IT’S ABOUT HOW WELL YOU USE IT: SKATING STRIDE IN NOVICE, INTERMEDIATE AND ADVANCED INLINE SKATERS

Adequate skating technique is imperative to roller sports. Characteristics that differ between inline skating competencies have not been addressed. This study assessed skating parameters associated with coaching cues across three levels of experience. Inline-skaters (n=24) were divided into novice, intermediate and advanced groups based on experience. Skate trajectories were captured through 3D analysis as participants skated maximally down a 10 m runway. One-way ANOVA was used to compare differences for the skating parameters between skill levels. Significant differences (P < 0.016) were found for stride-width, recovery, stride-width-recovery and stride-length-recovery and stride rate. Results have implications for delivery of coaching and skating skill development

IT’S ABOUT HOW WELL YOU USE IT: SKATING STRIDE IN NOVICE, INTERMEDIATE AND ADVANCED INLINE SKATERS

Adequate skating technique is imperative to roller sports. Characteristics that differ between inline skating competencies have not been addressed. This study assessed skating parameters associated with coaching cues across three levels of experience. Inline-skaters (n=24) were divided into novice, intermediate and advanced groups based on experience. Skate trajectories were captured through 3D analysis as participants skated maximally down a 10 m runway. One-way ANOVA was used to compare differences for the skating parameters between skill levels. Significant differences (P < 0.016) were found for stride-width, recovery, stride-width-recovery and stride-length-recovery and stride rate. Results have implications for delivery of coaching and skating skill development

READ AND REACT: EFFECTS OF TASK COMPLEXITY ON MOTOR SKILL EXECUTION

Performance in team sports requires players to both observe their game environment and proceed with technical skill. This case study evaluated if changing the complexity of a perceptual-motor task caused technical performance changes. Kinematic data were collected and analysed for 34 handballs across four levels of complexity using visual and auditory stimuli (simple-response, choice response, choice response with distractor, choice response with cross modality distractor). Kinematic differences were found between the simple response and choice response task for six out of 10 parameters. Although differences occurred, the effect of distractor stimuli on handball kinematics was unclear. The cognitive complexity of a task may affect technical performance and therefore has implications for biomechanical testing environments

The Measurement of Eye Movements in Mild Traumatic Brain Injury: A Structured Review of an Emerging Area

Mild traumatic brain injury (mTBI), or concussion, occurs following a direct or indirect force to the head that causes a change in brain function. Many neurological signs and symptoms of mTBI can be subtle and transient, and some can persist beyond the usual recovery timeframe, such as balance, cognitive or sensory disturbance that may pre-dispose to further injury in the future. There is currently no accepted definition or diagnostic criteria for mTBI and therefore no single assessment has been developed or accepted as being able to identify those with an mTBI. Eye-movement assessment may be useful, as specific eye-movements and their metrics can be attributed to specific brain regions or functions, and eye-movement involves a multitude of brain regions. Recently, research has focused on quantitative eye-movement assessments using eye-tracking technology for diagnosis and monitoring symptoms of an mTBI. However, the approaches taken to objectively measure eye-movements varies with respect to instrumentation, protocols and recognition of factors that may influence results, such as cognitive function or basic visual function. This review aimed to examine previous work that has measured eye-movements within those with mTBI to inform the development of robust or standardized testing protocols. Medline/PubMed, CINAHL, PsychInfo and Scopus databases were searched. Twenty-two articles met inclusion/exclusion criteria and were reviewed, which examined saccades, smooth pursuits, fixations and nystagmus in mTBI compared to controls. Current methodologies for data collection, analysis and interpretation from eye-tracking technology in individuals following an mTBI are discussed. In brief, a wide range of eye-movement instruments and outcome measures were reported, but validity and reliability of devices and metrics were insufficiently reported across studies. Interpretation of outcomes was complicated by poor study reporting of demographics, mTBI-related features (e.g., time since injury), and few studies considered the influence that cognitive or visual functions may have on eye-movements. The reviewed evidence suggests that eye-movements are impaired in mTBI, but future research is required to accurately and robustly establish findings. Standardization and reporting of eye-movement instruments, data collection procedures, processing algorithms and analysis methods are required. Recommendations also include comprehensive reporting of demographics, mTBI-related features, and confounding variables

VALIDATION OF INERTIAL MEASUREMENT UNITS FOR TRACKING 100M SPRINT DATA

Wearable micro sensor measurement devices are a promising development in sports technology. This paper presents preliminary data evaluating the accuracy of an inertial measurement unit during 100m sprints against a criterion measure from a tripod-mounted Laveg laser. The inertial measurement units were found to be a valid tool for the analysis of peak velocity (r = 0.92) and average split velocities for splits after the first 10m (r = 0.85 - 0.95). Validation data suggests some caution should be taken in interpretation of the first lorn split (r = 0.32). Whilst data from the two devices for this split were correlated, the inertial measurement unit showed an overestimation for this parameter in comparison to the athlete velocity as measured by the laser. Further in-depth analysis should investigate this period

THE EFFECT OF A GAME-SPECIFIC SHORT TERM FATIGUE PROTOCOL ONKICKING IN AUSTRALIAN FOOTBALL

The purpose of this study was to three dimentionally evaluate the effects of a short term game specific fatigue protocol on the kinetics of elite and sub-elite Australian Footballers (AF) during a drop punt kick. Five AF players performed kicks pre and post fatigue protocol. Three dimensional data of the pelvis and kick leg was obtained using a three tower optotrak Certus system (200Hz) and joint torques and moments were calculated in Visual 3D from kick foot toe off until ball contact. Sprint time indicated the protocol induced fatigue. Hip flexion torque significantly increased following fatigue indicating a change in movement strategy similar to that found for jump landing. This greater hip reliant post-fatigue kicking strategy has implications for both skill enhancement and injury prevention

Saccade and Fixation Eye Movements During Walking in People With Mild Traumatic Brain Injury

Background: Clinical and laboratory assessment of people with mild traumatic brain injury (mTBI) indicate impairments in eye movements. These tests are typically done in a static, seated position. Recently, the use of mobile eye-tracking systems has been proposed to quantify subtle deficits in eye movements and visual sampling during different tasks. However, the impact of mTBI on eye movements during functional tasks such as walking remains unknown. Objective: Evaluate differences in eye-tracking measures collected during gait between healthy controls (HC) and patients in the sub-acute stages of mTBI recovery and to determine if there are associations between eye-tracking measures and gait speed. Methods: Thirty-seven HC participants and 67individuals with mTBI were instructed to walk back and forth over 10-m, at a comfortable self-selected speed. A single 1-min trial was performed. Eye-tracking measures were recorded using a mobile eye-tracking system (head-mounted infra-red Tobbii Pro Glasses 2, 100 Hz, Tobii Technology Inc. VA, United States). Eye-tracking measures included saccadic (frequency, mean and peak velocity, duration and distance) and fixation measurements (frequency and duration). Gait was assessed using six inertial sensors (both feet, sternum, right wrist, lumbar vertebrae and the forehead) and gait velocity was selected as the primary outcome. General linear model was used to compare the groups and association between gait and eye-tracking outcomes were explored using partial correlations. Results: Individuals with mTBI showed significantly reduced saccade frequency (p = 0.016), duration (p = 0.028) and peak velocity (p = 0.032) compared to the HC group. No significant differences between groups were observed for the saccade distance, fixation measures and gait velocity (p > 0.05). A positive correlation was observed between saccade duration and gait velocity only for participants with mTBI (p = 0.025). Conclusion: Findings suggest impaired saccadic eye movement, but not fixations, during walking in individuals with mTBI. These findings have implications in real-world function including return to sport for athletes and return to duty for military service members. Future research should investigate whether or not saccade outcomes are influenced by the time after the trauma and rehabilitation

Gait Performance in People with Symptomatic, Chronic Mild Traumatic Brain Injury

There is a dearth of knowledge about how symptom severity affects gait in the chronic (>3 months) mild traumatic brain injury (mTBI) population despite up to 53% of people reporting persisting symptoms following mTBI. The purpose of this investigation was to determine if gait is affected in a symptomatic, chronic mTBI group and to assess the relationship between gait performance and symptom severity on the Neurobehavioral Symptom Inventory (NSI). Gait was assessed under single- and dual-task conditions using five inertial sensors in 57 control subjects and 65 people with chronic mTBI (1.1 year from mTBI). The single- and dual-task gait domains of Pace, Rhythm, Variability, and Turning were calculated from individual gait characteristics. Dual-task cost (DTC) was calculated for each domain. The mTBI group walked (domain z-score mean difference: single-task = 0.70; dual-task = 0.71) and turned (z-score mean difference: single-task = 0.69; dual-task = 0.70) slower (p<0.001) under both gait conditions, with less rhythm under dual-task gait (z-score difference = 0.21, p=0.001). DTC was not different between groups. Higher NSI somatic sub-score was related to higher single- and dual-task gait variability as well as slower dual-task pace and turning (p<0.01). People with chronic mTBI and persistent symptoms exhibited altered gait, particularly under dual-task, and worse gait performance related to greater symptom severity. Future gait research in chronic mTBI should assess the possible underlying physiological mechanisms for persistent symptoms and gait deficits

Free-living gait does not differentiate chronic mTBI patients compared to healthy controls

Background Physical function remains a crucial component of mild traumatic brain injury (mTBI) assessment and recovery. Traditional approaches to assess mTBI lack sensitivity to detect subtle deficits post-injury, which can impact a patient’s quality of life, daily function and can lead to chronic issues. Inertial measurement units (IMU) provide an opportunity for objective assessment of physical function and can be used in any environment. A single waist worn IMU has the potential to provide broad/macro quantity characteristics to estimate gait mobility, as well as more high-resolution micro spatial or temporal gait characteristics (herein, we refer to these as measures of quality). Our recent work showed that quantity measures of mobility were less sensitive than measures of turning quality when comparing the free-living physical function of chronic mTBI patients and healthy controls. However, no studies have examined whether measures of gait quality in free-living conditions can differentiate chronic mTBI patients and healthy controls. This study aimed to determine whether measures of free-living gait quality can differentiate chronic mTBI patients from controls. Methods Thirty-two patients with chronic self-reported balance symptoms after mTBI (age: 40.88 ± 11.78 years, median days post-injury: 440.68 days) and 23 healthy controls (age: 48.56 ± 22.56 years) were assessed for ~ 7 days using a single IMU at the waist on a belt. Free-living gait quality metrics were evaluated for chronic mTBI patients and controls using multi-variate analysis. Receiver operating characteristics (ROC) and Area Under the Curve (AUC) analysis were used to determine outcome sensitivity to chronic mTBI. Results Free-living gait quality metrics were not different between chronic mTBI patients and controls (all p > 0.05) whilst controlling for age and sex. ROC and AUC analysis showed stride length (0.63) was the most sensitive measure for differentiating chronic mTBI patients from controls. Conclusions Our results show that gait quality metrics determined through a free-living assessment were not significantly different between chronic mTBI patients and controls. These results suggest that measures of free-living gait quality were not impaired in our chronic mTBI patients, and/or, that the metrics chosen were not sensitive enough to detect subtle impairments in our sample

De Man et al.: Activity tracker validation Sensoria: A Journal of Mind, Brain &amp; Culture Validity and inter-device reliability of dominant and non-dominant wrist worn activity trackers in suburban walking

Abstract Wearable activity trackers have become a popular way for general and athletic populations to measure daily physical activity and rest patterns. The validity and reliability of step count is often unknown for these devices