Relationship of Step Width with Sprinting Performance
and Ground Reaction Forces
Ryu Nagahara, Mirai Mizutani and Akifumi Matsuo
National Institute of Fitness and Sports, 1 Shiromizu-cho, Kanoya, Kagoshima, Japan
Keywords: Running, Foot Placement, Mediolateral, Acceleration.
Abstract: The purpose of this study was to clarify the relationship of step width with sprinting performance and
ground reaction forces in order to understand the sprinting mechanism and its relation to better sprinting
performance.
1 OBJECTIVES
Relationships between sprinting performance and
spatiotemporal variables such as step frequency and
length have broadly been investigated (Debaere et
al., 2013; Hunter et al., 2004; Nagahara et al., 2014).
However, little is known about the relationship of
step width, which is the mediolateral distance
between two consecutive steps, with sprinting
performance. For example, Ito et al. (2006) showed
step width at initial acceleration and at maximal
speed phase during 100-m race. Although they
reported no significant difference in the step width
between elite and national level sprinters, the result
was obtained with the investigation at initial
acceleration and maximal speed phase. Thus, when
considering the entire acceleration phase of sprinting,
an importance of narrower or wider step width may
be able to be found.
While a study has investigated the influence of
difference in step width on some kinetic variables
during running (Brindle et al., 2014), the influence
of step width on ground reaction force (GRF) during
sprinting has never been examined. Accordingly, it
is still unknown how difference in step width
associate with GRFs during sprinting.
The purpose of this study was to clarify the
relationship of step width with sprinting
performance and GRFs in order to understand the
sprinting mechanism and its relation to better
sprinting performance.
2 METHODS
2.1 Experiment
Seventeen male athletes (mean ± SD: age, 20.7 ± 1.2
y; stature, 1.73 ± 0.03 m; body mass, 66.5 ± 4.2 kg;
personal best 100-m race time, 11.22 ± 0.28 s)
participated in this study. After warming-up, the
participants performed 60-m maximal effort
sprinting from starting blocks. GRF over 52-m
distance was sampled with 54 force platforms (1000
Hz) connected to a single computer (TF-90100, TF-
3055, TF-32120, Tec Gihan, Uji, Japan).
2.2 Data Processing
Spatiotemporal variables were calculated at every
step during 50-m distance with following procedures.
Foot strike and toe-off instants were determined with
a threshold of vertical GRF as 20 N. Based on the
foot strike and toe-off instants, step duration from
the foot strike of one leg to the next foot strike of the
other leg was calculated. Step frequency was
computed as an inverse of step duration. Foot
placement was determined as the centre of pressure
position at the middle of the support phase. Step
length and width were calculated as anterior–
posterior and mediolateral distances between two
consecutive steps. For the step width, to standardise
the value, ratio of step width relative to the
corresponding subject stature was calculated.
Running speed was calculated as a product of step
length and frequency. Step-to-step mediolateral and
anterior–posterior impulses during the support phase
8
Nagahara, R., Mizutani, M. and Matsuo, A.
Relationship of Step Width with Sprinting Performance and Ground Reaction Forces.
In Extended Abstracts (icSPORTS 2016), pages 8-10
Copyright
c
2016 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
over 50-m distance were calculated from GRF
signals. Moreover, effective vertical impulse during
the support phase was computed (Weyand et al.,
2000).
2.3 Statistical Analysis
To examine the relationship among variables during
accelerated sprinting with macroscopic perspective,
each variable at all steps during 50-m distance was
averaged out. Means and standard deviations were
calculated for each variable. Pearson’s product
moment correlation coefficient was calculated to test
relationship among the average variables. The
significance level was set at 5%. All statistical
values were calculated using JMP 12 statistical
software (SAS Institute Japan Ltd, Tokyo, Japan).
3 RESULTS
Averaged running speed, step length and step
frequency over 50-m distance were 8.20 ± 0.17 m/s,
1.82 ± 0.10 m, 4.45 ± 0.22 Hz, respectively. Figure 1
shows changes in step width during the entire
acceleration phase. The step width from the first step
after block clearance decreased to the 14th step (3.43
s), and the magnitude of decrease became small
afterward during the entire acceleration phase. The
averaged step width over 50-m distance and its ratio
were 0.15 ± 0.05 m and 8.9 ± 3.0 % of stature.
Table 1 shows averaged GRF variables over 50-
m distance. The medial (inward) impulse was
greater than the lateral (outward) impulse while
running on straight line.
Figure 1: Step-to-step changes in step width during
accelerated sprinting for 50-m. Black and grey lines
indicate means and standard deviations. The value at the
first step was from block clearance to the first foot strike
on the ground.
The ratio of step width was significantly
positively correlated with running speed (r = .484, P
= .049), whereas no significant correlation was
found between the ratio of step width and step length
or frequency (r = .279 and .066, P = .279 and .800)
(Figure 2). The ratio of step width was significantly
correlated positively with medial (r = .816, P < .001),
lateral (r = .833, P < .001), net mediolateral (r
= .880, P < .001) and propulsive impulses (r = .539,
P = .026) (Figure 2). No significant relationship was
found between the ratio of step width on the one
hand and braking impulse (r = .447, P = .072),
anterior–posterior net impulse (r = .423, P = .091)
and effective vertical impulse (r = .015, P = .955) on
the other hand.
4 DISCUSSION
This study aimed to clarify the relationships of step
width with sprinting performance and GRFs. The
results in this study demonstrate the probable
importance of relatively wide step width for better
accelerated sprinting performance. Because the
relationship of step width with both step length and
frequency did not show significant relationship, the
benefit of wider step width may have no specific
effect on longer step length or higher step frequency.
In contrast to the results of this study, Ito et al.
(2006) reported no significant difference in the step
width between elite and national level sprinters. The
reason of this discrepancy may be the difference in
methodological approach in addition to the
difference in the performance levels between our
study and the study by Ito et al. (2006), i.e. sprinting
was investigated at initial acceleration and at
maximal speed phase in the study of Ito et al. (2006),
while it was investigated over the entire 50-m
distance in this study.
The wider step width was associated with greater
medial impulse and smaller lateral impulse, as well
as greater mediolateral net impulse, indicating that
the wide step width will be accompanied by large
mediolateral velocity of body within a step.
Although the mediolateral velocity of body is
theoretically disadvantageous for better sprinting
performance, the wide step width is interestingly
also associated with greater propulsive impulse. This
result suggests that wider step width may be feasible
to produce greater propulsive force during the
support phase of sprinting. While it is difficult to
clearly explain the mechanism of how wider step
width induces greater propulsive impulse during
sprinting, one possible reason is the difference in
Relationship of Step Width with Sprinting Performance and Ground Reaction Forces
9
Table 1: Averaged GRF variables over 50-m distance. ML and AP mean anterior–posterior and mediolateral, respectively.
ML and AP positive values indicate medial and propulsive GRFs. ML and AP negative values indicate lateral and braking
GRFs.
Negative Positive Net
ML impulse [Ns/kg] 0.04 ± 0.03 0.13 ± 0.05 0.09 ± 0.07
AP impulse [Ns/kg] 0.11 ± 0.02 0.52 ± 0.04 0.40 ± 0.03
Effective Vertical impulse [Ns/kg] 1.02 ± 0.09
Figure 2: Relationship of step width with spatiotemporal
and GRF variables.
adductor muscle activations during hip extension
between wide or narrow stances. In the study with
squat exercise (McCaw and Melrose, 1999), the
integrated electromyography values of adductor
muscle for the ascent phase of squat with use of a
wide stance were approximately 20% greater than
that with use of narrow stance. Wiemann and Tidow
(1995) indicated the importance of adductor muscles
to generate propulsive force together with major hip
extensor muscles. Consequently, relatively wide step
width during sprinting possibly induces greater
activity of adductor muscles and better sprinting
performance through greater propulsive force.
In conclusion, the wider step width may be
beneficial for better accelerated sprinting performan-
ce. This finding may deepen the understanding of
sprinting performance and be beneficial for athletes
and coaches, trying to improve accelerated sprinting
performance.
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