THE EFFECT OF HORIZONTAL FORCE ON ACCELERATION PERFORMANCE IN
SPRINTING
Jiabin Yu1, Chen Yang1, Yuliang Sun2 and Yu Liu1
Department of Kinesiology, Shanghai University of Sport, Shanghai, China1
School of Physical Education, Shaanxi Normal University, Xi’an, China2
The purpose of the study is to investigate the differences of ground reaction force
(GRF) during the acceleration and maximum velocity phase, and further to discuss
the effect of propulsive force and braking force on acceleration performance. 3
recessed Kistler force platforms sampling at a rate of 1000 Hz were used to
measure the GRF. The result showed that the peak horizontal braking force was
significantly lower for the acceleration phase compared with the maximal velocity
phase (p < 0.001), whereas the peak horizontal propulsive force was similar for
both phases. In conclusion, compared with the maximum velocity phase, the lower
horizontal braking force served to increase the running velocity during the
acceleration phase.
KEY WORDS: ground reaction force, propulsive force, kinetics
INTRODUCTION: A sprint race is made up of various phases: high acceleration phase
(0-10m); low acceleration phase (10-36m) and maximum velocity phase (Delecluse,
1995). Success in these phases poses different requirements to the biomechanics of
sprinting. During the acceleration phase, the net horizontal impulse is the major
determining factor of acceleration (Kawamori, 2013). The magnitude of propulsive and
braking force affect the value of the net horizontal impulse. Mero (1988) reported that
the propulsive force was larger and the braking force was smaller during the highacceleration phase compared with maximum velocity phase. However, no previous
studies reported the GRF differences during the low-acceleration and maximum
velocity phase.
The purpose of this study is to investigate the horizontal GRF differences during the
low acceleration and maximum velocity phase, and furtherer to discuss the effect of
propulsive force and braking force on sprint acceleration. The information gathered
here is critical to inform training program designs aimed at enhancing performance.
METHODS: 20 male sprinters was recruited to participate. 3 recessed Kistler force
platforms (60 x 90 cm) sampling at a rate of 1000 Hz (Kistler 9287B; Kistler Corporation,
Switzerland) were used to measure the GRF. Subjects performed maximum-effort
sprints. In particular, Subjects started sprinting 12m away from force platforms for the
low-acceleration phase and 40m away from force platforms for the maximum velocity
phase. For data reduction, Raw GRF data were filtered using a fourth-order
Butterworth digital low-pass filter with cutoff frequency of 72Hz (Yu, B., 1989). GRF
data were normalized to body weight. Maximum and minimum points that were readily
identifiable on GRF were chosen for analysis. In addition, to average GRF for 20
subjects, the data were interpolated into 100 data points to represent 100% of the
stance stage. Paired-sample t-tests were used to determine differences in GRF
between the acceleration and maximum velocity phases.
RESULTS AND DISCUSSION: the horizontal braking impulse was significantly lower,
but the horizontal propulsive and net horizontal impulse was significantly greater during
the low acceleration phase (12 m) than maximum velocity phase (40 m). The most
interesting finding was GRF differences between the two sprint phases. The horizontal
braking forces were significantly different (p < 0.001), but the horizontal propulsive
forces were similar during the acceleration (12 m) and maximum velocity phases (40
m). This result may indicate that the greater acceleration during the acceleration phase
was achieved by a lower horizontal braking force, not a larger horizontal propulsive
force. The magnitude of horizontal propulsive force in this study was different from
previous study. Mero et al. reported that the horizontal propulsive force during the first
ground contact was 46% greater than that observed during the maximum velocity
phase. The differences were due to different acceleration phases analyzed. Mero’s
study focused on high acceleration phase (first ground contact), whereas this study
investigated low acceleration phase (12m). This discrepancy between our result and
the result of Mero et al. indicated that the horizontal propulsive force may decrease
from the first ground contact and reach a plateau at the very beginning of the low
acceleration phase.
Table 1
Horizontal GRF during the low acceleration and the maximum velocity phase
Variables
Peak horizontal
braking force* (BW)
Peak horizontal
propulsive force (BW)
Horizontal Braking
impulse* (BW.S)
Horizontal Propulsive
impulse* (BW.S)
Net horizontal impulse*
(BW.S)
*Significantly different
(P<0.05).
Acceleration
phase
Maximum
velocity phase
Differences
P Value
0.63±0.25
<0.001
-0.67±0.25
-1.30±0.20
0.90±0.11
0.88±0.13
0.02±0.07
0.063
-0.009±0.005
-0.019±0.004
0.01±0.01
<0.001
0.042±0.004
0.030±0.004
0.012±0.004
<0.001
0.034±0.006
0.011±0.005
0.023±0.007
<0.001
between the acceleration and the maximum velocity phase
Figure 1. Average horizontal force-time curves during the low acceleration and
maximum velocity phase for 20 sprinters
In terms of the horizontal braking force, we found that it was smaller during the
acceleration phase than the maximum velocity phase. Previous studies reported that
the horizontal braking force increased from the 1st to 12th stride. Afterward, it started
to plateau (Cronin, J, 2006). It seems like that the horizontal braking force increased
with the increasing running speed and reached a plateau once the maximum velocity
had been reached.
A recent sprint study found that horizontal propulsive impulse during the acceleration
phase was significantly correlated with 40 m mean speed, whereas horizontal braking
impulse were not, and further suggested faster sprinters pushed more (higher
propulsive impulse), but not braked less (lower braking impulse) during the
acceleration phase(Morin et al., 2015). We absolutely agreed with the opinion of this
study. Our study investigated the GRF differences between acceleration and maximum
velocity phase, so the conclusion about the acceleration phase was based on
comparison with maximum velocity phase. Our study might be a supplement for the
sprint acceleration study.
CONCLUSION: The horizontal propulsive force reached the plateau at the start of the
low acceleration phase. The horizontal braking force reached the plateau until the
maximum velocity was achieved. Compared with the maximum velocity phase, the
lower horizontal braking force served to increase the running velocity during the low
acceleration phase.
REFERENCES:
Cronin, J & Hansen, KT (2006). Resisted sprint training for the acceleration phase of sprinting.
Journal of Strength and Conditioning Research, 28: 42–51.
Delecluse, C.H., Van Coppenolle, H., Willems, E., Diels, R., Goris, M., Van Leemputte, M., &
Vuylsteke, M (1995). Analysis of 100 meter sprint performance as a multi-dimensional skill.
Human Movement Science, 28: 87–101.
Mero, A (1988). Force-time characteristics and running velocity of male sprinters during the
acceleration phase of sprinting. Research Quarterly for Exercise and Sport, 59: 94–98.
Kawamori, N., Nosaka, K., & Newton, RU (2013). Relationships between ground reaction
impulse and sprint acceleration performance in team sport athletes. Journal of Strength and
Conditioning Research, 27: 568–573.
Yu, B (1989). Determination of the optimum cutoff frequency in the digital filter data smoothing
procedure. In: Proceedings of the XII International Congress of Biomechanics. Los Angeles,
CA, University of California.
Morin, J. B., Slawinski, J., Dorel, S., de Villareal, E. S., Couturier, A., Samozino, P., Brughelli,
M., Rabita, G (2015). Acceleration capability in elite sprinters and ground impulse: Push more,
brake less?. Journal of Biomechanics, 48(12): 3149-3154.