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ST6P01
Common parkour vaulting techniques, landing styles, and
their effects on landing forces
James Adams | 16033827
Supervisor: Karl Grainger
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Acknowledgements
I am grateful to Karl Grainger and the London Metropolitan University Sports Department for
their support and guidance. I also wish to thank Sophie Koonin, Juwad Malik, Thuli Lamb, and
Andrew Pearson for their help and patience as sounding boards during the writing process.
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Table of Contents
Acknowledgements ........................................................................................................................ 2!
Table of Contents ........................................................................................................................... 3!
List of Figures ................................................................................................................................. 5!
List of Tables .................................................................................................................................. 6!
List of Appendices .......................................................................................................................... 7!
Abstract .......................................................................................................................................... 8!
List of Abbreviations ...................................................................................................................... 9!
Chapter 1. Literature Review ....................................................................................................... 10!
1.1. Background ....................................................................................................................... 10!
1.2. Parkour Research .............................................................................................................. 11!
1.3. Landing Injuries ................................................................................................................. 13!
1.4. Parkour Vaults ................................................................................................................... 15!
1.5. Aim and Hypothesis .......................................................................................................... 18!
Chapter 2. Method ....................................................................................................................... 19!
2.1. Participants ....................................................................................................................... 19!
2.2. Protocol ............................................................................................................................. 20!
2.3. Statistical Analysis ............................................................................................................. 23!
Chapter 3. Results ........................................................................................................................ 25!
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Chapter 4. Discussion ................................................................................................................... 31!
4.1. Effects of Landing Style ..................................................................................................... 31!
4.2. Parkour Vault Characteristics ............................................................................................ 33!
4.3. Implications for Injury Risk ................................................................................................ 36!
4.4. Limitations ......................................................................................................................... 38!
Chapter 5. Conclusion .................................................................................................................. 43!
References ................................................................................................................................... 44!
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List of Figures
Figure 2.2.1. Illustration of a step vault ....................................................................................... 22!
Figure 2.2.2. Illustration of a kong vault ...................................................................................... 22!
Figure 2.2.3. Illustration of a dash vault ....................................................................................... 23!
Figure 3.1. Intraclass correlation coefficients for peak vertical and braking ground reaction
forces for all movement and landing style combinations ............................................................ 25!
Figure 3.2. Interaction plots for peak vertical and braking ground reaction forces ..................... 30!
Figure 4.3.1. Intensity plots for peak vertical and braking ground reaction forces ..................... 38!
Figure 4.4.1. Example vertical ground reaction force profile plot for a single participant
performing a step vault with a precision landing ......................................................................... 39!
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List of Tables
Table 2.1.1. Participant characteristics ........................................................................................ 19!
Table 2.1.2. Participant categorical characteristics for gender and preferred landing foot ........ 20!
Table 3.1. Two-way repeated-measures ANOVA results for peak vertical and braking ground
reaction forces ............................................................................................................................. 26!
Table 3.2. Pairwise comparisons for the effect of landing style on peak vertical and braking
ground reaction forces for each movement ................................................................................ 27!
Table 3.3. Pairwise comparisons for the effect of movement choice on peak vertical and braking
ground reaction forces within each landing style ........................................................................ 29!
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List of Appendices
Appendix 1: Means and Standard Deviations for All Groups ....................................................... 57!
Appendix 2: Parkour Vault Techniques ........................................................................................ 58!
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Abstract
The emerging sport of parkour has developed a landing technique focused on soft, quiet and
controlled landings. The proficiency of practitioners (traceurs) for two-legged drop landing tasks
is becoming increasingly established, but it is unknown whether the same aptitude will be
demonstrated for different movements and with different landing techniques. This study will
investigate the ground reaction forces (GRFs) produced during three common parkour vaulting
techniques utilising two common landing styles, with the aim of understanding how GRFs may
change between the different scenarios and the subsequent implications for injury risk. 10
traceurs (age 29.4 ± 7.2 years, height 173.8 ± 8.1 cm, weight 74.2 ± 8.4 kg, experience 9.7 ± 3.6
years) performed a drop landing, step vault, dash vault, and kong vault onto a force plate with a
two-legged precision landing (precision) and a single-legged running landing (running). Peak
vertical (vGRF) and braking (bGRF) GRFs per limb were analysed by repeated-measures two-way
ANOVA. A significant interaction effect between movement choice and landing style was found
for both peak vGRF (p = 0.007) and peak bGRF (p < 0.001). All movements increased in vGRF
when using a running landing, but only the drop and kong vault increased in bGRF while the
step and dash vaults decreased in bGRF. The kong vault resulted in the greatest peak vGRFs and
bGRFs, differing significantly from all other movements with a precision landing and, even in
comparisons that did not achieve significance, always producing at least a medium to large
effect size. The dash vault produced the least peak vGRF and bGRF of all movements in both
landing styles, differing significantly from all others in bGRF and the drop and kong vault in
vGRF. Movement choice and landing style affect landing GRFs for common parkour vaulting
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techniques. While GRFs increased in running style landings, they still did not exceed those
typically experienced in jogging, indicating that traceurs mimic their performance in two-legged
drop landings and continue to effectively mitigate GRFs when vaulting. As a result traceurs are
unlikely to be at risk of acute lower limb injury when vaulting, but may remain at risk of chronic
lower limb injury.
Keywords: Parkour · freerunning · traceur · vaulting · ground reaction forces
List of Abbreviations
GRF - ground reaction force
vGRF - vertical ground reaction force
bGRF - braking ground reaction force
PKV - parkour vault
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Chapter 1. Literature Review
1.1. Background
Parkour is one of the newest sports practised today, having only been recognised by Sport
England in 2017 (Parkour UK, 2017). Parkour is the traversal of an environment and the
obstacles within it, but the nature of that traversal can differ between practitioners (known as
traceurs) and involve a wide array of movements (O’Loughlin, 2012). While influenced by
movements from a broad range of disciplines, including dance and acrobatics (Aggerholm and
Højbjerre, 2017), some movements have emerged as identifiably distinct parkour techniques
(O’Grady, 2012). The establishment in the UK of accredited coaching qualifications and a
national governing body has helped codify some parkour techniques (Sterchele and Ferrero
Camoletto, 2017), but data is still sparse on the physical demands of parkour with traceurs
often reliant on personal experimentation or anecdotal evidence spread via word of mouth and
the internet to guide their training (Gilchrist and Wheaton, 2011). Data on the kinetic and
kinematic effects of parkour practice may help coaches and traceurs further develop the sport,
as understanding the forces produced by a sporting technique can help improve performance
or reduce injury risk (McNitt-Gray, 2008). Analysing the ground reaction forces (GRFs) produced
when performing these parkour movements can give an insight into their effect on traceurs.
The level of GRF produced is described as a key indicator of the level of mechanical stress
applied to the body during movement (McClay et al., 1994). GRFs are the forces exerted by the
ground on a body in contact with it, measured by executing the movement in question on a
force plate. Force plates measure in three axes: vertical, anterior-posterior, and medial-lateral
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(Bartlett, 2007). The harder an athlete pushes against the ground about one of these axes to
accelerate or decelerate themselves, then by Newton’s Third Law, the more force is applied
back onto the athlete’s body in the same axis (Blazevich, 2007). Vertical (vGRF) and anterior-
posterior axes are of the most interest to biomechanists for jumping or running related
activities when studying performance or causes of injury (Hunter, Marshall and McNair, 2005).
Anterior-posterior GRF is further subdivided into braking and propulsive forces. Braking GRFs
(bGRF) occur as the foot first contacts the floor and resists forward motion, with propulsive
GRFs following as the centre of mass passes over the midpoint of the foot and the lower limb
pushes off the floor to accelerate forward (Cavanagh and Lafortune, 1980). GRFs fluctuate
throughout a movement, but the maximum or peak level of GRF produced during execution is
often analysed as an important measure of the maximum mechanical stress applied to a body
resulting from a movement.
1.2. Parkour Research
Research into GRFs in parkour has commonly aimed to compare traceurs with athletes from
other sports or the untrained, with a predominant focus on vGRF in jumping and landing tasks.
Jumping is often used as a predictor of general athletic ability (McLellan, Lovell and Gass, 2011),
with traceurs shown to reach significantly greater heights in drop and countermovement jumps
than gymnasts and power athletes (Grosprêtre and Lepers, 2016). Grosprêtre, Gimenez and
Martin (2018) attribute this to the large amounts of eccentric lower limb training traceurs
undertake, as well as increased neuromuscular coordination for jumping tasks. The forefoot-
only landing technique employed by traceurs, known as the precision landing, has also been
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studied. Forefoot landing is not a new concept, with forefoot landings known to reduce vGRF in
basketball players for some time (Gross and Nelson, 1988). However, the focus on keeping the
heel raised as opposed to allowing it to lower to the floor may differentiate the parkour
precision landing from other traditional landing strategies. This position reduces the contact
area of the foot with the floor and consequently requires good postural control to maintain
stability after landing (Maldonado et al., 2015), which may explain why it has not seen
widespread use before adoption within parkour.
Precision landings have been shown to produce lower vGRF when compared to traditional
landings in a study by Puddle and Maulder (2013). However, traceurs also performed the
traditional landings in this study, which may not have been habitual to them and may have
distorted the results. Standing and Maulder (2015) subsequently found very similar results to
Puddle and Maulder, with decreased vGRF in landing tasks by traceurs when comparing
landings by traceurs to recreational athletes. Standing and Maulder further speculated that the
significantly longer time traceurs took to reach maximum vGRF on landing allowed for
improved dissipation of mechanical forces acting upon the body. Increased time to peak vGRF
was attributed to high eccentric strength in the lower limb, as the more an athlete can
eccentrically prolong a landing, the lower peak vGRF they produce (Cortes et al., 2007). The role
of the knee was also emphasised, with greater knee flexion found in landings by traceurs
contributing to the majority of energy dissipation compared to the ankle and hip joints.
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1.3. Landing Injuries
The ability of traceurs to minimise vGRF when landing is critical for a sport focused on jumping.
Large amounts of vGRF during landings are associated with an increased risk of acute lower
limb injury (Elvin, Elvin and Arnoczky, 2007). Most commonly, trauma occurs to the anterior
cruciate ligament (ACL) of the knee (Ingram et al., 2008). ACL injuries occur more than any
other acute knee injury (Majewski, Susanne and Klaus, 2006) and are caused by excessive
anterior translation of the tibia in relation to the femur (Sell et al., 2007) due to high valgus
motion and abduction forces at the knee joint (Shin, Chaudhari and Andriacchi, 2009). Due to
their proximity and the mechanism of injury, injury to the ACL is also often associated with
damage to other ligaments and the menisci of the knee (Stevens and Dragoo, 2006). Good
deceleration technique to reduce vGRF is a key component of decreasing the likelihood of ACL
injury when landing (Silvers and Mandelbaum, 2011). Further, a study of lower limb
biomechanics in stop jump tasks by Yu, Lin and Garrett (2006) found that reducing joint
stiffness by increasing active knee flexion during landing is important for reducing the risk of
ACL injury. The precision landing results in large amounts of flexion and energy dissipation in
the knee (Maldonado, Soueres and Watier, 2018), potentially reducing the risk of acute injury
to the structures of the knee when landing (Butler, Crowell and Davis, 2003).
Increased flexion in landings, however, is in turn associated with an increase in the risk of
chronic knee injuries (Derrick, 2004). Tendinopathy of the patellar tendon is the most common
chronic injury in jumping sports, earning the colloquial name “jumper’s knee” (Myer et al.,
2015). Patellar tendinopathy is common in other jumping sports such as volleyball and
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basketball (Cook et al., 2000), affecting up to 50% of volleyball players (Lian, Engebretsen and
Bahr, 2005), and can be difficult enough to rehabilitate that it can end athletic careers (Zwerver,
Bredeweg and Akker-Scheek, 2011).
The patellar tendon transmits the muscular force of the quadriceps muscles to the tibia,
facilitating knee extension concentrically and resisting knee flexion eccentrically (Tan and Chan,
2008). Muscle force generated by the quadriceps can be up to three times larger in eccentric
muscle contraction than concentric (Stanish, Rubinovich and Curwin, 1986) and athletes who
exhibit higher knee extensor loads are at increased risk of patellar tendinopathy (Visnes,
Aandahl and Bahr, 2012). The demanding eccentric component and high degree of knee flexion
in the precision landing could, therefore, cause very high levels of patellar tendon loading
(Witvrouw et al., 2000), causing microtrauma to the tendon (Peers and Lysens, 2005).
If not allowed time to repair, the cumulative effect of these microtraumas could mean a high
risk of degenerative damage developing within the tendon (Galloway, Lalley and Shearn, 2013).
Appropriate eccentric strengthening of the knee extensors may mitigate this (Seynnes et al.,
2009), but tendon microtrauma recovery and strength increases take time (Prilutsky, 2008).
Experienced traceurs train up to an average to 12 hours per week (Grosprêtre and Lepers,
2016), a volume that may not allow for adequate tendon recovery from microtrauma (Visnes
and Bahr, 2013). The precision landing technique, while potentially reducing the risk of acute
ACL injury, could instead place a traceur at an increased risk of chronic patellar tendinopathy
when training over an extended period.
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1.4. Parkour Vaults
The precision landing technique is taught and encouraged not just when jumping but
throughout all parkour movements. Movements in parkour are commonly taught with the cue
“land quietly”, with sound used as a coaching tool in the field to judge landing quality (Standing
and Maulder, 2015). This leads to an adoption of the precision landing as the default landing
technique for all parkour movement. Consequently, the acute and chronic injury risks of
precision landings may be relevant to other parkour techniques or even the sport as a whole,
not solely two-legged jumping and landing tasks.
One common area of movement in parkour concerns vaulting an obstacle. Parkour vault (PKV)
techniques focus on traversal of an obstacle that is too high to directly jump over but not high
enough to require climbing; usually between hip and shoulder height. As an example, indoor
parkour training often uses gymnastic vaulting horses or tables with a standard height of 1.35 m
(Fédération Internationale de Gymnastique, 2017). PKVs are also often performed outdoors,
over and onto solid surfaces such as concrete rather than the padded vaulting horses and crash
mats used in gymnastics. As the traceur must clear the height of the obstacle to pass over it,
there is potential for numerous repetitions of high GRF landings onto hard surfaces during PKV
training and subsequently a high potential for injury.
However, a PKV does not necessarily equate to a direct drop from the height of the obstacle.
Using the hands or feet as support on the obstacle may reduce vertical drop velocity, but
different levels of support provided by different PKV techniques could result in an equally
varied range of GRFs. PKVs also emphasise the maintenance of horizontal speed throughout,
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rather than converting horizontal speed to vertical height as in a gymnastics vault (Koh et al.,
2003). Given an emphasis on horizontal motion, the traceur’s centre of mass may not follow a
path directly up and down on either side of the obstacle. It may instead take a much shallower
projection arc, like those seen in long jumping (Linthorne, Guzman and Bridgett, 2005),
reducing the resulting drop height on the far side of an obstacle.
Three common PKVs are the step vault, the kong vault, and the dash vault (see Appendix 2).
The step vault involves using the hands and a foot on the obstacle to pass over it, while the
kong and dash vaults only involve the use of the hands on the obstacle. Step vaults are
commonly the first vault taught to beginners due to their relative safety and increased ability to
control the movement throughout an extended contact time with the top of the obstacle
(Gerling, Pach and Witfeld, 2013). The landing strategies used to exit a PKV can also vary. A
traceur may come to a complete stop on two feet (precision landing style), or land with a single
foot and keep moving (running landing style), often used to transition into a run or link with
another technique. Even when landing on a single foot, the forefoot style landing of the
precision technique is encouraged by coaches, but not exclusively depending on the preceding
technique and desired outcome.
Running style landings may increase the risk of acute lower limb injury in PKVs. vGRF
significantly increases when switching from a two-legged to single-legged landing in drop
landing tasks, with an associated increase in the risk of acute injury (Yeow, Lee and Goh, 2011).
Endeavouring to maintain horizontal velocity in a running style landing may also lead to a
conscious decrease in lower limb joint flexion to avoid excessive downward travel of the body.
Reductions in lower limb joint flexion have been found to increase vGRF in other jumping sports
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such as volleyball (Bisseling et al., 2007) and potentially contribute to lower limb injuries in
gymnasts (Seegmiller and McCaw, 2003). Contact time between the foot and the floor also
decreases as horizontal velocity increases (Grabowski and Kram, 2008). A short ground contact
time would not allow traceurs to fully apply the long eccentric phase of the precision landing
technique, resulting in higher vGRFs. This could lead to a reversal of the injury scenarios posited
for the precision style landing, with increased vGRFs and reduced knee flexion in running style
landings increasing the risk of acute injury (Kulig, Fietzer and Popovich Jr, 2011).
As well as vGRF, landings also produce bGRF, particularly in jumping exercises involving
horizontal motion (Kossow and Ebben, 2018). The level of bGRF produced varies according to
the movement executed prior to landing, with varied angular momentums in the air producing
different bGRFs in models for gymnastic techniques (Mills, Pain and Yeadon, 2009). bGRF has
been found to increase with greater vertical travel in a movement (Gottschall and Kram, 2005),
a stiffer knee joint, (Milner et al., 2006), and an increase in horizontal speed (Gutekunst,
Frykman and Seay, 2010). While bGRF is less commonly associated with acute injury in jumping
sports, increases in bGRFs have been linked to stress fractures in runners (Zadpoor and
Nikooyan, 2011) and with patellar tendinopathy in dancers (Fietzer, Chang and Kulig, 2012).
Maldonado, Soueres and Watier (2018) recorded bGRF in the precision landing and found that
it was lower in traceurs than an untrained subject in drop landings, but still increased at greater
drop heights. This indicates that frequent repetitions of high bGRFs may also be a risk factor for
chronic injuries in traceurs.
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1.5. Aim and Hypothesis
Such a wide variety of contributing factors mean that it is currently unclear how GRFs may vary
between PKVs and landing styles. As PKVs are some of the most frequent movements traceurs
perform, the forces exerted upon the body during their execution need to be understood to
effectively allow safe and appropriate training. Some variable elements in PKV execution
(support on the obstacle and shallow projectile arc) may reduce GRFs, while others (single leg
landings, obstacle height, and reduced ground contact time) may have the inverse effect.
The aim of this study is to examine the vGRF and bGRF experienced by a single limb during
three common parkour vault techniques and a drop jump of an equivalent height, performed
with both two-legged precision and one-legged running style landings. The research hypothesis
is that vGRF and bGRF will differ between the four movements and between landing styles.
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Chapter 2. Method
2.1. Participants
Following ethical approval by the London Metropolitan University School of Human Sciences
Research Ethics Review Panel and a priori power analysis (α = 0.05, β = 0.8, η2p = 0.6), 10
parkour practitioners were recruited for this study. All participants were screened for
contraindications or injuries and required a minimum of 2 years experience in parkour training
(Puddle and Maulder, 2013). Participants completed a CSEP Get Active Questionnaire (Canadian
Society for Exercise Physiology, 2017) and informed consent forms following a full explanation
of the study aims and protocol.
Participant characteristics are reported in Tables 2.1.1 and 2.1.2.
Table 2.1.1. Participant characteristics (n = 10).
Mean (SD)
Age (yrs)
29.4 (7.2)
Height (cm)
173.8 (8.1)
Weight (kg)
74.2 (8.4)
Years Training (yrs)
9.7 (3.6)
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Table 2.1.2. Participant categorical characteristics for gender and preferred landing foot.
Left Foot
Right Foot
Male
6
2
Female
0
2
2.2. Protocol
Participants were instructed to attend in comfortable athletic clothing and footwear that they
would normally wear for parkour training. Height was measured using a stadiometer (Leicester
Height Measure, Chasmors Limited, UK) as per protocol in Milašinović et al. (2016). Weight and
GRF data was measured using a force platform (Kistler Type 9826AA, Kistler Instrumente AG,
Switzerland), connected to BioWare software (type 2182A, version 5.3.0.7).
Movements were carried out using a vaulting box (Niels Larsen Ltd, UK) with a height of 0.96 m
and a depth of 0.55 m. The force platform was placed on a solid floor surrounded by rubber
mats to create a landing runway extending 3 m away from the vaulting box to minimise any risk
of injury if landing off-target. Force plate data were collected for 8 seconds per trial at a
sampling rate of 1000 Hz (Linthorne, 2001).
Participants were given time to warm up and to practise each movement with each landing
style onto the force plate as they desired and until the satisfaction of researchers that all
movements were being performed as required. Participants performed 8 movements in a
sequence, consisting of a drop landing and three PKVs each executed with a two-legged stop
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landing (precision landing) and a single-legged landing with the preferred leg that continued
into a short run (running landing). Sequences were generated and assigned using a randomised
Latin square of movement combinations and a random number generator. Movement order
within each sequence was arranged in a counter-balanced crossover design to mitigate fatigue
and learning effects (Moir et al., 2004). This was repeated for a total of 3 sequences, or 24 total
movements, per participant.
Each participant was allowed a run-up distance comfortable to them for typical execution of
each movement, mimicking field conditions (Gratton and Jones, 2010). Movements were
deemed unsuccessful if the participant performed the movement and did not land, or landed
only partially, on the force plate. Unsuccessful movements were repeated until successful. A
30-second rest was given between movements within a sequence and a 2-minute rest between
sequences. All participants completed all their sequences in a single testing session.
Movements were performed as follows:
Drop landing: the participant crouched to full depth atop the vaulting box before dropping to
the force platform.
Step vault: the participant jumped at the box and used one hand and the contralateral foot in
contact with the box, with the non-contact foot stepping through before leaving the box, as
illustrated in Figure 2.2.1.
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Figure 2.2.1. Illustration of a step vault.
Kong vault: the participant dived forward with their hands first, placing both hands atop the
box simultaneously whilst in the air. The hands pushed off as the knees tucked into the torso
and the body followed over the box, as illustrated in Figure 2.2.2.
Figure 2.2.2. Illustration of a kong vault.
Dash vault: the participant jumped at the box feet first, with the feet passing over and both
hands coming down to push off the box from behind the body, as illustrated in Figure 2.2.3.
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Figure 2.2.3. Illustration of a dash vault.
PKV execution is further illustrated in Appendix 2.
2.3. Statistical Analysis
GRF data for each movement in both vertical and anterior-posterior axes was exported from
Bioware to tab-delimited text files and imported into R (version 3.5.1) in RStudio (version
1.2.1335). For each movement, peak vertical force was determined as the maximum force
output recorded in the vertical axis and peak braking force as the maximum positive force
recorded in the horizontal axis. Force measurements in Newtons were standardised to
multiples of body weight using the formula
!"#$%
&
'()* + !"#$%
&
',*
("-./%0123
&
',*
For precision style landings, force figures were then halved to obtain estimates of the peak
force experienced by a single limb during each landing (Jensen and Ebben, 2007). The median
value of the three repetitions of each movement and landing style for each participant was
calculated to form the final dataset for analysis. Normality for each movement and landing style
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combination within each dependent variable was tested using a Shapiro-Wilk test. Time series
data for all trials were normalised using interpolation for the impact phase (defined as the time
from contact with the force plate to leaving the force plate or achieving a return to bodyweight
levels for the single foot and double foot landings respectively) for graphical representation
only.
All statistical analyses were performed using R (version 3.5.1) in RStudio (version 1.2.1335).
Results were analysed using a two-way repeated-measures analysis of variance (ANOVA) for
each dependent variable to examine the effect of movement choice and landing style.
Sphericity was checked with Mauchly’s test and, if failed, a Greenhouse-Geisser correction was
applied. Simple effects analysis was performed for significant interactions by comparing means
of groups from one term at all levels of the second term with a pairwise comparison test using a
Holm-Bonferroni adjustment. Significance for all tests was set at α = 0.05. Partial eta-squared
(η2p) was calculated for ANOVA effect sizes and Cohen’s d with Hedge’s correction g was
calculated for all pairwise comparisons. η2p and g effect sizes were interpreted using
recommendations by Lakens (2013).
Intraclass correlation coefficient (ICC) estimates between repetitions for each participant in
each dependant variable were calculated using the IRR package (Gamer et al., 2019) based on a
single measurement, absolute agreement, 2-way mixed-effects model (Weir, 2005). ICC results
were interpreted using recommendations by Koo and Li (2016).
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Chapter 3. Results
ICCs for each dependent variable across all movements are reported in Figure 3.1. Moderate to
good reliability was found for all combinations except drop (ICC = 0.41, p = 0.021) and dash (ICC
= 0.29, p = 0.059) running style landings for peak vGRF, and dash (ICC = 0.49, p = 0.007) and
kong (ICC = 0.30, p = 0.033) precision landings in peak bGRF.
Figure 3.1. Intraclass correlation coefficients for peak vertical (A) and braking (B) ground
reaction forces for all movement and landing style combinations using a single measurement,
absolute agreement, 2-way mixed-effects model. Error bars represent 95% confidence intervals.
Horizontal dashed lines represent 0.5 (moderate), 0.75 (good), and 0.9 (excellent) reliability as
per Koo and Li (2016).
Page 26 of 60
Results from the two-way repeated-measures ANOVA are reported in Table 3.1. A significant
interaction effect between movement choice and landing style was found for peak vGRF (F3, 27 =
4.98, p = 0.007, η2p = 0.36) and peak bGRF (F3, 27 = 12.00, p < 0.001, η2p = 0.57). The main effect
of movement choice was found to be highly significant for peak vGRF (F3, 27 = 14.14, p < 0.001)
and peak bGRF (F3, 27 = 36.81, p < 0.001), but with a larger effect size on bGRF (η2p = 0.80) than
vGRF (η2p = 0.61). The main effect of landing style was significant for vGRF (F1, 9 = 136.60, p <
0.001) with a large effect size (η2p = 0.94), but was not significant for bGRF (F1, 9 = 0.10, p =
0.758) alongside a very small effect size (η2p = 0.01).
Table 3.1. Two-way repeated-measures ANOVA results for each dependent variable. * indicates
significance (p < 0.05).
Effect
DFn
DFd
F
p
η2p
Peak vGRF
Movement
3
27
14.14
< 0.001*
0.61
Landing Style
1
9
136.60
< 0.001*
0.94
Movement:Landing Style
3
27
4.98
0.007*
0.36
Peak bGRF
Movement
3
27
36.81
< 0.001*
0.80
Landing Style
1
9
0.10
0.758
0.01
Movement:Landing Style
3
27
12.00
< 0.001*
0.57
Page 27 of 60
Results from pairwise comparison testing on the effect of switching landing style within each
movement are reported in Table 3.2. All movements significantly increased in peak vGRF with a
large effect size when switching from precision to running landings. The step (t = 3.37, p =
0.025, g = -0.84) and dash (t = 6.11, p = 0.001, g = -1.52) vaults both significantly decreased in
peak bGRF with a large effect size when switching from precision to running landings, while the
drop and kong vault did not differ significantly in peak bGRF between landing styles.
Table 3.2. Pairwise comparisons for the effect of landing style (precision vs. running) on each
movement. Δ shows mean change in force (BW) when switching from a running to precision
landing style. * indicates significant difference between landing styles (p < 0.05).
Movement
Δ
t
p
g
Peak vGRF
Drop
-1.64
-19.42
< 0.001*
4.84
Step
-1.10
-6.72
< 0.001*
1.68
Dash
-0.82
-5.29
0.002*
1.32
Kong
-1.68
-5.32
0.002*
1.33
Peak bGRF
Drop
-0.06
-1.24
0.246
0.31
Step
0.05
3.37
0.025*
-0.84
Dash
0.15
6.10
0.001*
-1.52
Kong
-0.10
-1.96
0.163
0.49
Page 28 of 60
Results from pairwise comparison testing on the effect of switching movement within each
landing style are reported in Table 3.3. The kong vault was significantly greater in peak vGRF
and bGRF than all other movements when using a precision landing. With a running landing, the
kong vault produced significantly greater peak bGRF than all other movements, but only
significantly greater peak vGRF than the dash vault (t = -3.71, p = 0.024, g = -0.87). Though
significant difference was not found, the kong vault still produced medium effect sizes on peak
vGRF in comparisons to the drop (g = -0.57) and step (g = -0.69) vault.
The dash vault did not significantly differ from any movement with a precision landing other
than the kong vault in either dependent variable. When using a running landing, the dash vault
produced significantly lower peak bGRF than all other movements and significantly lower peak
vGRF than the drop (t = 4.11, p = 0.016, g = 0.96) and kong vault, all with large effect sizes. The
step vault was not found to significantly differ from the drop in any dependent variable in
either landing style, although the effect size on peak vGRF when using a running landing was
medium (g = 58) while all other effect sizes were small to negligible.
Page 29 of 60
Table 3.3. Pairwise comparisons for the effect of movement choice within each landing style. Δ
shows mean change in force (BW) when switching from column movement to row movement.
denotes significant difference (p < 0.05).
Peak vGRF
Precision
Running
Step
Dash
Kong
Step
Dash
Kong
Drop
Δ = -0.02
t = -0.25
p = 1.000
g = -0.06
Δ = 0.03
t = 0.27
p = 1.000
g = 0.06
Δ = -0.56
t = -5.94
p = 0.001*
g = -1.39
Δ = 0.52
t = 2.49
p = 0.104
g = 0.58
Δ = 0.86
t = 4.11
p = 0.016*
g = 0.96
Δ = -0.60
t = -2.45
p = 0.104
g = -0.57
Step
Δ = 0.05
t = 0.84
p = 1.000
g = 0.20
Δ = -0.54
t = -8.91
p < 0.001*
g = -2.08
Δ = 0.34
t = 1.40
p = 0.194
g = 0.33
Δ = -1.12
t = -2.97
p = 0.063
g = -0.69
Dash
Δ = -0.59
t = -5.61
p = 0.001*
g = -1.31
Δ = -1.45
t = -3.71
p = 0.024*
g = -0.87
Peak bGRF
Precision
Running
Step
Dash
Kong
Step
Dash
Kong
Drop
Δ = -0.02
t = -0.65
p = 0.878
g = -0.15
Δ = 0.03
t = 0.81
p = 0.878
g = 0.19
Δ = -0.21
t = -8.25
p < 0.001*
g = -1.93
Δ = 0.10
t = 1.39
p = 0.199
g = 0.32
Δ = 0.24
t = 3.61
p = 0.014*
g = 0.84
Δ = -0.25
t = -4.37
p = 0.007*
g = -1.02
Step
Δ = 0.05
t = 1.74
p = 0.349
g = 0.41
Δ = -0.19
t = -9.32
p < 0.001*
g = -2.18
Δ = 0.14
t = 3.71
p = 0.014*
g = 0.87
Δ = -0.35
t = -8.23
p < 0.001*
g = -1.92
Dash
Δ = -0.24
t = -7.84
p < 0.001*
g = -1.83
Δ = -0.49
t = -12.86
p < 0.001*
g = -3.00
Page 30 of 60
Interaction plots for both dependent variables are shown in Figure 3.2, highlighting in particular
the increase in peak vGRF for all movements when switching from a precision to a running
landing style. Figure 3.2 also illustrates the kong vault as resulting in the greatest GRFs of any
movement in either landing style, while the dash vault results in the least. The close clustering
of the drop, step vault, and dash vault movements can also be seen in both vGRF and bGRF for
the precision landing style.
Figure 3.2. Interaction plots for peak vertical (A) and braking (B) ground reaction forces. Error
bars depict 95% confidence intervals for means with a Cousineau-Morey adjustment for
repeated-measures studies (O’Brien and Cousineau, 2014).
Means and standard deviations for all movement and landing style combinations are reported
in full in Appendix 1.
Page 31 of 60
Chapter 4. Discussion
The findings in this study show that landing style (precision or running style landing) and
movement choice (drop, step vault, dash vault, or kong vault) affect GRFs for parkour vaults.
Landing style was found to have the greatest effect on vGRF, while movement choice had the
greatest effect on bGRF. All movements significantly increased in vGRF when using a running
landing. The kong vault was found to produce the greatest vGRF and bGRF, differing
significantly from all other movements in bGRF when using a running landing, and in both vGRF
and bGRF for precision landings. The dash vault produced the least vGRF of all movements in
both landing styles, but only significantly differed from the drop and kong vault in vGRF when
using a running landing. The dash also produced significantly lower bGRF than any other
movement when using a running landing. The step vault was not found to differ significantly
from any other movement except the kong vault in vGRF and, in particular, did not significantly
differ from the drop in any dependent variable with any landing style.
4.1. Effects of Landing Style
vGRFs for precision style drop landings were 1.57 x BW per leg in this study. These values are in
line with those found by Puddle and Maulder (2013) (3.2 / 2 = 1.6 x BW per leg) and Standing
and Maulder (2015) (3.6 / 2 = 1.8 x BW per leg) for drop landings by traceurs. Puddle and
Maulder (2013) used a fixed platform height of 0.75 m while Standing and Maulder (2015) used
a maximum drop height of 50% participant height, which the obstacle used in the present study
exceeded for all participants. Yeow, Lee and Goh (2009) modelled vertical ground reaction force
and drop height as a regression relationship, proposing that vGRF increases exponentially as
Page 32 of 60
drop height increased. This relationship has so far not been demonstrated for traceurs. Drop
landing vGRFs remain similar among these studies despite height increases. However,
participants in the present study were instructed to crouch fully before dropping, as opposed to
standing upright and stepping off as they were in Puddle and Maulder (2013) and Standing and
Maulder (2015). As such, the true drop heights between studies may not differ greatly if
participant centre of mass is considered rather than platform height. Even so, the present study
results are lower than those previously reported, despite participants not being explicitly
instructed to land as softly as possible as they were in prior parkour studies. This may indicate
that efforts to minimise GRFs in precision landings are habitual and automatic in experienced
traceurs, adopted as a default landing strategy.
While peak vGRF increased for running style drop landings, the peak vGRF found in this study
remains lower (3.21 x BW) than those found in a study on single foot landings by figure skaters
(3.5 x BW), which used a much lower platform height of only 0.2 m (Saunders et al., 2014).
Yeow, Lee and Goh (2011) also found larger peak vGRFs in single-leg drop landings (4+ x BW)
performed by recreational athletes with a platform height of 0.6 m. If no mitigating techniques
for single-leg landings were being utilised by traceurs, it could be expected to see similar or
larger vGRFs with the increase in platform height in this study. It appears that traceurs are
applying techniques to minimise vGRF in single-leg landings, in similarity to the previously
established findings of reduced vGRF in two-legged drop landings performed by traceurs.
The knee is the primary dissipator of energy in precision landings (Maldonado, Soueres and
Watier, 2018). The knee has been shown to respond less effectively to single-leg landings than
double-leg landings in drop jumps (Yeow, Lee and Goh, 2010) and therefore higher vGRF due to
Page 33 of 60
the lack of knee flexion in a running style landing, regardless of movement choice, could be
expected. While vGRFs did increase in running landings in this study, they were still lower than
vGRFs reported for single-leg landings by other athletes. The plantar flexors of the calf have
been shown to be effective at absorbing impact through the ankle joint when knee flexion is
restricted, possibly even more so than when the knee can freely flex (Self and Paine, 2001). The
lack of knee flexion may instead shift responsibility onto the other joints of the lower limb to
absorb vGRF. As such, it may not solely be the long duration of eccentric loading of the
quadriceps and hip muscles that contributes to reduced vGRFs in traceur landings, but also
contributions from an effectively engaged calf complex due to a raised heel.
It should be noted that cited studies utilised a stop landing on a single-leg, whereas the present
study utilised a running style single-leg landing. Yeow, Lee and Goh (2011) also found that
frontal plane energetics increased in single-legged stop landing tasks due to the increased
demand for stability, which could not be as effectively dissipated as sagittal energetics due to
the lack of range of motion in the knee joint in that plane. It may be that continued motion
when landing on one leg decreases the need to seek stability compared to a stop landing,
similar to how increased speed requires less rider input to keep a bicycle upright (Sharp, 2008).
Future research may consider the effect of various speeds when exiting a vault and the effect
on GRF, particularly in running style landings.
4.2. Parkour Vault Characteristics
The kong vault resulted in significantly greater vGRFs and bGRFs than all other movements with
a precision landing, and even in comparisons that did not achieve significance, always produced
Page 34 of 60
at least a medium to large effect size. This may be due to the need for an increase in height of
the traceur’s centre of mass to allow space for the knees and feet to pass over the obstacle,
increasing the height of the drop on the landing side. Yet, the increase in vGRF is greater than
could be expected for the relatively small height gain needed to clear the obstacle with a kong
vault, given the similarity between vGRFs for drop landings from different heights discussed
above. The diving nature of the movement may also increase horizontal speed, with a resultant
increase in bGRF on landing. This diving execution also places the traceur in a flexed hip
position once over the obstacle, with a more anteriorly tilted trunk. Trunk flexion is an
important contributor to mitigating landing GRFs (Blackburn and Padua, 2008) and, as drop
heights increase, the role of proximal joints in energy dissipation also increases (Nordin and
Dufek, 2017). Reduced hip flexion range due to an already anteriorly tilted trunk when landing
may result in a decreased ability for the hip to contribute to energy dissipation and result in
greater GRFs. Further, vGRF for the kong was not significantly greater than a drop landing when
using a running landing style. The need to stretch the landing leg towards the ground and raise
the trunk into a running stance would extend the hip joint, differentiating it from a kong
performed with a precision landing. However the role of trunk position in landing is still being
investigated, with an overly upright trunk on landing shown to increase knee valgus angles and
the risk of ACL injury (Saito et al., 2020). The role of trunk position in PKVs could be further
studied through kinematic 2D or 3D motion tracking of traceurs paired with kinetic GRF
analysis.
Although consistently producing the least GRFs of any movement, performance of the dash
vault varied between the two landing styles. Dash vaults with precision landings did not differ
Page 35 of 60
from the drop or step vault in vGRF; however in running style landings, the dash vault was
found to produce significantly lower vGRFs than the drop landing and kong vault and lower
bGRFs than all other movements. This may be due to the differing levels of support provided by
the hands on the obstacle as the traceur descends to land. In a running dash vault, the leading
leg reaches the floor before the hands leave the obstacle, while in a precision landing both
hands leave the obstacle before landing occurs. Further, due to the sole use of the hands on the
obstacle without a concurrent trailing lower limb, this ability to reach for the floor before the
supporting limbs leave the obstacle is maintained for a greater height than the step vault. This
may indicate that the longer a traceur can maintain support on the obstacle behind them, the
greater the contribution of the upper limbs to reductions in vGRF. In turn, this may increase the
risk of wrist injury in the dash vault, with GRFs through the hands in some high-intensity
gymnastic vaults found to exceed 1.3 x BW (Penitente and Sands, 2015). Further research on
the forces experienced in the upper limb during PKVs may reveal more about this relationship
and provide insight on potential upper limb injury risks inherent to PKVs.
The step vault did not significantly differ from a drop of equivalent height in peak vGRF or bGRF
for either landing style, although there was still a moderate effect on the reduction of peak
vGRF with the step vault when using a running landing. The height of the obstacle used in these
trials may have affected this outcome. The step vault technique requires reaching down to the
ground while one foot and hand remains behind the traceur on the obstacle. If the obstacle is
sufficiently low enough that the reaching foot can contact the floor without the trailing limbs
leaving the obstacle, then more support may be provided to the landing foot. This was not
possible for all participants due to height differences, with the trailing limbs leaving the
Page 36 of 60
obstacle before contact was made with the floor. Execution of the step vault in this study also
tried to simulate typical use of a step vault as part of a route, resulting in performance at speed.
Moderating the speed a movement is performed can increase control of that movement (Frost
et al., 2015). Moderation of speed of execution, with an effort to more deliberately lower the
leading foot to the floor with prolonged support of the hand and foot on the obstacle, could
result in lower GRFs for the step vault. Nonetheless, the step vault is often taught as a beginner
vault, and so this finding may be of importance in determining the risk of injury for new
practitioners. As such, the step vault should not be considered the absolute safest or least
impactful of the PKVs by default. Due care and attention to obstacle height and speed of
execution should be considered when teaching the step vault to beginners to mitigate the risk
of exposing them to larger GRFs before they are physically prepared for them.
4.3. Implications for Injury Risk
The results of this study show that, despite still displaying an ability to mitigate landing forces
when landing on a single limb, a traceur does increase GRFs when utilising a running landing
compared to a precision landing. Yet, vGRF figures reported in this study are lower than those
reported in traditional flat running of around 3 x BW (Trowell et al., 2019) for the step and dash
vault and only slightly above it for the kong vault. Such levels of GRF are considered unlikely to
cause acute injury through impact alone (Kuntze, Sellers and Mansfield, 2009). This is in
agreement with a survey by Wanke et al. (2013) whereby traceurs reported that most acute
parkour injuries occurred due to misjudgement or overestimation rather than impact trauma in
Page 37 of 60
an otherwise ideal landing scenario. Consequently, the overall risk of acute injury to the lower
limb with single-leg running style landings likely remains low for experienced traceurs.
However, chronic injury remains a potential risk for traceurs of all levels. Frequent exposure to
the vGRF and bGRF levels found in this study for both precision and running style landings could
place an athlete at risk of chronic injury (Hreljac, 2004). To that end, the GRF results obtained in
this study have allowed the development of a rudimentary intensity index between all four
movements across both landing styles, demonstrated in Figure 4.3.1. A drop precision landing is
used as a baseline intensity of 1 for both vGRF and bGRF, with all other movements
standardised to this same scale using the formulas
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Parkour is a developing sport. Practitioners and coaches rely mostly on personal subjective
experience to effectively determine the appropriate intensity of training. An intensity index
could instead be used as a tool in the field to objectively control training intensity alongside
traditional training parameters such as volume and frequency (Wallace et al., 2010). Given the
limitations and scope of the present study, this index is presented as an example only. Further
development of an index utilising such things as different heights, speeds, landing distances,
and a wider subject pool may further aid in developing it as a useful tool for field use.
Page 38 of 60
Figure 4.3.1. Intensity plots for peak vertical (A) and braking (B) ground reaction forces,
standardised with the drop precision landing as an intensity of 1.
4.4. Limitations
As can be seen in Figure 3.1, ICCs for movement and landing style combinations varied; while
most achieved at least a ‘moderate’ reliability, confidence intervals were broad for all groups.
Visual analysis of the force profiles for the three trials of each combination for each participant
seemed to show a trend where, if the peak values were not evenly spaced, one trial would be
noticeably above or below the other two. An example of this can be seen in Figure 4.4.1, where
peak vGRF for the 3rd repetition stands apart from the closer grouped 1st and 2nd repetitions in
magnitude. It appears that vaulting movements may be highly variable in execution, even
amongst experienced practitioners, although some limitations in this study may also have
affected this result. While practitioners were instructed to keep run-up distances the same for
Page 39 of 60
each movement repetition, this was not strictly measured and standardised. Variations in run-
up distance may have contributed to intra-participant variation between trials. Participants also
attended in their own footwear, which may have contributed to inter-participant differences
due to differing levels of cushioning affecting the amount of GRFs absorbed by the sole (Cheung
and Ng, 2008).
Figure 4.4.1. Example vertical ground reaction force profile plot for a single participant
performing a step vault with a precision landing, showing all 3 repetitions of a step vault
performed with a precision landing style. Horizontal dashed lines mark the peak vGRF values.
Page 40 of 60
One phenomenon of the data noted on examination of the force curves is the presence of
multiple force peaks in the vertical axis. Multiple vGRF peaks in a drop landing are common,
with the first peak commonly representing toe contact, the second peak for heel contact, and
the third peak for muscle activation slowing descent (Bauer et al., 2001). Usually the second
peak is the largest, but in the present study this was not always the case, with the first peak
sometimes exceeding the second. This may be due to the lack of heel contact during a precision
technique landing. The present study did not distinguish between maximum vGRF occurring at
the first or second peak. As a result, the maximum vGRF for some movements and landing
styles was taken from the first peak and some from the second. Future studies may wish to
isolate the peaks to determine how each contributes to the energy dissipation of a landing. In
particular, if the goal is to analyse the rate of force development (RFD) in these movements,
careful analysis of the patterns of peaks presenting should be considered to ensure correct RFD
calculations.
Single limb GRFs were estimated for the precision landing style by halving the measurements
obtained from both legs on the force platform, with the assumption that participants have no
bilateral asymmetries in their lower limbs. While measuring GRFs with two feet and halving the
figure is not expected to give an exact figure for the peak GRF of a single limb due to small
timing difference between limbs, it is shown to produce results close to modelled figures for
single-legged landings (Niu et al., 2014). Two-legged landings in the precision style usually
involve keeping the ankles close together; splitting the feet across two force plates, while
potentially improving single limb GRF measurement accuracy, may result in altered landing
mechanics and a loss of validity. Nonetheless the figures obtained for the force per single limb
Page 41 of 60
in precision landings used in this study should be considered with this possible degree of
imprecision in mind.
Ensuring ecological and external validity (Pinder et al., 2011) when studying parkour movement
is difficult due to the inherent free-form nature of the sport and the many different
environments in which it is practised. This study has attempted to examine some of the most
commonly observed parkour vaults and landing styles, but a wide variety remains. Precise
execution of the same technique may vary between traceurs, determined by their training
history and practice rather than some agreed-upon, centrally-defined, method. Only 10
traceurs participated in this study, many of whom had previously trained together. Traceurs
from other social groups, locales, and demographics may have developed different approaches
to techniques and their execution with different landing styles.
There is currently no widely accepted standardisation of parkour movement, either in the form
of a rulebook for a competitive event, guidelines from a governing body, or even in some cases,
a common consensus among traceurs. Therefore in order to study parkour, some constraints
have to be selected by researchers and placed upon the wide variety of parkour movements
available for a given task. It is important to the nature of the sport that these efforts to
constrain movements for study are purely descriptive, and not intended to prescribe or restrict
parkour movement in any fashion beyond the scope of the study being undertaken.
The obstacle’s height and distance from the force plate may have artificially constrained the
performance of some techniques, with some participants describing the landing point as being
too close for regular execution of some movements and some landing styles. In some ways this
Page 42 of 60
may increase ecological validity for the study, as when performing parkour outside there is a
similar inability to adjust your choice of landing distance - a traceur cannot move a brick wall or
a steel railing forward to be more accommodating. But a traceur’s movement choice is dictated
not just by preference, but by the environment and their reaction to it (Croft and Bertram,
2017). A certain technique may better suit a desired landing distance. Such difference may be
dictated by the projectile path that the participant takes over the obstacle, similar to changing
the projectile arc for a ball to better hit a target in a certain plane. Future studies on the
projectile motion of traceurs during the execution of vaults to different landing distances could
investigate the task-specific suitability of individual vaults.
Page 43 of 60
Chapter 5. Conclusion
Movement and landing style choice affect landing GRFs for common parkour vaulting
techniques. vGRFs increase when switching from a precision style landing to a running style
landing, regardless of PKV choice. The kong vault was found to produce the greatest vGRF and
bGRF of all PKVs in both landing styles, while the dash vault produced the least vGRF and bGRF
of all PKVs. The step vault was not found to significantly differ from a drop landing with either
landing style.
Traceurs mimic their performance in two-legged drop landings and continue to effectively
mitigate landing forces when vaulting with both precision and running style landings. As a
result, traceurs are unlikely to be at risk of acute lower limb injury with the force levels
produced but remain at risk of chronic lower limb injury caused by high repetitions of vaulting
movements. The development of an intensity index is proposed as a possible field tool for
coaches and athletes to appropriately plan parkour training sessions to minimise the risk of
chronic injury.
Page 44 of 60
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Appendix 1: Means and Standard Deviations for All Groups
Table 1. Means ± standard deviations for all dependent variable, movement, and landing style combinations. Matching subscripts (a-
c) indicate significant differences (p < 0.05) between movements within landing style. Cross superscript (†) indicates a significant
difference (p < 0.05) between landing styles within the movement.
Drop
Step
Dash
Kong
Landing Style Avg.
Peak vGRF (BW)
Precision
1.57 ± 0.34†a
1.59 ± 0.42†b
1.54 ± 0.32†c
2.13 ± 0.49†abc
1.71 ± 0.45
Running
3.21 ± 0.38†a
2.69 ± 0.60†
2.35 ± 0.37†ac
3.81 ± 1.09†c
3.02 ± 0.85
Movement Avg.
2.39 ± 0.91
2.14 ± 0.76
1.95 ± 0.54
2.97 ± 1.19
Peak bGRF (BW)
Precision
0.36 ± 0.13a
0.37 ± 0.12†b
0.33 ± 0.06†c
0.57 ± 0.12abc
0.41 ± 0.14
Running
0.42 ± 0.26a
0.32 ± 0.14†b
0.18 ± 0.10†abc
0.67 ± 0.18abc
0.40 ± 0.25
Movement Avg.
0.39 ± 0.20
0.35 ± 0.13
0.26 ± 0.11
0.62 ± 0.16
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Appendix 2: Parkour Vault Techniques
Figure 1. Sequence of movements in a Step Vault (Gerling, Pach and Witfeld, 2013, p. 132).
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Figure 2. Sequence of movements in a Kong Vault (Gerling, Pach and Witfeld, 2013, p. 144).
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Figure 3. Sequence of movements in a Dash Vault (Gerling, Pach and Witfeld, 2013, p. 152).
