EMG activity and kinematics of human cycling movements at different constant velocities

Surface electromyographic (EMG) activity was recorded from the rectus femoris, vastus medialis, biceps femoris, gastrocnemius and tibialis anterior in the human lower extremity while subjects performed bicycling movements over a range of constant pedalling velocities. Kinematics of knee and hip cyclical movements were analyzed from 16 mm film. The reciprocal pattern of activation in agonist and antagonist muscles and timing of EMG initiation relative to knee joint were studied.

Reciprocal activation of rectus femoris and biceps femoris muscles was generally observed to occur during the mid-extension or mid-flexion phase of knee movements. This timing of activation pattern coincided well the period of peak angular velocity and zero angular acceleration.

As pedalling speeds approached maximum, activation times of the bifunctional, biarticular rectus femoris, biceps and gastrocnemius muscles were considerably advanced in phase relative to knee joint angles, whereas, EMG initiation of monofunctional, single joint, tibalis anterior and vastus medialis muscles maintained a relatively stable knee position-activation time relationship. At higher velocities, biceps femoris EMG activity was characterized as having a double burst pattern of activation. A less distinctive double burst pattern was seen in the rectus femoris EMG at higher cycling speeds.

EMG pattern analysis of the rectus femoris and biceps femoris muscles revealed an earlier onset of activity for both muscles during maximum cycling velocities, relative to cyclical phases of the knee joint angle. Considerable overlapping of the EMG bursts was seen beyond pedalling rates of 1 Hz. Co-contraction between rectus femoris and biceps femoris muscles could be observed during the acceleration period involving an abrupt switch to maximum pedalling performance. When co-contraction was observed, the joint angular acceleration curves observed during the knee flexion period accounted for a larger portion of a single cycle, and were more irregular than the angular accelerations observed during knee extension.     

RECTUS FEMORIS TRANSFER TO IMPROVE KNEE FUNCTION OF CHILDREN WITH CEREBRAL PALSY

Stance phase stability and swing phase clearance, prerequisites for normal ambulation, often are lost in the gait of children with cerebral palsy. Lengthening of the hamstrings usually will improve stance-phase knee extension but will not greatly alter swing-phase knee flexion. This paper presents the outcome of transfer of the distal end of the rectus femoris in conjunction with hamstrings lengthening in 37 knees, and compares it with a control group of 24 knees in which only hamstrings lengthening was done. In the first group swing-phase knee flexion was improved by 16.0 +/- 14.4 degrees, compared to 9.5 +/- 7.5 degrees in the control group, and residual knee flexion in stance was reduced to 8.9 +/- 8.1 degrees, compared to 15.1 +/- 13.8 degrees in the controls. Poor outcome in the transfer-plus-lengthening group was associated mainly with foot rotation in excess of 8 degrees internally or externally, or postoperative knee flexion in stance. Criteria for selection of cases and methods of improving surgical outcome are discussed.     

Gait Electromyography in Normal and Spastic Children, with Special Reference to Quadriceps Femoris and Hamstring Muscles

Telemetered gait electromyography was used to investigate gait patterns and the phasic behavior of the quadriceps femoris and medial hamstring muscles in 26 normal children and 32 children with spastic cerebral palsy. The average child with spastic cerebral palsy was found to have a shorter stance phase than the normal, but the cadence, while more variable, was nearly the same as normal. The spastic muscles typically exhibited prolonged phasic activity or a dysphasic pattern. Most of the patients with spastic hamstrings also had spastic quadriceps, suggesting that over-weakening the hamstrings may produce an unwanted genu recurvatum or hyperextended knee gait. Care must be taken to balance hamstring spasticity with quadriceps spasticity. A final result with slight knee flexion is preferable to hyperextension.     

Gait recovery is not associated with changes in the temporal patterning of muscle activity during treadmill walking in patients with post-stroke hemiparesis.

OBJECTIVE: To establish whether functional recovery of gait in patients with post-stroke hemiparesis coincides with changes in the temporal patterning of lower extremity muscle activity and coactivity during treadmill walking. METHODS: Electromyographic (EMG) data from both legs, maximum walking speed, the amount of swing phase asymmetry and clinical measures were obtained from a group of post-acute patients with hemiparesis, as early as possible after admission in a rehabilitation centre (mean time post-stroke 35 days) and 1, 3, 6, and 10 weeks later, while all patients participated in a regular rehabilitation program. EMG data from the first assessment were compared to those obtained from a group of healthy controls to identify abnormalities in the temporal patterning of muscle activity. Within subject comparisons of patient data were made over time to investigate whether functional gait recovery was accompanied by changes in the temporal patterns muscle (co-)activity. RESULTS: EMG patterns during the first assessment showed a number of abnormalities on the paretic side, namely abnormally long durations of activity in biceps femoris (BF) during the single support (SS) phase and in gastrocnemius medialis (GM) during the first double support phase (DS1). Furthermore, in both legs a prolongation of the activity was seen in the rectus femoris (RF) during the SS phase. In addition, the duration of BF-RF coactivation was longer on the paretic side than it was in controls. Over time, the level of ambulatory independence, body mobility, and maximum walking speed increased significantly, indicating that substantial improvements in gait ability occurred. Despite these improvements, durations of muscle (co-) activity and the level of swing phase asymmetry did not change during rehabilitation. More specifically, timing abnormalities in muscle (co-)activity that were found during the first assessment did not change significantly, indicating that these aberrations were not an impediment for functional gait improvements. CONCLUSIONS: Normalization of the temporal patterning of gait related muscle activity in the lower extremities is not a prerequisite for functional recovery of gait in patients with post-stroke hemiparesis. Apparently, physiological processes other than improved temporal muscular coordination must be important determinants of the restoration of ambulatory capacity after stroke. SIGNIFICANCE: Recovery of walking ability in post-stroke hemiparesis is not necessarily associated with, or dependent on, reorganization in the temporal control of gait related muscle activity. Normalization of the temporal coordination of muscle activity during gait may not be an important clinical goal during post-acute rehabilitation.     

Characteristics of the electromyographic patterns of lower limb muscles during gait in patients with Parkinson's disease when OFF and ON L-Dopa treatment

The purpose of this study was to compare the electromyographic (EMG) behavior of the triceps surae (TS), tibialis anterior (TA), quadriceps and hamstring muscles of the lower limbs during self-initiated free gait in a group of patients (n=15) with Parkinson's disease (PD), when OFF and ON L-Dopa, with that of normal controls. When OFF L-Dopa, we observed qualitative disturbances in muscle activation patterns, such as an absence or extreme reduction in TA activations in early stance or during the early and late swing phases. Other disturbances included flatter profiles of the TS activation burst at push off, and temporal alterations that included prolonged activation of the proximal muscles during the stance phase. Statistical analysis showed that the TA was the most affected muscle in most of the patients particularly during the activation burst in late swing (p<.0004). After medication (ON L-Dopa), the amplitude and timing of distal muscle activations became more similar to normal values, with the increase in EMG amplitude being dramatic in some patients. In the proximal muscles, the effects on EMG amplitude were less marked and prolonged activation often persisted even after the administration of L-Dopa.     

Surface EMG profiles during different walking cadences in humans

The ensemble electromyogram (EMG) patterns associated with different walking cadences were examined in 11 normal subjects. Five muscle groups were studied: the rectus femoris, vastus lateralis, lateral hamstring, tibialis anterior and soleus muscles of the right lower extremity. The myoelectric signals were telemetered, full-wave rectified and smoothed. Subjects walked at cadences of 115, 95 and 75 steps/min. Footswitches indicated the different phases of the stride. Six or more strides per subject were averaged for each cadence. Cadence-related changes in (1) mean EMG amplitude during stance, and during swing, and (2) the shape of the EMG patterns, were analyzed. One-way repeated-measures analyses of variance on the mean EMG amplitude in stance and in swing revealed significant changes with cadence (P less than 0.05) in all muscles examined. The magnitude of these changes could be related to the mechanical function of the muscles involved. The shape of the EMG patterns generally remained similar at the different cadences. The timing of EMG activity was closely related to the normalized stride time and remained invariant at different cadences.     

Characteristics of the electromyographic patterns of lower limb muscles during gait in patients with Parkinson''s disease when OFF and ON L-Dopa treatment

The purpose of this study was to compare the electromyographic (EMG) behavior of the triceps surae (TS), tibialis anterior (TA), quadriceps and hamstring muscles of the lower limbs during self-initiated free gait in a group of patients (n=15) with Parkinson's disease (PD), when OFF and ON L-Dopa, with that of normal controls. When OFF L-Dopa, we observed qualitative disturbances in muscle activation patterns, such as an absence or extreme reduction in TA activations in early stance or during the early and late swing phases. Other disturbances included flatter profiles of the TS activation burst at push off, and temporal alterations that included prolonged activation of the proximal muscles during the stance phase. Statistical analysis showed that the TA was the most affected muscle in most of the patients particularly during the activation burst in late swing (p<.0004). After medication (ON L-Dopa), the amplitude and timing of distal muscle activations became more similar to normal values, with the increase in EMG amplitude being dramatic in some patients. In the proximal muscles, the effects on EMG amplitude were less marked and prolonged activation often persisted even after the administration of L-Dopa.This work was supported by grants from Laval University.     

DISTAL RECTUS FEMORIS TRANSFER

A major concern in the management of children with cerebral palsy is crouch gait with its excessively flexed knee and hip stance. Earlier, attention was given to the flexed hip and it was assumed that the rectus femoris, as an active component of the quadriceps, contributed an unwanted effect. Proximal surgical release of the rectus from its attachment on the ilium was recommended. However, dynamic electromyographic records of 45 children with cerebral palsy demonstrated that the rectus more commonly was active in the swing phase, and such an approach is appropriate only when electromyography confirms that rectus function is occurring in stance. The recording technique must be capable of differentiating rectus femoris action from that of the underlying vasti, which surface electrodes are not able to do. Past experience indicates that routine inclusion of a proximal rectus femoris release (without confirmation that the muscle's action was limited to stance) resulted in the patient having a stiff-legged gait. Hence the actions of the rectus femoris need closer attention.     

Lower limb muscle activity in ambulatory children with cerebral palsy before and after the treatment with Botulinum toxin A

Purpose: The study investigated the effect of Botulinum toxin A on the gait and lower limb muscle activity of ambulatory CP children. Methods: 19 spastic diplegic and 4 left hemiparetic CP children were injected with a mean dose of 23.5 units of Botulinum toxin A/kg body weight into the gastrocnemius and hamstring muscles. Muscle tone and gait analysis including the kinesiological electromyogram of the shank and thigh muscles were assessed before and four weeks after injection and compared with the help of a multivariate analysis (p < 0.05). Results: Botulinum toxin A caused a definite reduction of plantarflexor, knee and hip hypertonia in 21 children, resulting in a more plantar grade and erect gait in 17 children four weeks after injection. Gait analysis showed a statistically significant improvement in peak ankle dorsi-flexion and knee extension during stance, and the length of the force point of action under both feet increased. Electromyography revealed sig-nificantly less co-contraction of the lower leg muscles, due to a more phasic instead of a tonic activity of the tibialis anterior muscle, and an improved activation pattern of the left rectus and biceps femoris muscles. Conclusions: The present study demonstrated that the injection of Botulinum toxin A resulted in a more mature muscle activation pattern of CP children. Most of the children walked more plantigrade and erect, the functional gait parameters, however, did not change.     

Quadrupedal coordination of bipedal gait: implications for movement disorders

During recent years, evidence has come up that bipedal locomotion is based on a quadrupedal limb coordination. A task-dependent neuronal coupling of upper and lower limbs allows one to involve the arms during gait but to uncouple this connection during voluntarily guided arm/hand movements. Hence, despite the evolution of a strong cortico-spinal control of hand/arm movements in humans, a quadrupedal limb coordination persists during locomotion. This has consequences for the limb coordination in movement disorders such as in Parkinson’s disease (PD) and after stroke. In patients suffering PD, the quadrupedal coordination of gait is basically preserved. The activation of upper limb muscles during locomotion is strong, similar as in age-matched healthy subjects although arm swing is reduced. This suggests a contribution of biomechanical constraints to immobility. In post-stroke subjects a close interactions between unaffected and affected sides with an impaired processing of afferent input takes place. An afferent volley applied to a leg nerve of the unaffected leg leads to a normal reflex activation of proximal arm muscles of both sides. In contrast, when the nerve of the affected leg was stimulated, neither on the affected nor in the unaffected arm muscles EMG responses appear. Muscle activation on the affected arm becomes normalized by influences of the unaffected side during locomotion. These observations have consequences for the rehabilitation of patients suffering movement disorders.     

Biomechanical factors behind toe clearance during the swing phase in hemiparetic patients

Background: The toe clearance of a paretic limb in the swing phase of gait is related to tripping, which is considered a major cause of falls. The biomechanical factors for obtaining toe clearance are more complicated in hemiparetic gait than that in normal gait because of the compensatory movements during swing phase. Understanding the biomechanical factors should help in targeting the point for rehabilitative interventions.

Objective: To clarify the biomechanical factors behind toe clearance during swing phase in hemiparetic gait.

Methods: Fifty patients with hemiparesis after a stroke participated in this study. Three-dimensional motion analysis was used for the kinematic analysis of the hemiparetic gait. The correlation coefficients between limb shortening and angle changes and between limb shortening and hip elevation and foot lateral shift were calculated. Limb shortening was defined as the shortening of the hip–toe distance. The significant factors that determine toe clearance were examined by multiple regression analysis. Independent variables were limb shortening, hip elevation, and foot lateral shift.

Results: Limb shortening was negatively correlated with hip elevation (r = ?0.75) and foot lateral shift (r = ?0.41). Multiple regression analysis showed a significant contribution of limb shortening and hip elevation to toe clearance. The coefficient of determination was 0.95.

Conclusions: Toe clearance was mainly determined by limb shortening and hip elevation, which were found to be in a trade-off relationship. These results warrant further investigation into the use of three-dimensional motion analysis in the rehabilitation clinic to facilitate targeted rehabilitative training to restore gait ability.     

Detection of abnormal muscle activations during walking following spinal cord injury (SCI)

In order to identify optimal rehabilitation strategies for spinal cord injury (SCI) participants, assessment of impaired walking is required to detect, monitor and quantify movement disorders. In the proposed assessment, ten healthy and seven SCI participants were recruited to perform an over-ground walking test at slow walking speeds. SCI participants were given assistance from physiotherapists, if required, while they were walking. In agreement with other research, larger cadence and smaller step length and swing phase of SCI gait were observed as a result of muscle weakness and resultant gait instability. Muscle activation patterns of seven major leg muscles were collected. The EMG signal was processed by the RMS in frequency domain to represent the muscle activation power, and the distribution of muscle activation was compared between healthy and SCI participants. The alternations of muscle activation within the phases of the gait cycle are highlighted to facilitate our understanding of the underlying muscular activation following SCI. Key differences were observed (p-value = 0.0006) in the reduced activation of tibialis anterior (TA) in single stance phase and rectus femoris (RF) in swing phase (p-value = 0.0011). We can then conclude that the proposed assessment approach of gait provides valuable information that can be used to target and define therapeutic interventions and their evaluation; hence impacting the functional outcome of SCI individuals.     

Neuronal coordination of arm and leg movements during human locomotion

We aimed to study the neuronal coordination of lower and upper limb muscles. We therefore evaluated the effect of small leg displacements during gait on leg and arm muscle electromyographic (EMG) activity in walking humans. During walking on a split-belt treadmill (velocity 3.5 km/h), short accelerations or decelerations were randomly applied to the right belt during the mid or end stance phase. Alternatively, trains of electrical stimuli were delivered to the right distal tibial nerve. The EMG activity of the tibialis anterior (TA), gastrocnemius medialis (GM), deltoideus (Delt), triceps (Tric) and biceps brachii (Bic) of both sides was analysed. For comparison, impulses were also applied during standing and sitting. The displacements were followed by specific patterns of right leg and bilateral arm muscle EMG responses. Most arm muscle responses appeared with a short latency (65-80 ms) and were larger in Delt and Tric than in Bic. They were strongest when deceleration impulses were released during mid stance, associated with a right compensatory TA response. A similar response pattern in arm muscles was obtained following tibial nerve stimulation. The arm muscle responses were small or absent when stimuli were applied during standing or sitting. The arm muscle responses correlated more closely with the compensatory TA than with the compensatory GM responses. The amplitude of the responses in most arm muscles correlated closely with the background EMG activity of the respective arm muscle. The observations suggest the existence of a task-dependent, flexible neuronal coupling between lower and upper limb muscles. The stronger impact of leg flexors in this interlimb coordination indicates that the neuronal control of leg flexor and extensor muscles is differentially interconnected during locomotion. The results are compatible with the assumption that the proximal arm muscle responses are associated with the swinging of the arms during gait, as a residual function of quadrupedal locomotion.     

Pedaling improves gait ability of hemiparetic patients with stiff-knee gait: fall prevention during gait

Background and PurposeStiff-knee gait, which is a gait abnormality observed after stroke, is characterized by decreased knee flexion angles during the swing phase, and it contributes to a decline in gait ability. This study aimed to identify the immediate effects of pedaling exercises on stiff-knee gait from a kinesiophysiological perspective.MethodsTwenty-one patients with chronic post-stroke hemiparesis and stiff-knee gait were randomly assigned to a pedaling group and a walking group. An ergometer was set at a load of 5 Nm and rotation speed of 40 rpm, and gait was performed at a comfortable speed; both the groups performed the intervention for 10 min. Kinematic and electromyographical data while walking on flat surfaces were immediately measured before and after the intervention.ResultsIn the pedaling group, activity of the rectus femoris significantly decreased from the pre-swing phase to the early swing phase during gait after the intervention. Flexion angles and flexion angular velocities of the knee and hip joints significantly increased during the same period. The pedaling group showed increased step length on the paralyzed side and gait velocity.ConclusionsPedaling increases knee flexion during the swing phase in hemiparetic patients with stiff-knee gait and improves gait ability.     

Effect of a rigid ankle-foot orthosis on hamstring length in children with hemiplegia

Eighteen children with hemiplegia, mean age 8 years 5 months, underwent gait analysis and musculoskeletal modelling using specially designed software. The maximum lengths of the hamstrings were determined for each child walking in and out of an ankle-foot orthosis (AFO). The muscles were deemed to be short if shorter than the normal average -1SD. In bare feet 8 participants had short medial hamstrings with a higher proportion of these in the less involved individuals. All participants showed an increase in maximum hamstring length when wearing an AFO. In all but one child this was sufficient to restore hamstring length to within normal limits. These finding suggest that hamstring pathology in hemiplegic gait is usually secondary to more distal lower limb pathology.     

Effect of Electrical Stimulation of Hamstrings and L3/4 Dermatome on Gait in Spinal Cord Injury

Objective. To determine the effect of electrical stimulation of hamstrings and L3/4 dermatome on the swing phase of gait. Materials and Methods. Five subjects with incomplete spinal cord injury (SCI) with spasticity were included. Two electrical stimulation methods were investigated, i.e., hamstrings and L3/4 dermatome stimulation. Both interventions were applied during the swing phase of gait. The main outcome measures were step length, maximum hip, and knee flexion during the swing phase of gait. In three subjects changes of spinal inhibition during gait were evaluated using the Hoffman reflex/m (motor)–wave (H/M) ratio at mid swing. Results. The hip flexion decreased 4.6° (p < 0.05) when the hamstrings were stimulated during the swing phase, whereas the knee flexion was not changed. The step length did not change significantly. One subject showed a decrease of the H/M ratio to a nonpathologic level during hamstrings stimulation. Conclusion. It was concluded that hamstrings stimulation during the swing phase results in a reduction of the hip flexion in all five SCI subjects. The H/M ratio of the vastus lateralis was normalized using hamstrings stimulation in one of three subjects. Stimulation of the L3/4 dermatome provides no significant changes in gait performance, but in one subject the H/M ratio increased.     

To what extent is mean EMG frequency during gait a reflection of functional muscle strength in children with cerebral palsy?

The aim of the current paper was to analyze the potential of the mean EMG frequency, recorded during 3D gait analysis (3DGA), for the evaluation of functional muscle strength in children with cerebral palsy (CP). As walking velocity is known to also influence EMG frequency, it was investigated to which extent the mean EMG frequency is a reflection of underlying muscle strength and/or the applied walking velocity. Surface EMG data of the lateral gastrocnemius (LGAS) and medial hamstrings (MEH) were collected during 3DGA. For each muscle, 20 CP children characterized by a weak and 20 characterized by a strong muscle (LGAS or MEH) were selected. A weak muscle was defined as a manual muscle testing score <3; a strong muscle was defined as a manual muscle testing score ≥4. Patient selection was based on the following inclusion criteria: (a) predominantly spastic type of CP (3-15 years old), (b) either (near) normal muscle strength or muscle weakness in at least one of the studied lower limb muscles, (c) no lower limb Botulinum Toxin-A treatment within 6 months prior to the 3DGA, (d) no history of lower limb surgery, and (e) high-quality noise-free EMG-data. For each muscle, twenty age-related typically developing (TD) children were included as controls. In both muscles a consistent pattern of increasing mean EMG frequency with decreasing muscle strength was observed. This was significant in the LGAS (TD versus weak CP). Walking velocity also had a significant effect on mean EMG frequency in the LGAS. Furthermore, based on R² and partial correlations, it could be concluded that both walking velocity and muscle strength have an impact on EMG, but the contribution of muscle strength was always higher. These findings underscore the potential of the mean EMG frequency recorded during 3DGA, for the evaluation of functional muscle strength in children with CP.     

Obstacle avoidance locomotor tasks: adaptation, memory and skill transfer

The aim of this study was to explore the neural basis of adaptation, memory and skill transfer during human stepping over obstacles. Whilst walking on a treadmill, subjects had to perform uni- and bilateral obstacle steps. Acoustic feedback information about foot clearance was provided. Non-noxious electrical stimuli were applied to the right tibial nerve during the mid-stance phase of the right leg, i.e. 'prior' to the right or 'during' the left leg swing over the obstacle. The electromyogram (EMG) responses evoked by these stimuli in arm and leg muscles are known to reflect the neural coordination during normal and obstacle steps. The leading and trailing legs rapidly adapted foot clearance during obstacle steps with small further changes when the same obstacle condition was repeated. This adaptation was associated with a corresponding decrease in arm and leg muscle reflex EMG responses. Arm (but not leg) muscle EMG responses were greater when the stimulus was applied 'during' obstacle crossing by the left leg leading compared with stimulation 'prior' to right leg swing over the obstacle. A corresponding difference existed in arm muscle background EMG. The results indicate that, firstly, the somatosensory information gained by the performance and adaptation of uni- and bilateral obstacle stepping becomes transferred to the trailing leg in a context-specific manner. Secondly, EMG activity in arm and leg muscles parallels biomechanical adaptation of foot clearance. Thirdly, a consistently high EMG activity in the arm muscles during swing over the obstacle is required for equilibrium control. Thus, such a precision locomotor task is achieved by a context-specific, coordinated activation of arm and leg muscles for performance and equilibrium control that includes adaptation, memory and skill transfer.     

Characteristics of the locomotor-like muscle activity during orthotic gait in paraplegic persons

We previously found that orthotic gait training can induce 'locomotor-like' coordinated muscle activity of the paralyzed lower limb in persons with spinal cord injury (SCI). The purpose of the present study was to characterize the locomotor-like muscle activity based on data obtained from electromyographic recordings and motion analysis during orthotic gait in nine motor complete SCI subjects. Seven of nine subjects showed a common EMG activation pattern mainly in the ankle (soleus: Sol) and hip extensor (biceps femoris: BF) muscles. The locomotor-like muscle activity was well synchronized with the gait cycle, namely, the EMG amplitude of both Sol and BF muscle had common temporal relationships with the ground reaction force, and hip and ankle joint motions. While the presence or absence of the EMG activity during orthotic gait was consistent with those of mechanically-induced stretch reflex, the duration and amount area of the locomotor-like muscle activity were significantly longer than those of the stretch reflex in the Sol muscle. Moreover, the Sol EMG magnitude had strong relevance to hip as well as ankle angular velocities. These results indicate that the locomotor-like muscle activity during orthotic gait is not a mere reflex response, but includes an activity of the central pattern generator (CPG) and its interaction with afferent inputs. Orthotic gait training for complete SCI persons might have a potential to activate the spinal locomotor center.     

Clinical utility of the Duncan-Ely test for rectus femoris dysfunction during the swing phase of gait

The Ely Test (or Duncan-Ely test) has been accepted as a clinical tool to assess rectus femoris spasticity by passively flexing the knee rapidly while the patient lies prone in a relaxed state. In this retrospective review, patients' dynamic knee range of motion (ROM) during gait and an electromyogram (EMG) were compared with the results of the Ely test. Data for 70 patients (44 males, 26 females; 104 limbs) were included. Mean age of patients was 13 years, SD 9 years, range 4 years 5 months to 54 years. All patients were diagnosed with cerebral palsy (spastic diplegia, n = 42; spastic quadriplegia, n = 15, and hemiplegia, n = 13). All patients were ambulatory (50 independent, 20 with assistive devices). A standard matrix was used to calculate sensitivity and specificity of the Ely test as well as its positive and negative predictive value. For the gait variables examined (decreased dynamic knee ROM, timing of peak knee flexion, and abnormal EMG in swing) the sensitivity of the Ely test ranged from 56 to 59% and the specificity ranged from 64 to 85%. For the same variables the positive predictive value ranged from 91 to 98% and the negative predictive value ranged from 4 to 19%. The Ely test was shown to have a good positive predictive value (i.e. the certainty about the presence of rectus spasticity in patients with a positive Ely test result) for rectus femoris dysfunction during gait.