Yves Lajoie
University of Ottawa
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Featured researches published by Yves Lajoie.
Archives of Gerontology and Geriatrics | 2004
Yves Lajoie; S.P Gallagher
Simple reaction time, the Berg balance scale, the Activities-specific Balance Confidence (ABC) scale and postural sway were studied in order to determine cut-off scores as well as develop a model used in the prevention of fallers within the elderly community. One hundred and twenty-five subjects, 45 fallers and 80 non-fallers were evaluated throughout the study and results indicated that non-fallers have significantly faster reaction times, have higher scores on the Berg balance scale and the ABC scale as well as sway at slower frequencies when compared to fallers. Furthermore, all risk factors were subsequently entered into a logistic regression analysis and results showed that reaction time, the total Berg score and the total ABC score contributed significantly to the prediction of falls with 89% sensitivity and 96% specificity. A second logistic regression was carried out with the same previous variables as well as all questions of the Berg and ABC scales. Results from the logistic analysis revealed that three variables were associated with fall status with 91% sensitivity and 97% specificity. Results from the following study would seem rather valuable as an assessment tool for health care professionals in the identification and monitoring of potential fallers within nursing homes and throughout the community.
Experimental Brain Research | 1993
Yves Lajoie; Normand Teasdale; Chantal Bard; Michelle Fleury
Upright standing and walking tasks require the integration of several sources of sensory information. In a normal and highly predictable environment, locomotor synergies involving several muscles may take place at lower spinal levels with neural circuitry tuned by local loops of assistance or self-organizing processes generated in coordinative networks. When ongoing regulation of gait is necessary (obstacles, changes in direction) supraspinal involvement is necessary to perform movements adapted to the environment. Using a classical information processing framework and a dual-task methodology, it is possible to evaluate the attentional demands for performing static and dynamic equilibrium tasks. The present experiment evaluates whether the attentional requirements for a control sitting condition and for standing and walking conditions vary with the intrinsic balance demands of the tasks. The results show that standing and walking conditions required more attention than sitting in a chair. The attentional cost for walking was also significantly greater than for standing. For the walking task, reaction times when subjects were in singlesupport phase (small base of support) were significantly longer than those in double-support phase, suggesting that the attentional demands increased with an increase in the balance requirements of the task. Balance control requires a continuous regulation and integration of sensory inputs; increasing balance demands loads the higher level cognitive system.
Experimental Aging Research | 1996
Yves Lajoie; Normand Teasdale; Chantal Bard; Michelle Fleury
This study evaluates attentional requirements for maintaining an upright posture and for walking among young and elderly persons to determine if, with normal aging, there is a deficit and/or a modification in the allocation of the attentional resources necessary for balance control. Eight young adults and 8 elderly persons were asked to respond to an auditory reaction time (RT) task (secondary task) while in a seated position, while in a broad-support or narrow-support upright standing position, and while walking (primary tasks). Reducing the base of support yielded slower RTs for the elderly than for the young persons. When walking, the elderly persons adopted a slower speed than young persons. They also had a shorter stride length. These adaptations have been reported to produce a more secure gait. Even so, they responded to the probe RT task with greater delays than young adults. Together, the results suggest that normal aging requires that a greater proportion of attentional resources be allocated to the balance demands of postural tasks.
Archives of Physical Medicine and Rehabilitation | 1996
Richard Courtemanche; Normand Teasdale; Pierre Boucher; Michelle Fleury; Yves Lajoie; Chantal Bard
OBJECTIVE To examine whether a reduced peripheral sensibility caused by diabetic neuropathy increases the attentional demands necessary for controlling and regulating gait. DESIGN Nonrandomized control trial. SETTING University motor performance laboratory. SUBJECTS Twelve diabetic patients with peripheral neuropathy and 7 control subjects, all volunteers. INTERVENTIONS All subjects first performed a control seated reaction time task. For the walking task, auditory stimuli were randomly presented in the third, fourth, or fifth walking cycle on left foot toe off on left foot heel contact. The subjects task was to respond verbally as fast as possible to the auditory stimulus, while maintaining progression. MAIN OUTCOME MEASURES Simple reaction times and kinematics of the gait pattern (cycle amplitude, cycle duration, cycle speed, cadence and percentage of time spent in the single support phase) were evaluated. RESULTS For the walking task, diabetic neuropathic patients had a smaller cycle amplitude, cycle speed, and percentage of time spent in the single support phase than control subjects. Also, reaction times while walking were higher for diabetic neuropathic patients than for control subjects. CONCLUSIONS Diabetic neuropathic patients show a less destabilizing and more conservative gait than control subjects. The increased attentional demands in gait for the diabetic neuropathic patients, along with their more conservative gait pattern, suggest that a lack of proprioception from the legs affects the control of gait. Diminished sensory information makes gait control more cognitively dependent in diabetic neuropathic persons than in control subjects.
Cyberpsychology, Behavior, and Social Networking | 2007
Etienne J. Bisson; Bruce Contant; Heidi Sveistrup; Yves Lajoie
Virtual reality (VR) training has been used successfully to rehabilitate functional balance and mobility in both traumatic brain injury (TBI) survivors and elderly subjects. Similarly, computer-based biofeedback (BF) training has resulted in decreased sway during quiet stance and decreased reaction times during a dual-task reaction time paradigm in elderly subjects. The objective of this study was to determine the effect of VR and BF training on balance and reaction time in older adults. Two groups of twelve healthy older adults completed 10-week training programs consisting of two 30-min sessions per week. VR training required that participants lean sideways to juggle a virtual ball. Participants in the BF group viewed a red dot representing their center of gravity on a screen and were required to move the dot to the four corners of the monitor. Measures of functional balance and mobility (Community Balance and Mobility Scale [CB&M]), sway during quiet stance, and reaction time during a dual task paradigm were recorded before training, as well as 1 week and 1 month after the end of the program. Both groups showed significant improvements on the CB&M, as well as decreased reaction times with training. Postural sway during quiet stance did not change significantly.
Neuropsychologia | 1992
Chantal Bard; Jacques Paillard; Yves Lajoie; Michelle Fleury; Normand Teasdale; Robert Forget; Y. Lamarre
The accuracy of the motor system in synchronizing simultaneous movements initiations was tested in two conditions: (1) when the motor commands were triggered by an external signal (reactive condition), and (2) when subjects self-paced their movement onsets (self-paced condition). The task consisted of initiating simultaneously ipsilateral finger extension and heel raising. Eight normal subjects and a deafferented patient were tested. In the reactive condition, both normal subjects and the deafferented patient exhibited a precession of finger initiation over heel raising. This delay corresponds to the difference observed in the reaction time of the two limbs when measured independently. It reflects the difference in conduction times of the efferent pathways, as if the two motor commands were released simultaneously through a common triggering signal in the motor cortex. In contrast, in the self-paced condition normal subjects showed precession of heel over finger onsets, suggesting that synchrony is based upon the evaluation of afferent information. Unlike normal subjects, the patient showed no heel precession in the self-paced condition. These findings suggest that reactive and self-paced responses are produced through two different control modes and that afferent information contributes to the timing of motor commands in the self-paced mode.
Gerontology | 2003
Ginette Azizah Mbourou; Yves Lajoie; Normand Teasdale
Background: Normal aging is characterized by functional changes in the sensory, neurological and musculoskeletal systems. These changes affect several motor tasks including postural balance and gait. Gait variability has been suggested to be an important predictor of the risk of falling: the age-related increased variability may result of errors in the control of foot placement and/or center of mass displacement. Falls occur most frequently in elderly populations who scored poorly during transfer of quasi-static to dynamic situations, turning and reaching tasks in clinical tests. This suggests that gait initiation, which is a transient phase between standing and walking, could contribute to an increase in variability because, for elderly, muscular synergies associated with gait initiation occur less frequently than for young adults. Objective: To examine if gait initiation and more particularly the variability of the first step length and the duration of the first double support period are more important for elderly fallers than for eldery non-fallers and young adults. Methods: Elderly fallers, elderly non-fallers, and young adults were asked to initiate gait and walk at least 3 strides. Spatio-temporal characteristics of the first step and following strides were collected and across-trials variability analysed. Results: Elderly fallers showed a much smaller first step length and a longer duration of the double support period. The first step length variability of elderly fallers was more than twice greater than that observed for elderly non-fallers. Conclusion: Considering the importance of proper initial foot placement for gait initiation and for stepping recovery responses, the first step length variability observed for the elderly fallers may be an important predictor of postural problems.
Archives of Gerontology and Geriatrics | 2002
Yves Lajoie; A Girard; M Guay
Postural sway, reaction time, the Berg Scale and the Activities-specific Balance Confidence Scale (ABC) were administered to 80 elderly subjects (40 fallers and 40 healthy non-fallers) in order to determine reliable predictor for those at risk of falling. Non-fallers showed significantly faster reaction times when compared with fallers experimental group. Postural sway results show a higher oscillation displacement in the Y axis (lateral) than the X axis (anterior-posterior) and that fallers oscillate at a higher frequency than non-fallers. All variables were submitted to a multiple regression analysis. Only three of the four variables were found to be significant predictors of fall status. The variables in order of their inclusion are reaction time, Total Berg Balance Score and mean ABC. It was further determined that reaction time was indeed the best predictor of fall status in the present study.
Gait & Posture | 2011
Etienne J. Bisson; Daniel McEwen; Yves Lajoie; Martin Bilodeau
The effect of muscle fatigue on quiet standing is equivocal, including its duration/recovery and whether it leads to an increase in attentional demands. The purpose of this study was to assess the effects of ankle and hip muscle fatigue on postural sway and simple reaction time during a unipedal task. Two groups of 14 young adults (mean age=22.50±3.23) had to stand on their dominant leg for 30-s trials before and after fatigue of hip or ankle flexors and extensors. Half of the unipedal trials were performed in a dual-task condition where subjects, in addition to standing, had to respond verbally to an auditory stimulus. Sway area, and sway variability and velocity in the AP and ML planes were calculated using center of pressure data obtained from a force platform. Voice reaction time was recorded seated and during the dual-task condition to assess attentional demands. A main effect of fatigue was found for AP sway variability (p=0.027), AP sway velocity (p=0.017) and ML sway velocity (p=0.004). Both groups showed increased sway velocity in both directions and in reaction time during the dual-task condition (p<0.001), but reaction time did not increase with fatigue. A group by fatigue interaction was found significant for ML sway velocity (p=0.043). Results suggest that hip and ankle fatigue affected postural control in the fatigued plane (AP) but only hip fatigue affected postural control in the non-fatigued plane (ML sway velocity). However, fatigue did not lead to an increase in attentional demands and increased AP and ML sway velocity had recovered within 30min.
Aging Clinical and Experimental Research | 2004
Yves Lajoie
Background and aims: Previous research on various fall prevention strategies, in an effort to help the aging population has lead to inconsistent results. In this experiment, an 8-week computerized training program with a feedback fading protocol was given to 12 community-dwelling elderly subjects twice a week. Methods: Postural sway (force plate measures), attentional demands (dual-task paradigm), the Berg Balance Scale and the Activities-specific Balance Confidence Scale (ABC) were measured in pre-, post-, and retention test assessments. Results: Results indicated that the experimental group showed a significant decrease in reaction time during standing compared with the control group, and the difference remained significant even after a two-week period (retention test). Postural sway and ABC results showed no significant changes between groups in either post-test or retention test. The Berg Balance Scale scores were significantly higher in the post-test compared with the pre-test. The Berg scale is a functional mobility scale, and the increase observed may be associated with a decrease of at least 4% in the risk of falling. This study further illustrates that postural sway (mode frequency) may not be the best variable to measure the efficiency of a treatment or training protocol. Reaction time in the dual-task paradigm, which was used to measure attentional demands during posture, was found to be affected more by the training program. Conclusions: Postural training in combination with a feedback fading protocol seems to improve the automaticity of posture significantly.