Lower Extremity Support during Toddler Gait
1
S.Potoczny ,
1
Robertson
1,2
Sveistrup
D.G.E.
& H.
1School of Human Kinetics and 2School of Rehabilitation Sciences ,University of Ottawa
Purpose: To examine whether toddler lower extremity support
moments, net moments of force and their powers differ from that of
adults and to determine if and when these kinetic patterns develop
within the first year of walking.
Hypothesis: Toddler support moments, net moments and powers will
differ from adults and will develop to more adult like patterns over the first
year of walking.
Results
Introduction
Moment / Body Mass (N.m/kg)
Walking is one of the most purposeful and fundamental movement patterns for humans. The first two years of life are
characterized by some of the greatest physical development and motor ability changes in a child including the
acquisition of gait, yet there is little research available on the kinetic gait patterns of toddlers. Brenière & Bril (1988)
proposed that children within their first few months of independent walking actually “walk while falling,” whereas
adults “fall while walking.” The purpose of this study was to determine whether this transition was consistent with
developmental changes resulting in increasingly adult-like support moments as well as net moments and powers.
0.8
Conclusion: Toddler support moments, net moments and powers all differ
from that of adults. Toddler joint kinetics also develop over the first year of
walking. There is a general trend in the lower limb joint kinetics to develop
patterns closer to that of ?normal adult-like joint kinetics from ankle to hip?.
Support Moments
One month
Two month
Four month
Five month
0.6
Moment Powers
0.4
One Month
0.2
-0.2
0.8
Eleven month
Nine month
2
0.6
1.5
0.4
1
0.2
0.5
0
0
-0.2
20
40
60
80
20
40
60
80
Adult natural
0.0
Adult slow
20
-0.5
40
60
80
20
40
60
80
Table 1. Subject Characteristics and Body Segment Parameters
Sub #
10
2
4
8
6
12
13
7
11
3
9
14
5
Age
(months)
12
15
17
14
14
18
17
16
18
21
21
23
22
Months
Walking
1
2
3
3
4
4
4
5
5
7
9
11
12
Sex
F
F
M
F
F
F
F
F
F
F
F
F
M
Weight
(kg)
11.7
8.1
11
12
10.3
11.1
14.2
10.4
10.9
9.2
12.6
12.4
11.7
Height
(cm)
84
73
79.5
83
73.5
78
86
74.5
78.5
84
83
84
85
Thigh
Length
Girth
17
26
14.8
24.2
15.2
24.5
17
30.5
14
28
14.5
31
17.5
30.3
14.5
20.1
14
27.5
14.5
23.9
16
31.5
18.5
30.1
16.2
24.3
Shank
Length
Girth
16.8
21
13.7
18.1
13.9
20.5
16.5
22
15
21.5
14
21.5
17
22.9
14.2
19.7
13.5
20
15
20
14.8
23
15.5
23
16
20
Foot
Length
Width
6.1
5.8
6.2
4.2
6.5
5.5
6.5
6
6.1
5
5.5
5
7
6.1
6.1
5.3
6.2
5.5
6.1
5.2
6.5
6
7.2
6.5
6.4
5.6
Table 2. Gait Characteristics
Stride length(cm)
/Height(cm)
Sub #
Mean (sd)
10
0.40 (0.06)
2
0.46 (0.07)
4
0.54 (0.08)
8
0.47 (0.14)
6
0.40 (0.09)
12
0.48 (0.07)
13
0.47 (0.14)
7
0.56 (0.09)
11
0.43 (0.09)
3
0.69 (0.06)
9
0.53 (0.04)
14
0.51 (0.06)
5
0.68 (0.08)
Adult
Slow
Natural
Stride Velocity
(m/s)
Mean (sd)
0.34 (0.08)
0.45 (0.10)
0.69 (0.18)
0.51 (0.15)
0.34 (0.03)
0.54 (0.08)
0.50 (0.18)
0.74 (0.19)
0.51 (0.11)
1.32 (0.11)
0.55 (0.06)
0.57 (0.12)
0.81 (0.22)
Cadence
Mean (sd)
40.28 (9.29)
53.45 (12.36)
82.54 (21.82)
60.79 (18.51)
40.56 (4.07)
64.86 (9.03)
60.08 (21.51)
88.93 (22.71)
61.23 (12.96)
158.40 (13.45)
65.83 (6.97)
68.55 (14.83)
97.32 (25.87)
84.7 (10.4)
105 (7.7)
% Stance
Mean (sd)
68.32 (0.04)
65.17 (0.06)
62.95 (0.02)
65.54 (0.05)
70.48 (0.05)
69.07 (0.04)
67.02 (0.06)
63.87 (0.04)
69.91 (0.05)
49.96 (0.04)
64.45 (0.04)
66.09 (0.05)
64.74 (0.03)
63.5 (1.9)
63.3 (1.0)
% Double
Support
Stride Time (s)
Mean (sd)
Mean (sd)
38.55 (0.06)
1.03 (0.15)
32.77 (0.08)
0.78 (0.13)
33.70 (0.05)
0.65 (0.10)
33.49 (0.04)
0.78 (0.06)
39.70 (0.09)
0.87 (0.13)
39.39 (0.03)
0.70 (0.10)
38.41 (0.05)
0.84 (0.13)
35.27 (0.08)
0.58 (0.09)
46.89 (0.21)
0.67 (0.03)
19.70 (0.07)
0.44 (0.03)
34.25 (0.03)
0.81 (0.06)
32.68 (0.05)
0.76 (0.11)
34.48 (0.07)
0.74 (0.12)
0.0
Knee
Knee
1.0
0.0
0.0
-1.0
-1.0
% Stance
Net and Support Moments
One month
Support
0.8
Adult slow
Eleven month
Five month
Support
Support
Support
2
0.4
1
0.0
-0.4
0
-1
0.6
Hip
Hip
Hip
0.2
Hip
1
Power / Body Mass (Watts/kg)
Participants: Thirteen healthy toddlers autonomously walking for less than a year participated in this study.
Procedure: Ground reaction forces were recorded (240 Hz) and video images (3 cameras; 60 Hz) as toddlers
walked toddlers walked unsupported across two AMTI force platforms. Eight reflective surface markers were placed
over the anterior superior iliac spine, sacrum, greater trochanter, knee, tibial tuberosity, ankle, heel and fifth
metatarsophalangeal joint. Toddler body segment parameters (BSP) were recorded according to Schneider and
Zernicke (1992) and were used in inverse dynamics calculations. Steps were included for analysis if all surface
markers were visible in at least two cameras, if the right foot only was in full contact with a single plate, and if the
toddler was not running or toe walking. Between six and fifteen steps were analyzed for each toddler. All
calculations were done using the Biomech software (Robertson, 2002).
Hip
1.0
-1.0
1.0
curves of individual steps for a one, two, four, five, nine and eleven month autonomous walker are plotted. Also plotted are adult
(mean +/-sd; data from Winter, 1980) support moment curves for both natural and slow walking cadences. Note the different scalings
for the adult support moments. Toddler support moments are approximately two-fold smaller than adults in relative amplitude. Also,
the first twenty percent of stride for both the one and two month walker show negative support moments in approximately 50% of
the trials indicating a controlled fall during the initial part of stance period. The number of steps with negative support moments then
diminish for the four and five month walkers, while the nine and eleven month walkers’ support moments show minimal to no
negative values. The amplitudes of the support moments increase over the first year of walking indicating greater contributions by
the moments of force during stance.
Moment / Body Mass (N.m/kg)
Methodology
Hip
-1.0
Figure 2. Is “falling while walking” reflected in the toddler support moments? Do toddler support moments
show increasingly greater control becoming more adult-like over the first year of walking? Support moment
Figure 1. Illustration of a toddler with digitized segments and force signature overlaid for that trial.
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
#DIV/0!
1.0
0.0
Five Month
Ankle
1.0
1.0
0.5
0.5
0.0
0.0
IFS
-0.5
Ankle
IFS
-0.5
Eleven Month
Adult Slow
Hip
1.0
Hip
1.0
0.0
0.0
-1.0
-1.0
0
-0.2
-1
0.6
Knee
Knee
Knee
0.2
Ankle
Ankle
0.6
Ankle
0.0
0.0
-1.0
-1.0
-1
Ankle
2
1
0.2
Knee
1.0
Knee
1
0
-0.2
Knee
1.0
0
-0.2
20
40
60
80
20
40
60
80
20
40
60
80
-1
20
40
60
80
Ankle
1.0
% Stance
Ankle
4.0
Figure 3. Is the transition observed in the support moments reflected by a parallel transition in joint
moments? Is the development of gait characterized by a sequential development of joint moments? Support,
0.5
2.0
hip, knee, and ankle moments (mean +/-sd) for three toddlers (one, five and eleven months autonomously walking) and adult slow
walking (mean +/-sd; data from Winter, 1980) are plotted. All moments were normalized to body mass and percent of stance.
Extensor moments are plotted as positive values and flexor moments plotted as negative values. Note the different range on the y axis
of the adult slow graphs. Pearson product-moment correlation ranges were also obtained for each toddler by comparing adult slow
walking mean curves with each toddler walking step to obtain the range of correlations. Correlation averages were obtained by
dividing the sum of the range correlation values by the number of steps (between 6 and 15) analyzed for that toddler.
Although the amplitude of the joint moments remain approximately two-fold lower than that of adults, the pattern of joint
flexor and extensor moments approaches that of the adult pattern over the first year. This transition in the pattern of extensor and
flexor moments is characterized by a sequential development over the first year of walking beginning with the ankle, proceeding to
the knee and then the hip. The pattern of ankle joint moment is adult-like after as little as one month of walking and remains
consistent over the first year of walking as indicated by both the shape of the moment curves and the correlation ranges and
(averages) of 0.78 to 0.95 (0.87), 0.68 to 0.98 (0.86) and 0.78 to 0.98 (0.89) for the one, five and eleven month autonomous walkers
respectively. The patterns of knee moments develop over this first year as seen by the increase in the range and (average) correlation
values from -0.35 to 0.36 (0.04), -0.36 to 0.47 (0.18) and 0.1 to 0.84(0.49) and the change in shape of the joint moment curve. Even
with this development of the knee moment by 11 months, the knee has an inconsistent flexor moment that spans less of the stance
phase then adults and is only present in approximately half of the trials. The hip also develops over this first year of independent
walking as indicated by the correlation ranges and (averages) of -0.47 to 0.74 (0.29), -0.03 to 0.85 (0.61) and 0.09 to 0.84 (0.43) for
the one, five and eleven month walkers, but even by the first year of walking the hip continues to remain in extension longer and
lacks the shift to a flexor moment around midstance. These data suggest that joint moment development occurs from distal to
proximal. It is hypothesized that this order of developmental occurs as a function of the increased resources utilized for posture
control by toddlers with less walking experience.
0.0
0.0
IFS
-0.5
20
40
Figure 4. Does the progression
observed in the toddler joint
moments show similar progression
in the moment power production?
Is
development
of
gait
characterized by a sequential
development of moment power
production? Hip, knee, and ankle
powers (mean +/-sd) for three toddlers
(one, five and eleven month autonomous
walkers) and adult slow walking (mean +/sd; data from Winter 1991). All moments
were normalized to body mass and to
percent of stride. Note the different
scalings of the adult slow ankle powers.
The vertical dotted line represents the foot
strike of the right foot and the beginning of
stance phase.
Despite the differences in toddler
and adult ankle moment power amplitudes,
a very similar pattern of power production
occurs at the ankle throughout the first year
of walking. This was evident in both the
ankle moment powers as well as the
correlation ranges of 0.37 to 0.87, 0.57 to
0.93 and 0.18 to 0.88 for the one, five and
eleven month walkers respectively. The
knee power production correlation ranges
of -0.35 to 0.36, -0.24 to 0.44 and -0.016 to
0.55 show that the increases in power
production by the fifth month corresponds
to a development into a more adult-like
pattern. By the fifth month the hip also
begins to exhibit a more adult like pattern
as seen in the average correlations of 0.25,
0.496 and 0.45 for the one, five and eleven
month walkers, respectively, but begins to
exhibit more adult-like power production
amplitudes by the first year of walking as
seen by the hip powers.
IFS
60
80
-2.0
20
40
60
80
% Stride
References:
•Brenière Y, Bril B (1988) Why does the child walk in falling while the adult falls in walking? C. R. Acad. Sci. Paris, 111:617-622.
•Robertson DGE (2002) http://www.health.uottawa.ca/biomech/csb/software/biomech.htm.
•Schneider K, Zernicke R (1992) Mass, center of mass, and moment of inertia estimates for infant limb segments. J. Biomechanics,
25:145-148.
•Winter DA (1980) Overall principle of lower limb support during stance phase of gait. J. Biomechanics, 13:923-927.
•Winter DA (1991) The Biomechanics and Motor Control of Human Gait. Waterloo: Waterloo Biomechanics.
Acknowledgements:
These experiments were funded in part through an operating grant from the Natural Sciences and Engineering Research Council of
Canada. Stefan Potoczny holds a Ontario Graduate scholarship and a academic excellence scholarship. Heidi Sveistrup is a Career
Scientist with the Ministry of Health and Long-term Care of Ontario.
email: spotoczny@hotmail.com, dger@uottawa.ca & hsveist@uottawa.ca