Dynamical biomarkers in teams and other multiagent systems.

Effective team behavior in high-performance environments such as in sport and the military requires individual team members to efficiently perceive the unfolding task events, predict the actions and action intents of the other team members, and plan and execute their own actions to simultaneously accomplish individual and collective goals. To enhance team performance through effective cooperation, it is crucial to measure the situation awareness and dynamics of each team member and how they collectively impact the team's functioning. Further, to be practically useful for real-life settings, such measures must be easily obtainable from existing sensors. This paper presents several methodologies that can be used on positional and movement acceleration data of team members to quantify and/or predict team performance, assess situation awareness, and to help identify task-relevant information to support individual decision-making. Given the limited reporting of these methods within military cohorts, these methodologies are described using examples from team sports and teams training in virtual environments, with discussion as to how they can be applied to real-world military teams.

Physical activity in university health science students: Motivations influencing behaviors.

Objective: To understand how competence, self-efficacy, enjoyment and motivation relates to physical activity behavior during transition from school to university. Participants: Health science students (n = 558) studying first year biology at an Australian university. Methods: Cross-sectional correlational survey design using five self-report questionnaires to establish relationships between a physical activity index and motivational variables. Results: Self-reported physical activity index scores of satisfactory or above were achieved by 80% of students with scores significantly higher for males than females. Enjoyment, self-efficacy and competence were predictive of physical activity index scores across genders. Conclusions: The physical activity index is a useful measure of activity dimensions across a variety of physical activities. Health science students need to underpin health messages with personal practice in modeling a healthy lifestyle. Universities have a special responsibility for building and supporting physical activity for all students, but especially for future health professionals.

Intergenerational living and learning: The value and risks of co-locating retirement villages on secondary school campuses - Evaluating the GrandSchools vision.

OBJECTIVES: GrandSchools is a new concept which co-locates retirement villages with secondary schools in one physical environment. Designed to enhance the health and well-being of both younger and older generations, this intergenerational-shared campus model promotes intergenerational inclusivity and active learning and living. In this paper, we explore stakeholder experts' perceptions of current opportunities and impediments to this proposed intergenerational learning and living model. METHODS: A qualitative study reporting on findings from an industry seminar (n = 50) and key interviews (n = 10) from stakeholders in education, health, higher education, the management and operation of retirement villages, and design firms. RESULTS: Three key themes summarised participants' assessment of the value, risks and what needs to change in order for intergenerational living and learning to become a reality. CONCLUSIONS: By bringing younger and older generations together in one shared campus location, GrandSchools is a novel idea to promote intergenerational inclusivity, enhancing the health and well-being of our whole community.

Acute effect of traditional and adaptive metronomes on gait variability in older individuals with a history of falls.

BACKGROUND: Metronome cueing has been shown to reduce gait variability and thereby potentially reduce falls risk in individuals with Parkinson's disease. It is unclear however, if metronome cueing has a similar effect in healthy older adults with a history of falls. AIM: To investigate whether a traditional and/or an adaptive metronome, based on an individual's gait pattern, were effective in reducing gait variability in older adults with a history of falls. METHODS: Twenty older adults (15 women, 71 ± 4.9 years) with a history of falls were included in this cross-over study. Participants received two types of cueing (adaptive and traditional metronome) 1 week apart. The variability of the participants' stride time, stride length, walking speed and duration of double leg support were recorded during three walking conditions (baseline, during feedback and post-feedback gait). Repeated-measures ANOVA was used to assess the possible effects of the two cueing strategies on gait variables. RESULTS: Compared with the baseline condition, participants had significantly increased stride time variability during feedback (F (2) = 9.83, p < 0.001) and decreased double leg support time variability post-feedback (F (2) 3.69, p = 0.034). Increased stride time variability was observed with the adaptive metronome in comparison to the traditional metronome. CONCLUSION: Metronome cueing strategies may reduce double leg support variability in older adults with a history of falls but seem to increase stride time variability. Further studies are needed to investigate if metronome cueing is more beneficial for individuals with greater baseline gait variability than those included in the current study.

The effects of fatiguing exercise and load carriage on the perception and initiation of movement.

Perceptual-motor coordination relies on the accurate coupling of the perceptual and movement systems. However, individuals must also be able to recalibrate to perturbations to perceptual and movement capabilities. We examined the effects of fatigue and load carriage on perceptual-motor coordination for a maximal leaping task. 23 participants completed an incremental fatigue protocol (light to fatiguing intensity stages) on two separate occasions (loaded/unloaded). At baseline and the end of every stage of the protocol, participants made perceptual judgments for the affordance of leaping. The accuracy of responses and reaction times were calculated and mean differences were assessed across exercise intensity and load carriage conditions. No interaction of exercise intensity and load carriage was detected, or main effect of load carriage. A main, quadratic effect of exercise intensity was detected on reaction times, with times decreasing through the moderate stage and increasing through post-fatigue. No effect of exercise/fatigue was detected on perceptual accuracy. The results indicate that exercise at high intensities through fatigue has a significant effect on perceptual-motor calibration. Contrastingly, in response to an action-scaled task, individuals can adequately recalibrate to increased load carriage.

Conceptualizing the Human Health Outcomes of Acting in Natural Environments: An Ecological Perspective.

Human-nature interactions have been presented as important for promoting and sustaining wellbeing and health benefits. Research has shown that pictures of nature, interacting with nature, physical activity in nature, immersion in nature and even feeling connected to nature can improve health. While considerable research supports this notion that nature can have positive health impact, theoretical and conceptual frameworks that help explain how the natural environment provides benefits to human health and wellbeing have proved limited. In extreme cases, theoretical approaches reinforce a problematic notion where nature is viewed as a separate entity, as a treatment to be taken as prescribed to remediate health problems that arise. Such approaches are limited as they fail to address how beneficial person-nature relations may be captured in interventions. There is a need for a deeper understanding of the processes underlying the observed benefits of the person-nature link in order to design effective research and interventions. It is especially important to consider the implications of research on person-nature relations for people living in urban contexts. In this paper, we present an ecological perspective building on James Gibson's conceptualization of human behavior. Specifically, we outline a framework that emphasizes the person-environment system as the most appropriate scale of analysis. We present three relevant concepts from the ecological approach: form of life, affordances and niche construction, as helpful for appreciating how acting in natural environments might benefit human health and wellbeing. This approach urges policy makers and urban designers to rethink environmental designs to provide and support a landscape of affordances that makes use of the richness of natural environments.

Constraints on visual exploration of youth football players during 11v11 match-play: The influence of playing role, pitch position and phase of play.

Visual exploratory action, in which football players turn their head to perceive their environment, improves prospective performance with the ball during match-play. This scanning action, however, is relevant for players throughout the entire match, as the information perceived through visual exploration is needed to guide movement around the pitch during both offensive and defensive play. This study aimed to understand how a player's on-pitch position, playing role and phase of play influenced the visual exploratory head movements of players during 11v11 match-play. Twenty-two competitive-elite youth footballers (M = 16.25 years) played a total of 1,623 minutes (M = 73.8). Inertial measurement units, global positioning system units and notational analysis were used to quantify relevant variables. Analyses revealed that players explored more extensively when they were in possession of the ball, and less extensively during transition phases, as compared to team ball-possession and opposition ball-possession phases of play. Players explored most extensively when in the back third of the pitch, and least when they were in the middle third of the pitch. Playing role, pitch position and phase of play should be considered as constraints on visual exploratory actions when developing training situations aimed at improving the scanning actions of players.

Learner-adapted practice promotes skill transfer in unskilled adults learning the basketball set shot.

The current study used a complex, sport-specific movement skill to explore the effects of a win-shift/lose-stay practice schedule on learning and compared its effectiveness with that of blocked and random practice schedules. Thirty-six adults (24.9 ± 3.3 years) were assigned to blocked, random and learner-adapted training groups. Each participant performed 360 trials of the basketball set shot from multiple locations across six practice sessions. For the learner-adapted group, switching between task variations was performance-contingent; switching between shooting locations occurred only following a successful shot. Shooting success was calculated as the percentage of successful shots performed, and measured during pre-acquisition (i.e. baseline), acquisition (i.e. practice) and post-acquisition (i.e. retention and transfer). Despite scoring less shots throughout practice compared to baseline testing, the learner-adapted group showed a significant improvement for shooting success in transfer (d = 1.02). Blocked practice demonstrated significant improvements for shooting success in immediate retention (d = 1.83), delayed retention (d = 1.69) and transfer (d = 1.39). Random practice significantly improved shooting success in both immediate (d = 1.03) and delayed retention (d = 0.81). The current findings highlight that performance during practice does not necessarily represent the permanency and adaptability of skill learning. The implications of the findings and their practical applications are discussed in the context of practice scheduling during learning of a sports skill.

Increased Risk of Musculoskeletal Injury Following Sport-Related Concussion: A Perception-Action Coupling Approach.

Recent studies have concluded that athletes have increased risk of musculoskeletal injury following sport-related concussion. While an underlying explanation is still unknown, perceptual-motor control may be implicated in this increased risk. Some authors have purported that indirect perception (i.e., a "top-down" view of neuromuscular control) may be disrupted following sport-related concussion. Direct perception theory states that the athlete and environment are inextricably linked in a continuous perception-action coupling loop. That is, the athlete is able to directly perceive opportunities for action (e.g., "affordances") in the environment. Based on these notions, the aim of the current paper was to introduce a theoretical model that argues that sport-related concussion may dysregulate the direct perception process, potentially increasing behavioral risk of musculoskeletal injury during sport. Our model is integrated with a sport-related concussion clinical treatment model, which highlights individualized profiles that characterize the heterogeneous response to sport-related concussion. These profiles have a typical constellation of symptoms (e.g., anxiety, fatigue, ocular dysfunction, etc.), which themselves have been associated with disrupted perception-action coupling, independent of sport-related concussion. Therefore, we argue that athletes who have not re-established perception-action coupling loops following sport-related concussion may be at increased risk of subsequent musculoskeletal injury.

Action Boundary Proximity Effects on Perceptual-Motor Judgments.

INTRODUCTION: Designed as a more ecological measure of reaction times, the Perception-Action Coupling Task (PACT) has shown good reliability and within-subject stability. However, a lengthy testing period was required. Perceptual-motor judgments are known to be affected by proximity of the stimulus to the action boundary. The current study sought to determine the effects of action boundary proximity on PACT performance, and whether redundant levels of stimuli, eliciting similar responses, can be eliminated to shorten the PACT.METHODS: There were 9 men and 7 women who completed 4 testing sessions, consisting of 3 familiarization cycles and 6 testing cycles of the PACT. For the PACT, subjects made judgments on whether a series of balls presented on a tablet afford "posting" (can fit) through a series of apertures. There were 8 ratios of ball to aperture size (B-AR) presented, ranging from 0.2 to 1.8, with each ratio appearing 12 times (12 trials) per cycle. Reaction times and judgment accuracy were calculated, and averaged across all B-ARs. Ratios and individual trials within each B-AR were systematically eliminated. Variables were re-averaged, and intraclass correlation coefficients (ICC) and coefficients of variation (CVTE) were calculated in an iterative manner.RESULTS: With elimination of the 0.2 and 1.8 B-ARs, the PACT showed good reliability (ICC = 0.81-0.99) and consistent within-subject stability (CVTE = 2.2-14.7%). Reliability (ICC = 0.81-0.97) and stability (CVTE = 2.6-15.6%) were unaffected with elimination of up to 8 trials from each B-AR.DISCUSSION: The shortened PACT resulted in an almost 50% reduction in total familiarization/testing time required, significantly increasing usability.Johnson CD, LaGoy AD, Pepping G-J, Eagle SR, Beethe AZ, Bower JL, Alfano CA, Simpson RJ, Connaboy C. Action boundary proximity effects on perceptual-motor judgments. Aerosp Med Hum Perform. 2019; 90(12):1000-1008.

Principles of the Guidance of Exploration for Orientation and Specification of Action.

To control movement of any type, the neural system requires perceptual information to distinguish what actions are possible in any given environment. The behavior aimed at collecting this information, termed "exploration", is vital for successful movement control. Currently, the main function of exploration is understood in the context of specifying the requirements of the task at hand. To accommodate for agency and action-selection, we propose that this understanding needs to be supplemented with a function of exploration that logically precedes the specification of action requirements with the purpose of discovery of possibilities for action-action orientation. This study aimed to provide evidence for the delineation of exploration for action orientation and exploration for action specification using the principles from "General Tau Theory." Sixteen male participants volunteered and performed a laboratory-based exploration task. The visual scenes of different task-specific situations were projected on five monitors surrounding the participant. At a predetermined time, the participant received a simulated ball and was asked to respond by indicating where they would next play the ball. Head movements were recorded using inertial sensors as a measure of exploratory activity. It was shown that movement guidance characteristics varied between different head turns as participants moved from exploration for orientation to exploration for action specification. The first head turn in the trial, used for action-orientation, showed later peaks in the velocity profile and harder closure of the movement gap (gap between the start and end of the head-movement) in comparison to the later head turns. However, no differences were found between the first and the final head turn, which we hypothesized are used mainly for action orientation and specification respectively. These results are in support of differences in the function and control of head movement for discovery of opportunities for action (orientation) vs. head movement for specification of task requirements. Both are important for natural movement, yet in experimental settings,orientation is often neglected. Including both orientation and action specification in an experimental design should maximize generalizability of an experiment to natural behavior. Future studies are required to study the neural bases of movement guidance in order to better understand exploration in anticipation of movement.

Using Microtechnology to Quantify Torso Angle During Match-Play in Field Hockey.

Warman, GE, Cole, MH, Johnston, RD, Chalkley, D, and Pepping, GJ. Using microtechnology to quantify torso angle during match-play in field hockey. J Strength Cond Res 33(10): 2648-2654, 2019-Field hockey is played in a dynamic environment placing specific postural demands on athletes. Little research has been devoted to understanding the nature of a player's torso postures in field hockey match-play and its relationship with the perceptuomotor demands of the sport. We used commercially available microtechnology worn by 16 athletes during a 6-match national tournament to quantify torso flexion/extension angles. Orientation was derived using the inertial and magnetic sensors housed within global positioning system devices, assessing torso angle in the sagittal plane from 91 individual match files. The main independent variable was playing position, whereas the dependent variable was torso flexion/extension, presented as a percentage of playing time spent in 15 × 10° torso postural bands ranging from ≥40° extension to ≥90° flexion. It was shown that athletes spent 89.26% of their playing time in various torso postures, ranging from 20 to 90° of flexion. Defenders spent more time than midfielders (p = 0.004, effect size [ES] = 0.43) and strikers (p = 0.004; ES = 0.44) in the posture band of 10-20° torso flexion, whereas midfielders spent more time between 20 and 30° of torso flexion (p = 0.05; ES = 0.32) than strikers. Conversely, strikers spent more time between 30 and 40° of flexion than defenders (p < 0.001; ES = 0.74). These results reflect the sport-specific and role-specific torso angles adopted by field hockey athletes during match-play. Coaching staff can use these data to gain insight into the postural demands of their sport and inform the preparation of athletes for the perception-action demands of competition.

Influence of age and falls incidence on tau guidance of centre of pressure movement during gait initiation.

BACKGROUND: Prospective balance control can be assessed in terms of the characteristics of a tau-guidance function that summarizes the velocity profile of Centre of Pressure (CoP) movement during gait initiation. This allows the nature of CoP movement to be assessed on a continuum between controlled 'soft'- and unstable 'hard' CoP-motion gap-closure. Previous research has shown less stable movement patterns with harder closures with increasing age, which makes movements more prone to overshooting and could possibly explain the increasing falls risk with age. RESEARCH QUESTIONS: The primary research question was 'what is the relationship between falls incidence and tau-guidance in the mediolateral centre of pressure movements during gait initiation?' The secondary research question was 'what are the influences of age and task demands on the variability of tau-guidance characteristics?'. METHODS: Sixteen young adults and 76 older adults performed 33 gait initiations from a force platform, stepping onto stepping-targets imposing differing task demands. Older participants completed a one-year follow-up screening for falls. An analysis was performed investigating linear relationships between a tau-guidance function and the time-to-closure (tau) of the mediolateral centre of pressure motion-gap with coupling constant K (dependent variable). RESULTS: Gait-related falls during the 12-month follow-up period were associated with higher tau-K values. Furthermore, longer movement preparation time was associated with lower K values, particularly in fallers. Previously-reported age-related increases of the tau-coupling constant values which were found in studies of unconstrained gait initiation were not present in our results. SIGNIFICANCE: The presence of the targeting task provided a more prescriptive environment compared to unconstrained gait initiation and could explain the absence of age-related changes to the produced K values. Falls incidence was found to be associated with higher values of K, indicating less stable movement. Future studies should investigate the practical implications of these findings for falls prevention.

Intersession Reliability and Within-Session Stability of a Novel Perception-Action Coupling Task.

BACKGROUND: The perception-action coupling task (PACT) was designed as a more ecologically valid measure of alertness/reaction times compared to currently used measures by aerospace researchers. The purpose of this study was to assess the reliability, within-subject variability, and systematic bias associated with the PACT.METHODS: There were 16 subjects (men/women = 9 / 7; age = 27.8 ± 3.6 yr) who completed 4 identical testing sessions. The PACT requires subjects to make judgements on whether a virtual ball could fit into an aperture. For each session, subjects completed nine cycles of the PACT, with each cycle lasting 5 min. Judgement accuracy and reaction time parameters were calculated for each cycle. Systematic bias was assessed with repeated-measures ANOVA, reliability with intraclass correlation coefficients (ICC), and within-subject variability with coefficients of variation (CVTE).RESULTS: Initiation time (Mean = 0.1065 s) showed the largest systematic bias, requiring the elimination of three cycles to reduce bias, with all other variables requiring, at the most, one. All variables showed acceptable reliability (ICC > 0.70) and within-subject variability (CVTE < 20%) with only one cycle after elimination of the first three cycles.CONCLUSIONS: With a three-cycle familiarization period, the PACT was found to be reliable and stable.Connaboy C, Johnson CD, LaGoy AD, Pepping G-J, Simpson RJ, Deng Z, Ma L, Bower JL, Eagle SR, Flanagan SD, Alfano CA. Intersession reliability and within-session stability of a novel perception-action coupling task. Aerosp Med Hum Perform. 2019; 90(2):77-83.

Associations Between Gait-Related Falls and Gait Adaptations When Stepping Onto a Curb: A Prospective Falls Study.

Objectives: To examine gait regulation during the approach to stepping onto a curb for older adults who did or did not report gait-related falls over a 12-month follow-up. Methods: A total of 98 participants aged 60 years and older were analyzed. Primary outcomes were step length adaptations (lengthening or shortening) during a curb approach and the occurrence of a gait-related fall during a 12-month follow-up. Results: Linear mixed-effects modeling indicated stronger adaptations toward the end of the approach. Participants who reported experiencing a gait-related fall showed a stronger relationship between the adjustment required and adjustment produced, indicating different gait adaptations during the step leading onto the curb. Discussion: The link between prospective gait-related falls and gait adaptations indicated that older adults with reduced capabilities require stronger adaptations to complete tasks reminiscent of everyday life. This finding may provide insight into the mechanisms of falls in older adults and should inform new fall prevention interventions.

Regulation of locomotor pointing across the lifespan: Investigating age-related influences on perceptual-motor coupling.

INTRODUCTION: The regulation of one's step length by placing one's foot at a specific position within gait, otherwise known as 'locomotor pointing', is well understood in walking and running gait. The current study was the first to broaden this understanding to a larger cohort and to describe the influence of age on the regulation of locomotor pointing when walking up to and stepping onto a curb-like platform. METHODS: Younger (n = 17, mean age: 25.35 years, range: 19-33) and older adults (n = 105, mean age: 71.49 years, range: 61-86) participated in a walking experiment, requiring them to approach and step onto a curb-like platform. Linear mixed effects modeling was used to study the main outcome variables: onset of regulation, the regulation strategy and the strength of perceptual-motor coupling. RESULTS: Results showed that with older age, participants showed less variability in foot placement during their approach and seemed to prefer to shorten their steps. Furthermore, the strength of the perceptual-motor relationship was found to be related to age; regulation of step length of both younger and older participants was based on a participant's current foot position. The strength of this relationship increased as participants got closer to the curb and was stronger with increasing age. Furthermore, younger adults on average lengthened their steps as they got closer to the curb, whereas older adults showed significantly less lengthening compared to their younger counterparts. No age-related differences were found in terms of onset of regulation. DISCUSSION: The results suggest that the strength of the perceptual-motor relationship in gait is related to age. It is argued that this age-related increase in the strength of perceptual-motor coupling is required to cope with increasing demands linked to the age-related declines of action capabilities. The implications of the findings are discussed in the context of increased falls risks and deficits in perceptual-motor functioning.

Don't Turn Blind! The Relationship Between Exploration Before Ball Possession and On-Ball Performance in Association Football.

Visual exploratory action - scanning movements expressed through left and right rotation of the head - allows perception of a surrounding environment and supports prospective actions. In the dynamically changing football environment, the extent to which exploratory action benefits a player's subsequent performance with the ball is likely influenced by how and when the exploratory action occurs. Although few studies have examined the relationship between visual exploration and on-pitch football performance, it has been reported that a higher frequency of exploratory head movement up to 10-s before receiving the ball increases the likelihood of successful performance with the ball. This study investigated the relationship between head turn frequency and head turn excursion, and how and when exploratory head movement - within 10-s before ball possession - is related to performance with the ball in 11v11 match-play. Thirty-two semi-elite football players competed in 11v11 match-play. Head turn frequency and head turn excursion before ball possession were quantified with wearable inertial measurement units, and actions with the ball were coded via notational analysis. Odds ratio calculations were conducted to determine the associations between exploration variables and on-ball performance outcomes. A total of 783 actions with the ball were analyzed. Results revealed a strong relationship between head turn frequency and head turn excursion. Further, a higher than average head turn frequency and head turn excursion before receiving the ball resulted in a higher likelihood of turning with the ball, playing a pass in the attacking direction, and playing a pass to an area that is opposite to which it was received from. The strength of these outcomes varied for different time periods before receiving the ball. When players explored their environment with higher than average head turn frequency and excursion, they used more complex action opportunities afforded by the surrounding environment. Considerations for future research and practical implications are discussed.

Children's perception of action boundaries and how it affects their climbing behavior.

There are some concerns that children today may be less calibrated to their action capabilities because of the "risk-free" culture that has proliferated during recent decades. This study investigated the extent to which judgments of reaching affordances presented in different directions (i.e., overhead, diagonal, and horizontal) are related to children's climbing behavior on a climbing wall. A sample of 30 schoolchildren from 6 to 11years old (20 boys and 10 girls) estimated maximum reach and grasp distances and subsequently attempted to climb across an indoor climbing wall. Children who perceived the extents of their reach more accurately completed the climb more often and more quickly. Judgments in the primary directions of climbing locomotion (horizontal and diagonal) were better predictors of success than vertical judgments. Judgments about whether objects are reachable and graspable are complex and influenced by various dynamic factors (including perceptual-motor calibration), and as such different levels of accuracy are likely in different reaching directions. It appears that young children are relatively sensitive to their action boundaries for climbing and, therefore, may be able to make informed decisions themselves about whether a surface is climbable.

Perceptual-motor regulation in locomotor pointing while approaching a curb.

Locomotor pointing is a task that has been the focus of research in the context of sport (e.g. long jumping and cricket) as well as normal walking. Collectively, these studies have produced a broad understanding of locomotor pointing, but generalizability has been limited to laboratory type tasks and/or tasks with high spatial demands. The current study aimed to generalize previous findings in locomotor pointing to the common daily task of approaching and stepping on to a curb. Sixteen people completed 33 repetitions of a task that required them to walk up to and step onto a curb. Information about their foot placement was collected using a combination of measures derived from a pressure-sensitive walkway and video data. Variables related to perceptual-motor regulation were analyzed on an inter-trial, intra-step and inter-step level. Similar to previous studies, analysis of the foot placements showed that, variability in foot placement decreased as the participants drew closer to the curb. Regulation seemed to be initiated earlier in this study compared to previous studies, as shown by a decreasing variability in foot placement as early as eight steps before reaching the curb. Furthermore, it was shown that when walking up to the curb, most people regulated their walk in a way so as to achieve minimal variability in the foot placement on top of the curb, rather than a placement in front of the curb. Combined, these results showed a strong perceptual-motor coupling in the task of approaching and stepping up a curb, rendering this task a suitable test for perceptual-motor regulation in walking.