frequency, complexity, explaining 64% of the variance in 27 gait outcomes. Walking conditions affected all gait domains (p < 0.01) but age only affected the time & frequency domain (p < 0.05). Age and walking conditions differently affected the domains variability, stability, time & frequency. The largest age-differences occurred mainly during straight walking in a hallway (variability: 31% higher in older adults), or during treadmill walking (stability: 224% higher, time&frequency: 120% lower in older adults).ConclusionWalking conditions affect all domains of gait independent of age. Treadmill walking and walking on a straight path in a hallway, were the most constrained walking conditions in terms of limited possibilities to adjust step characteristics. The age by condition interaction suggests that for the gait domains variability, stability, and time & frequency, the most constrained walking conditions seem to magnify the age-differences in gait.     

Gait measurement in chronic mild traumatic brain injury: A model approach

IntroductionMild traumatic brain injury (mTBI) can impact gait, with deficits linked to underlying neural disturbances in cognitive, motor and sensory systems. Gait is complex as it is comprised of multiple characteristics that are sensitive to underlying neural deficits. However, there is currently no clear framework to guide selection of gait characteristics in mTBI. This study developed a model of gait in chronic mTBI and replicated this in a separate group of controls, to provide a comprehensive and structured methodology on which to base gait assessment and analysis.MethodsFifty-two people with chronic mTBI and 59 controls completed a controlled laboratory gait assessment; walking for two minutes back and forth over a 13 m distance while wearing five wirelessly synchronized inertial sensors. Thirteen gait characteristics derived from the inertial sensors were selected for entry into the principle component analysis based on previous literature, robustness and novelty. Principle component analysis was then used to derive domains (components) of gait.ResultsFour gait domains were derived for our chronic mTBI group (variability, rhythm, pace and turning) and this was replicated in a separate control cohort. Domains totaled 80.8% and 77.4% of variance in gait for chronic mTBI and controls, respectively. Gait characteristic loading was unambiguous for all features, with the exception of gait speed in controls that loaded on pace and rhythm domains.ConclusionThis study contributes a four component model of gait in chronic mTBI and controls that can be used to comprehensively assess and analyze gait and underlying mechanisms involved in impairment, or examine the influence of interventions.     

N-of-1 methods: A practical guide to exploring trajectories of behaviour change and designing precision behaviour change interventions

Objectives(1) To introduce N-of-1 methods and how they can help the researchers identify predictors of behavioural outcomes, (2) to provide examples of studies that test individual theory-based predictions of physical activity and/or exercise; (3) to provide a practical example dataset to illustrate how to design and undertake a basic analysis for an N-of-1 study; and (4) to suggest a future agenda for N-of-1 physical activity and exercise research.DesignFactors for consideration when designing an N-of-1 study include variability of predictors and outcomes, assessment frequency and appropriate analysis methods. Existing literature and piloting can help inform these aspects.MethodsWe use a dataset of 24 individuals who collected data over 28 days to illustrate example analysis procedures. Data, guidance and associated SPSS and R syntax are made available to provide researchers with tools to learn about and practice N-of-1 analysis.ResultsGuidance on dealing with missing data, looking at graphical representations of N-of-1 data, managing autocorrelation using the prewhitening method and analysing N-of-1 datasets is provided. Using the example dataset, we demonstrate how to identify antecedents of physical activity (steps) to assess directionality of associations. We also include an overview of aggregating N-of-1 datasets using multilevel modelling.ConclusionsN-of-1 methodology provides a means of tracking individual patterns of behaviour and identifying potential antecedents of physical activity and exercise to help determine causality. Assisted by mobile technologies, there is great potential to enrich our understanding of movement behaviour using this approach to inform interventions.     

Upper limb movement analysis during gait in multiple sclerosis patients

PurposeGait disorders in multiple sclerosis (MS) are well studied; however, no previous study has described upper limb movements during gait. However, upper limb movements have an important role during locomotion and can be altered in MS patients due to direct MS lesions or mechanisms of compensation. The aim of this study was to describe the arm movements during gait in a population of MS patients with low disability compared with a healthy control group.MethodsIn this observational study we analyzed the arm movements during gait in 52 outpatients (mean age: 39.7 ± 9.6 years, female: 40%) with relapsing-remitting MS with low disability (mean EDSS: 2 ± 1) and 25 healthy age-matched controls using a 3-dimension gait analysis.ResultsMS patients walked slower, with increased mean elbow flexion and decreased amplitude of elbow flexion (ROM) compared to the control group, whereas shoulder and hand movements were similar to controls. These differences were not explained by age or disability.ConclusionUpper limb alterations in movement during gait in MS patients with low disability can be characterized by an increase in mean elbow flexion and a decrease in amplitude (ROM) for elbow flexion/extension. This upper limb movement pattern should be considered as a new component of gait disorders in MS and may reflect subtle motor deficits or the use of compensatory mechanisms.     

To adjust or not adjust: Nonparametric effect sizes,confidence intervals,and real-world meaning

ObjectivesThe main objectives of this article are to: (a) investigate if there are any meaningful differences between adjusted and unadjusted effect sizes (b) compare the outcomes from parametric and non-parametric effect sizes to determine if the potential differences might influence the interpretation of results, (c) discuss the importance of reporting confidence intervals in research, and discuss how to interpret effect sizes in terms of practical real-world meaning.DesignReview.MethodA review of how to estimate and interpret various effect sizes was conducted. Hypothetical examples were then used to exemplify the issues stated in the objectives.ResultsThe results from the hypothetical research designs showed that: (a) there is a substantial difference between adjusted and non-adjusted effect sizes especially in studies with small sample sizes, and (b) there are differences in outcomes between the parametric and non-parametric effect size formulas that may affect interpretations of results.ConclusionsThe different hypothetical examples in this article clearly demonstrate the importance of treating data in ways that minimize potential biases and the central issues of how to discuss the meaningfulness of effect sizes in research.     

Physical activity and posttraumatic growth: A systematic review of quantitative and qualitative studies

ObjectivesThis systematic review aimed to examine the relationships between physical activity and posttraumatic growth (PTG) following a highly stressful life event.DesignA systematic review was conducted to identify eligible articles. A meta-analysis was conducted for quantitative studies and a meta-ethnographic synthesis was conducted for qualitative studies.MethodAfter systematic searches of five databases and literature screening, 20 quantitative studies and 12 qualitative studies were included in the final review. A meta-analysis of 14 quantitative studies was conducted to examine association between leisure-time physical activity and PTG. A meta-ethnographic synthesis of 10 qualitative studies was conducted to examine the relationship between physical activity and the experience of PTG.ResultsThe meta-analysis revealed a positive, yet small, association between leisure-time physical activity and PTG (average correlation = 0.120; 95% confidence interval: 0.071 to 0.168; p < 0.001). The effect sizes did not differ by measurements of PTG and participants’ age and gender but were smaller in studies with a binary variable of physical activity, a sample of participants with moderate or advanced diseases, and a longer period since the stressful event. The meta-ethnographic synthesis identified potential processes linking physical activity and PTG, including perceptions of self, social experiences, philosophical re-evaluation, and health effects.ConclusionsThis review suggest physical activity is a behavioral factor that may facilitate PTG. It highlights methodological considerations for further research.     

The influence of proximal motor strategies on pianists' upper-limb movement variability

Repetitive movements are considered a risk factor for developing practice-related musculoskeletal disorders. Intra-participant kinematic variability might help musicians reduce the risk of injury during repetitive tasks. No research has studied the effects of proximal motion (i.e., trunk and shoulder movement) on upper-limb movement variability in pianists. The first objective was to determine the effect of proximal movement strategies and performance tempo on both intra-participant joint angle variability of upper-limb joints and endpoint variability. The second objective was to compare joint angle variability between pianist's upper-limb joints. As secondary objectives, we assessed the relationship between intra-participant joint angle variability and task range of motion (ROM) and documented inter-participant joint angle variability. The upper body kinematics of 9 expert pianists were recorded using an optoelectronic system. Participants continuously performed two right-hand chords (lateral leap motions) while changing movements based on trunk motion (with and without) and shoulder motion (counter-clockwise, back-and-forth, and clockwise) at two tempi (slow and fast). Trunk and shoulder movement strategies collectively influenced variability at the shoulder, elbow and, to a lesser extent, the wrist. Slow tempi led to greater variability at wrist and elbow flexion/extension compared to fast tempi. Endpoint variability was influenced only along the anteroposterior axis. When the trunk was static, the shoulder had the lowest joint angle variability. When trunk motion was used, elbow and shoulder variability increased, and became comparable to wrist variability. ROM was correlated with intra-participant joint angle variability, suggesting that increased task ROM might result in increased movement variability during practice. Inter-participant variability was approximately six times greater than intra-participant variability. Pianists should consider incorporating trunk motion and a variety of shoulder movements as performance strategies while performing leap motions at the piano, as they might reduce exposure to risks of injury.     

Effects of dichotic listening on gait domains of healthy older adults during dual-tasking: An exploratory observational study

BackgroundIdentification of the cognitive mechanisms behind gait changes in aging is a prime endeavor in gerontology and geriatrics. For this reason, we have implemented a new dual-task paradigm where an auditory attentional task is performed during over-ground walking. Dichotic listening assesses spontaneous attention and voluntary attention directed to right and left-ear. The uniqueness of dichotic listening relies on its requirements that vary in difficulty and recruitment of resources from whole brain to one brain hemisphere. When used in dual-tasking, asymmetric effects on certain gait parameters have been reported.ObjectivesThe present study aims to acquire a more global understanding on how dichotic listening affects gait domains. Specifically, we aimed to understand how spontaneous vs lateralized auditory attention altered the Principal Component Analysis (PCA) structure of gait in healthy older adults.MethodsSeventy-eight healthy older adults (mean age: 71.1 years; 44 women and 34 men) underwent the Bergen dichotic listening test while walking. As this study only focuses on the effects of the cognitive task on gait, only dual-task costs for gait were calculated and entered into the PCA analyses. We explored the PCA structure for the effects on bilateral gait parameters (i.e., both limbs together) as well as on lateralized gait parameters (i.e, separate parameters by limb). We first established gait domains during single-task walking. Then, dual-task cost scores for gait were entered in a series of PCAs.ResultsResults from the PCAs for bilateral gait parameters showed limited alterations on gait structure. In contrast, PCAs for lateralized data demonstrated modifications of the gait structure during dichotic listening. The PCAs corresponding for all dichotic listening conditions showed different factor solutions ranging between 4 and 6 factors that explained between 73.8% to 80% of the total variance. As a whole, all conditions had an impact on “pace”, “pace variability” and “base of support variability” domains. In the spontaneous attention condition, a six-factor solution explaining 78.3% of the variance showed asymmetrical disruptions on the PCA structure. When attention was focused to right-ear, a five-factor solution explaining 89% of the variance and similar to baseline was found. When attention was directed to left-ear, a four-factor solution explaining 73.8% of the variance was found with symmetrical impact on all factors.ConclusionsThese findings demonstrate for the first time that specific facets of attentional control affects gait domains both symmetrically and asymmetrically in healthy older adults.     

A critical commentary on follow-up studies and “desistance” theories about transgender and gender-nonconforming children

ABSTRACT

Background: It has been widely suggested that over 80% of transgender children will come to identify as cisgender (i.e., desist) as they mature, with the assumption that for this 80%, the trans identity was a temporary “phase.” This statistic is used as the scientific rationale for discouraging social transition for pre-pubertal children. This article is a critical commentary on the limitations of this research and a caution against using these studies to develop care recommendations for gender-nonconforming children.

Methods: A critical review methodology is employed to systematically interpret four frequently-cited studies that sought to document identity outcomes for gender-nonconforming children (often referred to as “desistance” research).

Results: Methodological, theoretical, ethical, and interpretive concerns regarding four “desistance” studies are presented. The authors clarify the historical and clinical contexts within which these studies were conducted to deconstruct assumptions in interpretations of the results. The discussion makes distinctions between the specific evidence provided by these studies versus the assumptions that have shaped recommendations for care. The affirmative model is presented as a way to move away from the question of, “How should children's gender identities develop over time?” toward a more useful question: “How should children best be supported as their gender identity develops?”

Conclusion: The tethering of childhood gender diversity to the framework of “desistance” or “persistence” has stifled advancements in our understanding of children's gender in all its complexity. These follow-up studies fall short in helping us understand what children need. As work begins on the 8th version of the Standards of Care by the World Professional Association for Transgender Health, we call for a more inclusive conceptual framework that takes children's voices seriously. Listening to children's experiences will enable a more comprehensive understanding of the needs of gender-nonconforming children and provide guidance to scientific and lay communities.     

Reproducible research in sport and exercise psychology: The role of sample sizes

ObjectivesWe aim to introduce the discussion on the crisis of confidence to sport and exercise psychology. We focus on an important aspect of this debate, the impact of sample sizes, by assessing sample sizes within sport and exercise psychology. Researchers have argued that publications in psychological research contain numerous false-positive findings and inflated effect sizes due to small sample sizes.MethodWe analyse the four leading journals in sport and exercise psychology regarding sample sizes of all quantitative studies published in these journals between 2009 and 2013. Subsequently, we conduct power analyses.ResultsA substantial proportion of published studies does not have sufficient power to detect effect sizes typical for psychological research. Sample sizes and power vary between research designs. Although many correlational studies have adequate sample sizes, experimental studies are often underpowered to detect small-to-medium effects.ConclusionsAs sample sizes are small, research in sport and exercise psychology may suffer from false-positive results and inflated effect sizes, while at the same time failing to detect meaningful small effects. Larger sample sizes are warranted, particularly in experimental studies.     

Goal-setting in diabetes self-management: A systematic review and meta-analysis examining content and effectiveness of goal-setting interventions

Background: Goal-setting is recommended and widely used within diabetes self-management programmes. However, empirical evidence around its effectiveness lacks clarity. This review aims to evaluate the effectiveness of goal-setting interventions on diabetes outcomes and to determine which behaviour change techniques (BCTs) are frequently used within these interventions.

Methods: A systematic search identified 14 studies, describing 12 interventions targeting diabetic-control which incorporated goal-setting as the main intervention strategy. Study characteristics, outcome measures and effect sizes of the included studies were extracted and checked by two authors. The BCT taxonomy v1 was used to identify intervention content. Meta-analyses were conducted to assess intervention effects on the primary outcome of average blood glucose levels (HbA1c) and on body-weight. Psycho-social and behavioural outcomes were summarised in narrative syntheses.

Results: Significant post-intervention improvements in HbA1C were found (?.22, 95% CI, ?.40, ?.04) across studies. No other main effects were identified. The BCT ‘goal-setting (behaviour)’ was most frequently implemented and was identified in 84% of the interventions.

Conclusions: Goal-setting interventions appear to be associated with reduced HbA1C levels. However, the low numbers of studies identified and the risk biases across studies suggest more research is needed to further explore goal-setting BCTs in diabetes self-management.     

The Effect of External and Internal Focus of Attention on Gait Variability in Older Adults

Internal focus of attention on a movement or focusing on an external target are both strategies that can affect motor performance. The authors explored whether manipulating subjects' focus of attention while walking would alter gait variability, a measure reflecting consistency of gait and associated with the risk of falling in older adults. Twenty community-living older adults participated in the study and were tested while focusing their attention on (a) gait consistency (internal focus) or (b) metronome beats (external focus). In both conditions gait variability increased (i.e., worsened p < .05) or did not change. No benefit was found in instructing subjects to focus on gait consistency or metronome beats. Such instructions may actually have distracted and interfered with the execution of gait.     

Spontaneous and experimentally induced action planning and coping planning for physical activity: A meta-analysis

ObjectivesThe main objective of this review was to provide summary effects for spontaneous and experimentally induced action planning (AP) and coping planning (CP) for physical activity (PA). These summary effects were then used to test key theoretical postulates using meta-analytic path analysis, and examine possible boundary conditions via moderation analyses.DesignThis review employed a quantitative research synthesis design.MethodUsing the method of Lipsey and Wilson (2001), fixed- and random-effects meta-analysis was performed on over 150 effect sizes from 23 correlational and 21 experimental studies. The method of Viswesvaran and Ones (1995) was used to test two mediation models using the correlational meta-analytic data. Group comparisons and meta-regression were used to test moderation.ResultsAmong the correlational studies, findings indicated a medium-to-large summary effect of spontaneous AP (φ = .41) and CP (φ = .38) on PA. Among the experimental studies, results revealed a small-to-medium summary effect (φ = .24) when comparing all experimental conditions versus all controls and a medium-to-large summary effect (φ = .37) when comparing purely planning conditions versus neutral controls. Support was found for AP and CP as partial mediators in the relation between intention and PA. Numerous significant moderators emerged.ConclusionThis review offers the first meta-analytic estimates of both spontaneous and experimentally induced AP and CP for PA, while supporting the role of both spontaneous AP and CP as mediators in both a multiple and sequential mediation model. Relevant moderators will serve to inform future research in this area.     

Using dynamic walking models to identify factors that contribute to increased risk of falling in older adults

Falls are common in older adults. The most common cause of falls is tripping while walking. Simulation studies demonstrated that older adults may be restricted by lower limb strength and movement speed to regain balance after a trip. This review examines how modeling approaches can be used to determine how different measures predict actual fall risk and what some of the causal mechanisms of fall risk are. Although increased gait variability predicts increased fall risk experimentally, it is not clear which variability measures could best be used, or what magnitude of change corresponded with increased fall risk. With a simulation study we showed that the increase in fall risk with a certain increase in gait variability was greatly influenced by the initial level of variability. Gait variability can therefore not easily be used to predict fall risk. We therefore explored other measures that may be related to fall risk and investigated the relationship between stability measures such as Floquet multipliers and local divergence exponents and actual fall risk in a dynamic walking model. We demonstrated that short-term local divergence exponents were a good early predictor for fall risk. Neuronal noise increases with age. It has however not been fully understood if increased neuronal noise would cause an increased fall risk. With our dynamic walking model we showed that increased neuronal noise caused increased fall risk. Although people who are at increased risk of falling reduce their walking speed it had been questioned whether this slower speed would actually cause a reduced fall risk. With our model we demonstrated that a reduced walking speed caused a reduction in fall risk. This may be due to the decreased kinematic variability as a result of the reduced signal-dependent noise of the smaller muscle forces that are required for slower. These insights may be used in the development of fall prevention programs in order to better identify those at increased risk of falling and to target those factors that influence fall risk most.     

Keep your head down: Maintaining gait stability in challenging conditions

BackgroundPeripheral vision often deteriorates with age, disrupting our ability to maintain normal locomotion. Laboratory based studies have shown that lower visual field loss, in particular, is associated with changes in gaze and gait behaviour whilst walking and this, in turn, increases the risk of falling in the elderly. Separately, gaze and gait behaviours change and fall risk increases when walking over complex surfaces. It seems probable, but has not yet been established, that these challenges to stability interact.Research questionHow does loss of the lower visual field affect gaze and gait behaviour whilst walking on a variety of complex surfaces outside of the laboratory? Specifically, is there a synergistic interaction between the effects on behaviour of blocking the lower visual field and increased surface complexity?MethodsWe compared how full vision versus simulated lower visual field loss affected a diverse range of behavioural measures (head pitch angle, eye angle, muscle coactivation, gait speed and walking smoothness as measured by harmonic ratios) in young participants. Participants walked over a range of surfaces of different complexity, including pavements, grass, steps and pebbles.ResultsIn both full vision and blocked lower visual field conditions, surface complexity influenced gaze and gait behaviour. For example, more complex surfaces were shown to be associated with lowered head pitch angles, increased leg muscle coactivation, reduced gait speed and decreased walking smoothness. Relative to full vision, blocking the lower visual field caused a lowering of head pitch, especially for more complex surfaces. However, crucially, muscle coactivation, gait speed and walking smoothness did not show a significant change between full vision and blocked lower visual field conditions. Finally, head pitch angle, muscle coactivation, gait speed and walking smoothness were all correlated highly with each other.SignificanceOur study showed that blocking the lower visual field did not significantly change muscle coactivation, gait speed or walking smoothness. This suggests that young people cope well when walking with a blocked lower visual field, making minimal behavioural changes. Surface complexity had a greater effect on gaze and gait behaviour than blocking the lower visual field. Finally, head pitch angle was the only measure that showed a significant synergistic interaction between surface complexity and blocking the lower visual field. Together our results indicate that, first, a range of changes occur across the body when people walk over more complex surfaces and, second, that a relatively simple behavioural change (to gaze) suffices to maintain normal gait when the lower visual field is blocked, even in more challenging environments. Future research should assess whether young people cope as effectively when several impairments are simulated, representative of the comorbidities found with age.     

Integrating sport psychology and sports medicine in research: The dilemmas

Abstract

The recent acceleration of interest in conducting sport psychology research within sports medicine settings has prompted an introspection on the stringency of sport injury-focused research protocols and methodology. Much of the literature relating to the psychology of sport injury is anecdotal, comprised of conjecture, or is an extrapolation from allied psychological study. In addition, retrospective studies, involving the recall of an unpleasant event (i.e., sport injury) proliferate the literature. Quality research that integrates sport psychology and sports medicine presents a unique challenge because of the multifactorial nature of sport injury and the necessity for sound interpretation of research outcomes relative to the nature of psychology. sport, and injury. Confounding and complicating aspects of this integrated research include definition of injury variables, timing of data collection. evaluation of pain. and the physiological sequelae of injury. Research and methodological issues relating to sport psychology and sport injury are discussed.