Investigating the effect of induced stress on dual-task performance

Doing two tasks concurrently is an inevitable situation that occurs in daily life. Several factors such as pathological conditions, the aging process, and even stress may have a detrimental effect on both tasks’ performances. The aim of this study was to monitor perceived stress during dual-task to investigate how inducing stress affects dual-task performance. Eighteen healthy young participants, (24.76±3.56 years; 68.85 ±11.85 kg; 1.72±0.07 m) were recruited. Participants were asked to perform a single task (no secondary task) and DTs (wire maze with or without buzzer) randomly while standing on a firm surface. Perceived stress was obtained after each trial as a subjective measure. Ground reaction force (GRF) regularity in anterior-posterior and mediolateral directions, as well as wire maze error (ring to path contact), were calculated as dual-task performance. Subjects were able to perceive an increase in mental stress across conditions and, the increase in perceived stress led to fewer errors in the wire maze during the most stressful condition. Further, the addition of a secondary task increased the regularity of GRF in both directions, which might be due to more automatic GRF and less flexible postural control. The presence of DT and mental stress increased the regularity of GRF, while wire maze errors were reduced despite an increase in perceived stress. Induced stress during dual task appears to have caused a cost for standing, yet a benefit for wire maze performance, indicating task prioritization under stress

Dynamic stability association with cost of transport is different in patients with COPD compared to healthy controls

Patients with chronic obstructive pulmonary disease (COPD), suffer from deficits in their functional performance besides their lung disease. In this situation, increased muscle activity is needed to provide safe walking patterns, stability while walking. This increase in muscle activity leads to increased metabolic cost, i.e., using more oxygen to complete the task. The main objective of this study is to investigate the relationship between walking stability and metabolic cost in patients with COPD in comparison with age-matched controls. Seventeen patients with COPD and 23 healthy controls walked on a treadmill at three different speeds: preferred, fast (+20% preferred) and slow (-20% preferred) speeds. Metabolic cost was calculated by subtracting metabolic rate at standing from walking metabolic rate. Stability of walking was measured by margin of stability (MOS) in anterior-posterior (AP) and medio-lateral (ML) directions. We observed that mean MOS AP had an inverse relationship with COT in both groups for all speeds indicating people with lower margins of stability (higher chance of losing balance), have higher COT while walking. However, the relationship was stronger in healthy subjects and weaker in COPD. The weaker relationship in patients with COPD, could be due to the changes in lung function and muscular system due to the disease. Patients with COPD may decrease their speed to achieve a more stable walking pattern, which costs them more to move

The effect of walking speed and magnitude of perturbation on compensatory responses

Imposing a perturbation can induce an unstable condition during gait. Measuring the compensatory responses may be an accurate indicator of the ability to control stability. Responses to a perturbation can be quantified through the perturbed walking pattern deviations from an unperturbed condition. The aim of this study was to determine the effect of perturbation magnitude or speed of walking on compensatory responses to lateral perturbations during walking. Twenty healthy young participants recruited to this study and they were perturbed with the medium magnitude of perturbation, while walking on the treadmill at three different speeds (slow, preferred, and fast). They also walked on the treadmill at their preferred speed while perturbed with three different magnitudes of perturbation (small, medium, large). All perturbations were delivered toward the walker’s right side at the right heel contact. According to the results, there was a significant effect of speed of walking on the maximum deviation from unperturbed condition, indicating less deviation in faster speeds of walking. Moreover, increasing the magnitude of perturbation led to increased deviation from the unperturbed pattern. According to these results, walking with faster speed, and increasing the body momentum could be useful for maintaining stable in a perturbed condition

Ankle–foot orthosis alters biomechanics of lower extremities during walking

Lower extremity peripheral artery disease (PAD) is a cardiovascular condition caused by narrowed or blocked arteries supplying blood to the legs. Leg pain and myopathy significantly impair gait from the first step. Using AFO may assist the gait and prolong the distance patients with PAD can walk. This study aimed to investigate the effect of AFO on the gait biomechanics of patients with PAD. Fourteen Participants walked over the force platforms with and without an AFO and kinetics and kinematics were combined to quantify torques and powers of the hip, knee, and ankle joints. Our data demonstrate that use of an AFO by PAD patients can increase power absorption in ankle and hip while reducing power generation in hip. Use of an AFO produces potential benefits with respect to biomechanical improvements in gait, with some of the values approaching those found in healthy individuals. These findings are beneficial for further studies of devices designed to improve the gait of PAD patients

Strength of Plantar- and Dorsiflexors Mediates Step Regularity During a High Cognitive Load Situation in a Cross-sectional Cohort of Older and Younger Adults

Background and Purpose: Completing simultaneous tasks while standing or walking (ie, a high cognitive load situation [HCLS]) is inevitable in daily activities and can lead to interference in task performances. Age-related physical and cognitive changes may confound performance variability during HCLS in older and younger adults. Identification of these confounding effects may reveal therapy targets to maintain optimal physical function later in life. The aim of this study was to investigate the effect of increasing the difficulty levels of an additional motor task and restricting visual information, on gait parameters in younger and older adults while considering the effect of cognitive and physical covariates. Methods: Fifteen healthy younger and 14 healthy older adults were asked to complete assessments of cognitive function, balance, and strength. They were then asked to walk on a self-paced treadmill with or without carrying a plastic tray. Opaqueness of the tray (vision) and the presence of water in glasses placed on the tray (increasing task difficulty) were varied. Mean, standard deviation, and regularity (sample entropy) of step width and length were compared across conditions and groups using repeated-measures analyses of variance with and without covariate analysis. Only significantly correlated covariates of cognition, balance, and strength were entered into each model. Results and Discussion: Older adults had greater step width irregularity compared with younger adults across all conditions when controlling for concentric plantar- and dorsiflexion strength. A decline in strength may likely alter neuromuscular control of gait, specifically control of step width, which has been associated with fall risk in older adults. Adjusting for the same covariates revealed increased regularity of step length, as visual feedback from the feet was restricted. Specifically, step length was more regular while carrying an opaque tray compared with not carrying a tray. Visual restriction was a contributing factor, which led to more predictable gait kinematics, indicating the role of sensory information to enhance the adaptability during walking under HCLS. Conclusion: The knowledge of the regularity behavior of human movement can expand physical therapists\u27 treatment approaches to promote further interactivity and coordination across body systems that model behavior of healthy young individuals. Targeting strength during therapy may provide additional benefits for gait performance under HCLS

Dual tasking and the effect of short term training on risk of falling in patients with COPD

The main objective of this study is to investigate the changes of gait variability as a potential predictor of falls in patients with chronic obstructive pulmonary disease (COPD); while performing two attention demanding motor tasks at the same time on both even and uneven surfaces. Patients with COPD suffer from significant decreases in physical activity and deficits in their balance control. These patients are also at greater risk of falls than other older adults. These falls could lead to injury, hospitalization and even mortality in this population. For this purpose, in this study, the intrinsic changes of gait pattern in patients with COPD will be compared to healthy controls while doing two motor tasks at once. Walking on an uneven surface will be considered in addition to even surface as a challenging condition. As a complementary goal, the effect of training dual task behavior on improving locomotor performance will be investigated in these patients. To be more specific, the performance of trained patients with COPD will be compared to un-trained subjects. We hypothesize that performing motor- motor dual task (doing two motor tasks at once) may increase the risk of falling. Moreover; adapting to dual-task training may decrease the required concentration for doing the second additional task and prevent falling

Dynamic stability of human walking during perturbed conditions

Imposing a perturbation can induce an unstable condition during gait. Measuring the compensatory responses may be an accurate indicator of the ability to control stability. Responses to a perturbation can be quantified through the perturbed walking pattern deviations from an unperturbed condition, and the rate of return towards the unperturbed walking pattern. This study aims to determine the effect of perturbation magnitude or speed of walking on compensatory responses to medial and lateral perturbations during walking. Fifteen healthy young participants will be perturbed with the medium magnitude of perturbation (5 cm, 0.98 m/s, 0.88 m/s2), while walking on the treadmill at three different speeds (slow, preferred, and fast). They also will walk on the treadmill at their preferred speed while perturbed with three different magnitudes of perturbation (small, medium, large). All perturbations will be delivered as a platform translation toward the walker’s left side at right heel contact (medial) and toward the walker’s left side at left heel contact (lateral). The impulse to the participant is analyzed using the integral of the ground reaction force result vector. The response to the perturbation can be divided into two compensatory phases: 1) (resistance) and 2) recovery phase. It is expected that Increasing walking speed will improve resistance to the perturbation while decreasing the performance in the recovery phase of the compensatory response. Increasing perturbation magnitudes is assumed to negatively affect recovery compensatory responses while resistance to the perturbation will remain unchanged

Comparing Home-based Pulmonary Rehabilitation Nursing on Fatigue and quality of life in Patients with COPD

  Background & Objective:The aim of the present study is to compare the effects of home-based pulmonary rehabilitation nursing care on Fatigue and QOL in patients with COPD. Materials & Methods: This study was a semi experimental research. The samples were consisted of 36 patients who were selected based on inclusion and exclusion criteria into control and experimental groups through random block sampling. For each of the experimental group 3 sessions of 1 hour raining over three consecutive days were done individually and it continuous up to 7 days after the patients discharged from the hospital. However, the control group was under the regular manner. Fatigue and quality of life in both groups before the intervention and 7 weeks after discharge using the Fatigue Severity Scale (FSS) and quality of life questionnaire SF-12 were compared. The data were analyzed through inferential and descriptive statistic (Independent and paired t-test, chi-square and covariance analysis). Results: Eta squared values ​​obtained in this experiment also showed that the effect of home-based pulmonary rehabilitation program on fatigue (89%) is greater than the quality of life (50%), respectively. Conclusion: As the findings indicate, the effect of home-based pulmonary rehabilitation nursing care, which has the decreasing factor on fatigue is more than the quality of life in patients with COPD.&nbsp