1. References
Yeow et al. 2011. Human Movement Science 30, 624-635
Boden et al. 2009. Am J Sports Med 37, 252-259
Coventry et al. 2006. Clinical Biomechanics 21, 1090-1097
Yeow et al. 2009. The Knee 16, 381-386
Ali et al. 2014. The Knee 21, 38-46.
Does drop height affect ground reaction forces acting on the foot during uni-
lateral landing?
Liverpool John Moores University, Liverpool, UK
Remy Hughes, Abbie Hull, Joshua Hull, Joel Huskisson, and Joey Hutton
Results
On figure 1, there is a high impact VGRF peak between 0-10% of landing for all heights.
There was a quicker rate of force production as drop height increased between 0-10% of
landing. There is a proportional relationship between drop height and the magnitude of
the VGRF. The impact peak was 5BW during landing from a height of 30cm, 3BW from
20cm and 2.5BW from 10cm. There’s a slight peak for the drop height of 10cm
Discussion
• Based on our results we found that as landing height increases, there’s an increase in
peak VGRF, posterior GRF and anterior GRF.
• In comparison with Ali et al (2014), they found similar results where peak VGRF and
posterior GRF increased with height during landing. Yeow et al (2009) also found
similar results. However the magnitudes were different in Ali et al (2014) paper, peak
VGRF at height of 30cm lower (4BW) compared to ours (5BW), however at 20cm peak
VGRF was similar. Peak posterior GRF was larger in Ali et al (2014), compared to ours
where their peak posterior GRF was 0.6BW at 30cm compared 0.4BW of our data.
• Limitations: Use of only one subject and trials to increase reliability of results. Did not
use males and females as females also had a lot of anterior-cruciate ligament injuries
within sport. No use of shoes, which makes the study less ecologically valid. However
we did not use shoes as different sports have different types of shoe cushioning which
may effect GRF. Use of heel technique which has larger GRF exerted on the leg (Yeow
et al 2009).
• Future Research- Look at different landing techniques such as knee and hip flexion
and forefoot landing which may reduce the effect of peak GRF which may prevent
injury (Coventry et al, 2006).
Introduction
Landing is vital in sports such as volleyball, basketball, football, badminton and
gymnastics etc. These athletes land by the use of either unilateral or bilateral landing
techniques (Yeow et al, 2011).There is a large landing impact on the lower extremity of
the body (Coventry et al, 2006), which may cause injuries. Boden et al (2009) found that
single leg landing may be a factor of anterior cruciate ligament injuries. Within sport,
athletes land from different heights and we want to see if landing height can effect the
ground reaction forces exerted on the lower extremity. The aim of the study is to see if
landing height has an effect on vertical ground reaction force (VGRF) and anterior-
posterior ground reaction force (APGRF) whilst landing uni-laterally.
Methods
• Subject: Male, aged 20, weighed 102kg (1009N)
• Protocol:
o Participant dropped from heights of 10cm, 20cm and 30cm onto a force plate using
barefoot heel landing. (Kistler, Winterthur, Switzerland).
o Measured VGRF and APGRF using a force plate, and data was collected using
AcqKnowledge 4.0.
• Analysis: Excel was used to graph the data collected.
Figure 1. Vertical Ground reaction force during
landing from heights of 10cm, 20cm and 30cm.
Figure 2. Anterior-Posterior ground reaction
forces whilst landing from heights of 10cm, 20cm
and 30 cm.
between 20-30% of landing which made peak VGRF similar to the drop height of 10cm
(3BW). During 10-30% of landing, there was a decrease in VGRF however there was a
quicker rate in decline of VGRF as drop height increases.
On figure 2, between 0-15% of contact, there’s a larger force in the posterior direction
from a height of 30cm (0.4BW) compared to 20cm (0.3BW) and 10cm (0.2BW). Then
there’s a larger force in the anterior direction whilst landing from a height 30cm
compared to 20cm and 10cm between 15-20% of landing phase. However our data
shows that 10cm had a larger anterior GRF compared to 20cm. Then there was a
decrease for all heights (20-25% of landing phase) then there was an increase in GRF
however the rate of increase was quicker as landing height increases (30-60% of
landing). Peak anterior force increased with height (30cm- 0.45BW, 20cm-0.4BW, 10cm-
0.33BW).Then anterior GRF decreases for all heights.
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0 10 20 30 40 50 60 70 80 90 100
APGRF(BW)
Landing Phase (%)
10cm 20cm 30cm
0
1
2
3
4
5
6
0 10 20 30 40 50 60 70 80 90 100
VGRF(BW)
Landing Phase (%)
10cm 20cm 30cm
• Conclusion- Based on our study and previous studies (Ali et al, 2014), there was an
effect of landing height on peak VGRF and posterior GRF. Therefore when landing
height increases, peak vertical and posterior ground reaction forces increases.
AnteriorPosterior