Smooth pursuit eye movements (SPEMs) and saccadic eye movements are both commonly impaired following sportrelated concussion (SRC). Typical oculomotor assessments measure individual eye movements in a series of restrictive tests designed to isolate features such as response times. These measures lack ecological validity for athletes because athletes are adept at simple tasks designed for the general population. Yet, because eye movement metrics are sensitive and well-characterized neuroanatomically, it would be valuable to test whether athletes exhibit abnormal eye movements with more challenging tasks. To address this gap in knowledge, we collected eye-tracking data during a sport-like task to gain insight on gaze behavior during active self-motion. SPEMs and saccadic eye movements were recorded during a sport-like visual task within 24-48 h following SRC. Thirty-six Division I student-athletes were divided into SRC and control (CON) groups. All participants completed two blocks of the Wii Fit Ó soccer heading game (WF) while wearing a monocular infrared eye tracker. Eye movement classification systems quantified saccadic amplitude (SA), velocity (SV), and count (SC); as well as SPEM velocity (SPV) and amplitude (SPA). Separate Mann-Whitney U tests evaluated SPA and SC and found no significant effects (SPA, p = 0.11; SC, p = 0.10). A multi-variate analysis of variance (MANOVA) for remaining variables revealed SPV was significantly greater in CON ( p < 0.05), but the SRC group had greater SA and SV ( p < 0.05). These findings suggest that during a sport-like task, to maintain foveation SRC subjects used larger amplitude, faster saccades, but exhibited slower SPEMs. Measuring oculomotor function during ecologically valid, sport-like tasks may serve as a concussion biomarker and provide insights into eye movement control after SRC.

Objective: Postural control deficits have been extensively reported following sport-related concussions. Concussed athletes demonstrate these deficits as early as 24 h post-concussion and may persist for up to six months. Many of these prior studies have included mixed samples with prior injury history that may affect the postural control data. The purpose of this investigation was to evaluate the effect of concussion history on postural control 24-48 h following sport-related concussion in Division I athletes. Approach: Twenty-eight Division I athletes (seven athlete controls (CON), seven no history (SRC0), seven with a previous concussion (SRC1), and seven with 2-3 concussions (SRC3) participated in this study. All participants were assessed within 24-48 h postsubsequent SRC and performed three trials of quiet stance in the eyes closed (EC) conditions for 30 s each on a force platform (1000 Hz). The data were analyzed with root mean square (RMS) and mean excursion velocity (MEV) in the anteroposterior (AP) and mediolateral (ML) directions. Two 3 × 2 MANOVAs were run by direction for group comparisons. Main results: SRC2 had significantly greater RMS than CON, SRC0, and SRC1 in the AP direction and ML direction. SRC2 exhibited significantly greater AP and ML MEV than CON, SRC0, and SRC1. Significance: These results demonstrate that having 2-3 prior concussions negatively affects the postural system after a subsequent head injury. Sports medicine staff should approach the recovery process with caution with those that have a prior history of concussion, due to the negative effects that history of concussion has on postural control strategies.

Context Lower extremity musculoskeletal (LEMSK) injury may be more prevalent among those with a history of sport-related concussion (SRC). Objective To investigate the relationship between baseline postural control metrics and the LEMSK injury incidence in National Collegiate Athletic Association Division I student-athletes with a history of SRC. Setting National Collegiate Athletic Association Division I athletes. Design Cohort study. Patients or Other Participants Of 84 total athletes (62 males), 42 had been previously diagnosed with an SRC, and 42 were matched controls based on age, sex, height, weight, and sport. Main Outcome Measure(s) During the preseason baseline evaluation, all participants performed 3 trials of eyes-open and eyes-closed upright quiet stance on a force platform. Medical charts were assessed for all the LEMSK injuries that occurred from preseason baseline to 1 year later. Center-of-pressure data in the anteroposterior and mediolateral directions were filtered before we calculated root mean square and mean excursion velocity; the complexity index was calculated from the unfiltered data. Factorial analysis-of-variance models were used to examine differences between groups and across conditions for root mean square; mean excursion velocity, complexity index, and tests of association to examine between-groups LEMSK differences; and logistic regression models to predict LEMSK. Results Concussion history and injury incidence were related in the SRC group (P = .043). The complexity index of the SRC group was lower with eyes closed (14.08 ± 0.63 versus 15.93 ± 0.52) and eyes open (10.25 ± 0.52 vs 11.80 ± 0.57) in the mediolateral direction than for the control participants (P &lt; .05). Eyes-open root mean square in the mediolateral direction was greater for the SRC group (5.00 ± 0.28 mm) than the control group (4.10 ± 0.22 mm). Logistic regression models significantly predicted LEMSK only in control participants. Conclusions These findings may suggest that LEMSK after SRC cannot be predicted from postural-control metrics at baseline.

Recent evidence suggests that perceptual and cognitive functions are codetermined by rhythmic bodily states. Prior investigations have focused on the cardiac and respiratory rhythms, both of which are also known to synchronise with locomotion - arguably our most common and natural of voluntary behaviours. Unlike the cardiorespiratory rhythms, walking is entirely under voluntary control, enabling a test of how natural and voluntary rhythmic action may affect sensory function. Here, we show that the speed and phase of human locomotion constrains sensorimotor performance. We used a continuous visuo-motor tracking task in a wireless, body-tracking virtual environment, and found that the accuracy and reaction time of continuous reaching movements were decreased at slower walking speeds, and rhythmically modulated according to the phases of the step-cycle. Decreased accuracy when walking at slow speeds suggests an advantage for interlimb coordination at normal walking speeds, in contrast to previous research on dual-task walking and reach-to-grasp movements. Phasic modulations of reach precision within the step-cycle also suggest that the upper limbs are affected by the ballistic demands of motor-preparation during natural locomotion. Together these results show that the natural phases of human locomotion impose constraints on sensory function and demonstrate the value of examining dynamic and natural behaviour in contrast to the traditional and static methods of psychological science.

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