RESEARCH ARTICLE
Training Mobility Tasks after Stroke with
Combined Mental and Physical Practice:
A Feasibility Study
Francine Malouin, Carol L. Richards, Julien Doyon,
Johanne Desrosiers, and Sylvie Belleville
This study examines the potential of using mental practice (MP) to promote the learning of 2 mobility tasks in
persons with stroke. Twelve patients were trained with MP
to increase the loading of the affected limb while standing up from a chair and sitting down. Vertical forces
were recorded using force plates under each foot and the
chair. Changes in the loading of the affected limb and in
task duration, immediately after 1 training session and
24 h later, served as outcomes. After training, the loading
of the affected limb had increased (P < 0.001) during
standing up (16.2%) and sitting down (17.9%), and the
improvement remained significant 24 h later, indicating
a learning effect. In contrast, the duration of the performance did not change with training. The results indicate that, in the early stage of learning with MP, changes
in limb-loading strategies are a more sensitive measure of
performance than is speed.
Key Words: Standing up—Sitting down—Hemiparesis—
Postural asymmetry—Motor imagery—Vertical ground
reaction force
T
he use of mental practice in sports, through
motor imagery, has gained much attention
over the past decades as a means of promoting the learning of motor skills and to maintain
performance when physical practice is not possible.1-3 Mental practice is defined as the act of
From the Department of Rehabilitation, Laval University and
Center for Interdisciplinary Research in Rehabilitation and Social
Integration, Quebec City, PQ, Canada (FM, CLR); Department of
Psychology, University of Montreal, PQ, Canada (JD, SB); and
the Research Centre on Aging, Université de Sherbrooke, PQ,
Canada (JD).
Address correspondence and reprint requests to Dr. Francine
Malouin, CIRRIS (Rehabilitation Research Center), IRDPQ, 525,
Boul Hamel est, Quebec City, PQ, Canada G1M 2S8. E-mail:
francine.malouin@rea.ulaval.ca.
Malouin F, Richards CL, Doyon J, Desrosiers J, Belleville S.
Training mobility tasks after stroke with combined mental and
physical practice: a feasibility study. Neurorehabil Neural Repair
2004;18:66–75.
DOI: 10.1177/0888439004266304
66
repeating, through motor imagery, an imagined
movement several times with the intention of
improving motor performance, whereas motor
imagery corresponds to a dynamic state during
which the representation of a specific action is
internally reactivated within working memory without any overt motor output.4 Sport psychology literature has previously demonstrated that mental
practice can improve the performance of motor
skill behaviors.1-3 These studies have generally
shown that subjects who practice only mentally a
specific task usually display less improvement than
those who practice physically, although mental
practice leads to a superior increase in performance when compared to a no-practice condition.1
Different combinations of physical and mental
practice, however, have been shown to be more
efficient than either form of practice alone,5-7 with
the effect of mental practice being greater when
physical practice is added, even in small amounts.8
There is also some evidence that motor imagery
performed using a 1st-person perspective (i.e.,
internally) yields better improvement than when
performed in the 3rd-person perspective.9-11
Recent advances in the neurosciences have provided evidence that motor imagery activates brain
regions similar to the areas activated during the
physical execution of the same action.12-14 Using
transcranial magnetic stimulation (TMS), PascualLeone and colleagues15 found that mental practice
produced representational changes in the brain
comparable to those yielded by physical practice.
In addition, subjects who had been practicing mentally for 5 sessions reached the same level of performance as those who practiced physically for 5
sessions, after adding only 1 session of physical
practice. This suggests that part of the behavioral
improvement seen with mental practice may be
latent, waiting to be expressed after minimal physical practice, hence supporting the combination of
Copyright © 2004 The American Society of Neurorehabilitation
Mental Practice and Mobility after Stroke
mental and physical practice.15 Several investigators
have proposed the use of mental practice in physical rehabilitation as a cost-efficient means of promoting motor recovery after damage to the central
nervous system.16-20 However, the few studies21-24
that have investigated the use of mental practice in
neurorehabilitation have focused on the training of
the upper extremity, using mostly case study
design.21,23,24 Results from these studies, however,
are generally encouraging and suggest that mental
practice can be used with good results for training
the upper extremity after stroke.
To our knowledge, the effects of mental practice
to promote the learning of motor skills involving
the lower extremities have not been studied in persons with stroke. Moreover, it is questionable if
results obtained for unilateral manual tasks are
applicable to locomotor-related tasks of the lower
extremity, such as standing up and sitting down,
that require coordinated actions of the trunk and
both lower extremities. When compared to healthy
subjects rising from a chair, persons with stroke
take 25% to 61% longer, put much more load on
the unaffected leg, and decrease the loading on the
affected leg by 20% to 25%.25-27 Similar impairments
of loading have been observed with sitting
down.25,26 The relearning of motor strategies to
obtain a more symmetrical loading on the lower
limbs during these 2 mobility tasks early after
stroke is critical to prevent compensations.28 The
amount of physical practice a person early after
stroke can manage, however, is reduced because of
weakness, lack of endurance, and poor balance,
hence limiting the practice time. Given the difficulty that each of these mobility tasks presents for persons after stroke, the addition of mental practice is
a means of increasing the practice time without the
physical constraints and fatigue associated with
physical training.
The main purpose of the present study was to
examine the feasibility of using mental practice in
combination with a small amount of physical practice to improve the motor strategy of persons with
impaired loading of the affected leg while standing
up from a chair and sitting down. The specific
objectives were to (1) describe the deficits specific
to partial loading (PL) and full loading (FL) phases
of each task, (2) examine the response of a biomechanical limb-loading measure to change in motor
strategies immediately after 1 training session, and
(3) assess whether the changes in motor strategies
were retained 1 day later (learning).
Neurorehabilitation and Neural Repair 18(2); 2004
Table 1. Subject Characteristics
Patients (n = 12)Healthy (n = 6)
Gender (male/female)
10/2
Age (years)
56.1 (9.1)
Mass (kg)
86.9 (12.8)
Height (cm)
174 (6.0)
Kinesthetic and Visual
Imagery Questionnaire
(max score = 50)
Visual
38.1 (7.8)
Kinesthetic
30.8 (8.9)
Onseta (mo)a
20.3 (17.5)
Sideb (left/right)b
6/6
ChedokeSASc (1-7)c
Leg
6
Foot
5
Timed Up and Go (s) 16.5 (11.2)
5/1
50.2 (14.1)
71.4 (12.6)
170 (9)
36.9 (9.3)
35.0 (8.4)
Values are presented as Mean (SD) unless otherwise indicated.
a. Stroke onset to study entry.
b. Side of the hemiparesis.
c. Median score of the Chedoke-McMaster Stroke Assessment
Scale.
METHODS
Subjects and Design
Twelve persons with residual motor impairment
on 1 side of the body (hemiparesis) resulting from
a 1st cerebral vascular accident (patients) and a
group of 6 age-matched healthy subjects participated in the study (Table 1). The patients included in
the study were between 30 and 75 years old, had a
unilateral locomotor disability consecutive to a
stroke (ischemic or hemorrhagic origin), demonstrated motor imagery ability, and were able to
stand up and sit down from a chair without using
their arms. The exclusion criteria were cerebellar or
brain stem lesions, receptive aphasia, moderate to
severe body hemineglect, or other problems apt to
interfere with the rehabilitation process or the
motor tasks being trained (e.g., hip replacement,
ankle sprain). The loading of the affected leg during standing up and sitting down was assessed at 3
time points: before training (baseline), after 1 training session (post-training), and 1 day later (followup). The motor imagery ability was also assessed at
baseline. Motor imagery ability and limb loading
were also assessed in the group of healthy subjects
for comparison purposes. Since the healthy subjects demonstrated almost a 50% body weight distribution, they were not trained, but the values of
67
F. Malouin et al.
selves perform the movements from within. The
subjects rated their capacity to elicit mental images
of the action on two 5-point scales (5 = high
imagery, 1 = low imagery). One scale rates the clarity of the image (visual score), and the other rates
the intensity at which they can feel themselves executing the movement (kinesthetic score).
The Timed Up and Go32 (TUG) and the
Chedoke-McMaster Stroke Assessment Scale33 were
used respectively as measures of motor disability
and motor impairment. The TUG is a mobility test
that includes a series of tasks: standing up from a
chair, walking 3 m, turning around and walking
back to the chair, and turning around and sitting
down. The Chedoke-McMaster Stroke Assessment
Scale assesses the level of motor recovery on a 7stage scale ranging from 1 to 7 (stage 1 = lowest
level). More specifically, it assesses the ability to
perform dissociated movements and was used to
assess motor impairment of the foot and the leg.
Evaluation of Standing up
and Sitting Down Tasks
Figure 1. Experimental setup illustrating the position of
the subject during testing. The chair and each foot were
placed on 3 force plates (A, B, C).
the leg with less loading were used to calculate the
loading deficits of the affected leg of the patients.
Clinical Evaluations
A prerequisite for mental practice is the ability to
engage in motor imagery. Therefore, at baseline,
the Kinesthetic and Visual Imagery Questionnaire
(KVIQ), which includes a series of 10 gestures
scored on a 5-level ordinal scale,29 was used to
evaluate motor imagery ability. This questionnaire,
a modified version of the Movement Imagery
Questionnaire (MIQ),30 has been validated
(Cronbach’s α = 0.92), and its concurrent validity
(with the MIQ: r = 0.61) in a group of healthy subjects has been reported.31 In this test, the participants were required to execute each movement
physically and to immediately imagine the same
movement as if they were seeing and feeling them-
68
Subjects were seated on a chair with a seat
height standardized to 100% of lower leg length
(Figure 1), and the chair and each foot were placed
on 3 force plates.29 On hearing an auditory cue, the
subjects were required to stand without using their
hands and to sit down on a 2nd auditory cue. They
were instructed to hold their paretic hand with
their sound hand and to keep their elbows flexed
in front of them. Five trials were recorded at baseline, immediately after the training session, and 24
h later. Signals from the force plates were collected
synchronously at a sampling rate of 1000 Hz and
recorded for further analysis.
Training Procedures
Prior to training, patients followed a familiarization procedure. In the familiarization period, the
subjects were provided with visual feedback of
their motor performance. This feedback, displayed
on a monitor located in front of them, was the net
vertical force trace indicating overloading on the
affected (green trace) or the unaffected (red trace)
leg when standing up and sitting down. Patients
were instructed to modify their motor strategies to
increase the loading of the affected leg (green
Neurorehabilitation and Neural Repair 18(2); 2004
Mental Practice and Mobility after Stroke
trace). Most important, they were asked to relate
their movements to the outcome viewed on the
screen and to remember the feeling and the movement sequences associated with success or error, to
develop an inner representation of their performance. They were also instructed to verbally
describe (explicit knowledge) what they did to
improve their performance (e.g., “shift my body to
the right and then move forward and up”) so that
they could reactivate these pointers later during
mental practice.20,29 The visual display was then
removed, and the patients had to rely on their
memory to repeat and rehearse mentally the proper motor strategies. The familiarization period
ended after about 10 min, when the patients were
able to provide a good autoestimation of their performance (whether they were able to increase the
loading on the affected leg) as judged by the physical therapist who continued to monitor the limb
loading on the visual display. The visual display
was then taken away and not used any further for
training. The familiarization period was followed
by the training period, which consisted of a series
of 7 blocks, each including 1 physical repetition
(PP) and 5 mental repetitions (1PP:5MP training
ratio). The 1PP:5MP ratio was based on preliminary
findings in patients with stroke. It was found that 1
physical repetition after 5 mental repetitions provided the necessary feedback to go on with mental
practice and be successful in imagining the task.
During physical practice, the patients were
instructed to stand up and sit down to an auditory
cue as they had done during the baseline testing.
Then they were instructed to close their eyes and
to imagine they were standing up and sitting down
and to verbally signal the beginning and end of
each repetition. To control for mental practice, the
therapist recorded the duration of the physical and
the mental repetitions that are expected to have a
similar duration.20 The training period required 25
to 30 min.
DATA REDUCTION AND
STATISTICAL ANALYSES
The total scores from each scale of the motor
imagery questionnaire (KVIQ) were averaged for
each group. Each task was divided into a PL phase
and an FL phase (see Figure 2) using the signals
from the force plate under the chair. The PL phase
is defined as the period when body weight is supported by the chair and both feet, whereas the FL
phase represents the period without contact with
Neurorehabilitation and Neural Repair 18(2); 2004
Figure 2. (A) Top graphs illustrate the mean vertical
force exerted with each lower limb (right and left) when
standing up and sitting down in the group of healthy subjects. The vertical forces are normalized in percentage of
total body weight, and tasks are normalized in percentage of total duration. The vertical broken lines on the xaxis indicate the time of seat-off and separate the PL
phase from the FL phase. Each task starts at time 0. (B)
The middle graph represents corresponding patterns of
vertical forces exerted by the affected and unaffected legs
in the group of subjects with stroke. Note the large interlimb difference, with greater force exerted by the unaffected leg. Each task starts at time 0. (C) The lower
graphs represent the changes in vertical force loading
patterns after the training (open squares) and at followup (filled circles). Each task starts at time 0.
the chair. Standing up started with the PL phase
and sitting down with the FL phase (Figure 2). The
onset of the standing-up task was determined by a
change (10 N or more) in the vertical force signal
69
F. Malouin et al.
Table 2. Mean (SD) Limb Loading (%) and Deficit (%) of the Affected Leg
Standing Up
Phase
Patients with stroke (n = 12)
Baseline
Limb loading
Deficit
Post-training
Limb loading
Deficit
Follow-up
Limb loading
Deficit
Healthy subjects (n = 6)
Limb loading
PL
FL
Sitting Down
Total
PL
FL
Total
43.6 (4.8)
12.1 (9.7)
40.5 (7.9)
16.3 (16.4)
—
14.2 (12.0)
45.1 (4.2)
7.8a (8.5)
41.3 (7.2)
15.3 (14.8)
—
11.6 (10.4)
47.0b (5.5)
5.2 (11.2)
46.1b (5.2)
4.7 (10.8)
—
4.9 (10.5)
48.8b (3.8)
0.2 (7.8)
46.9b (5.6)
3.4 (11.4)
—
2.0 (8.7)
46.5b (6.8)
6.3 (13.6)
44.8b (6.7)
7.5 (13.8)
—
6.9 (13.0)
48.1b (4.5)
1.7 (9.3)
45.1b (5.3)
7.5 (10.8)
—
4.6 (9.5)
49.6 (1.0)
48.4 (2.3)
—
49 (2.9)
48.8 (2.6)
—
PL, partial loading phase; FL, full loading phase; total, mean of PL and FL.
a. Baseline deficits: deficit in PL phase was smaller (P < 0.03) than in FL for the sitting-down task, smaller than in PL phase of the standing-up task (P < 0.01).
b. Training effects: significant increase post-training (P < 0.01) and at follow-up (P < 0.01).
Table 3. Mean (SD) Duration (s) and Deficit (%)
Standing Up
Phase
Patients with stroke (n = 12)
Baseline
Time
Deficit
Post-training
Time
Deficit
Follow-up
Time
Deficit
Healthy subjects (n = 6)
Time
PL
FL
Sitting Down
Total
PL
FL
Total
0.54 (0.32)a
60.9 (97.1)
1.41 (0.53) 1.95 (0.76)
59.5 (59.9) 59.9 (62.5)
0.81 (0.27)
47.7 (49.9)
1.52 (0.65)
60.1 (68.8)
2.33 (0.78)
55.5 (52)
0.62 (0.33)
—
1.34 (0.43) 1.96 (0.71)
—
60.7 (58.5)
0.72 (0.17)
—
2.02 (0.18)
—
2.74 (0.18)
82.7 (120)
0.56 (0.32)
—
1.27 (0.39) 1.83 (0.61)
—
50.4 (49.7)
0.79 (0.14)
—
1.72 (0.10)
—
2.49 (0.11)
66.1 (71)
0.33 (0.27)
0.89 (0.07)
0.55 (0.11)
0.95 (0.11)
1.5 (0.16)
1.2 (0.07)
PL, partial loading phase; FL, full loading phase; total, mean of PL and FL.
a. All duration values were significantly larger (Mann-Whitney U test; P < 0.001) than values from the comparison group.
recorded from the force plate under the chair and
the end of the task to full body elevation as determined visually by an observer29,34 who interrupted
the recording. The sitting-down task started with
the auditory cue and ended when the signals from
the force plate under the chair were stable. The
duration of each task was normalized to 100%, and
the vertical ground reaction force (vertical impulse)
from each leg was converted into percentage of
body weight. For each task, a mean vertical force
value (area under the curve) was calculated from 5
trials. The effects of training on limb loading and
task duration were statistically examined using a 3factor ANOVA with repeated measures (time = 3
levels, tasks; 2 levels and phases 2 levels), followed
by the post hoc Tukey procedure. The deficit levels of limb loading in the patients were calculated
using mean loading values from the healthy sub-
70
jects. For each phase of each task, the percentage
change from baseline values in loading of the
affected leg and task duration were computed after
training and at follow-up and expressed as a measure of improvement. Pearson correlation coefficients were used to determine whether the amount
of improvement of limb loading was associated
with the initial limb-loading deficit. Last, betweenand within-group comparisons (KVIQ, loading
deficits and gains) were made using, respectively,
the Mann-Whitney U test and the Wilcoxon rank
sum test.
RESULTS
The subject characteristics are reported in Table
1. The mean age of the subjects in the 2 groups
Neurorehabilitation and Neural Repair 18(2); 2004
Mental Practice and Mobility after Stroke
Standing up
60
Partial loading phase
Table 4. Relationships between Limb Loading Deficits at
Baseline
Full loading phase
Sitting
Down (FL)
Limb loading gains (%)
50
Condition
40
Standing up
(FL)
Standing up
(PL)
Sitting down
(FL)
30
20
10
r
P
Sitting
Down (PL)
r
Standing
Up (PL)
P
r
0.92 <0.0001 0.60 <0.04
P
0.68 <0.01
0.64 <0.03
0.90 <0.0001 1
1
0.58 <0.05
0.64 <0.03
PL, partial loading phase; FL, full loading phase.
0
Post-T
F-Up
Post-T
F-Up
Table 5. Between-Task Relationships of Limb Loading
Improvement after Training and at Follow-up
Sitting down
60
Partial loading phase
Post Training
Full loading phase
Limb loading gains (%)
Condition
r
P
Follow-up
r
P
50
Full loading phase 0.96
Partial loading phase 0.45
40
<0.0001
NS
0.91
0.64
<0.0001
<0.03
NS, not significant.
30
20
10
0
Post-T
F-Up
Post-T
F-Up
Figure 3. Bar graphs representing mean (±1 SD) percentage improvement in the loading of the affected leg
when standing up (top) and sitting down (bottom), posttraining (Post-T) and at follow-up (F-Up).
was not different (Mann-Whitney U test; P > 0.05).
Similar mean KVIQ scores were found for both
groups (Mann-Whitney U test; P > 0.05), indicating
that the patients had a motor imagery ability that
compared to control subjects. Further comparisons,
however, indicated that the patients had higher
visual than kinesthetic scores (Wilcoxon rank sum
test: P < 0.05).
Impaired Performance: Limb Loading
and Task Duration
The patterns of limb loading illustrated in
Figures 2A and 2B indicate that the difference in
loading between legs was greater in the patients
(Figure 2A, 2B). The mean loading, expressed as a
percentage of body weight, is reported for each
phase of both tasks for the 2 groups in Table 2.
Data from the control group were used to calculate
Neurorehabilitation and Neural Repair 18(2); 2004
the deficits reported in Table 2. For the standing-up
task, there was no difference in the amount of
loading deficit between phases, but for the sittingdown task, the loading deficit was smaller in the PL
phase compared to the FL phase (Wilcoxon rank
sum test: P < 0.03). Although there was no difference between tasks in the loading deficit in the FL
phase, a smaller deficit was found in the PL phase
of the sitting-down task (Wilcoxon rank sum test: P
< 0.01).
At baseline, the duration of both tasks was
longer in the patients who took on average 60%
and 55.5% more time than healthy subjects to stand
up and sit down, respectively (Table 3). All duration values were significantly larger (Mann-Whitney
U test; P < 0.001) than values from the comparison
group. The duration of the PL phase represented
27% of the standing-up task compared to 35% for
the sitting-down task, and these proportions were
similar for the 2 groups of subjects.
Effects of Training on Limb Loading
and Task Duration
After the training session, the patients increased
the loading on the affected leg (Figure 2C) for both
tasks, resulting in a smaller difference in the
amount of loading exerted by each leg as compared to baseline (Figure 2B). As reported in Table
2, the loading deficits dropped markedly post-train71
F. Malouin et al.
ing and at follow-up. Comparisons of loading values over time for both tasks (ANOVA) revealed an
effect for time (F = 15.6, P < 0.001) and phase (F =
5.9, P < 0.03) but not for task and no interaction,
indicating a similar improvement for both tasks and
phases. A post hoc Tukey test carried out to determine whether the improvement was maintained
over time indicated significant increases in loading
(P < 0.01) post-training and at follow-up. The percentage gains in the loading of the affected leg are
illustrated in Figure 3. Gains in the FL phase ranged
from 11.3% to 18% and from 6.3% to 8.5% in the PL
phase; there was no difference between tasks or
phases (Wilcoxon rank sum test: P > 0.05). The
task duration at baseline, post-training, and followup are reported in Table 3. Comparisons of task
duration over time for both tasks (ANOVA) did not
reveal a main effect for time and no interaction
between time, task, or phase, indicating no significant change of duration with training.
Relationship between Tasks in
the Loading Deficit and Training Effect
At baseline, high correlation coefficients were
found (Pearson coefficient: r > 0.90) in loading
deficits between similar phases of the mobility
tasks but not between phases of the same task
(Table 4). High Pearson correlation coefficients
were also found in the magnitude of the loading
improvement post training and at follow-up
between tasks for the FL phase but not for the PL
phase (Table 5).
DISCUSSION
A single training session of mental practice combined with physical practice resulted in an
improvement of the motor strategies as determined
by the loading patterns when standing up and sitting down. In addition, the improvement was
retained 1 day later, indicating a learning effect. In
contrast, training did not improve the speed of the
performance.
Effects of Training on Limb Loading
and Task Duration
The gains in loading obtained after a single 30min training period that included 7 physical repeti-
72
tions and 35 mental repetitions in the present study
were similar to the magnitude of changes reported
by Engardt and colleagues26 in patients after 3
weeks of regular training in a physiotherapy program. Thus, even if our patients physically executed the tasks 5 to 8 times during the familiarization
period, the learning took place with a relatively
small amount of physical practice. The reason for
improvement with such little physical practice is
possibly the combination with mental practice that
required rehearsing mentally and explicitly the
sequence of movements associated with each task.
Such rehearsal made them focus each time on the
preparation and planning of the proper strategy,
hence increasing their awareness of the required
movements. Present findings are in line with the
results of Pascual-Leone and colleagues15 who
demonstrated with TMS that mental practice had
preparatory effects and increased the efficiency of
subsequent physical training. Likewise, using
positron emission tomography, Jackson and colleagues35 found that after 5 days of intensive mental practice, the changes in brain activity were not
found in motor-related areas but were restricted to
the medial aspect of the orbitofrontal cortex, supporting the idea that mental practice initially
improves performance by acting on motor preparation and planning.
At variance with previous studies,21-24 patients
engaged in mental practice using a 1st-person perspective instead of a 3rd-person perspective.
Moreover, rather than using audiotaped instructions that described scripts of functional activities to
be imagined with the affected limb, patients were
required to generate their own mental representation of the motor tasks. The latter training conditions may have contributed to optimizing the
effects of motor imagery since the 1st-person perspective has been reported to be best to elicit
kinesthetic components of a movement during
imagery.9-11 Moreover, recent findings in the neurosciences have shown that only the 1st-person perspective activates regions that partly overlap with
actual execution of motor behavior.36 Likewise,
using internal signals for motor imagery eliminates
the shortcomings associated with the use of audiotapes, which makes motor imagery a more passive
process in which the patient is dependent on an
external source to engage in motor imagery.7,20,37
Present results also indicate that initially, the
improvement of the motor strategies is not necessarily associated with a faster execution, and our
findings suggest a change in the quality of movement (improved loading of the affected leg) to be
Neurorehabilitation and Neural Repair 18(2); 2004
Mental Practice and Mobility after Stroke
the first indicator of learning. The latter may be
related to the fact that in the early stage of learning, the subjects rely more on declarative knowledge of the tasks (conscious level), and such a cognitive process requires more attention and time.20
The other factor that may explain the lack of
change in movement speed is likely of peripheral
origin as it takes more training over a longer period to increase muscle strength and improve balance associated with faster movements. In fact,
changes in both motor strategies and speed of
movement have been documented after several
weeks of training.26,38,39 Last, a faster performance
may not necessarily reflect improvement in the
quality of movement. On the contrary, it was found
in a follow-up study40 that although gains in loading of the affected leg were lost, movement time in
rising and sitting down had further improved.
Latter findings suggest caution in the interpretation
of changes related to spatiotemporal parameters, as
a faster performance could be the result of more
use of the unaffected leg or from other compensatory means.40
Finding that initial improvement in quality of
movement without concomitant gain in speed in
the initial phase of learning is also in keeping with
the construct of the Motor Assessment Scale,41
which is based on the premise that improvement of
motor performance precedes the increase in speed.
Indeed, in this 7-level ordinal scale, the indicators
for the lower levels of performance of the sit-tostand task are related to the symmetry of weight
bearing, whereas the higher levels correspond to
indicators of movement speed.
Impaired Motor Performance after
Stroke: Limb Loading and Task Duration
The deficits measured while patients were bearing full weight were similar for both tasks, suggesting that both require as much training. Our findings
concur with those of Engardt and Olsson25 who
also observed, in a group of 42 patients with
stroke, equivalent deficits in weight-bearing distribution for similar mobility tasks. The dividing up of
the tasks into 2 phases, however, allowed us to
demonstrate that deficits were present even when
patients were not bearing full weight (PL phase)
and that patients need to be reminded to sit with
weight equally distributed before standing up. Our
results also show that the deficits were smaller in
the PL phase during sitting down compared to that
during the standing-up task (Table 2), which fur-
Neurorehabilitation and Neural Repair 18(2); 2004
ther emphasizes the difficulty in the transition from
sitting to standing.
When examining the nature of the deficits in
loading, greater deficits occurred in the FL phases
than in the PL phases, suggesting a phase-specific
difference in motor strategies. This was confirmed
by the correlation analysis (Table 4), which shows
a strong intraphase relationship and a weaker interphase relationship. These findings are likely related to the nature of the control of the body momentum within each phase.42,43 For instance, the PL
phase corresponds with the control of horizontal
body momentum either in the forward direction for
standing up or in the backward direction for sitting
down.42,43 Likewise, the vertical body momentum
has to be controlled in the FL phase by the extensor muscles of the lower limbs either by concentric
contractions when standing up or eccentric contractions when sitting down.42 As for the correlation
coefficients in Table 5, they revealed a strong relationship for the FL phase and a weaker one for the
PL phase, suggesting the response to training
across tasks is less consistent for the PL phase.
IMPLICATIONS
The present study has described a training
approach to promote the learning of mobility tasks
with mental practice. The 1PP:5MP training ratio
method wherein mental practice is combined with
a minimal amount of physical practice resulted in
an increase of loading on the affected leg that was
retained at follow-up. Although the study included
a small number of subjects and did not tease out
the additive effects of mental practice, this study
described an innovative approach in using mental
practice to augment physical practice to promote
the learning of mobility tasks after stroke. The
information relative to training methods and outcome measures gathered in this preliminary study
has been applied to the design of the randomized
trial that is now underway to evaluate the potential
of mental practice for promoting the relearning of
mobility tasks in a larger group of patients with
stroke.
Future studies are needed to compare the effects
of different training programs combining physical
and mental practice and to determine the optimal
timing for the introduction of such training over the
rehabilitation period. For example, in a recent case
study,44 it was shown that the addition of mental
practice in a patient who had reached a plateau
after being trained only physically yielded an extra
73
F. Malouin et al.
10.3% improvement, and continuing his training
with mental practice alone after discharge induced
another small increase of 2.2%. This example illustrates how mental practice can gradually be introduced in a patient’s rehabilitation program. In general, once the patient has a good representation of
the movements to be rehearsed, mental practice
could be added to regular interventions. Thus, on
discharge, the patient, already familiar with the
method, should be able to continue training with
mental practice on his or her own, hence further
optimizing physical performance of the task.
ACKNOWLEDGMENTS
We thank the subjects who participated in this
study. We also extend our gratitude to Lise Dion for
her assistance in data collection and Daniel Tardif
for preparing the figures. This work was supported
by a grant from the Quebec Rehabilitation Research
Network (REPAR) from the Fonds de la Recherche
en Santé du Québec. C. L. Richards holds a Canada
Research Chair in Rehabilitation.
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