Grasping the handrails during treadmill walking does not alter sagittal plane kinematics of walking

The effects of metronome frequency differentially affects gait on a treadmill and overground in people with Parkinson disease

BACKGROUND

Treadmills and rhythmic auditory cueing can influence stepping rhythm for individuals with Parkinson disease (PD). Of concern, however, is that auditory cueing directly addresses the temporal features of gait, whereas adjusting step length may be more important for people with PD. Stepping to a faster cadence when walking overground may increase gait speed, but without requiring an increased step length. Furthermore, given the potentially valuable role of walking on a treadmill for individuals with PD, we are concerned that increasing cadence with rhythmic auditory cueing while walking at a constant treadmill speed will induce even shorter steps.

RESEARCH QUESTION

What is the effect of different metronome cue frequencies on spatiotemporal gait parameters when walking overground compared to walking on a treadmill in people with PD?

METHODS

Using a repeated-measures design, 21 people with PD (stage 1-3) walked overground and on a treadmill with and without metronome cues of 85 %, 100 %, and 115 % of their baseline cadence frequency for one minute each. We assessed step length, and cadence during all conditions. Gait speed was assessed during overground gait.

RESULTS

An interaction effect between cue frequency and walking environment revealed that participants took longer steps during the 85 % condition on the treadmill only. When walking overground, metronome cues of 85 % and 115 % of baseline cadence yielded decreases and increases, respectively, in both cadence and gait speed with no associated change in step length.

SIGNIFICANCE

These data suggest that people with PD are able to alter spatiotemporal gait parameters immediately when provided the appropriate metronome cue and walking environment. We propose to target shortened step lengths by stepping to the beat of slow frequency auditory cues while walking on a treadmill, whereas the use of fast frequency cues during overground walking can facilitate faster walking speeds.

Novel patterns of functional electrical stimulation have an immediate effect on dorsiflexor muscle function during gait for people poststroke

BACKGROUND

Foot drop is a common gait impairment after stroke. Functional electrical stimulation (FES) of the ankle dorsiflexor muscles during the swing phase of gait can help correct foot drop. Compared with constant-frequency trains (CFTs), which typically are used during FES, novel stimulation patterns called variable-frequency trains (VFTs) have been shown to enhance isometric and nonisometric muscle performance. However, VFTs have never been used for FES during gait.

OBJECTIVE

The purpose of this study was to compare knee and ankle kinematics during the swing phase of gait when FES was delivered to the ankle dorsiflexor muscles using VFTs versus CFTs.

DESIGN

A repeated-measures design was used in this study.

PARTICIPANTS

Thirteen individuals with hemiparesis following stroke (9 men, 4 women; age=46-72 years) participated in the study.

METHODS

Participants completed 20- to 40-second bouts of walking at their self-selected walking speeds. Three walking conditions were compared: walking without FES, walking with dorsiflexor muscle FES using CFTs, and walking with dorsiflexor FES using VFTs.

RESULTS

Functional electrical stimulation using both CFTs and VFTs improved ankle dorsiflexion angles during the swing phase of gait compared with walking without FES (X+/-SE=-2.9 degrees +/- 1.2 degrees). Greater ankle dorsiflexion in the swing phase was generated during walking with FES using VFTs (X+/-SE=2.1 degrees +/- 1.5 degrees) versus CFTs (X+/-SE=0.3+/-1.3 degrees). Surprisingly, dorsiflexor FES resulted in reduced knee flexion during the swing phase and reduced ankle plantar flexion at toe-off.

CONCLUSIONS

The findings suggest that novel FES systems capable of delivering VFTs during gait can produce enhanced correction of foot drop compared with traditional FES systems that deliver CFTs. The results also suggest that the timing of delivery of FES during gait is critical and merits further investigation.

Functional electrical stimulation of ankle plantarflexor and dorsiflexor muscles: effects on poststroke gait

BACKGROUND AND PURPOSE

Functional electrical stimulation (FES) is a popular poststroke gait rehabilitation intervention. Although stroke causes multijoint gait deficits, FES is commonly used only for the correction of swing-phase foot drop. Ankle plantarflexor muscles play an important role during gait. The aim of the current study was to test the immediate effects of delivering FES to both ankle plantarflexors and dorsiflexors on poststroke gait.

METHODS

Gait analysis was performed as subjects (N=13) with chronic poststroke hemiparesis walked at their self-selected walking speeds during walking with and without FES.

RESULTS

Compared with delivering FES to only the ankle dorsiflexor muscles during the swing phase, delivering FES to both the paretic ankle plantarflexors during terminal stance and dorsiflexors during the swing phase provided the advantage of greater swing-phase knee flexion, greater ankle plantarflexion angle at toe-off, and greater forward propulsion. Although FES of both the dorsiflexor and plantarflexor muscles improved swing-phase ankle dorsiflexion compared with noFES, the improvement was less than that observed by stimulating the dorsiflexors alone, suggesting the need to further optimize stimulation parameters and timing for the dorsiflexor muscles during gait.

CONCLUSIONS

In contrast to the typical FES approach of stimulating ankle dorsiflexor muscles only during the swing phase, delivering FES to both the plantarflexor and dorsiflexor muscles can help to correct poststroke gait deficits at multiple joints (ankle and knee) during both the swing and stance phases of gait. Our study shows the feasibility and advantages of stimulating the ankle plantarflexors during FES for poststroke gait.

Limits of locomotor ability in subjects with a spinal cord injury

STUDY DESIGN

Case-control study with pair-wise matching.

OBJECTIVES

To investigate the level of locomotor performance in spinal cord injury (SCI) subjects.

SETTING

Spinal Cord Injury Center of Balgrist University Hospital in Zurich, Switzerland.

METHODS

Seven well-recovered SCI subjects and controls performed three tests: (1) 6-Min Walk Test (6MWT), (2) treadmill walking with full and restricted vision and (3) repetitive stepping over an obstacle. In the latter task, the subjects had to step over an obstacle as low as possible, without touching it. The subjects performed three blocks of 50 trials each. They received acoustic signals that indicated obstacle approach and foot clearance. During the third block, vision was restricted. The main outcome measures were: (1) distance walked, (2) leg muscle activity, joint kinematics and double-support duration, (3) foot clearance, number of obstacle hits, leg muscle activity, joint kinematics and swing phase duration.

RESULTS

(1) No difference in the 6MWT between the groups. (2) Independent from vision, the double-support duration was increased in SCI subjects. (3) SCI subjects learned generally at a slower rate. They touched the obstacle more frequently when vision became restricted. Furthermore, we observed differences between the groups in rectus femoris and tibialis anterior EMG activity and swing phase duration.

CONCLUSION

It appears that even in well-recovered SCI subjects, small deficiencies in functional gait can be determined, which remain undetected by clinical walking tests. In addition, SCI subjects learned a locomotor task at a slower rate. This indicates that rehabilitation programs should train (adaptive) locomotion in different (sensory) environments.

Light touch and center of mass stability during treadmill locomotion

PURPOSE

To study the contributions of light fingertip touch on an earth-referenced object to body stability during treadmill locomotion.

METHOD

Twenty young healthy adults were tested in two blocks of five testing conditions while walking on the treadmill at 3 km/h. In each condition, subjects were tested with eyes open (EO) and with eyes closed (EC). In each block, four separate conditions of heavy (H) or light (L) touch to either a left or to a right force sensor mounted on the respective side rail, as well as one condition of no touch (N), were randomly applied. The 3D positions of the center of mass (COM) and the midpoint of the posterior aspect of each leg were monitored via a kinematic ultrasonic system, while the anterior-posterior (AP) acceleration of the COM was measured with a uniaxial linear accelerometer.

RESULTS

Light touch had a similar stabilizing effect as vision and as heavy touch on COM sway. Thus, COM sway and AP acceleration were comparable in conditions of eyes open and eyes closed as long as touch was applied. Conversely, without vision and touch, subjects drifted backwards, with complete disruption of the coordinated stepping pattern.

CONCLUSIONS

Somatosensory fingertip input from an external reference provides spatial orientation, which, similar to vision, enables the sustaining of body stability during treadmill walking.

Electromyographic analysis of locomotion for healthy and hemiparetic subjects--study of performance variability and rail effect on treadmill

This study quantified the performance variability and effect of rail support on the ankle joint for normal and hemiparetic subjects during treadmill walking. Muscle activities of the anterior tibialis (TA) and medial gastrocnemius (MG) from six hemiparetic patients and 14 healthy subjects were assessed with EMG linear envelope and variance ratio of consecutive strides at self-selected cadences. Our results indicate that (1) performance consistency of the hemiparetic patients was significantly undermined; (2) habituated process during treadmill walking was notable in the MG but not in the TA; and (3) rail support could reduce performance variability of the ankle antagonist pairs.