Is this walk normal?

Accuracy and Repeatability of Spatiotemporal Gait Parameters Measured with an Inertial Measurement Unit

In recent years, interest in finding alternatives for the evaluation of mobility has increased. Inertial measurement units (IMUs) stand out for their portability, size, and low price. The objective of this study was to examine the accuracy and repeatability of a commercially available IMU under controlled conditions in healthy subjects. A total of 36 subjects, including 17 males and 19 females were analyzed with a Wiva Science IMU in a corridor test while walking for 10 m and in a threadmill at 1.6 km/h, 2.4 km/h, 3.2 km/h, 4 km/h, and 4.8 km/h for one minute. We found no difference when we compared the variables at 4 km/h and 4.8 km/h. However, we found greater differences and errors at 1.6 km/h, 2.4 km/h and 3.2 km/h, and the latter one (1.6 km/h) generated more error. The main conclusion is that the Wiva Science IMU is reliable at high speeds but loses reliability at low speeds.

Normative Data for Gait Speed and Height Norm Speed in ≥ 60-Year-Old Men and Women

Purpose

To determine normative data for gait speed and height-normalized gait speed in community-dwelling older men and women.

Materials and Methods

In this cross-sectional study, we recruited 565 men and women aged ≥60 years old. Age was calculated from the date of birth and further classified into four categories: (1) 60-65 years, (2) 66-70 years, (3) 71-75 years and (4) ≥76 years. Gait speed was assessed by a pressure platform (ZEBRIS, Munich, Germany) in meters per second (m/s). Height and weight were objectively measured. Height-normalized gait speed was calculated by dividing gait speed by height. We created the 20th, 40th, 60th and 80th percentile curves for both outcome measures using Cole's Lambda (L), Mu (M) and Sigma (S) method.

Results

Mean gait speed and height-normalized gait speed was 1.24 (standard deviation 0.28) and 0.75 (0.17). Significant age-related decline in gait speed for both sexes was observed (p < 0.001). Being a woman (β = - 0.09, p < 0.001), being older (β = - 0.02, p < 0.001) and having higher body mass index values (β = - 0.02, p < 0.001) were significantly associated with slower gait speed.

Conclusion

Gait speed significantly declines with age in both older men and women. Providing normative data can be used in screening and monitoring "slow" walkers to prevent from foot pain and higher risk of falls.

Reliability of the OptoGait portable photoelectric cell system for the quantification of spatial-temporal parameters of gait in young adults

Determining progress in gait requires a reliable method. However, achieving standard assessment results in the clinical setting can be challenging. Searching for a reliable tool, we tested OptoGait, a tool that has floor-level, high-density photoelectric cells that can be used to determine patterns of spatial-temporal gait on the basis of 19 variables: step length, stride length, distance, total contact time, step time, walking speed, acceleration, progressive step time, cadence, gait cycle, stance phase, swing phase, heel contact phase, flatfoot phase, takeoff phase, single limb support, double limb support, load response phase, and pre-swing phase. The gait of 126 study participants (41 males, 85 females; 27.37±1.77 years) was assessed twice for each participant during 10 episodes of walking on a 10m walkway each 2 weeks apart. Intra-session and inter-session results were compared using data for each foot alone as well as both feet together. All variables resulted in a high consistency except for acceleration. The intra-session data showed substantial agreement; the intra-class correlation coefficient (ICC) ranged from 0.72-0.78 in the heel contact phase, 0.72-0.76 in the load response phase, and 0.76-0.85 in the pre-swing phase and a low SEM. The inter-session data for each foot alone and both feet together showed substantial agreement (0.77-0.79 in the load response phase) and slight agreement for acceleration (0.06-0.22) with a low SEM. Based on these results, we conclude that the OptoGait system can be used with confidence to evaluate spatial-temporal gait except for acceleration and progressive step time assessment.

Assessing mobility in multiple sclerosis using the Rivermead Mobility Index and gait speed

Measurement tools assessing disability in MS patients are essential to evaluate the effect of the growing number of drug treatments and to measure rehabilitation outcome. However, the most widely used EDSS (Expanded Disability Status Scale) has been shown to be insensitive to minor changes. The assessment of disability with simple measures such as the Rivermead Mobility Index (RMI) and gait speed timed over 10 m has been suggested. Two hundred MS patients attending a rehabilitation centre were assessed at the beginning and at the end of a four-week period (median 28.2 days; interquartile range (IQR) 1.8 days) using these two measures as well as the EDSS and the Ambulation Index (AI). The RMI was the most sensitive scale and measured changes in 39% of the patients, whereas AI changed in 18.5% and EDSS in only 7.5% of the patients. The RMI assessed more precisely ambulatory patients needing walking aids, for which EDSS proposes only two options (EDSS 6.0/6.5). To measure the variability of the 10 m walking time, 25 of the 115 ambulant patients were asked to cover the distance at five different times on the same day chosen at random. Variability within one patient on test-retest was calculated by dividing the standard deviation of the five measures by the mean value of the measures. In spite of its great variability of 20 ± 8%, gait speed timed over 10 m was as sensitive as the AI and measured changes in 16.5% of these ambulatory patients (AI in 15.6%). The RMI and gait speed timed over 10 m should be used more widely to assess disability and to measure the physiotherapeutic effort devoted to improving mobility of MS patients.

Variability of gait, bilateral coordination, and asymmetry in women with fibromyalgia

PURPOSE

To analyze how fibromyalgia affected the variability, asymmetry, and bilateral coordination of gait walking at comfortable and fast speeds.

METHODS

65 fibromyalgia (FM) patients and 50 healthy women were analyzed. Gait analysis was performed using an instrumented walkway (GAITRite system). Average walking speed, coefficient of variation (CV) of stride length, swing time, and step width data were obtained and bilateral coordination and gait asymmetry were analyzed.

RESULTS

FM patients presented significantly lower speeds than the healthy group. FM patients obtained significantly higher values of CV_StrideLength (p=0.04; p<0.001), CV_SwingTime (p<0.001; p<0.001), CV_StepWidth (p=0.004; p<0.001), phase coordination index (p=0.01; p=0.03), and p_CV (p<0.001; p=0.001) than the control group, walking at comfortable or fast speeds. Gait asymmetry only showed significant differences in the fast condition.

CONCLUSION

FM patients walked more slowly and presented a greater variability of gait and worse bilateral coordination than healthy subjects. Gait asymmetry only showed differences in the fast condition. The variability and the bilateral coordination were particularly affected by FM in women. Therefore, variability and bilateral coordination of gait could be analyzed to complement the gait evaluation of FM patients.

Comparison of Cervical Range-of-Motion Restriction and Craniofacial Tissue-Interface Pressure With 2 Adjustable and 2 Standard Cervical Collars

STUDY DESIGN

Randomized controlled trial.

OBJECTIVE

The aim of the study was to compare and contrast the restrictiveness and tissue-interface pressure (TIP) characteristics of 2 standard and 2 adjustable cervical collars.

SUMMARY OF BACKGROUND DATA

This study compared the restrictiveness and TIP of 4 commercially available cervical collars (2 standard and 2 adjustable). Adjustable collars offer potential advantages of individualized fit for patients and decreased inventory for institutions. The overall goal was to determine whether the adjustable collars provided the same benefits of cervical range-of-motion (CROM) restriction as the standard collars without increasing TIP and risk of pressure-related complications.

METHODS

A total of 48 adult volunteer subjects (24 men and 24 women) were fitted with 4 collars (Aspen, Aspen Vista, Miami J, and Miami J Advanced) in random order. Data collection included assessment of CROM restrictiveness and measurement of TIP on the mandible and occiput in upright and supine positions. The experimental, repeated measures design stratified the sample by body mass index (BMI) and sex.

RESULTS

All collars restricted CROM as compared with no collar (P ≤ 0.001 each). Aspen was more restrictive than Aspen Vista and Miami J in 4 movement planes (P ≤ 0.003 each), but not significantly different from Miami J Advanced. The Miami J standard collar was associated with significantly lower peak TIPs on all sites and in all positions compared with Aspen (P ≤ 0.001), Miami J Advanced (P < 0.001), and Aspen Vista (P = 0.01 for mandible site and upright position, P < 0.001 for remaining sites and positions). Increased peak TIP correlated with high BMI across all collar types, but was significantly lower for the Miami J collar than the Aspen collar.

CONCLUSION

All collars, compared with no collar, significantly restricted CROM. Although the collar-to-collar comparisons were statistically significant, the differences may have little clinical significance in the acutely injured trauma patient. The Miami J standard collar had the lowest overall TIP in both sites and positions. Ongoing effort should be devoted to staff education in proper sizing and fit, particularly for patients with high BMI.

Spatio-temporal gait disorder and gait fatigue index in a six-minute walk test in women with fibromyalgia

BACKGROUND

Gait disorders in fibromyalgia patients affect several gait parameters and different muscle recruitment patterns. The aim of this study was to assess the gait differences observed during a six-minute walk test between fibromyalgia patients and healthy controls.

METHODS

Forty-eight women with fibromyalgia and 15 healthy women were evaluated. Fibromyalgia patients met the American College of Rheumatology criteria for fibromyalgia selected of an ambulatory care. Both patients and controls had a negative history of musculoskeletal disease, neurological disorders, and gait abnormalities. The 15 controls were healthy women matched to the patients in age, height and body weight. Spatio-temporal gait variables and the rate of perceived exertion during the six-minute walk test (all subjects) and Fibromyalgia Impact Questionnaire (fibromyalgia subjects) were evaluated. All walking sets on the GaitRITE were collected and the gait variables were selected at three stages during the six-minute walk test: two sets at the beginning, two sets at 3 min and two sets at the end of the test. In addition, the Fibromyalgia Impact Questionnaire was used for the fibromyalgia patients.

FINDINGS

Fibromyalgia patients showed a significant decrease in all spatio-temporal gait variables at each of the three stages and had a lower walk distance covered in the six-minute walk test and higher rate of perceived exertion. No correlations were found between the Fibromyalgia Impact Questionnaire and gait variables. The fibromyalgia and control subjects showed lower gait fatigue indices between the middle and last stages.

INTERPRETATION

Gait analysis during a six-minute walk test is a good tool to assess the fatigue and physical symptoms of patients with fibromyalgia.

Minimal detectable change for spatial and temporal measurements of gait after incomplete spinal cord injury

BACKGROUND AND PURPOSE

Gait deviations in individuals after incomplete spinal cord injury (ISCI) that are quantified using spatiotemporal (ST) parameters are often targeted during therapeutic interventions. The purpose of our study was to establish reliability and responsiveness of ST parameters of gait after ISCI using an instrumented walkway (GaitMat II).

METHODS

Sixteen individuals with ISCI participated in the study. Each subject completed at least 2 walking trials at self-selected (SS) walking speed. Intraclass correlation coefficients model 2, 1 (ICC2,1) with 95% confidence intervals (CIs), standard error of measurement (SEM), SEM percent change (SEM%), the minimal detectable change (MDC), and the MDC percent change (MDC%) were determined for 8 ST parameters including step length, single limb support, and double limb support time for the more and less impaired limb, cadence, and speed.

RESULTS

Excellent test-retest agreement (0.84-0.99) was observed in all ST parameters. SEM% ranged from 8% to 29%, while MDC% ranged from 21% (cadence) to 80% (double limb support time). MDC% values were relatively higher (5-12 MDC%) for the more versus less impaired limb.

DISCUSSION

SEM% results indicate that small to moderate changes were needed to indicate a real change in walking performance. Differences in MDC% values between limbs indicated that variability in parameters might be sensitive to level of motor impairment.

CONCLUSION

In individuals with ISCI, different gait, balance, or strength training programs can be compared and contrasted based on a quantifiable and meaningful change in the ST parameter of interest.

Spring-like gait mechanics observed during walking in both young and older adults

A spring loaded inverted pendulum model successfully demonstrated the oscillatory behavior of the center of mass (CoM) and corresponding ground reaction forces (GRFs) of young healthy subjects. This study questioned whether spring-like leg walking dynamics are consistently observed in the walking of older adults that exhibit different gait characteristics, such as slower gait speed, from the young. Eight young and eight older adult subjects participated in overground walking experiments performed at four different gait speeds, ranging from their self-selected speed to a maximum walking speed. To calculate the effective leg stiffness, the damped compliant leg model with a curved foot was used. The model parameters of leg stiffness and damping constant were optimized to achieve the best fit between model and human GRFs data. We observed that the GRFs data from both age groups were reasonably well fitted by spring-like leg dynamics throughout the broad range of gait speeds. The leg stiffness and damping constant consistently increased as a function of the walking speed in both age groups, but slightly greater variations of the model parameters were observed for the older adults' trials. The results imply that human walking dynamics and the variation with respect to age can be well captured by spring-like leg dynamics.

Cognitive function, gait, and gait variability in older people: a population-based study

BACKGROUND

Gait impairments are associated with falls and loss of independence. The study of factors associated with poorer gait may assist in developing methods to preserve mobility in older people. The aim of this study was to examine the associations between a range of cognitive functions and gait and gait variability in a population-based sample of older people.

METHODS

Gait and intra-individual gait variability measures were obtained using the GAITRite walkway in a sample of older people, aged 60-85 years (N = 422), randomly selected from the Tasmanian electoral roll. Raw scores from a cognitive battery were subjected to principal component analyses deriving four summary domains: executive function/attention, processing speed, memory, and visuospatial ability. Multivariable linear regression was used to examine associations between cognitive domains and gait measures adjusting for age, sex, ambulatory activity, medication use, and mood.

RESULTS

The mean age of the sample was 72.0 years (SD = 7.0), with 238 men (56%). Poorer executive function was independently associated with poorer performance in most absolute gait measures and with greater variability in double support phase and step time. Processing speed was associated with absolute gait measures and double support phase variability. Visuospatial ability was only associated with greater double support phase variability, independently of executive function and processing speed. Memory was not independently associated with any gait measure.

CONCLUSIONS

In community-dwelling older people, executive function/attention and processing speed were associated with many aspects of gait, whereas visuospatial ability may only play a role in double support phase variability.

Gait initiation in older people--Time to first lateral movement may be the measure of choice

AIMS

There are few empirical data to guide the choice of a gait initiation (GI) measure in older people. We investigated the statistical characteristics of the components of GI, their inter-relationships and associations with sensorimotor variables, and the effect on them of cognitive interference.

METHODS

GI was measured for randomly selected participants aged 60-86 years using a force-platform with and without a cognitive interference task. Sensorimotor measures were obtained using the physiological profile assessment (PPA), and cognitive speed using the digit symbol and symbol search tests. GI was divided into its three components: time to first lateral movement (FLM); transfer time; and swing time. Six summary indices were assessed for suitability. Regression techniques and Spearman correlations were used to examine learning effects, inter-relationships between components, associations with other study factors and responsiveness to cognitive interference.

RESULTS

The median of trials per participant was the best summary index. Learning effects were observed under single and particularly dual-tasking. Time to FLM was most consistently associated with age, height, weight, sensorimotor variables, falls-risk score and cognitive speed, and was most responsive to dual-tasking. Overall time to GI was more predictive of falls risk than was time to FLM.

CONCLUSIONS

Multiple trials are recommended for GI component measurement and the median may provide the best summary measure across trials. Time to FLM is the GI component measure of choice in older people due to its relationship with other factors and responsiveness to cognitive interference but without advantage over overall time to GI.

Spatiotemporal components of the 3-D gait analysis of community-dwelling middle-aged and elderly Japanese: age- and sex-related differences

AIM

To describe age- and sex-related differences in gait patterns of community-living men and women using 3-D gait analysis.

METHODS

Subjects (n=2006) aged 40-84 years participated in the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA). Spatiotemporal components, including velocity, step length, step frequency, and double support time during a gait cycle, were calculated from 3-D coordinates and vertical force data. Velocity, step length and step frequency were normalized by leg length and acceleration due to gravity, and double support time was normalized to gait cycle duration.

RESULTS

Spatiotemporal walking variables of brisk velocity and step length were significantly greater in men than in women, while comfortable velocity and comfortable and brisk step frequencies and double support times were greater in women than in men. Age-related changes were marked at 70-84 years in most spatiotemporal variables in both sexes during comfortable walking. During brisk walking, age-related changes were observed from a younger age than during comfortable walking, and there were sex-related differences.

CONCLUSION

The age-related gait alteration was obvious among those aged 70 years and older, and it accelerated markedly in women's brisk walking intensity.

Responsiveness of 2 procedures for measurement of temporal and spatial gait parameters in older adults

OBJECTIVE

To determine the responsiveness of the GAITRite system and a stopwatch-footfall count technique for measurement of walking speed, cadence, and stride length during comfortable and fast-paced walking.

DESIGN

Criterion standard.

SETTING

Research laboratory in a physical therapy education program.

PARTICIPANTS

Twenty-four healthy volunteers (13 men, 11 women; mean age 74.5 years) without lower extremity injury or history of falls.

INTERVENTIONS

Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected comfortable and fast walking speeds. Simultaneously, an examiner, using a stopwatch, recorded the elapsed time necessary to cross the mat and counted the number of complete footfalls.

MAIN OUTCOME MEASURE(S)

Walking speed, cadence, and stride length were compared between the GAITRite system and the stopwatch-footfall count technique for both comfortable and fast walking speeds. Responsiveness values for each procedure were described by the 95% minimal detectable change (MDC).

RESULTS

During comfortable self-paced walking, MDC values for the stopwatch-footfall count technique ranged from 10% to 65% greater than those obtained for the GAITRite system. During fast self-paced walking MDC values for the stopwatch-footfall count technique ranged from 26% to 65% larger than those measured by the GAITRite system for the temporal and spatial gait performance parameters.

CONCLUSIONS

When measured by the GAITRite system, the 95% MDC values for temporal and spatial gait parameters of older community-dwelling adults were more responsive to change than those obtained by the stopwatch-footfall technique. Clinicians should recognize that self-selected walking speed, cadence, and stride length when obtained by an instrumented walkway must be equal to or exceed 12.6 cm/s, 8.4 steps/min, or 7 cm, respectively, for the change to be considered real change and not from measurement error.

Agreement between the GAITRite walkway system and a stopwatch-footfall count method for measurement of temporal and spatial gait parameters

OBJECTIVE

To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the stopwatch-footfall count technique.

DESIGN

Criterion standard.

SETTING

Research laboratory in a physical therapy education program.

PARTICIPANTS

Forty healthy volunteers (13 men, 27 women) without lower-extremity injury.

INTERVENTIONS

Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls.

MAIN OUTCOME MEASURES

Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the stopwatch-footfall count technique.

RESULTS

Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and -.05m/s for walking speed, between -1.5 and -24.3 steps/min for cadence, and between .01 and .37m for stride length.

CONCLUSIONS

This study shows that the GAITRite and stopwatch-footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the stopwatch-footfall count technique.

Does fear of falling influence spatial and temporal gait parameters in elderly persons beyond changes associated with normal aging?

BACKGROUND

Limited research exists on fear of falling and its affect on gait parameters. Studies have shown a relationship between fear of falling and restriction of activities. The purpose of this study was to determine if a fear of falling in elderly persons was associated with changes in spatial and temporal gait parameters, independent of a history of falls. It was hypothesized that, in elderly persons, gait changes would be associated with a preexisting fear of falling.

METHODS

Ninety-five community-dwelling adults, aged 60-97 years (mean age = 74, standard deviation = 8.5) participated in this study. Participant scores on the Modified Falls Efficacy Scale determined an individual's placement into the "fearful" or "fearless" category. Spatial and temporal gait parameters of speed, stride length, step width, and double limb support time were assessed using the GAITRite system, a computerized electronic walkway.

RESULTS

The fearful group had a significantly slower gait speed (p <.05) and shorter stride length (p <.05) when compared to the fearless group. Stride width was significantly longer (p =.05) and double limb support time was significantly prolonged (p <.05) in the fearful participants when measured against the fearless participants.

CONCLUSIONS

The results of this study support the hypothesis that fear of falling does influence spatial and temporal gait parameter changes in elderly persons. Slower gait speed, shorter stride length, increased stride width, and prolonged double limb support time were found to be associated with a preexisting fear of falling.

Reliability of the GAITRite walkway system for the quantification of temporo-spatial parameters of gait in young and older people

The purpose of this study was to evaluate the test-retest reliability of an instrumented walkway system (the GAITRite mat) for the measurement of temporal and spatial parameters of gait in young and older people. Thirty young subjects (12 males, 18 females) aged between 22 and 40 years (mean 28.5, S.D. 4.8) and 31 older subjects (13 males, 18 females) aged between 76 and 87 years (mean 80.8, S.D. 3.1) walked at a self-selected comfortable walking speed across the pressure-sensor mat three times and repeated the process approximately 2 weeks later. Intra-class correlation coefficients (ICC), coefficients of variation (CV) and 95% limits of agreement were then determined. For both groups of subjects, the reliability of walking speed, cadence and step length was excellent (ICCs between 0.82 and 0.92 and CVs between 1.4 and 3.5%). Base of support and toe in/out angles, although exhibiting high ICCs, were associated with higher CVs (8.3-17.7% in young subjects and 14.3-33.0% in older subjects). It is concluded that the GAITRite mat exhibits excellent reliability for most temporo-spatial gait parameters in both young and older subjects, however, base of support and toe in/out angles need to viewed with some caution, particularly in older people.

Relationship between muscle strength and the time taken to complete a standardized walk-turn-walk test

We examined the effects of age and gender on the relationship between knee strength and walking time during a walk-turn-walk test in 176 male and 168 female generally healthy participants of the Baltimore Longitudinal Study of Aging who were aged 21-89 years. Subjects were timed as they walked 50 ft (15.24 m), turned around, and walked back to the starting point, both at a comfortable pace and as fast as possible. Isokinetic concentric knee extensor strength was measured at 30 degrees /s by using a Kin-Com dynamometer. Both comfortable and fast gait times increased with increasing age for both women and men, starting in middle age. An interaction was found between gender and age showing that older women are slower than older men at both paces. Gait time decreased linearly with increasing knee extensor strength, plateauing at higher strength levels (>130 N m for comfortable gait, and 190 N m for fast gait). Most women occupied the linear part of the curve below the plateau. Adjustment for body size, age, physical activity, and particularly number of steps to complete the task removed the relationship between strength and gait time for the comfortable gait. Women took longer to complete the walk-turn-walk test than men at older ages, were on the linear part of the strength-gait time relationship, and used more steps to complete the task, all of which may contribute to their greater likelihood of frailty in later years.

Orthopedic or geriatric rehabilitation of hip fracture patients: a prospective, randomized, clinically controlled study in Malmö, Sweden

From November 1988 to December 1989, all hip fracture patients in the municipality of Malmö, excluding nursing-home patients and patients who were already hospitalized at the time of the fracture, were postoperatively randomized to rehabilitation at either the orthopedic or the geriatric department in Malmö. The study, which comprised 371 patients, compared the following end points: primary mortality; destination at discharge; total first-year mortality; and the number of hip protheses during the first postoperative year. No significant differences were found between the two regimens. One year after the fracture, patients discharged to their previous living arrangements were invited to a control visit conducted by a physiotherapist; no significant differences between the two groups were found in walking ability, use of walking aids, "walking speed", or absence or presence of pain in the operated hip. Patients in the orthopedic group spent fewer days in the hospital, but had significantly more re-admissions, primarily due to orthopedic-related diagnoses (p = 0.003). The men in the geriatric arm of the trial were on the average 5.5 years older. The types of fracture were not evenly distributed between the two regimens. More patients treated at the geriatric department received technical aids, and more had adjustments made in their homes.

Defining small differences in efficacy between anti-parkinsonian agents using gait analysis: a comparison of two controlled release formulations of levodopa/decarboxylase inhibitor

1. Stride length is highly relevant to mobility and is sensitive to the effects of levodopa in Parkinsonism. Its selection as the primary outcome criterion allowed comparison of two levodopa/decarboxylase inhibitor formulations using a small number of subjects. 2. It is also desirable to improve stability. An instrumental method, based on infrared telemetry, has been developed which obtains both distance/time measures of gait and broadness of base, as measured by foot separation at mid-swing. The latter was used as a subsidiary outcome criterion. 3. Nine patients (aged 57 to 77 years) then receiving maintenance therapy for idiopathic Parkinsonism with Sinemet CR alone, but who had previously experienced end of dose effect within 4 h of receiving a dose of a conventional formulation of levodopa/decarboxylase inhibitor, were studied. 4. They received, in random order and at least 4 days apart, single doses of one tablet of Sinemet CR (200 mg levodopa/50 mg carbidopa) and of two capsules of Madopar CR (each 100 mg levodopa/25 mg benserazide), with placebo balance, at 10.00 h. Gait analysis was carried out immediately before and half-hourly for 7 h after a challenge. No routine doses of Sinemet CR were taken between 22.00 h on the night before and 17.00 h on the day of a challenge. 5. Analysis of variance showed a highly significant difference in mean stride length (P < 0.001) and in mean foot separation (P = 0.01) between serial time points, irrespective of the nature of treatment. There appeared to be a useful therapeutic response to both challenges.(ABSTRACT TRUNCATED AT 250 WORDS)