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Context: An Optimizing Performance through Intrinsic Motivation and Attention for Learning theory-based motor learning intervention delivering autonomy support and enhanced expectancies (EE) shows promise for reducing cognitive-motor dual-task costs, or the relative difference in primary task performance when completed with and without a secondary cognitive task, that facilitate adaptive injury-resistant movement response. The current pilot study sought to determine the effectiveness of an autonomy support versus an EE-enhanced virtual reality motor learning intervention to reduce dual-task costs during single-leg balance. Design: Within-subjects 3 × 3 trial. Methods: Twenty-one male and 24 female participants, between the ages of 18 and 30 years, with no history of concussion, vertigo, lower-extremity surgery, or lower-extremity injuries the previous 6 months, were recruited for training sessions on consecutive days. Training consisted of 5 × 8 single-leg squats on each leg, during which all participants mimicked an avatar through virtual reality goggles. The autonomy support group chose an avatar color, and the EE group received positive kinematic biofeedback. Baseline, immediate, and delayed retention testing consisted of single-leg balancing under single- and dual-task conditions. Mixed-model analysis of variances compared dual-task costs for center of pressure velocity and SD between groups on each limb. Results: On the right side, dual-task costs for anterior–posterior center of pressure mean and SD were reduced in the EE group (mean Δ = −51.40, Cohen d = 0.80 and SD Δ = −66.00%, Cohen d = 0.88) compared with the control group (mean Δ = −22.09, Cohen d = 0.33 and SD Δ = −36.10%, Cohen d = 0.68) from baseline to immediate retention. Conclusions: These findings indicate that EE strategies that can be easily implemented in a clinic or sport setting may be superior to task-irrelevant AS approaches for influencing injury-resistant movement adaptations.

To examine the isolated and combined effects of sex and perceptual-motor function on single-leg squatting mechanics in males and females. We employed a cross-sectional design in a research laboratory. Fifty-eight females (22.2 ± 3.5 yrs, 1.60 ± .07 m, 64.1 ± 13.0 kg) and 35 males (23.5 ± 5.0 yrs, 1.80 ± .06m, 84.7 ± 15.3 kg) free from time-loss injury in the six months prior, vertigo, and vestibular conditions participated in this study. Independent variables were sex, perceptual-motor metrics (reaction time, efficiency index, conflict discrepancy), and interaction effects. Dependent variables were peak frontal plane angles of knee projection, ipsilateral trunk flexion, and contralateral pelvic drop during single-leg squatting. After accounting for the sex-specific variance and perceptual-motor function effects on frontal plane squatting kinematics, female sex amplified the associations of: higher reaction time, lower efficiency index, and higher conflict discrepancy with greater right ipsilateral peak trunk lean (R2 = .13; p = .05); higher reaction time, lower efficiency index, and higher conflict discrepancy with decreased right contralateral pelvic drop (R2 = .22; p < .001); higher reaction time and lower conflict discrepancy with greater right frontal plane knee projection angle (R2 = .12; p = .03); and higher reaction time with greater left frontal plane knee projection angle (R2 = .22; p < .001). Female sex amplified the relationship between perceptual-motor function and two-dimensional frontal plane squatting kinematics. Future work should determine the extent to which perceptual-motor improvements translate to safer movement strategies.

Resting heart rate variability (HRV) may be a useful index of both brain-based executive function and general health. Our purpose in this study was to quantify relationships among HRV, perceptual-motor performance metrics, and wellness survey responses. A cohort of 32 male Reserve Officer Training Corp (ROTC) cadets completed a dual-task upper extremity reaction time (UERT) test, two tests of whole-body reactive agility, and a 10-item wellness survey that produced a 0–100 Overall Wellness Index (OWI). We averaged participants’ resting HRV measurements twice per week over 10 weeks to derive an intra-individual grand mean (HRV-IIGM) and over a series of days we calculated an intra-individual coefficient of variation (HRV-IICV). We used median values for the two HRV metrics (HRV-IIGM and HRV-IICV) to separate the cadets into equal-sized high and low HRV groups to form the dependent variable for logistic regression analyses. We found a significant inverse relationship between HRV-IIGM and HRV-IICV ( r = –0.723, p < .001). Differences in UERT in the left versus right visual hemifields (L–R Diff) and OWI scores were strongly related to both HRV-IIGM ≤ 4.49 and HRV-IICV ≥ 6.95%. Logistic regression models that included L–R Diff and OWI showed 71% classification accuracy for HRV-IIGM (Model χ2 [2] = 12.47, p = .002, Nagelkerke R2 = 0.430) and 81% classification accuracy for HRV-IICV (Model χ2 [2] = 14.88, p = .001, Nagelkerke R2 = 0.496). These findings suggest that resting HRV, perceptual-motor efficiency, and overall wellness are highly interrelated, supporting a multi-factor biopsychosocial assessment to guide the design and implementation of interventions to maximize operational effectiveness for ROTC cadets and other military personnel.

BackgroundIntegrated movement and cognitive load paradigms are used to expose impairments associated with concussion and musculoskeletal injury. There is currently little information on the discriminatory nature of dual-task complexity and the relative influence of physical exertion on cognitive outcomes.PurposeAssess cognitive performance while under motor conditions of increasing complexity before and after a standardized exercise protocol.Methods34 participants were recruited (17 male and 17 female; 24 ± 1.4 yrs). A modified Eriksen flanker test was used to assess cognitive performance under four conditions (seated, single-leg stance, walking, and lateral stepping) before and after a 20-min moderate-to vigorous intensity treadmill protocol. The flanker test consisted of 20 sets of 5-arrow configurations, appearing in random order. To complete the response to cognitive stimulus, participants held a smartphone horizontally and were instructed to respond as quickly and as accurately as possible by tilting the device in the direction corresponding to the orientation of the middle arrow. The metrics used for analysis included average reaction time (ms), inverse efficiency index (average reaction time penalized for incorrect responses), and conflict effect (the average time cost of responding to an incongruent repetition vs. a congruent repetition). Mixed effects (condition by time) RMANOVAs were conducted to examine the effects of motor task complexity and physical exertion on cognitive performance.ResultsThere was a condition by time interaction for inverse efficiency index (p < 0.001), in which participants displayed higher cognitive efficiency for the pre-activity lateral stepping condition compared to the other three conditions (Cohen's d = 1.3–1.6). For reaction time and conflict effect, there were main effects for condition (p = 0.004 and 0.006, respectively), in which performance during lateral stepping was improved in relation to the seated condition (reaction time Cohen's d = 0.68; conflict effect Cohen's d = 0.64).ConclusionParticipants tended to display better dual-task cognitive performance under more stimulating or complex motor tasks before physical exertion, likely associated with the inverted-U arousal-performance relationship. When using dual-task assessments, clinicians should be mindful of the accompanying motor task and baseline exertion levels and their potential to disrupt or optimize cognitive performance.

Background: Efficient neural processing of visuospatial and proprioceptive input appears to be crucial for avoidance of sport injury. As such, clinically-feasible tests are needed to identify deficiencies found by advanced neuroimaging and electrophysiological tests. Three-dimensional motion capture in a laboratory setting is currently the gold standard for measurement of human movement parameters but is costly and requires extensive training. Non-immersive virtual reality systems with body motion tracking, such as TRAZER, may provide a clinically-feasible and portable means of acquiring similar variables. Test-retest reliability and concurrent validity of these systems are currently lacking. Aim: The aim of the study was to assess the concurrent validity of the TRAZER single-camera system with 3D motion capture system and to assess the test-retest reliability of TRAZER’s whole-body reactive agility metrics. Methods: Participants – For validity, 13 healthy individuals (24.8±3.1 years, 170.0±7.7 cm, 70.0±14.2 kg); for reliability, 18 healthy individuals (23.3±2.5 years, 168.2±11.2 cm, 78.2±17.8 kg). Design – Validity was a single-session cross-sectional study. Reliability was a 3 consecutive day test-retest study. Setting–Controlled laboratory study. Intervention – Assessments utilized randomized movements in eight directions for forty total repetitions as designated by the TRAZER system. TRAZER protocol was simultaneously tracked by Vicon Motion Capture and the TRAZER system. Reliability data were captured on three consecutive days by the TRAZER system. Main Outcome Measures – Maximum acceleration, maximum velocity, and total distance were recorded for validation. In addition to these measures, maximum deceleration, average velocity, average acceleration, average deceleration, and average reaction time were collected for reliability. Results: Overall, a lack of agreement exists between maximum outputs for TRAZER and 3D motion capture (velocity r=0.808, acceleration r=−0.090), but total distance correlation was high (r =.961). ICC values between days 1-2-3 for average measures were high (average velocity=0.847, average acceleration=0.919, and average deceleration=0.948) with the exception of average reaction time being fair (ICC=0.536). ICCs for maximum measures showed a much smaller correlation between days (velocity=0.654, acceleration=0.171, and deceleration=0.416). Conclusions: Even though there is a lack of strong concurrent validity between measures obtained from TRAZER and 3D motion capture systems, there is strong test-retest reliability of the TRAZER system. The applicability of these findings makes TRAZER clinically relevant in scenarios requiring pre- and post-testing for return to play decisions, or monitoring of a training regimen where demonstration of validation to a gold standard measurement is not relevant. Relevance for patients: When test-retest capability is desired, such as in return-to-play protocols following an injury, Trazer is a reliable option.