Results

Descriptive data on gait variables for each instructional set by groups are presented in table 1. The significant findings for the variables included a group effect for left step length (F(1, 14)=11.15), right step length (F(1, 14)=9.34), ambulation velocity (F(1, 14)=4.88), and elbow excursion )F(1, 14)=9.79). Compared with the control group, the left and right step lengths were 26% shorter, gait velocity 23% slower, and elbow excursion 53% less for the Parkinson’s disease group. Secondly, a significant effect was found for instructional set for right step length (F(4, 56)=32.95); left step length (F(4, 56)=14.10); ambulation velocity (F(4, 56)=35.5); cadence (F(4, 56)=12.96); shoulder excursion (F(4, 56)=8.49); and elbow excursion, (F(4, 56)=6.36). There was no significant group×instructional set interaction for any of the gait variables.

In response to the instructional set, both groups were able to voluntarily alter a gait variable—for example, arm swing amplitude—and showed a significant change in that variable. In addition to the participants’ response to single instructional sets, concomitant changes occurred in other gait variables. For instance, when instructed to walk while deliberately swinging the arms, both shoulder and elbow excursions increased (118% and 197% respectively), walking velocity increased by 20%, and step length increased by 18%. When instructed to walk with large steps, the right and left step length increased by 47% and 38%. Velocity concomitantly increased by 40% and arm swing excursion increased by 73%, whereas cadence decreased by 14%. When asked to walk fast, step lengths increased by 28%, arm swing excursion (shoulder by 52% and elbow by 335%) and cadence increased by 30%. When asked to walk while counting aloud, only velocity increased significantly by 14%. Lastly, when asked to walk fast, walking velocity increased in both groups by 65%.

The pattern of change in mean gait velocity for the five instructional sets was similar for the two groups (figure). However, in response to the instructions for fast walking and large steps, both groups demonstrated significant increases in gait velocity from their natural walking velocity. Compared with their natural speed, the Parkinson’s disease group increased their velocity 65% during fast walking and 50% when walking with large steps. The walking velocities of the Parkinson’s disease group were comparable or surpassed the natural walking velocity of the control group (1.02 m/s) for the three instructional sets: (1) while deliberately swinging the arms (0.93 m/s), (2) walking with large steps (1.16 m/s), and (3) fast walking (1.27 m/s, figure).

Discussion

This study showed that the walking patterns of patients with Parkinson’s disease improved in response to specific instructions to change a series of single gait variables. Patients with Parkinson’s disease can intentionally walk with larger steps, faster, and with increased arm swing amplitude. Furthermore, by increasing the intensity of one gait variable—for example, arm swing amplitude—other gait variables improved. These findings indicate that cognitive strategies have the potential to improve the overall walking patterns of patients with Parkinson’s disease.

This confirms previous findings that patients with Parkinson’s disease respond to verbal instructions to alter their walking pattern.1 2 For example, Morris et alreported that patients with Parkinson’s disease who focus deliberately on walking with normal stride length improve their walking patterns.5 They suggested that strategies employing instructional sets and deliberate attention to specific elements of “normal” walking may bypass basal ganglia circuitry and activate the frontal and prefrontal areas of the brain to prepare the motor cortex for locomotion.15 The use of this cognitive strategy may therefore provide an internal stimulus to improve Parkinsonian gait. Although skilled, automatic walking is disrupted due to basal ganglia dysfunction in Parkinson’s disease, cognitive strategies seem to elicit more normal movement.16 This approach is advantageous when compared with strategies reliant on external visual cues such as lines painted on the floor or an upturned walking stick.3 4

The benefits of each instructional strategy may vary based on severity of Parkinson’s disease and individual differences. For example, one patient with Parkinson’s disease at Hoehn and Yahr stage III responded to the instruction to walk fast without changes in step length or arm swing amplitude, yet with a dramatic increase in the speed of stepping. The patient walked 114% faster, yet, the increase was achieved by a 139% increase in cadence. By contrast, the cues for deliberate arm swing and large steps resulted in more normal walking patterns with significant increases in velocity, arm swing amplitude, and step length. The large step and arm swing instructions were therefore more effective strategies. Although this patient’s response to the walk fast instruction was an exception, it may be a consequence of the advanced stage of disease progression.6

In summary, following specific verbal instructions, patients with Parkinson’s disease intentionally and successfully altered single gait variables including step length, velocity, and arm swing excursion. Automatically activated increases in the amplitude of other variables also occurred, producing a more normal walking pattern. Thus the use of instructional sets is a rehabilitation strategy which may assist patients with Parkinson’s disease to immediately improve their movement. Notwithstanding, the benefits of instructional sets may diminish when the patient negotiates turns and corners and may therefore require self cueing to maintain gains.15Patients with Parkinson’s disease may also benefit from a practised self instructional strategy to enhance the retention of training. The effectiveness of this behavioural strategy may, however, be dependent on the progression of Parkinson’s disease and the severity of locomotor disturbance.