Influence of modified starches on mental performance and physical activity following an exhaustive bout of exercise.

Slow-releasing carbohydrates may delay the effects of fatigue after exhaustive exercise. The purpose of this study was to observe the influence that hydrothermally modified starches (HMS) and traditional maltodextrin (MAL) supplements had on physical endurance and mental performance following exhaustive exercise. Male participants completed a VO2 max and 2 days of cycling sessions using a Velotron ergometer. Cycling sessions were performed at 70% of the VO2 max workload for 150 min. Supplements were consumed 30 min before cycling and during exercise at the 120-min mark (1 g CHO/kg body weight). Brain activity was measured using a Neuroscan 64-channel electroencephalogram cap. Go-no-go and N-back tasks were performed before and after cycling bouts. Blood glucose, lactate, ketones, and urine-specific gravity were measured before, during, and after cycling. VO2 and rate of perceived exertion were recorded in 15-min intervals. Ketones increased significantly more for HMS than MAL from pre- to postcycling measurements (p < 0.05). Reaction times for go-no-go and N-back were faster for HMS postexercise. Event-related potential differences were present in both mental tasks following exhaustive exercise. HMS supplementation decreased the impact of cognitive and physical fatigue postexercise.

Gaze Control and Tactical Decision-Making Under Stress in Active-Duty Police Officers During a Live Use-of-Force Response.

Police officers during dynamic and stressful encounters are required to make rapid decisions that rely on effective decision-making, experience, and intuition. Tactical decision-making is influenced by the officer's capability to recognize critical visual information and estimation of threat. The purpose of the current study is to investigate how visual search patterns using cluster analysis and factors that differentiate expertise (e.g., years of service, tactical training, related experiences) influence tactical decision-making in active-duty police officers (44 active-duty police officers) during high stress, high threat, realistic use of force scenario following a car accident and to examine the relationships between visual search patterns and physiological response (heart rate). A cluster analysis of visual search variables (fixation duration, fixation location difference score, and number of fixations) produced an Efficient Scan and an Inefficient Scan group. Specifically, the Efficient Scan group demonstrated longer total fixation duration and differences in area of interests (AOI) fixation duration compared to the Inefficient Scan group. Despite both groups exhibiting a rise in physiological stress response (HR) throughout the high-stress scenario, the Efficient Scan group had a history of tactical training, improved return fire performance, had higher sleep time total, and demonstrated increased processing efficiency and effective attentional control, due to having a background of increased tactical training.

Assessing between-officer variability in responses to a live-acted deadly force encounter as a window to the effectiveness of training and experience.

We aimed to infer the effectiveness of officers' training and experience by assessing consistency of behavioural responses between them. If officers facing the same scenario respond in similar ways, this implies their use of shared cognition, through acquired in-common tactical knowledge. Officers (n = 42) responded to a live-acted scenario in which an assailant ultimately discharged his weapon. Triangulated camera positions assessed their movement patterns, final positions, and weapon responses relative to when the assailant fired his weapon. We also assessed the officers' visual search and gathered information regarding their experience and rest. Our second aim was to examine sources of variability in the officers' responses. We found extensive variability in all aspects of the response. Experience did not impact spatial or temporal behavioural responses. However, longer hours awake and lower reported rest negatively impacted officers' responses. We conclude that officers had insufficient training and experience to demonstrate in-common knowledge.Practitioner summary: Police officers showed high spatial and temporal variability in response to the same scenario. This implies inadequate tactical training, and is supported by our finding that training and experience did not impact performance. Instead, the officers' variability was constrained by their visual search, and the hours awake before being tested.

Concussed Neural Signature is Substantially Different than Fatigue Neural Signature in Non-concussed Controls.

Traumatic brain injuries can result in short-lived and long-lasting neurological impairment. Identifying the correct recovery timeframe is challenging, as balance-based metrics may be negatively impacted if testing is performed soon after exercise. Thirty-two healthy controls and seventeen concussed individuals performed a series of balance challenges, including virtual reality optical flow perturbation. The control group completed a backpacking protocol to induce moderate fatigue. Concussed participants had lower spectral power in the motor cortex and central sulcus when compared to fatigued controls. Moreover, concussed participants experienced a decrease in overall theta band spectral power while fatigued controls showed an increase in theta band spectral power. This neural signature may be useful to distinguish between concussed and non-concussed fatigued participants in future assessments.

Anterior-Posterior Balance Perturbation Protocol Using Lifelike Virtual Reality Environment.

Virtual reality (VR) paradigms have proved to be a valid method to challenge and perturb balance. There is little consensus in the literature on the best protocol design to perturb balance and induce postural sway. Current VR interventions still lack a well-defined standardized metric to generate a virtual environment that can perturb balance in an efficacious, lifelike, and repeatable manner. The objective of this study was to investigate different configurations of amplitude and frequency in an anterior-posterior translation VR environment, that is, lifelike and scaled. Thirteen young adults with no conditions affecting balance were recruited. Balance was challenged by anterior-posterior sinusoidal movement of the lab image within the VR headset. Four different amplitudes of the sinusoidal movement were tested: 1, 5, 10, and 20 cm, with each amplitude being presented at 2 test frequencies : 0.5 and 0.25 Hz. Mean center of pressure velocity was significantly greater than baseline at 0.5 Hz and amplitudes of 10 and 20 cm. Mean center of pressure at approximate entropy was greater than baseline at 0.5 Hz and amplitude of 20 cm. The results suggest that sinusoidal movement of a realistic VR environment produces altered balance compared with baseline quiet standing, but only under specific movement parameters.

The Cognitive Demands of Gait Retraining in Runners: An EEG Study.

High impact forces during running have been associated with tibial stress injuries. Previous research has demonstrated increasing step rate will decrease impact forces during running. However, no research has determined the cognitive demand of gait retraining. The primary purpose was to determine the cognitive demand and effectiveness of field-based gait retraining. We hypothesized that in-field gait retraining would alter running mechanics without increasing cognitive workload as measured by EEG following learning. Runners with a history of tibial injury completed a gait retraining protocol which included a baseline run, retraining phase, practice phase, and re-assessment following retraining protocol. Results demonstrated an increase in the theta, beta, and gamma power within prefrontal cortex during new learning and corresponding return to baseline following skill acquisition and changes across alpha, beta, gamma, mu, and theta in the motor cortex (p < .05). In the midline superior parietal cortex, spectral power was greater for theta activity during new learning with a corresponding alpha suppression. Overall, the results demonstrated the use of EEG as an effective tool to measure cognitive demand for implicit motor learning and the effectiveness of in-field gait retraining.