Investigation of motor unit behavior in exercise and sports physiology: challenges and perspectives

Several methods are in use to record and analyze neuronal activation, each with specific advantages and challenges. New developments like the decomposition of high-density surface electromyography (HDsEMG) have enabled novel insights into discharge characteristics noninvasively in laboratory settings but face certain challenges to be applied in sports physiology in a broader scope. Several challenges can be accounted for by methodological considerations, others require further technological developments to allow this technology to be used in more applied settings. This paper aims to describe the developments of surface electromyography and identify the challenges and perspectives of HDsEMG in the context of an application in sports physiology. We further discuss methodological possibilities to overcome some of the challenges to investigate specific research questions and identify areas that require further advancements.

The fear of spiders: perceptual features assessed in augmented reality

Background

Persons with specific phobias typically generalize the dangerousness of the phobic animal to all members of its species, possibly as a result of malfunctioning brain circuitry normally providing quick and dirty identification of evolutionary-relevant stimuli. An objective assessment of which perceptual features make an animal more or less scary to phobic and non-phobic people would help overcome the limitations of the few studies available so far, based on self-reports.

Objective

To achieve this aim, we built an augmented reality setting where volunteers with different levels of fear of spiders were asked to make holographic spiders that look either dangerous or harmless. To reach this goal, a computerized interface allowed participants to modify the spider's perceptual features (hairiness, body/leg size, and locomotion) in real time.

Results

On average, the dangerous spiders were made hairy, thick, and moving according to spider-like locomotion; coherently, the harmless spiders were made hairless, slim, and moving according to a butterfly-like locomotion. However, these averaged preferences could not fully describe the complex relationship between perceptual preferences with each other and with arachnophobia symptoms. An example of a key finding revealed by cluster analysis is the similarity in perceptual preferences among participants with little or no fear of spiders, whereas participants with more arachnophobia symptoms expressed more varying preferences.

Conclusion

Perceptual preferences toward the spider's features were behaviorally assessed through an observational study, objectively confirming a generalization effect characterizing spider-fearful participants. These results advance our knowledge of phobic preferences and could be used to improve the acceptability of exposure therapies.

A Comparison of Leg Muscle Oxygenation, Cardiorespiratory Responses, and Blood Lactate between Walking and Running at the Same Speed

It is not known whether different gait modes, or movement patterns, at the same speed elicit differences in muscle oxygen oxygenation, expressed as muscle oxygen saturation (SmO2). Thus, the aim of this study was to compare the oxygenation of two leg muscles (vastus lateralis and gastrocnemius medialis), as well as the heart rate, respiratory gases, and blood lactate between two gait modes (walking and running) of the same speed and duration. Ten men walked and ran for 30 min each at 7 km/h in a random, counterbalanced order. SmO2, heart rate, and respiratory gases were monitored continuously. Blood lactate was measured at rest, at the end of each exercise, and after 15 min of recovery. Data were analyzed by two-way (gait mode × time) or three-way (gait mode × muscle × time) ANOVA, as applicable. Heart rate and oxygen consumption were higher when running compared to walking. SmO2 was lower during exercise compared to rest and recovery, in gastrocnemius medialis compared to vastus lateralis, and in running compared to walking. Blood lactate increased during exercise but did not differ between gait modes. In conclusion, running caused higher deoxygenation in leg muscles (accompanied by higher whole-body oxygen uptake and heart rate) than walking at the same speed (one that was comfortable for both gait modes), thus pointing to a higher internal load despite equal external load. Thus, preferring running over walking at the same speed causes higher local muscle deoxygenation, which may be beneficial in inducing favorable training adaptations.

Decision-Making Time and Neuromuscular Coordination in Youth and Senior Soccer Goalkeepers

The aim of this study was to compare soccer goalkeepers' decision-making times following a shot on goal and to determine goalkeepers' movement pattern structures using EMG in a typical game situation (two-on-one). Two groups of goalkeepers (n = 60) took part in the study: Group A, the senior group (22.00 ± 2.35 years of age), and Group B, the youth group (15.38 ± 1.32 years of age). The goalkeepers' decision-making times were measured by using EMG from the moment the attacker struck the ball until the completion of the saving action by the goalkeeper. Subsequently, the goalkeepers' movement pattern structure was determined (for both Groups A and B), and the values of muscle bioelectrical tension during a typical defensive situation in training conditions were revealed. The findings clearly indicate a significantly (p = 0.001) shorter decision-making time in experienced goalkeepers (250-260 ms) than in novices (300-320 ms). In addition, the movement pattern structure confirmed the hypotheses on the economization of effort and the visual-muscular coordination of the postural muscles (calf muscles) that affect soccer goalkeepers. The study also demonstrated a lower bioelectric tension of the gastrocnemius muscle (GAS.MED. RT-p = 0.008; GAS.LAT. RT-p = 0.030) in the expert goalkeepers.

Focus of Attention in Coach Instructions for Technique Training in Sports: A Scrutinized Review of Review Studies

Literature reports superior performance when focusing one's attention during a movement on environmental effects of that movement (external focus, EF) compared to focusing on the moving body (internal focus, IF). Nevertheless, IF instructions still play an important role in the daily practice of coaches, trainers, and therapists. The current review compiles evidence for focus-of-attention concepts on movement form corrections and technique training. Reviews on the topic and selected additional papers addressing the effect of attentional focus on movement form or on kinetic, kinematic or muscle activity data were included. Both EF and IF instructions affect movement form. The reviews revealed that IF instructions seem to be better applicable to direct movement form changes than EF instructions. In contrast, EF instructions better facilitate optimization within the whole-body coordination, often resulting in better performance outcomes not directly linked to movement pattern changes. Several studies discuss focus-of-attention effects in the context of the optimal feedback control theory expanding on the constrained action hypothesis. In summary, EF and IF instructions both affect form and performance of movements, however, their relative efficacy is situation dependent. The often-purported superiority of EF over IF instructions cannot be generalized to all application contexts.

No Influence of Mechatronic Poles on the Movement Pattern of Professional Nordic Walkers

This study compared selected temporal and kinematic parameters of normal gait and Nordic Walking (NW) performed with classic and mechatronic poles (classic poles equipped with sensors). It was assumed that equipping NW poles with sensors for biomechanical gait analysis would not impair the NW walking technique. Six professional NW instructors and athletes, including three women, participated in the study. The MyoMotion MR3 motion analysis system was used to collect gait kinematic variables. The subject's task was to cover a 100-m distance with three types of gait: a gait without poles, a gait with classic NW poles, and a gait with mechatronic poles at the preferred speed. Parameters were measured both on the right and left sides of the body. No significant differences were found between gait types for three temporal parameters: step cadence, step, and stride time. For the other variables, all the differences identified were between free-walking and walking with poles, with no differences between standard and mechatronic poles. For nine kinematic parameters, differences between free-walking and walking with poles for both the left and right sides were found, while no differences were due to the pole type. All temporal parameters were characterized by symmetry, while among kinematic parameters, only two were asymmetrical (shoulder abduction-adduction in walking with regular poles and elbow flexion-extension in walking without poles). Equipping classic NW poles with additional signaling and measuring devices (mechatronic poles) does not impair the NW technique, making it possible to use them in further studies of gait biomechanics.

Does the Wolf (Canis lupus) Exhibit Human Habituation Behaviours after Rehabilitation and Release into the Wild? A Case Report from Central Italy

The knowledge of how wolves’ movement patterns and habitat selection are affected by habituation to persons after a period of veterinary isolation, treatment and non-agonistic experience with humans is scarce. Unnatural behaviours could be transferred by imitation to members of the pack and to subsequent generations, increasing direct interaction risks. We used GPS data from a rescued radio-collared female wolf after an 11-day rehabilitation to estimate home range, movement patterns, circadian rhythms, and habitat selection, searching for signals of eventual behavioural distortions. In the period 1 August−26 November 2013, 870 valid locations were acquired. The wolf moved within a minimum convex polygon (95%) of 6541.1 ha (79% wooded), avoiding anthropized areas. Nocturnal and diurnal displacements were significantly different (p < 0.01). Nocturnal displacements were 4409.4 ± 617.5 m during summer and 3684.8 ± 468.1 m during autumn, without differences between seasons. Diurnal movements were significantly higher (p < 0.01) in the summer (2239.0 ± 329.0 m) than in the autumn (595.9 ± 110.3 m), when the hunting season was running. As for a wild wolf, clear complementarity concerning human activities was recorded and no habituation signals were detected, but this is only a first case study that aims to be a stimulus for further research and a call for widespread data sharing.

The kinectome: A comprehensive kinematic map of human motion in health and disease

Human voluntary movement stems from the coordinated activations in space and time of many musculoskeletal segments. However, the current methodological approaches to study human movement are still limited to the evaluation of the synergies among a few body elements. Network science can be a useful approach to describe movement as a whole and to extract features that are relevant to understanding both its complex physiology and the pathophysiology of movement disorders. Here, we propose to represent human movement as a network (that we named the kinectome), where nodes represent body points, and edges are defined as the correlations of the accelerations between each pair of them. We applied this framework to healthy individuals and patients with Parkinson's disease, observing that the patients' kinectomes display less symmetrical patterns as compared to healthy controls. Furthermore, we used the kinectomes to successfully identify both healthy and diseased subjects using short gait recordings. Finally, we highlighted topological features that predict the individual clinical impairment in patients. Our results define a novel approach to study human movement. While deceptively simple, this approach is well-grounded, and represents a powerful tool that may be applied to a wide spectrum of frameworks.

Hip and knee joint angle patterns and kicking velocity in female and male professional soccer players: A principal component analysis of waveforms approach

This study used principal component analysis (PCA) of waveforms to extract movement patterns from hip and knee angle time-series data; and determined if the extracted movement patterns were predictors of ball velocity during a soccer kick. Twenty-three female and nineteen male professional soccer players performed maximal effort instep kicks while motion capture and post-impact ball velocities data were recorded. Three-dimensional hip and knee joint angle time-series data were calculated from the beginning of the kicking leg's backswing phase until the end of the follow-through phase and entered into separate PCAs for females and males. Three principal components (PC) (i.e., movement patterns) were extracted and PC scores were calculated. Pearson correlation coefficients were calculated to establish correlations between hip and knee PC scores and kicking velocity. Results showed better kicking performance in male players was associated with a greater difference between the hip extension at the end of the backswing/beginning of the leg cocking phases and hip flexion at the end of the follow-through phase (r = -0.519, p = 0.023) and a delayed internal rotation of the hip (r = 0.475, p = 0.040). No significant correlations between ball velocity and hip and knee kinematics were found for female players.

Similarity in Temporal Movement Patterns in Laying Hens Increases with Time and Social Association

We explored the relationship between social associations and individual activity patterns in domestic hens. Out of 1420 laying hens, 421 hens were equipped with RFID tags attached to RFID-specific leg bands (leg bands from Company Roxan, Selkirk, Scotland) to continuously track their change in location across four different areas (one indoor and three outdoor areas). Using a combination of social network analysis for quantifying social relationships and dynamic time warping for characterizing the movement patterns of hens, we found that hens were consistent in their individual variation in temporal activity and maintained stable social relationships in terms of preferred association partners. In addition to being consistent, social associations correlated with movement patterns and this correlation strengthened over the period of observation, suggesting that the animals aligned their activity patterns with those of their social affiliates. These results demonstrate the importance of social relationships when considering the expression of individual behaviour. Notably, differences in temporal patterns emerge despite rather homogeneous rearing conditions, same environment, and low genetic diversity. Thus, while variation in behavioural phenotypes can be observed across isolated individuals, this study shows that the social environment within a group can shape and enhance variation in general movement patterns of individual animals.

A Comparative Study of Two-Minute versus Three-Minute Passive Recovery on Sprint Skating Performance of Ice Hockey Forwards and Defensemen

The impact of two different passive recovery durations, two and three minutes, between sets of repeated sprint skating ability (RSSA) test on skating speed, speed decrement (S_dec), and heart rate (HR) response of ice hockey forwards (n = 12) and defensemen (n = 7) were determined. Six sets of 3 × 80 m sprint, with two-minute passive recovery between two consecutive sets, were performed in RSSA-2. A three-minute passive recovery period between two consecutive sets was allowed in RSSA-3. Skating speed, S_dec, and HR were measured in all tests. Subjects skated faster (p < 0.05) in most of the RSSA-3 sets than the corresponding set of RSSA-2. Defensemen were slower (p < 0.05) than forwards in most of the cases. The S_dec was higher in defensemen than in forwards, although the difference was significant occasionally. No difference in peak HR and minimum HR between forwards and defensemen was found. RSSA-3 is beneficial over RSSA-2 in both forwards and defensemen by increasing speed. Defensemen are slower and show early fatigability than forwards, and no difference in HR response was noted between forwards and defensemen. This study concludes that three-minute recovery is beneficial over two-minute recovery by increasing skating speed, although S_dec and HR response neither vary significantly between RSSA-2 and RSSA-3, nor between forwards and defensemen.

A Three-Dimensional Finite Element Analysis: Maxillary Dentition Distalization with the Aid of Microimplant in Lingual Orthodontics

Aim

To analyze the movement of anterior teeth by changing the height of the power-arm and changing the force application points during whole maxillary dentition distalization with the aid of micro-implants in lingual orthodontics to set a biomechanical reference for effective clinical use of lingual orthodontic appliance.

Methods

A three-dimensional finite element model of the maxillary teeth with lingual appliance and the associated support tissue was established. Maxillary dentition with the force of 200g was distalized using implant as anchorage, then the movement of anterior teeth was analyzed by changing the length of power-arm (1mm, 3mm, 6mm, 9mm) and by changing the force location from lingual side to buccal side.

Results

During whole maxillary dentition distalization with aid of the implants in lingual orthodontics: when the height of power arm was 1mm, the anterior teeth rotated clockwise, with the increasing of the height of power-arm, the anterior teeth rotated counterclockwise gradually. When the height of power-arm was 9mm, all anterior teeth rotated counterclockwise. Central incisor and lateral incisor rotated counterclockwise and canine rotated clockwise when the buccal side force was applied.

Conclusion

With the increase of the height of the power-arm, the movement pattern of the upper anterior teeth is different. The canine is more sensitive to the height of the power-arm than the central incisor and the lateral incisor. When the height of the power-arm reaches 9mm, the upper anterior teeth are displayed as crown tipping buccally movement. Compare with lingual side force, the buccal side force do better in preventing the loss of anterior tooth torque. If the upper anterior teeth are up-right or lingually tipped before treatment, it is preferable to use longer power-arm or buccal side traction force. If the anterior teeth are already tipped buccally, then short power-arm or lingual side force is advised.

Isolating the Unique and Generic Movement Characteristics of Highly Trained Runners

Human movement patterns were shown to be as unique to individuals as their fingerprints. However, some movement characteristics are more important than other characteristics for machine learning algorithms to distinguish between individuals. Here, we explored the idea that movement patterns contain unique characteristics that differentiate between individuals and generic characteristics that do not differentiate between individuals. Layer-wise relevance propagation was applied to an artificial neural network that was trained to recognize 20 male triathletes based on their respective movement patterns to derive characteristics of high/low importance for human recognition. The similarity between movement patterns that were defined exclusively through characteristics of high/low importance was then evaluated for all participants in a pairwise fashion. We found that movement patterns of triathletes overlapped minimally when they were defined by variables that were very important for a neural network to distinguish between individuals. The movement patterns overlapped substantially when defined through less important characteristics. We concluded that the unique movement characteristics of elite runners were predominantly sagittal plane movements of the spine and lower extremities during mid-stance and mid-swing, while the generic movement characteristics were sagittal plane movements of the spine during early and late stance.

Stride Pattern of the Lower Extremities Among Stride Types in Baseball Pitching

The present study investigated the differences in the stride pattern of the lower extremities among different stride types in baseball pitchers with the aim of evaluating stride movement and skills to improve training effectiveness. Thirty elite male college baseball pitchers volunteered to pitch on an indoor-mound-like force plate, where motion data of their fastest strike trials were collected using an eight-camera motion analysis system at a 200-250 Hz sampling rate. Pelvis center trajectories of each participant were calculated and further categorized into three groups: tall-and-fall (TF), dip-and-drive (DD), and mixed (MX) pitchers. Motion analysis revealed that DD pitchers initiated pivot-knee extension and pivot-hip adduction earlier than TF pitchers and accelerated their bodies sooner than TF pitchers. In addition, TF pitchers accelerated their bodies forward by pivoting their legs until the middle of the arm-cocking and acceleration phases. The movement patterns of MX pitchers were similar to those of DD pitchers in terms of pivot leg, although this occurred a little later in the stride. Our findings are useful in developing training strategies for coaches, players, and trainers to better meet the demands of different pitching styles.

Muscle Activity Asymmetry of The Lower Limbs During Sprinting in Elite Soccer Players

The analysis of movement patterns through EMG activity provides the opportunity to identify the muscle groups most involved in a particular exercise, and to determine the scope of inter-limb deficiencies. The aim of the present study was to investigate the effects of a side-to-side muscle activity asymmetry between the left and the right lower limb during sprinting in soccer players. Sixteen professional soccer players took part in the study. Their age, body mass and body height equaled 23.7 ± 7.6 years, 81.2 ± 10.8 kg and 179.3 ± 12.2 cm, respectively. The sprint test consisted of two maximal sprints over 30 m with a 5-min rest interval between each sprint. EMG was recorded bilaterally from the quadriceps, hamstrings and gluteal muscles. Regression analysis revealed a significant effect of a side-to-side average muscle activity asymmetry between the left and right hamstring (LH/RH) muscles during the speed tests at 5 m (p = 0.044), and 30 m (p = 0.045), as well as the left and right glutes (LG/RG) at 5 m (p = 0.044) and 30 m (p = 0.043). Our results indicate that hamstring and glute muscles should be selectively and additionally activated during resistance training in soccer players to prevent injuries and improve sprint performance.

Reproducibility of Internal and External Training Load During Recreational Small-Sided Football Games

Purpose: The aim of this study was to evaluate the reproducibility of internal and external load parameters during recreational small-sided football games. Methods: Ten healthy untrained young adult males (age: 20.2 ± 1.9 yr, body mass: 69.2 ± 6.3 kg, height: 175.4 ± 5.9 cm, body fat: 19.7 ± 5.2%) performed two 2 × 20-min sessions of four versus four plus goalkeeper small-sided games (SSG) 1 week apart on a standard, outdoor, 40 × 20-m artificial grass pitch. Twelve external (total distance, peak speed, player load, work rate and distance covered at 0-2, 2-5, 5-7, 7-9, 9-13, 13-16, 16-20 and >20 km/h) and seven internal load parameters (heart rate and time spent in different heart rate zones [<70%, 71-80%, 81-90%, 91-95%, 96-100%, 91-100%]) were measured. Reproducibility was reported as intraclass coefficient correlation (ICC), the coefficient of variation (CV), and the typical error of measurements (TE). Results: No statistical differences (p> .05) between sessions were found in any measures. Minimal test-retest variability was noted for mean and peak heart rate (HR_peak) relative to HR_peak with CV values of 3.4% and 2.6%, respectively. Acceptable variability (CV<10%) was demonstrated for total distance covered, distance covered at 2-5 km/h, and peak speed. Distance covered in different speed zones (CV = 15.7-47.6%) and percentage of time in each HR zone showed large-to-very large variability (CV = 36.2-128.4%). Mean heart rate (HR_mean), HR_peak, distance covered at 5-7, 13-16 and >20 km/h, and percentage of time above 95%HR_peak were the most reliable variables (ICC = 0.74-0.79), followed by total distance covered, peak speed, and percentage of time at 80-90% HR_peak (ICC = 0.39-0.67). The lowest reliability was observed for distance covered in the moderate speed zones 7-9 km/h (ICC = 0.12) and 9-13 km/h (ICC = -0.09), and percentage of time at 70-80% HR_peak (ICC = -0.01). Conclusions: Small-sided games can be used when planning training-induced exercise responses in relation to total distance covered, peak speed, and mean heart rate. This evidence further supports the use of SSG when organizing recreational football training, in young adult males, with the purpose of improving health profile due to the high reproducibility of HR_mean and total distance covered.

The Movement Profile of Habitual Vacuuming as a Cyclic Movement-A Pilot Study

Background: Vacuum cleaning, which is associated with musculoskeletal complaints, is frequently carried out in private households and by professional cleaners. The aim of this pilot study was to quantify the movements during habitual vacuuming and to characterize the movement profile with regard to its variability. Methods: The data were collected from 31 subjects (21 f/10 m) using a 3D motion analysis system (XSens). Eight vacuum cleaners were used to vacuum polyvinyl chloride (PVC) and carpet floors. In 15 joints of the right upper extremity, the trunk and the lower extremities, Principal Component Analysis was used to determine the predominantly varying joints during vacuuming. Results: The movements of the trunk and the lower extremities were relatively constant and, therefore, had less influence. The shoulder, elbow and wrist joints were identified as joints that can be decisive for the movement profile and that can be influenced. These joints were represented in the course of the vacuuming cycle by the mean movement with its standard deviation. Conclusion: In summary, the generalization of a movement profile is possible for the trunk and the lower extremities due to the relative homogeneity. In future it will be necessary to identify factors influencing variability in order to draw conclusions about movement ergonomics.

Statistical Parametric Mapping Reveals Subtle Gender Differences in Angular Movements in Table Tennis Topspin Backhand

Background: Statistical parametric mapping (SPM) is an innovative method based on the analysis of time series (data series) and is equivalent to statistical methods for numerical (discrete) data series. This study aimed to analyze the patterns of movement in the topspin backhand stroke in table tennis and to use SPM to compare these patterns between advanced female and male players. Methods: The research involved seven advanced male and six advanced female players. The kinematic parameters were measured using an inertial motion analysis system. The SPM was computed using the SPM1D Python package. Results: Our study made it possible to reproduce the pattern of movement in the joints during topspin backhand strokes in the studied athletes. During multiple comparisons, the analysis of variance (ANOVA) SPM test revealed many areas in the studied parameter series with statistically significant differences (p ≤ 0.01). Conclusions: The study presents the movement patterns in the topspin backhand shot and describes the proximal-to-distal sequencing principle during this shot. The SPM study revealed differences between men and women in the contribution of thoracic rotation, external shoulder rotation, dorsal flexion, and supination in the wrist during the hitting phase. These differences may result from the anatomical gender differences or variations in other functionalities of individual body segments between the study groups. Another possible source for these discrepancies may reside in tactical requirements, especially the need for a more vigorous attack in men. The gender differences presented in this study can help in the individualization of the training process in table tennis.

Rheoreaction impacts dispersal of fish larvae in restored rivers

Connectivity of nurseries and spawning habitats for young of the year life stage is essential for successful recruitment of fish populations and therefore provides a key indicator for river restoration measures. Models for dispersal offer the potential to draw conclusions regarding restoration scenarios and to fill knowledge gaps about possible implications for fish populations. A newly developed rheoreaction-based correlated random walk model (RCRW), in combination with a three-dimensional numerical model and a non-steady-state particle tracing model, was applied for nase carp larvae (Chondrostoma nasus) before and after a restoration project on the river Danube, Austria. Spatio-temporal patterns of dispersal of virtual larvae, attached with rheoreactive behaviour, were analysed within both scenarios. In comparison to the heavily modified river reach, the restored reach enabled a greater amount of upstream movement from the release site and showed a generally higher variability of spatio-temporal distribution patterns. In contrast, estimated total settlement of rheoreactive larvae was substantially higher for the situation prior to the restoration measure. By comparing model results with a previously field experiment it was found that model simulations including rheoreaction as a single behaviour for navigation could not explain the whole pattern of larval dispersal. Therefore it is highly recommended for future studies to develop larval dispersal models by considering other factors (i.e., behaviour, bio-energetics and environmental factors) of existing and future individual-based models, which could serve as a tool to analyse the effect of restoration measures for recruitment of riverine fish populations.

Relationship Between Lumbar Motor Control Ability and Spinal Curvature in Elderly Individuals

This study aimed to clarify the relationship between spine curvature and the movement pattern/motor control ability of the lumbar and hip joints during prone hip extension in elderly individuals. The participants were 14 elderly people who attended a community health class. We measured the motion angle, motion ratio (movement pattern), and motor control ability of the lumbar and hip joints during prone hip extension. In addition, the lumbar lordosis angle and thoracic kyphosis angle were measured in the standing position. There was no correlation between the spinal curvature in the standing position and the lumbar/hip joint movement pattern and motor control ability during prone hip extension. When evaluating the lumbar spine, it is necessary to perform a comprehensive evaluation by interpreting static evaluations such as spinal alignment or dynamic evaluations such as movement patterns and motor control abilities.

Effects of ankle dorsiflexion limitation on lower limb kinematic patterns during a forward step-down test: A reliability and comparative study

BACKGROUND

Altered lower limb movement patterns (LLMP) during the forward step down (FSD) test have been studied in people suffering from knee instability. However, ankle dorsiflexion range of motion (ADROM) seems to be related to LLMP but no causal inference has been defined between those variables.

OBJECTIVE

Our goals were to evaluate (1) psychometric quality of the FSD test in healthy people and (2) the influence of experimental restricted ADROM on LLMP.

METHODS

Kinematics were measured by a motion capture system. Angular displacement and speed were calculated as well as center of mass (COM) and knee linear displacement. Forty-two healthy participants; firstly, performed the test three times to assess reliability, and secondly the same test in an experimental condition limiting the ADROM.

RESULTS

Reliability was excellent for all parameters (ICC: 0.75-0.99, SEM%: 2.0-34.0%). ADROM limitation significantly decreased Knee flexion range of motion (ROM) (-3.8∘), increased Hip flexion ROM (6∘), Hip adduction ROM (6.1∘), Pelvis drop ROM (3.5∘), Pelvic rotation ROM (3.1∘). No significant effect was found for Hip rotation ROM.

CONCLUSIONS

LLMP was affected by this experimental ADROM limitation in healthy people. As this limitation is often encountered in post-traumatic ankle sprain patients, clinicians should consider this point during FSD assessment test.

Investigating Home Range, Movement Pattern, and Habitat Selection of Bar-headed Geese during Breeding Season at Qinghai Lake, China

The Bar-headed Goose is the only true goose species or Anserinae to migrate solely within the Central Asian Flyway, and thus, it is an ideal species for observing the effects of both land use and climate change throughout the flyway. In this paper, we investigate the home range, movement pattern, and habitat selection of Bar-headed Geese (Anser indicus) during the breeding season at Qinghai Lake, which is one of their largest breeding areas and a major migration staging area in the flyway. We identified several areas used by the geese during the breeding season along the shoreline of Qinghai Lake and found that most geese had more than one core use area and daily movements that provided insight into their breeding activity. We also observed the intensive use of specific wetlands and habitats near Qinghai Lake. These data provide interesting insights into the movement ecology of this important species and also provide critical information for managers seeking to understand and respond to conservation concerns threatening Bar-headed Geese, such as landscape and habitat changes.

Social network analysis for poultry HPAI transmission

In this survey study, the networks among poultry farms and related poultry enterprises in two counties in China (Feixi County in Anhui Province and Beizhen city in Liaoning Province) were analysed and evaluated focusing on the connectivity of contacts, movements, and potential pathogen transmission. The Feixi County poultry production network exhibited greater connectivity, which incorporated approximately 94% of the farms interviewed in a major component (a set of connected farms not linked with each other), mainly due to linkages of backyard farms through local produce stores and individual agents, whilst the Beizhen City network was more fragmented owing to independent in-house operations (from breed, raise, to slaughter and process) of a few large companies, with multiple smaller components. A range of factors influencing the contacts/movements among farms (act as bridges) were identified in this study. Ability to predict the pathway with the network characteristics on the basis of the factors, such as entity type and geographic location, is useful for developing risk-based approaches for disease prevention, surveillance, early detection, and effective controlling.

Agreement Between Visual Assessment and 2-Dimensional Analysis During Jump Landing Among Healthy Female Athletes

CONTEXT

  Altered movement patterns, including increased frontal-plane knee movement and decreased sagittal-plane hip and knee movement, have been associated with several knee disorders. Nevertheless, the ability of clinicians to visually detect such altered movement patterns during high-speed athletic tasks is relatively unknown.

OBJECTIVE

  To explore the association between visual assessment and 2-dimensional (2D) analysis of frontal-plane knee movement and sagittal-plane hip and knee movement during a jump-landing task among healthy female athletes.

DESIGN

  Cross-sectional study.

SETTING

  Gymnasiums of participating volleyball teams.

PATIENTS OR OTHER PARTICIPANTS

  A total of 39 healthy female volleyball players (age = 21.0 ± 5.2 years, height = 172.0 ± 8.6 cm, mass = 64.2 ± 7.2 kg) from Divisions I and II of the Israeli Volleyball Association.

MAIN OUTCOME MEASURE(S)

  Frontal-plane knee movement and sagittal-plane hip and knee movement during jump landing were visually rated as good, moderate, or poor based on previously established criteria. Frontal-plane knee excursion and sagittal-plane hip and knee excursions were measured using free motion-analysis software and compared among athletes with different visual ratings of the corresponding movements.

RESULTS

  Participants with different visual ratings of frontal-plane knee movement displayed differences in 2D frontal-plane knee excursion ( P < .01), whereas participants with different visual ratings of sagittal-plane hip and knee movement displayed differences in 2D sagittal-plane hip and knee excursions ( P < .01).

CONCLUSIONS

  Visual ratings of frontal-plane knee movement and sagittal-plane hip and knee movement were associated with differences in the corresponding 2D hip and knee excursions. Visual rating of these movements may serve as an initial screening tool for detecting altered movement patterns during jump landings.

Mobility of moose-comparing the effects of wolf predation risk, reproductive status, and seasonality

In a predator–prey system, prey species may adapt to the presence of predators with behavioral changes such as increased vigilance, shifting habitats, or changes in their mobility. In North America, moose (Alces alces) have shown behavioral adaptations to presence of predators, but such antipredator behavioral responses have not yet been found in Scandinavian moose in response to the recolonization of wolves (Canis lupus). We studied travel speed and direction of movement of GPS‐collared female moose (n = 26) in relation to spatiotemporal differences in wolf predation risk, reproductive status, and time of year. Travel speed was highest during the calving (May–July) and postcalving (August–October) seasons and was lower for females with calves than females without calves. Similarly, time of year and reproductive status affected the direction of movement, as more concentrated movement was observed for females with calves at heel, during the calving season. We did not find support for that wolf predation risk was an important factor affecting moose travel speed or direction of movement. Likely causal factors for the weak effect of wolf predation risk on mobility of moose include high moose‐to‐wolf ratio and intensive hunter harvest of the moose population during the past century.

THE NINE TEST SCREENING BATTERY - NORMATIVE VALUES ON A GROUP OF RECREATIONAL ATHLETES

BACKGROUND

A variety of risk factors predispose athletes to injury, such as impaired neuromuscular control, insufficient core stability, and muscular imbalances. The goal of assessing functional movement patterns is to detect imbalances and correct them with prevention strategies and thereby decrease injuries, and improve performance and quality of life.

PURPOSE

The purpose of this study was to generate normative values for the 'Nine Test Screening Battery' (9TSB) in a group of recreational athletes. A secondary aim was to study gender differences and differences between subjects with (more than six weeks before test occasion) and without previous injury (regardless of injury location). A third aim was to investigate the psychometric properties of the 9TSB.

METHODS

Eighty healthy recreational athletes, (40 men and 40 women) aged 22-58, were included. The subjects were tested according to strict criteria during nine functional movement exercises that comprise the 9TSB; each graded using a ordinal scale of 0-3, at one occasion. The maximum possible score is 27 points.

RESULTS

The median score for the whole group was 18 (Range 12 - 24). A normal distribution of the test scores, with no floor-ceiling effects was found. There was no significant gender difference (p = 0.16) or difference between the group that reported previous injuries (regardless of injury location) and the group that did not (p = 0.65). The internal consistency was 0.41 with Cronbach's alpha.

CONCLUSION

A normal distribution of test results with no floor-ceiling effect was found. History of previous injury (more than six weeks before testing) or gender did not affect the results. In order to determine and cut scores for what is considered optimal or dysfunctional movement patterns, further cohort studies are required.

The Association of Ankle Dorsiflexion Range of Motion With Hip and Knee Kinematics During the Lateral Step-down Test

Study Design Controlled laboratory study. Background Altered hip and knee kinematics have been associated with several knee disorders, including anterior cruciate ligament tear, patellofemoral pain, and iliotibial band syndrome. Limited ankle dorsiflexion (DF) range of motion (ROM), which has been linked with some of these disorders, has also been associated with altered knee kinematics. Objective To explore the association of ankle DF ROM with hip and knee kinematics during a step-down task. Methods Thirty healthy participants underwent a 3-D analysis of hip and knee kinematics during a lateral step-down test, followed by measurement of ankle DF ROM in weight bearing (WB) and non-weight bearing (NWB). Participants were dichotomized using the median values into low- and high-DF subgroups within both WB and NWB. Hip and knee kinematics were compared between the low- and high-DF subgroups. Results Participants in the low-DF subgroups exhibited greater peak hip adduction (WB, P = .02; NWB, P<.01) and greater peak knee external rotation (WB, P = .02; NWB, P<.01) compared with participants in the high-DF subgroups. In addition, participants in the low-DF WB subgroup exhibited decreased peak knee flexion compared with participants in the high-DF WB subgroup (P<.01). Conclusion Individuals with lower ankle DF ROM exhibited hip and knee kinematics previously associated with several knee disorders, suggesting that this impairment may be involved in the pathogenesis of the same disorders. Assessment of ankle DF ROM may be useful as part of a preparticipation screening. Furthermore, deficits in ankle DF ROM may need to be addressed in individuals with altered movement patterns. J Orthop Sports Phys Ther 2016;46(11):-1. Epub 29 Sep 2016. doi:10.2519/jospt.2016.6621.

Maximum Velocities in Flexion and Extension Actions for Sport

Speed of movement is fundamental to the outcome of many human actions. A variety of techniques can be implemented in order to maximise movement speed depending on the goal of the movement, constraints, and the time available. Knowing maximum movement velocities is therefore useful for developing movement strategies but also as input into muscle models. The aim of this study was to determine maximum flexion and extension velocities about the major joints in upper and lower limbs. Seven university to international level male competitors performed flexion/extension at each of the major joints in the upper and lower limbs under three conditions: isolated; isolated with a countermovement; involvement of proximal segments. 500 Hz planar high speed video was used to calculate velocities. The highest angular velocities in the upper and lower limb were 50.0 rad·s-1 and 28.4 rad·s-1, at the wrist and knee, respectively. As was true for most joints, these were achieved with the involvement of proximal segments, however, ANOVA analysis showed few significant differences (p<0.05) between conditions. Different segment masses, structures and locations produced differing results, in the upper and lower limbs, highlighting the requirement of segment specific strategies for maximal movements.

Electromyographic Analysis of the Hip Extension Pattern in Visually Impaired Athletes

The objective of the study was to determine the order of muscle recruitment during the active hip joint extension in particular positions in young visually impaired athletes. The average recruitment time (ART) of the gluteus maximus (GM) and the hamstring muscle group (HMG) was assessed by the means of surface electromyography (sEMG). The sequence of muscle recruitment in the female and male group was also taken into consideration. This study followed a prospective, cross - sectional, randomised design, where 76 visually impaired athletes between the age of 18-25 years were enrolled into the research and selected on chosen inclusion and exclusion criteria. Finally, 64 young subjects (32 men and 32 women) were included in the study (age: 21.1 ± 1.05 years; body mass: 68.4 ± 12.4 kg; body height: 1.74 ± 0.09 m; BMI: 22.20 ± 2.25 kg/m2). All subjects were analysed for the ART of the GM and HMG during the active hip extension performed in two different positions, as well as resting and functional sEMG activity of each muscle. Between gender differences were comprised and the correlations between the ART of the GM and HMG with their functional sEMG activity during hip extension in both positions were shown. No significant differences between the ART of the GM and HMG were found (p>0.05). Furthermore, there was no significant difference of ART among both tested positions, as well in male as female subjects (p>0.05).

Effect of game format on heart rate, activity profile, and player involvement in elite and recreational youth players

The purpose of this study was to evaluate activity profile, aerobic load, and player involvement in two game formats of recreational and elite youth football for two age groups. A total of 152 youth players participated, with 45 U10 players playing 5v5 and 8v8 games, and 41 U13 players playing 8v8 and 11v11 (20 min) games. Activity profile, heart rate (HR), and technical actions were measured during all games using 10 Hz GPS, video filming, and HR monitors. For U10, no difference was found in total distance covered (1754 ± 237 vs 1771 ± 314 m, P = 0.650, d = 0.06), whereas mean HR (174 ± 10 vs 168 ± 12 bpm, P = 0.001, d = 0.59) and number of technical actions (65.1 ± 24.0 vs 36.9 ± 20.4, P    0.001, d = 1.27) were higher in 5v5 than in 8v8. For U13, lower total distance covered (1821 ± 325 vs 2038 ± 328 m, P < 0.001, d = 0.66) and higher number of technical actions (36.2 ± 14.9 vs 26.9 ± 14.1, P < 0.001, d = 0.64) were observed in 8v8 than in 11v11, with no difference in mean HR (170 ± 10 vs 171 ± 10 bpm, P = 0.679, d = 0.10). In conclusion, HR is high in youth football matches irrespective of the level of play and the game format. Playing with fewer players on smaller pitches results in minor changes to the physical loading but elevates the technical involvement of youth players both at elite level and recreational level.

The activity pattern of the lumbo-pelvic muscles during prone hip extension in athletes with and without hamstring strain injury

BACKGROUND

Altered muscular activation pattern has been associated with musculoskeletal disorders. Some previous studies have demonstrated muscle weakness or tightness in athletes who have sustained hamstring (HAM) injuries. However, no study has clinically investigated the muscular activity pattern in subjects with HAM strain injuries.

OBJECTIVE

To investigate the activity pattern of the ipsilateral erector spinae (IES), contralateral erector spinae (CES), gluteus maximus (GM), and medial and lateral HAM muscles during the prone hip extension (PHE) test in athletes with and without history of HAM strain injury.

DESIGN

Cross-sectional non-experimental study design.

PARTICIPANTS

A convenience sample of 20 soccer athletes participated in the study. Subjects were categorized into two groups: those with history of HAM strain injury (n=10, mean age = 22.6 ± 3.74) and without history of HAM strain (n =10, mean age = 22.45 ± 3.77).

METHODS

Three repetitions of the PHE were performed by each subject, and the electromyographic (EMG) outputs of the IES, CES, GM, and HAM muscles were recorded, processed and normalized to maximum voluntary electrical activity (MVE). Independent t-tests were used for comparing activation means of each muscle between athletes with and without history of HAM strain injury.

RESULTS

There were significant differences in EMG activity of the GM (p= 0.04) and medial HAM (p = 0.01) between two groups. No significant difference was found in EMG signals of the IES (p= 0.26), CES (= 0.33) and lateral HAM (p= 0.58) between the two groups. Greater although non-significant normalized EMG outputes of IES, CES and lateral HAM were seen in athletes with history of HAM strain compared to those without HAM strain.

CONCLUSION

The findings of this study demonstrated greater normalized EMG activity of GM and medial HAM tested in athletes with history of HAM strain compared to those without HAM strain (altered activation pattern).

LEVEL OF EVIDENCE

3a.

Comparison of the effects of artificial and natural barriers on large African carnivores: implications for interspecific relationships and connectivity

1. Physical barriers contribute to habitat fragmentation, influence species distribution and ranging behaviour, and impact long-term population viability. Barrier permeability varies among species and can potentially impact the competitive balance within animal communities by differentially affecting co-occurring species. The influence of barriers on the spatial distribution of species within whole communities has nonetheless received little attention. 2. During a 4-year period, we studied the influence of a fence and rivers, two landscape features that potentially act as barriers on space use and ranging behaviour of lions Panthera leo, spotted hyenas Crocuta crocuta, African wild dogs Lycaon pictus and cheetahs Acinonyx jubatus in Northern Botswana. We compared the tendencies of these species to cross the barriers using data generated from GPS-radio collars fitted to a total of 35 individuals. Barrier permeability was inferred by calculating the number of times animals crossed a barrier vs. the number of times they did not cross. Finally, based on our results, we produced a map of connectivity for the broader landscape system. 3. Permeability varied significantly between fence and rivers and among species. The fence represented an obstacle for lions (permeability = 7.2%), while it was considerably more permeable for hyenas (35.6%) and wild dogs and cheetahs (≥ 50%). In contrast, the rivers and associated floodplains were relatively permeable to lions (14.4%) while they represented a nearly impassable obstacle for the other species (<2%). 4. The aversion of lions to cross the fence resulted in a relatively lion-free habitat patch on one side of the fence, which might provide a potential refuge for other species. For instance, the competitively inferior wild dogs used this refuge significantly more intensively than the side of the fence with a high presence of lions. 5. We showed that the influence of a barrier on the distribution of animals could potentially result in a broad-scale modification of community structure and ecology within a guild of co-occurring species. As habitat fragmentation increases, understanding the impact of barriers on species distributions is thus essential for the implementation of landscape-scale management strategies, the development and maintenance of corridors and the enhancement of connectivity.

The effect of individual variation on the structure and function of interaction networks in harvester ants

Social insects exhibit coordinated behaviour without central control. Local interactions among individuals determine their behaviour and regulate the activity of the colony. Harvester ants are recruited for outside work, using networks of brief antennal contacts, in the nest chamber closest to the nest exit: the entrance chamber. Here, we combine empirical observations, image analysis and computer simulations to investigate the structure and function of the interaction network in the entrance chamber. Ant interactions were distributed heterogeneously in the chamber, with an interaction hot-spot at the entrance leading further into the nest. The distribution of the total interactions per ant followed a right-skewed distribution, indicating the presence of highly connected individuals. Numbers of ant encounters observed positively correlated with the duration of observation. Individuals varied in interaction frequency, even after accounting for the duration of observation. An ant's interaction frequency was explained by its path shape and location within the entrance chamber. Computer simulations demonstrate that variation among individuals in connectivity accelerates information flow to an extent equivalent to an increase in the total number of interactions. Individual variation in connectivity, arising from variation among ants in location and spatial behaviour, creates interaction centres, which may expedite information flow.