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Introduction Some people with Parkinson’s disease (PD) frequently have an unsteady gait with shuffling, reduced strength, and increased rigidity. This study has investigated the difference in the neuromuscular strategies of people with early-stage PD, healthy older adults (HOA) and healthy young adult (HYA) during short-distance walking. Method Surface electromyogram (sEMG) was recorded from tibialis anterior (TA) and medial gastrocnemius (MG) muscles along with the acceleration data from the lower leg from 72 subjects—24 people with early-stage PD, 24 HOA and 24 HYA during short-distance walking on a level surface using wearable sensors. Results There was a significant increase in the co-activation, a reduction in the TA modulation and an increase in the TA-MG lateral asymmetry among the people with PD during a level, straight-line walking. For people with PD, the gait impairment scale was low with an average postural instability and gait disturbance (PIGD) score = 5.29 out of a maximum score of 20. Investigating the single and double support phases of the gait revealed that while the muscle activity and co-activation index (CI) of controls modulated over the gait cycle, this was highly diminished for people with PD. The biggest difference between CI of controls and people with PD was during the double support phase of gait. Discussion The study has shown that people with early-stage PD have high asymmetry, reduced modulation, and higher co-activation. They have reduced muscle activity, ability to inhibit antagonist, and modulate their muscle activities. This has the potential for diagnosis and regular assessment of people with PD to detect gait impairments using wearable sensors.

Background/objectives Little work to date has examined the relationship between gait performance and blood pressure (BP) recovery after standing in later life. The aim of this study is to clarify the association of orthostatic BP with spatiotemporal gait parameters in a large cohort of older people. Design Cross-sectional study using multilevel linear regression to ascertain the difference in orthostatic BP patterns across tertiles of gait speed, and linear regression to analyze the association of orthostatic hypotension 30 seconds after standing (OH-30) with specific gait characteristics. Setting The Irish Longitudinal Study on Ageing. Participants A total of 4311 community-dwelling adults, aged 50 years or older (mean age = 62.2 years; 54% female), one fifth (n = 791) of whom had OH-30. Measurements Continuous orthostatic BP was measured during active stand. OH-30 was defined as a drop in systolic BP of 20 mm Hg or more or drop in diastolic BP of 10 mm Hg or more at 30 seconds. Spatiotemporal gait was assessed using the GAITRite system, reporting gait speed, step length, step width, and double support time in both single and dual (cognitive task) conditions. Results OH-30 was associated with slower gait speed (β = -3.01; 95% confidence interval [CI] = -4.46 to -1.56) and shorter step length (β = -.73; 95% CI = -1.29 to -.16) in fully adjusted models during single task walking. Similar findings were observed in dual task conditions, in addition to increased double support phase (β = .45; 95% CI = .02-.88). Multilevel models demonstrated that participants in the slowest tertile for gait speed had a significantly larger drop in systolic BP poststanding compared to those with faster gait speeds in single and dual task conditions. Conclusions This study demonstrates that slower recovery of BP after standing is independently associated with poorer gait performance in community-dwelling older adults. Given the adverse outcomes independently associated with OH and gait problems in later life, increasing awareness that they commonly coexist is important, particularly as both are potentially modifiable. J Am Geriatr Soc 68:1286-1292, 2020.

Wearable inertial sensors have gradually been used as an objective technology for biomechanical assessments of both healthy and pathological movement patterns. This paper used foot-worn sensors for characterizing the spatiotemporal characteristics of walking and turning between older fallers and nonfallers. Thirty community-dwelling older fallers and 30 older nonfallers performed 10-m straight walking, turned 180° around a cone, and then walked 10-m back to the starting point. Specific algorithms were used to measure spatiotemporal gait (double support phase of the gait cycle, swing width, and minimal toe clearance) and turning parameters (turn duration and turn steps) using two foot-worn Physiolog inertial sensor system. The researchers directly exported data as reported by the system. Our findings indicated that older fallers showed 26.58% longer time (P = 0.036) and 13.21% more steps (P = 0.038) compared to nonfallers during turning. However, both groups decreased their walking velocity (both P < 0.001), increased double support (both P = 0.001), and increased the swing width (both P = 0.001) during the transition from walking to turning. The older nonfallers additionally increased toe clearance (P = 0.001). Compared with the fallers, the older nonfallers showed a larger change in the swing width (P = 0.025) and toe clearance (P = 0.025) in walking to turning. Older fallers may adopt a cautionary strategy while turning to reduce the risk of falls. Wearable sensors can provide the temporospatial characteristics of turning and reveal significant differences by fall status, indicating the potential of turning measures as possible markers for identifying those at fall risk.

The Timed Up & Go test (TUG) is functional test and is a part of routine clinical examinations. The instrumented Timed Up & Go test enables its segmentation to sub-tasks: sit-to-stand, walking forward, turning, walking back, stand-to-sit, and consequently the computation of task-specific parameters and sub-tasks separately. However, there are no data on whether walking forward parameters differ from the walking back parameters. This study tested the differences between walking forward and walking back in the TUG extended to 10 m for 17 spatio-temporal gait parameters. All parameters were obtained from a GAITRite® pressure sensitive walkway (CIR Systems, Inc.). The differences were assessed for healthy controls and Parkinson's disease (PD) patients. None of investigated parameters exhibited a difference between both gait subtasks for healthy subjects group. Five parameters of interest, namely velocity, step length, stride length, stride velocity, and the proportion of the double support phase with respect to gait cycle duration, showed a statistically significant difference between gait for walking forward and walking back in PD patients. Therefore, we recommend a separate assessment for walking forward and walking back rather than averaging both gaits together.

Gait variability (GV), which is a variable for predicting mobility issues and risk of falling in elderly people, is defined as the fluctuation in spatiotemporal characteristics from one step to the next in walking. The goal of this study was to analyze the age- and sex-related spatiotemporal variability characteristics of elderly individuals using the measurements taken while walking on a treadmill for one minute based on gait speed variation. Gait testing was conducted on 225 healthy male and female individuals aged 60–79 years who were able to walk and move on their own and, specifically, walk on a treadmill for one minute. The test was performed at three speed conditions—the preferred speed of the participant, 20% higher than the preferred speed, and 20% lower than the preferred speed—and data were recorded using shoe-type data loggers. The different age groups and sex could be distinguished using the coefficient of variance (CV) of the double support phase and gait asymmetry (GA) at the preferred speed, and CVs of stride length and stance phase at faster speed. The results indicated that the values of GV obtained from the test were used to determine the variation in gait characteristics of elderly individuals.

The purpose of this study was to examine the changes in co-activation around the knee joint during different walking speeds in healthy females using the co-activation index. Ten healthy females (age: 21.20 &plusmn, 7.21 years, height: 164.00 &plusmn, 4.00 cm, mass: 60.60 &plusmn, 4.99 kg) participated in this study and performed three walking speeds (slow, normal, and fast). A Qualisys 11-camera motion analysis system sampling at a frequency of 200 Hz was synchronized with a Trigno EMG Wireless system operating at a 2000 Hz sampling frequency. A significant decrease in the co-activation index of thigh muscles was observed between the slow and fast, and between the normal and fast, walking speeds during all walking phases. A non-significant difference was observed between the slow and normal walking speeds during most walking phases, except the second double support phase, during which the difference was significant. A negative relationship was found between walking speed and the co-activation index of thigh muscles in all speeds during walking phases: first double support (r = &minus, 0.3386, p &lt, 0.001), single support (r = &minus, 0.2144, p &lt, 0.01), second double support (r = &minus, 0.4949, p &lt, 0.001), and Swing (r = &minus, 0.1639, p &lt, 0.05). In conclusion, the results indicated high variability of thigh muscle co-activation in healthy females during the different walking speeds, and a decrease in the co-activation of the thigh muscles with the increase of speed.

Increasingly, electric motors are being incorporated into wheeled walkers to implement various smart features to better assist their users physically. These modified walkers, known as Smart Walkers, use their electric motors to generate horizontal forces that can be used to reduce the physical load for walking, prevent falls and provide navigation support. However, these forces can also alter gait and may inadvertently increase the exertion of the users. This study aims to describe the effects of assistive and resistive horizontal forces (from -18.47 N to 27.70 N) from a Smart Walker on gait and perceived exertion of its users during steady-state walking. Self-selected comfortable walking speed, cadence, stride length, double support phase and ratings of perceived exertion (RPE) were significantly affected and different effects were found for resistive force, relatively low assistive force and high assistive force. With increasing force from -18.47 N to 0 N, RPE decreased and the users walked with lower double support time. From 0 N to 9.23 N, RPE continued to decrease to its lowest point while gait parameters remained constant. Further increasing force up to 27.70 N increased RPE and led to the users to choose to walk at higher speeds. This study demonstrates that users adapt their gait significantly to the forces applied and relatively high constant forces, whether assistive or resistive, will increase perceived exertion. Hence, these need to be carefully considered when developing Smart Walkers in order to provide safe and effective support to its users.

Background Gait disturbances have emerged as some of the main therapeutic concerns in late-stage Parkinson’s disease (PD) treated with dopaminergic therapy and deep brain stimulation (DBS). External cues may help to overcome freezing of gait (FOG) and improve some of the gait parameters. Aim To evaluate the effect of 3D visual cues and STN-DBS on gait in PD group. Methods We enrolled 35 PD patients treated with DBS of nucleus subthalamicus (STN-DBS). Twenty-five patients (5 females; mean age 58.9 ±6.3) and 25 sex- and age-matched controls completed the gait examination. The gait in 10 patients deteriorated in OFF state. The severity of PD was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Hoehn and Yahr (HY). The PD group filled the Falls Efficacy Scale-International (FES) and Freezing of Gait Questionnaire (FOGQ). Gait was examined using the GaitRite Analysis System, placed in the middle of the 10m marked path. The PD group was tested without dopaminergic medication with and without visual cueing together with the DBS switched ON and OFF. The setting of DBS was double-blind and performed in random order. Results The UPDRS was 21.9 ±9.5 in DBS ON state and 41.3 ±13.7 in DBS OFF state. HY was 2.5 ±0.6, FES 12.4 ±4.1 and FOGQ 9.4 ±5.7. In the DBS OFF state, PD group walked more slowly with shorter steps, had greater step length variability and longer duration of the double support phase compared to healthy controls. The walking speed and step length increased in the DBS ON state. The double support phase was reduced with 3D visual cueing and DBS; the combination of both cueing and DBS was even more effective. Conclusion Cueing with 3D visual stimuli shortens the double support phase in PD patients treated with DBS-STN. The DBS is more effective in prolonging step length and increasing gait speed. We conclude that 3D visual cueing can improve walking in patients with DBS.

Background There is no consensus on kinematics alterations during descending stairs in females with patellofemoral pain (PFP). In addition, there are no studies that have evaluated the three dimensional kinematics of the trunk, pelvis, hip, knee, and ankle using a multi-segmental model of the foot simultaneously during this task in patients with PFP and evaluated the subphases of stair descent. The objectives of this study were to compare the three dimensional kinematics of the trunk, pelvis, and lower limbs during different subphases of stair descent and identify the discriminatory capacity of the kinematic variables among women with PFP and healthy women. Methods In this cross-sectional study, thirty-four women with PFP and thirty-four pain free women between 18 and 35 years-old were submitted to three-dimensional kinematic evaluation during stair descent. Results It was observed that kinematic differences between the groups occurred in the first double support phase of the stair descent, with the variables of internal rotation of the hindfoot in relation to the tibia in the initial contact (2.1°; sensitivity = 68.6%, specificity = 61.8%) and contralateral pelvic drop in load response (1.3°, sensitivity = 65.7%, specificity = 63.7%) presenting the best ability to discriminate women with and without PFP. Conclusion Our results suggest that kinematic changes during stair descent should be used with caution during the evaluation and decision-making process in women with PFP.

The aim of this study was to investigate interlimb coordination in young and older adults with and without a history of falls during the combined task of walking and prehension with different levels of manual task difficulty. Participants walked on a pathway and grasped a dowel. A vector coding technique evaluated coordination patterns. The coordination pattern was not affected by the difficulty level of the manual task. Older adults seemed to prioritize the movement of the right shoulder to grasp the dowel and then 'froze' the movement of the other joint (left shoulder) not directly involved in the grasping task. The preference to pick up the dowel in the double support phase and the increase in right shoulder phase made by older adults with a history of falls suggests an even greater decoupling between walking and prehension.

In recent years, the availability of low-cost equipment capable of recording kinematic data during walking has facilitated the outdoor assessment of gait parameters, thus overcoming the limitations of three-dimensional instrumented gait analysis (3D-GA). The aim of this study is twofold: firstly, to investigate whether a single sensor on the lower trunk could provide valid spatio-temporal parameters in level walking in normal-weight and obese adolescents compared to instrumented gait analysis (GA); secondly, to investigate whether the inertial sensor is capable of capturing the spatio-temporal features of obese adolescent gait. These were assessed in 10 obese and 8 non-obese adolescents using both a single inertial sensor on the lower trunk and an optoelectronic system. The parameters obtained were not statistically different in either normal-weight or obese participants between the two methods. Obese adolescents walked with longer stance and double support phase compared to normal-weight participants. The results showed that the inertial system is a valid means of evaluating spatio-temporal parameters in obese individuals.

Background: Functional ambulation limitations are features of lumbar spinal stenosis (LSS) and knee osteoarthritis (OA). With numerous validated walking assessment protocols and a vast number of spatiotemporal gait parameters available from sensor-based assessment, there is a critical need for selection of appropriate test protocols and variables for research and clinical applications. Research question: In patients with knee OA and LSS, what are the best sensor-derived gait parameters and the most suitable clinical walking test to discriminate between these patient populations and controls?, Methods: We collected foot-mounted inertial measurement unit (IMU) data during three walking tests (fast-paced walk test-FPWT, 6-min walk test-6MWT, self-paced walk test-SPWT) for subjects with LSS, knee OA and matched controls (N = 10 for each group). Spatiotemporal gait characteristics were extracted and pairwise compared (Omega partial squared - omega(2)(p)) between patients and controls., Results: We found that normal paced walking tests (6MWT, SPWT) are better suited for distinguishing gait characteristics between patients and controls. Among the sensor-based gait parameters, stance and double support phase timing were identified as the best gait characteristics for the OA population discrimination, whereas foot flat ratio, gait speed, stride length and cadence were identified as the best gait characteristics for the LSS population discrimination., Significance: These findings provide guidance on the selection of sensor-derived gait parameters and clinical walking tests to detect alterations in mobility for people with LSS and knee OA.

Unicompartmental knee replacement (UKR) can provide reliable clinical and functional outcomes when performed simultaneously in both knees for treating bilateral osteoarthritis (OA). No studies to date have evaluated gait pattern after simultaneous bilateral UKR. The aim of this study was to evaluate changes in gait variables after bilateral single-stage UKR (B-UKR) and to compare them with the outcomes after unilateral UKR in two other groups of patients: one with bilateral knee OA (P-UKR) and one with the contralateral knee unaffected (H-UKR).Three-dimensional motion cohort data were prospectively collected before and six months after surgery; 37 were allocated to the B-UKR (n = 13), P-UKR (n = 12) or H-UKR (n = 12) group. Spatiotemporal variables (stride length, gait speed, gait cadence, stance phase, swing phase, and double support phase) and kinematic parameters (knee flexion and extension peak values, knee range of motion (ROM), and hip abduction peak value) were analyzed using mixed analysis of variance (ANOVA). The magnitude of effect for significant outcomes (ES) was determined using Cohen's d.Postoperative improvement in gait cadence (P 0.01; ES = 1.20), walking speed (P 0.05; ES = 0.58), stride length (P 0.05; ES = 0.67), knee ROM (P 0.05; ES = 0.89), knee flexion (P 0.05; ES = 0.94), and hip abduction (P 0.001; ES = 1.16) was noted for the B-UKR group, whereas only stride length improved (P 0.05; ES = 0.48) for the H-UKR group, and no changes in any gait parameter were seen for the P-UKR group.Postoperative improvement in gait parameters was observed in the B-UKR patients with bilateral OA. Whenever possible, simultaneous bilateral UKR should be considered in such patients.

Background: Gait impairment is a common symptom in multiple sclerosis (MS) patients, but there is a lack of evidence about gait performance in the group of MS patients with no apparent disability. The aim of our study was to evaluate gait characteristics in MS patients with no apparent impairment of walking and with an Expanded Disability Status Scale (EDSS 0-1.5), and to determine whether any abnormalities are detectable by common clinical tests. Methods: This was an observational study of 64 MS patients with an EDSS 0-1.5 and 47 age- and sex-matched healthy controls. We measured their performance in the timed 25-foot walk test (T25FWT) and the 2-minute walk test (2MWT). The spatiotemporal parameters of gait were measured using a GAITRite instrument. Results: MS patients with no apparent disability (EDSS 0-1.5) performed worse in T25FWT and 2MWT than normal controls. During the self-selected walking speed test on GAITRite, MS patients had a prolonged double support phase, and during the fast walking speed test, they had lower cadence and decreased step length.

Gait is a relevant and complex aspect of motor functioning. Disturbances are related to negative health outcomes. Gait characteristics of 31 adults with intellectual disability (ID) without Down syndrome (DS) (42.77±16.70 years) were investigated, and associations with age, sex, body mass index (BMI), and level of ID were assessed. Sex and BMI were significantly associated with some of the gait parameters, while age and level of ID were not. Gait characteristics of adults with ID seem to be comparable to those of the general population of older adults (average 20 years older), except that adults with ID seem to spend less time in stance and double support phase and walk more variable and with a broader base of support.

The aims of this study have been twofold: to attempt to reduce the number of spatiotemporal parameters used for describing gait through the factor analysis and component analysis; and to explore the critical age of decline for other gait parameters for healthy women.A total of 106 women (aged ≥ 40 years old (N = 76) and ≤ 31 years old (N = 30)) were evaluated using a pressure-sensitive mat (Zebris Medical System, Tübingen, Germany) for collecting spatiotemporal gait parameters.The factor analysis identified 2 factors - labelled Time and Rhythm - that accounted for 72% of the variation in significant free-gait parameters; the principal component analysis identified 4 of these parameters that permit full clinical evaluation of gait quality. No difference was found between the groups in terms of the values of parameters reflecting the temporal nature of gait (Rhythm), namely step time, stride time and cadence, whereas significant differences were found for total double support phase (p0.001). Next, seeking evidence of a critical decline in gait, we selected 3 parameters: total double support, stride time and velocity. We concluded that the women taking part in the experiment manifested significant signs of senile gait after the age of 60 years old, with the first symptoms thereof already manifesting themselves after 50 years of age.We show that among 26 spatiotemporal parameters that may be used for characterizing gait, at least a half of them may be omitted in the assessment of gait correctness; a finding that may be useful in clinical practice. The finding that the onset of senile gait occurs in the case of women after the age of 60 years old, in turn, may be useful in evaluating the ability for performing types of physical work that mainly require ambulation. Med Pr 2017;68(4):441-448.The aims of this study have been twofold: to attempt to reduce the number of spatiotemporal parameters used for describing gait through the factor analysis and component analysis; and to explore the critical age of decline for other gait parameters for healthy women.A total of 106 women (aged ≥ 40 years old (N = 76) and ≤ 31 years old (N = 30)) were evaluated using a pressure-sensitive mat (Zebris Medical System, Tübingen, Germany) for collecting spatiotemporal gait parameters.The factor analysis identified 2 factors – labelled Time and Rhythm – that accounted for 72% of the variation in significant free-gait parameters; the principal component analysis identified 4 of these parameters that permit full clinical evaluation of gait quality. No difference was found between the groups in terms of the values of parameters reflecting the temporal nature of gait (Rhythm), namely step time, stride time and cadence, whereas significant differences were found for total double support phase (p0.001). Next, seeking evidence of a critical decline in gait, we selected 3 parameters: total double support, stride time and velocity. We concluded that the women taking part in the experiment manifested significant signs of senile gait after the age of 60 years old, with the first symptoms thereof already manifesting themselves after 50 years of age.We show that among 26 spatiotemporal parameters that may be used for characterizing gait, at least a half of them may be omitted in the assessment of gait correctness; a finding that may be useful in clinical practice. The finding that the onset of senile gait occurs in the case of women after the age of 60 years old, in turn, may be useful in evaluating the ability for performing types of physical work that mainly require ambulation. Med Pr 2017;68(4):441–448.

Background Ulnar collateral ligament reconstruction (UCLR) has become a common procedure among baseball players of all levels. There are several graft choices in performing UCLR, one of which is a hamstring (gracilis or semitendinosus) autograft. It is unclear whether the hamstring muscle from a pitcher's drive leg (ipsilateral side of the UCLR) or landing leg (contralateral side of the UCLR) is more active during the pitching motion. We hypothesized that the landing leg semitendinosus will be more electromyographically active than the drive leg. Methods Healthy, elite male pitchers aged 16-21 years were recruited. Sixteen pitchers (average age, 17.6 ± 1.6 years; 67% threw right handed) underwent electromyographic analysis. Pitchers threw 5 fastballs at 100% effort from the wind-up with electromyographic analysis of every pitch. Activation of the semitendinosus and biceps femoris in both legs was compared within pitchers and between pitchers. Results Hamstring activity was higher in the drive leg than in the landing leg during each phase and in sum, although the difference was significant only during the double support phase ( P = .021). On within-pitcher analysis, 10 of 16 pitchers had significantly more sum hamstring activity in the drive leg than in the landing leg, while only 4 of 16 had more activity in the landing leg ( P = .043). Conclusion During the baseball pitch, muscle activity of the semitendinosus was higher in the drive leg than in the landing leg in most pitchers. Surgeons performing UCLR using hamstring autograft should consider harvesting the graft from the pitcher's landing leg to minimize disruption to the athlete's pitching motion.

O documento em anexo encontra-se na versão post-print (versão corrigida pelo editor)., Purpose: Mechanisms associated with energy expenditure during gait have been extensively researched and studied. According to the double-inverted pendulum model energy expenditure is higher during double support, as lower limbs need to work to redirect the centre of mass velocity. This study looks into how the ground reaction force (GRF) of one limb affects the muscle activity required by the medial gastrocnemius (MG) of the contralateral limb during step-to-step transition. Methods: Thirty-five subjects were monitored as to the MG electromyographic activity (EMGa) of one limb and the GRF of the contralateral limb during double support. Results: After determination of the Pearson correlation coefficient (r), a moderate correlation was observed between the MG EMGa of the dominant leg and the vertical (Fz) and anteroposterior (Fy) components of GRF of the non-dominant leg (r=0.797, p

Background Muscle mechanical work is likely affected by gait abnormalities in hemiparetic walking during the paretic pre-swing phase (i.e., double support phase preceding paretic toe-off). Previous experimental studies suggest that muscle work may be decreased in the paretic leg, but paretic work may have been underestimated since experimental approaches based on net joint moments do not account for co-contraction of antagonist muscles. Also, whether the non-paretic leg does more work compared to control subjects at matched speeds and how work generation may differ between hemiparetic subjects walking with different self-selected speeds remains unknown. Methods Three-dimensional forward dynamics simulations of two representative hemiparetic subjects walking with different self-selected speeds (i.e., limited community = 0.45 m/s and community walkers = 0.9 m/s) and a speed and age-matched control subject were generated to quantify musculotendon (fiber and in-series tendon) work during paretic pre-swing. Findings Total paretic and non-paretic fiber work were increased in both the limited community and community hemiparetic walkers compared to the control. Increased fiber work in the limited community walker was primarily related to decreased fiber and tendon work by the paretic plantar flexors requiring compensatory work by other muscles. Increased fiber work in the community walker was primarily related to increased work by the hip abductors and adductors. Interpretation The hemiparetic walkers would expend more metabolic energy during pre-swing if the hemiparetic and control subjects were to perform work with the same mechanical efficiency. These results may partly explain the increased metabolic cost of hemiparetic walkers compared to nondisabled walkers at matched speeds.

Clinical studies of hemiparetic walking have shown pre-swing abnormalities in the paretic leg suggesting that paretic muscle contributions to important biomechanical walking subtasks are different than those of individuals without disability. Three-dimensional forward dynamic simulations of two representative hemiparetic subjects with different levels of walking function classified by self-selected walking speed (i.e., limited community = 0.4–0.8 m/s and community walkers = >0.8 m/s) and a speed-matched control were generated to quantify individual muscle contributions to forward propulsion, swing initiation and power generation during the pre-swing phase (i.e., double support phase proceeding toe-off). Simulation analyses identified decreased paretic soleus and gastrocnemius contributions to forward propulsion and power generation as the primary impairment in the limited community walker compared to the control subject. The non-paretic leg did not compensate for decreased forward propulsion by paretic muscles during pre-swing in the limited community walker. Paretic muscles had the net effect to absorb energy from the paretic leg during pre-swing in the community walker suggesting that deficits in swing initiation are a primary impairment. Specifically, the paretic gastrocnemius and hip flexors (i.e., iliacus, psoas and sartorius) contributed less to swing initiation and the paretic soleus and gluteus medius absorbed more power from the paretic leg in the community walker compared to the control subject. Rehabilitation strategies aimed at diminishing these deficits have much potential to improve walking function in these hemiparetic subjects and those with similar deficits.

This study investigated the effect of prior knowledge of the potential loss of support during walking on muscle responses to the potential perturbation. Four conditions were tested; non-instructed control (NC), non-instructed perturbed (NP), instructed control (IC) and instructed perturbed (IP). Participants were perturbed by having them step into a hidden hole (8.5 cm) in a walkway during the NP and IP trials. Participants had no prior knowledge of the potential perturbation under the NC and NP conditions, but under the instructed conditions, participants were informed that there might be a hole in the walkway. A cautious landing strategy was observed in the IC trials. The participants exhibited flat-footed landings (plantar angle: NC: 13.7 +/- 2.8 degrees; IC: 8.5 +/- 5.2 degrees) and a prolonged double support phase (NC: 138 +/- 18 ms; IC: 161 +/- 17 ms) when they had prior knowledge of the possible hole. When the participants encountered a hole, we saw triggering of fast muscle responses in the ipsilateral plantarflexors and knee extensor, as well as in the contralateral dorsiflexors and knee flexors. This pattern was interpreted as a stop walking synergy. The opposite muscle activation pattern, which was thought of as a resume walking synergy, was induced when no hole was presented and actual foot contact occurred at the expected instant. The latencies between the onsets of muscle responses and the expected heel contact were shorter under the IP condition than under the NP condition (ipsilateral soleus: NP: 78 +/- 13 ms, IP: 64 +/- 14 ms; contralateral biceps femoris: NP: 94 +/- 25 ms; IP: 76 +/- 17 ms). Our results demonstrate that reactive muscle responses to perturbations depend on the anticipatory state with respect to potential perturbations.

Contains fulltext : 80471.pdf (Publisher’s version ) (Closed access) The impact phase during walking is sometimes characterised by an early loading peak, termed 'transient', followed by a brief decline in the force profile, termed 'unloading phase'. It was hypothesized that transients occur more frequently when subjects are unaware of the landing condition, and that the unloading phase represents a yield of the leg. This was tested experimentally by introducing an unexpectedly lowered or level support surface height during walking. Furthermore, associations between the unloading phase and type of foot placement, load-rate, kinesiology and centre of pressure were investigated. The transient occurred more frequently when subjects were unaware of the surface height. The amplitude of unloading was higher in flatfooted (combined), as compared to heel and toe landings. The percentage of combined landings, as well as the amplitude and duration of unloading were highest in the first unexpected level trials (UL1) and gradually decreased in the subsequent level trials, when subjects adapted to the situation. Following the UL1 unloading phase, the foot roll-off was halted, the ipsilateral knee flexed, the onset of the contralateral swing phase was delayed, and the double support phase increased. The unloading amplitude correlated significantly with the load-rate and knee flexion. It is concluded that an unexpected surface height frequently induces an early stance transient that is followed by an unloading phase, flexion response and halt in foot roll-off. These characteristics deserve further study in the context of the frequent falls induced by uneven surfaces during walking.

The present study evaluated spatiotemporal gait parameters in children when they were carrying school trolleys of different weights.We assessed four conditions: without trolley, 10%, 15% and 20% of the subject's body weight. Fourteen students from a primary school (aged 11.43±0.51 years) participated in this study. Velocity, cadence, stride length, stance phase, swing phase, single support phase and double support phase were analysed using an electronic walkway.Compared with normal walking, the three load conditions produced significant decreases in swing phase (p0.001) and single support phase (p0.001) and significant increases in cadence (p=0.019), stance phase (p0.001) and double support phase (p0.001). No statistically-significant differences were found between the three load conditions.Compared with normal walking, walking while carrying a trolley produced significant changes in most of the spatiotemporal gait parameters measured, perhaps due to the load-mediated changes in stability and balance. The spatiotemporal gait parameters were similar between the load conditions, indicating that the amount of load did not affect gait.

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Background and Purpose Backward walking is used increasingly as a rehabilitation technique for individuals with neurological and orthopaedic impairments. The purpose of the present study was to examine changes in the temporal-spatial characteristics of gait resulting from walking backwards as opposed to forwards, and to determine age and gender effects on these changes. Method Thirty young and 40 aged, independently functioning, subjects were asked to walk forwards and backwards across a computer-based walkway system, providing data on gait velocity, stride length, cadence, swing phase and double support phase. Subjects were divided into groups based on age (young and old) and gender, and each subject was tested under two walking conditions (forwards and backwards). Five temporal-spatial gait parameters were evaluated separately as a function of the three independent variables, with the walking condition repeated for each subject. Results Backwards ambulation is characterized by a slower velocity, shorter stride length and an increased double support phase in both young and older adults. These changes were significantly greater in the older subjects, among whom the swing phase was also decreased. Cadence, however, was not affected by direction of ambulation in either group. The female subjects had a shorter stride length in both movement directions, associated with reduced speed only in backwards ambulation. Conclusions Older individuals are capable of walking backwards for short distances. However, changes in gait characteristics typical to the reversal of movement direction are accentuated with age. These effects must be considered when planning to use backwards ambulation as a rehabilitation technique for older individuals. Copyright © 2003 Whurr Publishers Ltd.

Background: Only few studies have looked at electromyography (EMG) during prosthetic gait. Differences in EMG between normal and prosthetic gait for stance and swing phase were never separately analyzed. These differences can give valuable information if and how muscle activity changes in prosthetic gait. Methods: In this study EMG activity during gait of the upper leg muscles of six transfemoral amputees, measured inside their own socket, was compared to that of five controls. On and off timings for stance and swing phase were determined together with the level of co-activity and inter-subject variability. Results and conclusions: Gait phase changes in amputees mainly consisted of an increased double support phase preceding the prosthetic stance phase. For the subsequent (pre) swing phase the main differences were found in muscle activity patterns of the prosthetic limb, more muscles were active during this phase and/or with prolonged duration. The overall inter-subject variability was larger in amputees compared to controls.

The purpose of this study is to analyse the interlimb relation and the influence of mechanical energy on metabolic energy expenditure during gait. In total, 22 subjects were monitored as to electromyographic activity, ground reaction forces and VO2 consumption (metabolic power) during gait. The results demonstrate a moderate negative correlation between the activity of tibialis anterior, biceps femoris and vastus medialis of the trailing limb during the transition between mid-stance and double support and that of the leading limb during double support for the same muscles, and between these and gastrocnemius medialis and soleus of the trailing limb during double support. Trailing limb soleus during the transition between mid-stance and double support was positively correlated to leading limb tibialis anterior, vastus medialis and biceps femoris during double support. Also, the trailing limb centre of mass mechanical work was strongly influenced by the leading limbs, although only the mechanical power related to forward progression of both limbs was correlated to metabolic power. These findings demonstrate a consistent interlimb relation in terms of electromyographic activity and centre of mass mechanical work, being the relations occurred in the plane of forward progression the more important to gait energy expenditure.

Purpose To investigate the influence of base down (BD) and base up (BU) yoked prism wear on gait. Methods Gait was assessed in 31 young healthy adults (mean age, 24.0 ± 5.1 years) during and after wearing 5 prism diopter ((Δ)) BU yoked prisms, 5(Δ) BD yoked prisms, and plano (PL) (zero power; control condition) lenses, worn in a pseudorandom order. Velocity; cadence; step length; double support phase; step width; and variability in step time, step width, step length, and swing time were measured as participants walked at a freely chosen walking speed along a 5.3-m electronic mat placed in the center of a 7.5-m walkway. Gait parameters were analyzed for each viewing condition before, during, and after prism wear. Results BD yoked prisms, when compared with PL, led to slower velocity, lower cadence, decreased step length, and increased step time variability (P ≤ 0.001) These gait parameters did not significantly differ between BU yoked prisms and PL lenses (P > 0.05). Measurements taken immediately on removal did not differ from those taken after a time delay of 5 minutes. Conclusions BD yoked prisms affected gait in young healthy adults walking across an unobstructed path at their freely chosen walking speed, in that participants adopted a slower, apparently more cautious gait pattern; BU yoked prisms did not significantly affect gait. The effect of BD prism on gait may be due in part to a perception of increased height.

Joint or segment angle trajectories of able-bodied persons are often recorded or mimicked as reference trajectories for walking restoration in paraplegia. In this paper, lower limb segment angle trajectories are computed from simple mathematical models developed to represent functional electrical stimulation (FES) and a novel brace based walking. The new models incorporate the double support and single support phases of walking. Dynamic optimization is utilized to design walking trajectories that minimize muscle activations and arm reaction forces generated from the walker. Compared to the voluntary walking trajectories, the new trajectories are more representative of FES-based walking as only a limited number of muscle are stimulated to compute walking trajectories.

In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number φ known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with φ, the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620 ± 0.058, that between stance and the swing phase was 1.629 ± 0.173, and that between swing and the double support phase was 1.684 ± 0.357. All these ratios did not differ significantly from each other (F = 0.870, P = 0.422, repeated measure analysis of variance) or from φ (P = 0.670, 0.820, 0.422, resp., t-tests). The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait.

The aim of this study was to assess the kinematics disorder of gait in men with fibromyalgia. We studied 12 male with fibromyalgia and 14 healthy men. Each participant of the study walked five trials along a 18.6-m walkway. Fibromyalgia patients completed a Spanish version of Fibromyalgia Impact Questionnaire. Significant differences between fibromyalgia and control groups were found in velocity, stride length, and cadence. Gait parameters of men affected by fibromyalgia were impaired when compared to those of healthy group due to bradykinesia. According to previous studies to assess gait variables in female patients, the male with fibromyalgia also showed lower values of velocity, cadence, and stride length than healthy group but not reported significant differences in swing, stance, single, or double support phase.

The aim of this study was to examine the effects of different modes of carrying schoolbags on children. Ten girls and eight boys walked without a bag (NO-BAG), with a bag placed low at the back (LBACK), with a back placed high at the back (HBACK) and carrying the bag using the handle (HANDBAG). Ground reaction forces and temporal characteristics were recorded. When carrying a schoolbag, children walked with shorter strides, at lower speeds, with higher double support phase and increased vertical ground reaction forces compared with the NO-BAG condition (P

The biomechanical changes in postural control and in motor activities linked to obesity are still not fully understood. The aim of this study was to assess the adaptation in static and dynamic control of equilibrium when the body mass to be stabilized and moved is increased through obesity. Postural stability limits and gait initiation at slow and fast velocities were compared in a case control study that included a group of obese adolescents and a control group of adolescents with normal weight. The consequences of overweight are more clearly evident from the results on dynamic stability of the obese group than those on static equilibrium. Both the lower values of the biomechanical parameters characterizing the progression velocity of gait and the longer duration of the swing phase for the fast velocity condition suggest that obesity acts as a slowing factor. However, the reduction of the postural stability limits of the obese group, their inability to increase the anticipatory phase duration unlike the control group, the increase in the double support phase duration as well as some difficulty in controlling the fall of the centre of gravity suggest that, in these subjects, an adaptive strategy is adopted to preserve equilibrium by limiting progression velocity.

In order to assess the effect of rehearsal by eye movement alone on visuomotor performance, the eye movements and visually guided stepping of two cerebellar patients were monitored before and after a first and second batch of eye-movement rehearsals, in which patients made saccadic eye movements to the first 6 footfall targets (in a sequence of 18) whilst standing stationary at the start of the walkway. There was a marked improvement in oculomotor and locomotor performance following the second batch of eye-movement rehearsal. Both patients showed reduced occurrence of saccadic dysmetria, evident as a significant increase in the proportion of single to multi-saccadic eye movements (from 46 to 77% for DB and from 75 to 94% for TP). This was accompanied by increased regularity and accuracy of stepping in both patients, and decreased stance and double support phase durations (one patient only). Separate testing confirmed that these improvements in eye movements and stepping did not result from simple repetition of the task. This is the first demonstration of a technique – rehearsal by eye movement – that improves the visuomotor performance of cerebellar patients. It is compelling evidence for our proposal that during visually guided stepping the locomotor control system is dependent on assistance from the oculomotor control system.

The purpose of this study was to evaluate three defined locomotion patterns in cerebral palsy gait using computerised gait analysis. Ambulant diplegic children who had no previous surgery were included in the study and were divided into two groups: one group consisted of children having a crouch gait, and the other group did not have the crouch pattern of gait. An age-matched group of normal children served as the control group. Locomotion patterns studied were the hip hike, propulsive function of the hip extensors, and pseudo-adduction. A statistical analysis was performed between the groups, using defined parameters. The mechanism of hip hike was not utilised by any of the groups. Both groups of diplegic children showed power generation at the hip beginning in the first double support phase of the gait cycle and continuing in the first half of single limb support, while in the normals this was only in the first half of single limb support. Both the groups of diplegic children showed significantly more internal rotation in the first half of stance as compared to the group of normal children; the degree of hip adduction was the same in all the groups. Thus diplegic children had pseudo-adduction.

The purpose of this study was to identify those characteristics of the techniques used by elite discus throwers that are most closely related to the distances they record. The subjects were the competitors in the discus throw events at two major meetings. Two S-VHS video cameras were used to record the performances of the subjects; the direct linear transformation (DLT) procedure was used to obtain three-dimensional data from these records. For the males, the change in speed of the discus during the second double support phase was more influential than the change in speed during any other phase in accounting for differences in the distances of the throws recorded. For the females, the changes in speed during the flight phase and during the second double support phase were about equally influential in accounting for differences in the distance thrown. The findings suggest that emphasis placed on achieving a large change in the speed of the discus during the second double support phase is well founded; that the speed of release is the most influential determinant of the distance of the throw; and that, in most cases, the aerodynamic forces exerted on the discus during the flight increase the distance of the throw.

The purpose of the study was to quantify and compare the temporal aspects of the ice skating stride performed at three different velocities. Subproblems were (a) to determine how stride rate and stride length are affected by changes in skating velocity and (b) to ascertain the characteristics of the single and double support phase relationship over different velocities. A Locam 16 mm camera, operated at 100 frames per sec, was used to film a group of ten skaters, each of whom performed three trials at each of a maximal and two submaximal speeds. Graphic and statistical analysis was used to determine performance trends and the statistical significance of differences in performance parameters. Analysis of the data revealed that stride rate increased as a function of horizontal velocity but that stride length underwent no statistically significant changes. It was found that as speed increased, both single support time and double support time decreased significantly but double support time underwent proportio...

The left and right ground reactions are predicted from computed absolute motion data with the aid of some simple assumptions regarding symmetry between the forward shear forces during the double support phase and the rate at which support is transferred from one leg to the other. The computed ground forces are then used to evaluate forces, moments and power at the joints of the lower limb. The power supplied at the joints of the lower limbs is found to agree well with the power required to increase the energy level of the body.