Rebecca Reed-jones - Academia.edu (original) (raw)

Papers by Rebecca Reed-jones

Experimental Brain Research, 2009

We have previously shown that participants who step in place while viewing a moving scene that si... more We have previously shown that participants who step in place while viewing a moving scene that simulates walking towards and turning a corner demonstrate anticipatory sequential reorientation of axial body segments with timing characteristics similar to those seen during real turning. We propose that the coordination of axial body segments during steering represents a robust pre-programmed postural synergy triggered by gaze realignment in the desired direction of travel. The primary aim of the current study was to test this hypothesis by studying the eVects of constraining eye movement on visually evoked steering responses exhibited by participants stepping in place in a virtual environment. We predicted that preventing participants from generating anticipatory gaze shifts would sig-niWcantly attenuate or eliminate visually evoked postural responses. A secondary aim was to investigate the nature of the visual cues that trigger the coordinated eye and whole body response by testing whether spatial (distance from the corner) or temporal (time to contact with corner) parameters modulated with the speed of the visual scene (normal, half speed and double speed). Six university graduate student (27.8 § 5.0 years) participants were asked to step in place at a self-selected comfortable pace while immersed in a virtual environment which simulated walking down a hallway and turning a corner. In half of the trials participants were required to maintain gaze direction on a static target placed in the middle of the viewing screen. Whole body kinematics and gaze behaviour were recorded. In support of our hypothesis, gaze Wxation on a stationary target resulted in the suppression of anticipatory steering responses. Although postural adjustments were still observed during constrained gaze trials, they were reactive rather than anticipatory in nature and were signiWcantly smaller than trials in which gaze was unconstrained. Our results further suggest that the time of eye and body reorientation is dependent on the temporal rather than spatial visual cues, i.e. visually speciWed estimation time to contact with the virtual corner. These results indicate that gaze redirection is a prerequisite for the initiation of a pre-programmed steering synergy and suggest that these robust postural responses are intimately linked to the oculomotor control processes within the central nervous system.

Frontiers in Sports and Active Living

Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups... more Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups, such as Parkinson's disease (PD), do not produce anticipatory eye movements, leading to increased risk of falls. Visual cues may promote anticipatory eye movement by guiding the eyes into the turn. This study examined if visual cues could train anticipatory eye movement. Ten neurotypical young adults and 6 adults with PD completed three blocks of walking trials. Trials were blocked by visual condition: non-cued baseline turns (5 trials), visually cued turns (10 trials), and non-cued post turns (5 trials). A Delsys Trigno (Delsys, Boston, MA) recorded horizontal saccades at 1024 Hz via electrooculography (EOG). Two Optotrak cameras (Northern Digital Inc., ON, Canada) captured body segment kinematics at 120 Hz. Initiation of segment rotation with respect to ipsilateral foot contact (IFC1) prior to the turn was calculated. Neurotypical young adults (NYA) produced typical cranio-caudal rotation sequences during walking turns. Eyes led (407 ms prior to IFC1), followed by the head (50 ms prior to IFC1), then trunk and pelvis. In contrast, PD produced no anticipatory eye or segment movement at baseline. During pre-trials the eyes moved 96 ms after IFC1 and segment movement was initiated by the pelvis followed by trunk and head segments. After visual cue training however, PD produced anticipatory eye movements 161 ms prior to IFC1, followed by the head 88 ms following IFC1 but ahead of trunk and pelvis onset. These results suggest visual cues assist in producing cranio-caudal control during walking turns in PD.

Proceedings of the 4th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle

Electrical stimulation of the vestibular sensory system during virtual environment simulations ha... more Electrical stimulation of the vestibular sensory system during virtual environment simulations has been proposed as a method to reduce the incidence of simulator adaptation syndrome (SAS). However, there is limited empirical evidence to support this hypothesis. It is especially important to provide vestibular stimulation in driving simulators because an absence of vestibular cues may alter driver behaviour and reduce vehicle control. This study examined the application of galvanic vestibular stimulation (GVS) as a technique to reduce symptoms of SAS and improve vehicular control in a fixed-based driving simulator. Nineteen participants drove two visually distinct virtual environments (high and low visual cues). In addition, each of these worlds was experienced with and without GVS. Post-drive scores on the Simulator Sickness Questionnaire (SSQ) were used to evaluate the effect of GVS on SAS. In addition, three driving variables were measured to examine driving performance: steering variability, lane departures, and average vehicular speed. GVS application while driving resulted in significant decreases in total SSQ and disorientation symptoms. Greater vehicular control was also observed (as shown by reduced steering variability) when GVS was used in combination with visual cues along the simulated edge of the road. These results support that GVS may be used in fixed-base driving simulators to create vestibular motion cues and reduce SAS.

Seminars in Speech and Language

Postural instability is a cardinal indicator of concussion. Assessments of the postural control s... more Postural instability is a cardinal indicator of concussion. Assessments of the postural control system range from clinical to laboratory tests that assess the balance of the individual. In a previous article regarding clinical assessment of balance in adults with concussion, we reviewed the importance of balance as a component in concussion evaluations. The purpose of this review article is to update the information previously published in 2014. Since 2014, research has provided evidence for the incorporation of dynamic methods for evaluating balance postconcussion with particular emphasis on sensory system integration and dual tasking. Therefore, this review will examine the current state of knowledge on how concussion injuries affect postural control, advancements in evaluating balance postconcussion, such as novel eye-tracking techniques, and current recommendations for best practices for balance assessment.

Medicine & Science in Sports & Exercise

Previous research showed that morphological changes affect muscular strength only after six weeks... more Previous research showed that morphological changes affect muscular strength only after six weeks of training and that shortterm strength increases are primarily due to neuromuscular adaptations. It is hypothesized that early strength increases may be elicited through the practice of resistance training movements with minimal overload. PURPOSE: To compare the short-term strength changes between three groups of untrained young adults training with: a) overload resistance (OR); b) minimal resistance (MR); and 3) no active training (Control). METHODS: Thirty-nine untrained adults, (mean±SD age: 23.5±3.9; BMI: 25.4±5.2) with no experience in resistance training were assigned to the OR, MR, or Control groups using blocked randomization. The experiment focused on two multi-joint exercises, the bench press and the back squat. Subjects' strength was assessed by the one repetition maximum (1RM) tests and by an isometric bench press test with relevant force plate data collected. Subjects completed two training sessions weekly with three sets of ten repetitions of each exercise. The OR group used 75% of their latest measured 1RM, while the MR group used a weightless 5 ft. PVC pipe for both exercises. Subjects in the control group were asked to refrain from any training during the experiment. Follow-up tests were administered every two weeks. Strength data were analyzed using a general linear mixed model and alpha level was set at p<0.05. RESULTS: There were no initial strength differences between the groups for the 1RM bench press (p>0.9419), 1 RM squat (p=0.9564), or isometric bench press tests (p=0.06381). From pre-to post-test for the 1RM bench press the OR group improved 10.2% (p<0.0001), the MR group improved 5.4% (p<0.0001), while the control group showed only minimal (2.4%) and non-significant (p=0.0725) improvement. A significant group by time interaction (p<0.0001) was observed suggesting a different improvement pattern across the groups. For the 1RM back squat the OR group improved 12.1% (p<0.0001), the MR group improved 10.3% (p<0.0001), while the control group showed only minimal (5.2%) but significant (p=0.0415) improvement. A significant group by time interaction (p= 0.0291) was also observed, confirming the different improvement patterns across the groups. For the isometric bench press none of the groups showed significant improvements (p=0.6357). The OR group showed an improving trend (8.4%) from pre-to post-test, while the MR and Control groups showed decrements (-4.3% and-0.3%, respectively). Group by time interaction was not significant (p=0.2388), suggesting a similar response pattern across the groups. CONCLUSION: According to our results training with overload intensities appears to be superior even in the initial short timeperiod of neuromuscular adaptation. Yet, practicing resistance training movements without any training load appears to provide sufficient training stimulus to elicit initial strength changes in untrained subjects. It appears that strength improvement is testspecific, as improvements in 1RM bench press did not transfer to significant isometric bench press strength improvement for any group, although the overload resistance group showed a positive trend. PRACTICAL APPLICATION: Practicing proper exercise techniqueparticularly for multi-joint movementswith minimal or no resistance overloads may provide a safe and effective method of achieving initial strength adaptations in untrained individuals.

Medicine & Science in Sports & Exercise

Medicine & Science in Sports & Exercise

Clinical biomechanics (Bristol, Avon), 2017

Approximately 90% of athletes with concussion experience a certain degree of visual system dysfun... more Approximately 90% of athletes with concussion experience a certain degree of visual system dysfunction immediately post-concussion. Of these abnormalities, gaze stability deficits are denoted as among the most common. Little research quantitatively explores these variables post-concussion. As such, the purpose of this study was to investigate and compare gaze stability between a control group of healthy non-injured athletes and a group of athletes with concussions 24-48hours post-injury. Ten collegiate NCAA Division I athletes with concussions and ten healthy control collegiate athletes completed two trials of a sport-like antisaccade postural control task, the Wii Fit Soccer Heading Game. During play all participants were instructed to minimize gaze deviations away from a central fixed area. Athletes with concussions were assessed within 24-48 post-concussion while healthy control data were collected during pre-season athletic screening. Raw ocular point of gaze coordinates were tr...

The European journal of neuroscience, 2017

Falls are a growing concern among older adults and individuals living with a neurodegenerative di... more Falls are a growing concern among older adults and individuals living with a neurodegenerative disease that affects movement control. Growing evidence continues to encourage researchers and clinicians to consider vision when evaluating movement control and potential risk of falling (Lord & Dayhew, 2001; Lord et al., 2010); however, recommendations and guidelines for evaluating vision beyond standard classification of a visual impairment (e.g. near-sightedness) continue to be limited (AGS/BGS, 2010). Vision is not just the ability to see accurately, it also includes the ability to direct visual gaze in the surrounding environment, perceive the spatial relationships between external objects and the body and use this information to plan and execute movement or adapt ongoing motor patterns (Patla, 1997). Adaptation of motor patterns to environmental constraints, particularly during gait, is an essential part of mobility function in daily life, and reductions in the ability to adapt gait increase ones' risk of falling. Therefore, visual function as a whole is an essential component to fall risk and mobility function. Further, visual function may indirectly play a role in other aspects of fall risk. Research in the last decade or so has supported the idea that divided attention during dual tasking (performance of simultaneous motor and cognitive tasks) results in negative effects on gait and/or decreased cognitive task performance, for example increased stride to stride variability and decreased gait velocity (

Games for health journal, 2017

Use of the Nintendo Wii™ as a balance assessment and rehabilitation tool continues to grow. One a... more Use of the Nintendo Wii™ as a balance assessment and rehabilitation tool continues to grow. One advantage of the Wii is that games can serve as a virtual reality training tool; however, a disadvantage of the Wii is the human-machine interface and the learning effect over multiple trials. The purpose of this study was to assess changes in postural control during Wii gameplay over a series of trials in novice players. Thirty-one university athletes (aged 18-25 years) completed four trials of the Nintendo Wii Fit™ soccer heading (SH) balance game. Center of pressure (COP) was calculated in the anterior-posterior (AP) and medial-lateral (ML) directions for each 70-second time trial at 1000 Hz. COP was assessed using six linear and two nonlinear measures. Repeated measures analysis of variances compared COP measures over the four trials. Significant differences in COP magnitude and velocity were found between trials 1 and 2 in the ML direction. No significant effects of trial were found ...

Medicine & Science in Sports & Exercise, 2015

International journal of exercise science

Weightlifters have commonly believed that changing joint position can alter specific muscle activ... more Weightlifters have commonly believed that changing joint position can alter specific muscle activation. The magnitude of force produced by a muscle is highly dependent upon the length of the muscle. The purpose of this study was to determine the effect of foot positioning on muscle activation of the superficial quadriceps as measured by surface electromyography (sEMG) during a functional squatting movement in healthy adults. Twenty physically active asymptomatic adults (7 females and 13 males) were included in the study while four different foot positions (Neutral, Internally Rotated, Externally Rotated, and Staggered) were assessed. Three quadriceps muscles (Rectus Femoris (RF), Vastus Medialis Oblique (VMO), and Vastus Lateralis Oblique(VLO) were measured. Raw EMG was transformed using a root mean square algorithm. Six one-way repeated measure ANOVAs were conducted to examine the peak and average RMS amplitude for each muscle across each condition, with an alpha level of 0.05 set ...

Medicine and science in sports and exercise, 2016

Journal of Clinical and Translational Research, 2016

Background: Approximately 30% of individuals with a sport-related concussion present with postura... more Background: Approximately 30% of individuals with a sport-related concussion present with postural instability. Multiple clinical balance tests exist to diagnose postural instability; yet little is known about the potential relationship between these type of postural assessments and cognition post-concussion. Aim: The purpose of the current study was to assess the relationship between the Romberg test, the Wii Fit basic balance test (WBBT), and the composite scores on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test in a sample of athletes with concussions. Methods: Fifty five post-concussed athletes (40 males) completed the Romberg test (RT) (−/+), the WBBT, and ImPACT test. WBBT performance was operationalized as the number of successfully completed trials (of 5 trials of increasing difficulty) within 30 seconds. Pearson's and point-biserial correlations examined univariate associations among the variables. Results: The RT and WBBT were not significantly related (r = − 0.029, p = 0.832). The RT weakly correlated with ImPACT impairment scores (r = 0.26, p = 0.041), whereas WBBT the number of trials did not (r = − 0.20, p = 0.155). The RT scores were significantly correlated with ImPACT Visual Processing Speed Score (r = 0.27, p = 0.036) and Reaction Time score (r = 0.34, p = 0.006). In contrast, WBBT trials were significantly correlated with the ImPACT Visual Memory Score (r = − 0.41, p = 0.003). Conclusions: These results suggest that the WBBT and RT assess unique aspects of postural control. The RT may relate directly to single sensory cognitive and motor processing, while the WBBT may relate to multi-sensory visually driven cognitive and motor processing. Relevance for patients: Clinical balance tests could point to different cognitive impairments post-concussion.

Experimental brain research, Jan 20, 2016

Walking and turning is a movement that places individuals with Parkinson's disease (PD) at in... more Walking and turning is a movement that places individuals with Parkinson's disease (PD) at increased risk for fall-related injury. However, turning is an essential movement in activities of daily living, making up to 45 % of the total steps taken in a given day. Hypotheses regarding how turning is controlled suggest an essential role of anticipatory eye movements to provide feedforward information for body coordination. However, little research has investigated control of turning in individuals with PD with specific consideration for eye movements. The purpose of this study was to examine eye movement behavior and body segment coordination in individuals with PD during walking turns. Three experimental groups, a group of individuals with PD, a group of healthy young adults (YAC), and a group of healthy older adults (OAC), performed walking and turning tasks under two visual conditions: free gaze and fixed gaze. Whole-body motion capture and eye tracking characterized body segmen...

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are

Experimental Brain Research, 2009

We have previously shown that participants who step in place while viewing a moving scene that si... more We have previously shown that participants who step in place while viewing a moving scene that simulates walking towards and turning a corner demonstrate anticipatory sequential reorientation of axial body segments with timing characteristics similar to those seen during real turning. We propose that the coordination of axial body segments during steering represents a robust pre-programmed postural synergy triggered by gaze realignment in the desired direction of travel. The primary aim of the current study was to test this hypothesis by studying the eVects of constraining eye movement on visually evoked steering responses exhibited by participants stepping in place in a virtual environment. We predicted that preventing participants from generating anticipatory gaze shifts would sig-niWcantly attenuate or eliminate visually evoked postural responses. A secondary aim was to investigate the nature of the visual cues that trigger the coordinated eye and whole body response by testing whether spatial (distance from the corner) or temporal (time to contact with corner) parameters modulated with the speed of the visual scene (normal, half speed and double speed). Six university graduate student (27.8 § 5.0 years) participants were asked to step in place at a self-selected comfortable pace while immersed in a virtual environment which simulated walking down a hallway and turning a corner. In half of the trials participants were required to maintain gaze direction on a static target placed in the middle of the viewing screen. Whole body kinematics and gaze behaviour were recorded. In support of our hypothesis, gaze Wxation on a stationary target resulted in the suppression of anticipatory steering responses. Although postural adjustments were still observed during constrained gaze trials, they were reactive rather than anticipatory in nature and were signiWcantly smaller than trials in which gaze was unconstrained. Our results further suggest that the time of eye and body reorientation is dependent on the temporal rather than spatial visual cues, i.e. visually speciWed estimation time to contact with the virtual corner. These results indicate that gaze redirection is a prerequisite for the initiation of a pre-programmed steering synergy and suggest that these robust postural responses are intimately linked to the oculomotor control processes within the central nervous system.

Frontiers in Sports and Active Living

Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups... more Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups, such as Parkinson's disease (PD), do not produce anticipatory eye movements, leading to increased risk of falls. Visual cues may promote anticipatory eye movement by guiding the eyes into the turn. This study examined if visual cues could train anticipatory eye movement. Ten neurotypical young adults and 6 adults with PD completed three blocks of walking trials. Trials were blocked by visual condition: non-cued baseline turns (5 trials), visually cued turns (10 trials), and non-cued post turns (5 trials). A Delsys Trigno (Delsys, Boston, MA) recorded horizontal saccades at 1024 Hz via electrooculography (EOG). Two Optotrak cameras (Northern Digital Inc., ON, Canada) captured body segment kinematics at 120 Hz. Initiation of segment rotation with respect to ipsilateral foot contact (IFC1) prior to the turn was calculated. Neurotypical young adults (NYA) produced typical cranio-caudal rotation sequences during walking turns. Eyes led (407 ms prior to IFC1), followed by the head (50 ms prior to IFC1), then trunk and pelvis. In contrast, PD produced no anticipatory eye or segment movement at baseline. During pre-trials the eyes moved 96 ms after IFC1 and segment movement was initiated by the pelvis followed by trunk and head segments. After visual cue training however, PD produced anticipatory eye movements 161 ms prior to IFC1, followed by the head 88 ms following IFC1 but ahead of trunk and pelvis onset. These results suggest visual cues assist in producing cranio-caudal control during walking turns in PD.

Proceedings of the 4th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle

Electrical stimulation of the vestibular sensory system during virtual environment simulations ha... more Electrical stimulation of the vestibular sensory system during virtual environment simulations has been proposed as a method to reduce the incidence of simulator adaptation syndrome (SAS). However, there is limited empirical evidence to support this hypothesis. It is especially important to provide vestibular stimulation in driving simulators because an absence of vestibular cues may alter driver behaviour and reduce vehicle control. This study examined the application of galvanic vestibular stimulation (GVS) as a technique to reduce symptoms of SAS and improve vehicular control in a fixed-based driving simulator. Nineteen participants drove two visually distinct virtual environments (high and low visual cues). In addition, each of these worlds was experienced with and without GVS. Post-drive scores on the Simulator Sickness Questionnaire (SSQ) were used to evaluate the effect of GVS on SAS. In addition, three driving variables were measured to examine driving performance: steering variability, lane departures, and average vehicular speed. GVS application while driving resulted in significant decreases in total SSQ and disorientation symptoms. Greater vehicular control was also observed (as shown by reduced steering variability) when GVS was used in combination with visual cues along the simulated edge of the road. These results support that GVS may be used in fixed-base driving simulators to create vestibular motion cues and reduce SAS.

Seminars in Speech and Language

Postural instability is a cardinal indicator of concussion. Assessments of the postural control s... more Postural instability is a cardinal indicator of concussion. Assessments of the postural control system range from clinical to laboratory tests that assess the balance of the individual. In a previous article regarding clinical assessment of balance in adults with concussion, we reviewed the importance of balance as a component in concussion evaluations. The purpose of this review article is to update the information previously published in 2014. Since 2014, research has provided evidence for the incorporation of dynamic methods for evaluating balance postconcussion with particular emphasis on sensory system integration and dual tasking. Therefore, this review will examine the current state of knowledge on how concussion injuries affect postural control, advancements in evaluating balance postconcussion, such as novel eye-tracking techniques, and current recommendations for best practices for balance assessment.

Medicine & Science in Sports & Exercise

Previous research showed that morphological changes affect muscular strength only after six weeks... more Previous research showed that morphological changes affect muscular strength only after six weeks of training and that shortterm strength increases are primarily due to neuromuscular adaptations. It is hypothesized that early strength increases may be elicited through the practice of resistance training movements with minimal overload. PURPOSE: To compare the short-term strength changes between three groups of untrained young adults training with: a) overload resistance (OR); b) minimal resistance (MR); and 3) no active training (Control). METHODS: Thirty-nine untrained adults, (mean±SD age: 23.5±3.9; BMI: 25.4±5.2) with no experience in resistance training were assigned to the OR, MR, or Control groups using blocked randomization. The experiment focused on two multi-joint exercises, the bench press and the back squat. Subjects' strength was assessed by the one repetition maximum (1RM) tests and by an isometric bench press test with relevant force plate data collected. Subjects completed two training sessions weekly with three sets of ten repetitions of each exercise. The OR group used 75% of their latest measured 1RM, while the MR group used a weightless 5 ft. PVC pipe for both exercises. Subjects in the control group were asked to refrain from any training during the experiment. Follow-up tests were administered every two weeks. Strength data were analyzed using a general linear mixed model and alpha level was set at p<0.05. RESULTS: There were no initial strength differences between the groups for the 1RM bench press (p>0.9419), 1 RM squat (p=0.9564), or isometric bench press tests (p=0.06381). From pre-to post-test for the 1RM bench press the OR group improved 10.2% (p<0.0001), the MR group improved 5.4% (p<0.0001), while the control group showed only minimal (2.4%) and non-significant (p=0.0725) improvement. A significant group by time interaction (p<0.0001) was observed suggesting a different improvement pattern across the groups. For the 1RM back squat the OR group improved 12.1% (p<0.0001), the MR group improved 10.3% (p<0.0001), while the control group showed only minimal (5.2%) but significant (p=0.0415) improvement. A significant group by time interaction (p= 0.0291) was also observed, confirming the different improvement patterns across the groups. For the isometric bench press none of the groups showed significant improvements (p=0.6357). The OR group showed an improving trend (8.4%) from pre-to post-test, while the MR and Control groups showed decrements (-4.3% and-0.3%, respectively). Group by time interaction was not significant (p=0.2388), suggesting a similar response pattern across the groups. CONCLUSION: According to our results training with overload intensities appears to be superior even in the initial short timeperiod of neuromuscular adaptation. Yet, practicing resistance training movements without any training load appears to provide sufficient training stimulus to elicit initial strength changes in untrained subjects. It appears that strength improvement is testspecific, as improvements in 1RM bench press did not transfer to significant isometric bench press strength improvement for any group, although the overload resistance group showed a positive trend. PRACTICAL APPLICATION: Practicing proper exercise techniqueparticularly for multi-joint movementswith minimal or no resistance overloads may provide a safe and effective method of achieving initial strength adaptations in untrained individuals.

Medicine & Science in Sports & Exercise

Medicine & Science in Sports & Exercise

Clinical biomechanics (Bristol, Avon), 2017

Approximately 90% of athletes with concussion experience a certain degree of visual system dysfun... more Approximately 90% of athletes with concussion experience a certain degree of visual system dysfunction immediately post-concussion. Of these abnormalities, gaze stability deficits are denoted as among the most common. Little research quantitatively explores these variables post-concussion. As such, the purpose of this study was to investigate and compare gaze stability between a control group of healthy non-injured athletes and a group of athletes with concussions 24-48hours post-injury. Ten collegiate NCAA Division I athletes with concussions and ten healthy control collegiate athletes completed two trials of a sport-like antisaccade postural control task, the Wii Fit Soccer Heading Game. During play all participants were instructed to minimize gaze deviations away from a central fixed area. Athletes with concussions were assessed within 24-48 post-concussion while healthy control data were collected during pre-season athletic screening. Raw ocular point of gaze coordinates were tr...

The European journal of neuroscience, 2017

Falls are a growing concern among older adults and individuals living with a neurodegenerative di... more Falls are a growing concern among older adults and individuals living with a neurodegenerative disease that affects movement control. Growing evidence continues to encourage researchers and clinicians to consider vision when evaluating movement control and potential risk of falling (Lord & Dayhew, 2001; Lord et al., 2010); however, recommendations and guidelines for evaluating vision beyond standard classification of a visual impairment (e.g. near-sightedness) continue to be limited (AGS/BGS, 2010). Vision is not just the ability to see accurately, it also includes the ability to direct visual gaze in the surrounding environment, perceive the spatial relationships between external objects and the body and use this information to plan and execute movement or adapt ongoing motor patterns (Patla, 1997). Adaptation of motor patterns to environmental constraints, particularly during gait, is an essential part of mobility function in daily life, and reductions in the ability to adapt gait increase ones' risk of falling. Therefore, visual function as a whole is an essential component to fall risk and mobility function. Further, visual function may indirectly play a role in other aspects of fall risk. Research in the last decade or so has supported the idea that divided attention during dual tasking (performance of simultaneous motor and cognitive tasks) results in negative effects on gait and/or decreased cognitive task performance, for example increased stride to stride variability and decreased gait velocity (

Games for health journal, 2017

Use of the Nintendo Wii™ as a balance assessment and rehabilitation tool continues to grow. One a... more Use of the Nintendo Wii™ as a balance assessment and rehabilitation tool continues to grow. One advantage of the Wii is that games can serve as a virtual reality training tool; however, a disadvantage of the Wii is the human-machine interface and the learning effect over multiple trials. The purpose of this study was to assess changes in postural control during Wii gameplay over a series of trials in novice players. Thirty-one university athletes (aged 18-25 years) completed four trials of the Nintendo Wii Fit™ soccer heading (SH) balance game. Center of pressure (COP) was calculated in the anterior-posterior (AP) and medial-lateral (ML) directions for each 70-second time trial at 1000 Hz. COP was assessed using six linear and two nonlinear measures. Repeated measures analysis of variances compared COP measures over the four trials. Significant differences in COP magnitude and velocity were found between trials 1 and 2 in the ML direction. No significant effects of trial were found ...

Medicine & Science in Sports & Exercise, 2015

International journal of exercise science

Weightlifters have commonly believed that changing joint position can alter specific muscle activ... more Weightlifters have commonly believed that changing joint position can alter specific muscle activation. The magnitude of force produced by a muscle is highly dependent upon the length of the muscle. The purpose of this study was to determine the effect of foot positioning on muscle activation of the superficial quadriceps as measured by surface electromyography (sEMG) during a functional squatting movement in healthy adults. Twenty physically active asymptomatic adults (7 females and 13 males) were included in the study while four different foot positions (Neutral, Internally Rotated, Externally Rotated, and Staggered) were assessed. Three quadriceps muscles (Rectus Femoris (RF), Vastus Medialis Oblique (VMO), and Vastus Lateralis Oblique(VLO) were measured. Raw EMG was transformed using a root mean square algorithm. Six one-way repeated measure ANOVAs were conducted to examine the peak and average RMS amplitude for each muscle across each condition, with an alpha level of 0.05 set ...

Medicine and science in sports and exercise, 2016

Journal of Clinical and Translational Research, 2016

Background: Approximately 30% of individuals with a sport-related concussion present with postura... more Background: Approximately 30% of individuals with a sport-related concussion present with postural instability. Multiple clinical balance tests exist to diagnose postural instability; yet little is known about the potential relationship between these type of postural assessments and cognition post-concussion. Aim: The purpose of the current study was to assess the relationship between the Romberg test, the Wii Fit basic balance test (WBBT), and the composite scores on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test in a sample of athletes with concussions. Methods: Fifty five post-concussed athletes (40 males) completed the Romberg test (RT) (−/+), the WBBT, and ImPACT test. WBBT performance was operationalized as the number of successfully completed trials (of 5 trials of increasing difficulty) within 30 seconds. Pearson's and point-biserial correlations examined univariate associations among the variables. Results: The RT and WBBT were not significantly related (r = − 0.029, p = 0.832). The RT weakly correlated with ImPACT impairment scores (r = 0.26, p = 0.041), whereas WBBT the number of trials did not (r = − 0.20, p = 0.155). The RT scores were significantly correlated with ImPACT Visual Processing Speed Score (r = 0.27, p = 0.036) and Reaction Time score (r = 0.34, p = 0.006). In contrast, WBBT trials were significantly correlated with the ImPACT Visual Memory Score (r = − 0.41, p = 0.003). Conclusions: These results suggest that the WBBT and RT assess unique aspects of postural control. The RT may relate directly to single sensory cognitive and motor processing, while the WBBT may relate to multi-sensory visually driven cognitive and motor processing. Relevance for patients: Clinical balance tests could point to different cognitive impairments post-concussion.

Experimental brain research, Jan 20, 2016

Walking and turning is a movement that places individuals with Parkinson's disease (PD) at in... more Walking and turning is a movement that places individuals with Parkinson's disease (PD) at increased risk for fall-related injury. However, turning is an essential movement in activities of daily living, making up to 45 % of the total steps taken in a given day. Hypotheses regarding how turning is controlled suggest an essential role of anticipatory eye movements to provide feedforward information for body coordination. However, little research has investigated control of turning in individuals with PD with specific consideration for eye movements. The purpose of this study was to examine eye movement behavior and body segment coordination in individuals with PD during walking turns. Three experimental groups, a group of individuals with PD, a group of healthy young adults (YAC), and a group of healthy older adults (OAC), performed walking and turning tasks under two visual conditions: free gaze and fixed gaze. Whole-body motion capture and eye tracking characterized body segmen...

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are