Kinematic Analysis of the Upper Limbs in Stepping over the Hurdle

The Use of IMU-based Motion Capture

Janusz Iskra

, Krzysztof Przednowek

, Tomasz Krzeszowski

, Krzysztof Wiktorowicz

and Michal Pietrzak

Faculty of Physical Education and Physiotherapy, Opole University of Technology, Opole, Poland

Faculty of Physical Education, University of Rzeszow, Rzeszow, Poland

Faculty of Electrical and Computer Engineering, Rzeszow University of Technology, Rzeszow, Poland

Faculty of Physical Education, The Jerzy Kukuczka Academy of Physical Education in Katowice, Katowice, Poland

Keywords:

Hurdling, IMU-based Motion Capture, Kinematic Parameters, Upper Limbs Movement.

Abstract:

This paper presents an analysis of the kinematic parameters of the upper limbs in stepping over the hurdle.

Stepping over the hurdle is a speciﬁc exercise practised throughout the year. In this exercise, three key points

were analysed in take-off, ﬂight and landing phases. The aim of the study was to use the IMU-based (iner-

tial measurement unit) motion capture system to evaluate the movement of the hurdlers’ upper limbs while

stepping over the hurdle using both the better leg, and the worse leg. The sequences were obtained using 18

sensors working at a frequency of 120 Hz. The analysis was made using two high-achieving athletes. This pa-

per presents the linear velocities and the trajectory of selected segments of the upper limbs. In most cases the

velocities of the segments were higher for the better leg. The analysis shows that during the speciﬁc exercise

of stepping over the hurdle attention should be paid to the movement of the trail arm in the landing phase.

1 INTRODUCTION

Research in respect of hurdling is not only associated

with the typical hurdle distances (100/110 and 400

m), but also with steeplechasing (Hunter et al., 2008),

enthusiasts of physical effort clearing high obstacles

(Mauroy et al., 2014) and random people clearing low

obstacles (Austin et al., 1999). The hurdles race is

a difﬁcult athletics competition, where the technique

for clearing an obstacle between 0.84-1.067 m high

(depending on the distance of the race) is essential.

These competitions are usually associated with lower

limb movement, referred to in the literature as the

’lead leg’ (the leg attacking the hurdle) and the ’trail

leg’ (the leg opposite the attacking leg). Active work

by the torso is equally important when clearing the

hurdle. This is proved by numerous scientiﬁc publica-

tions, which only analyse the kinematic and dynamic

parameters of these elementary forms of clearing the

hurdle (Salo et al., 1997;

Coh et al., 2008; Krzes-

zowski et al., 2015). Evaluation of hurdles techniques

focuses primarily on assessing the individual phases

of hurdle clearance. These phases are a complex form

of dynamic movement.

Analysis of the kinematic parameters and the

course of the hurdle race has a rich tradition (espe-

cially in respect of the 110 m race (Valamatos et al.,

2005; Iskra and Coh, 2011)). In the most of re-

searches (especially those having practical applica-

tions), authors not focus on upper limb movements

(Salo et al., 1997; Li et al., 2011). Some rare stud-

ies are based solely on the observation of photos and

kinograms of the best athletes in the world (McKin-

non and Comerford, 2012). This problem is important

in the course of the whole race, with particular em-

phasis on hurdle clearance (McFarlane, 2000; Krzes-

zowski et al., 2015). Therefore, this study attempted

to analyse the movement of the upper limbs in step-

ping over the hurdle. Stepping over is a basic exercise

in teaching the technique of clearing the hurdle. This

exercise is performed throughout the year-long train-

ing cycle. It is also necessary during warm-up and

while preparing for the season.

The aim of this study is to use the IMU-based mo-

tion capture to evaluate the movement of the hurdlers’

upper limbs while stepping over the hurdle. The as-

sessment of the kinematic parameters was based on

the exercises being performed using both the better

(dominant) leg, and the worse leg. Additionally, the

Iskra J., Przednowek K., Krzeszowski T., Wiktorowicz K. and Pietrzak M.

Kinematic Analysis of the Upper Limbs in Stepping over the Hurdle - The Use of IMU-based Motion Capture.

DOI: 10.5220/0006503101020106

In Proceedings of the 5th International Congress on Sport Sciences Research and Technology Support (icSPORTS 2017), pages 102-106

ISBN: 978-989-758-269-1

Table 1: Athletes’ data.

Athlete 1 Athlete 2

Age [years] 26 28

Body mass [kg] 80 74

Body height [m] 1.85 1.84

Personal best (400 hurdles) [s] 50.84 51.08

Figure 1: The structure of the skeleton estimated by the

IMU-based system mocap along with the names of the seg-

ments.

method of clearing the hurdle by two top-class ath-

letes was compared.

2 MATERIAL AND METHODS

Two hurdlers took part in the study. They both rep-

resented a high level of training and they partici-

pated in World and European Championships, and the

Olympic Games. The basic data describing the ath-

letes are presented in Table 1. The kinematic analysis

included special exercises performed during the step-

ping. These exercises are the basis of hurdles training

at every distance and are performed throughout the

entire 12 month training cycle. Each contestant made

two attempts to step over the hurdle. In the ﬁrst at-

tempt, he cleared the hurdle with the better leg, which

is the leg that he uses more often to clear the hur-

dle. During the exercise, the athlete cleared the 1.067

metre-high hurdle. In the second attempt, the athlete

attacked the hurdle with the worse leg. In clearing

the hurdle, three time points were distinguished (Fig-

ure 3). The ﬁrst point (P

) is deﬁned by the moment

when the athlete positions himself to clear the hurdle.

The second point is determined by the position of the

athlete when both their legs are off the ground and the

feet are at the same height. The third point is deter-

mined by the moment when the athletes put their lead

leg behind the hurdle. During the clearance the ath-

lete was not allowed to touch the hurdle with either

leg. If the hurdle was touched the test was repeated.

The kinematic parameters of the stepping over the

IMU mocap

- calibration

- acquisition

- data export

Matlab

- coordinate transformation

- velocities estimation

.calc file

Figure 2: Data processing diagram.

hurdle were collected using inertial sensors. The Per-

ception Neuron system and Axis Neuron Pro (Noitom

Technology, 2017) software were used in the study.

The system consisted of 18 IMU sensors operating

at 120 Hz. Each sensor consists of an accelerome-

ter, a gyroscope and a magnetometer. The structure

of the estimated skeleton is shown in Figure 1. The

data were recorded wirelessly using WiFi. The main

features of Axis Neuron Pro are: motion data record-

ing/replay, motion data ﬁltering/smoothing, system

and sensors calibration, exporting data to .bvh and

.fbx formats. Before each measurement, the system

was calibrated. The data generated by the motion cap-

ture system (.calc ﬁle with global coordinates xyz of

segments) were processed using the Matlab software

(Figure 2). A script was developed that transformed

the data into the common coordinate system and cal-

culate the resultant linear velocities.

3 RESULTS AND DISCUSSION

The basic element of the analysis was the calcula-

tion of the resultant linear velocity in the key points

of the exercise (Table 2). Analysis of the data pre-

sented in Table 2 indicates signiﬁcant differences in

the velocity of the upper limb movement in the case

of the attack with the dominant leg and its opposing

upper limb. This concerns most of the analysed parts

(arm, forearm and hand) in all points of motion (P

–

). Athlete 1 demonstrated slight decreases in ve-

locity compared with the worse leg attacking, only in

case of P

for the lead arm and lead forearm. For ath-

lete 2, this decline was recorded for the segments of

trail arm, forearm and hand in P

and lead arm and

forearm in P

The most distinguishing feature of the upper limb

Figure 3: Key points of stepping over the hurdle; (a) P

- take-off, (b) P

- ﬂight, (c) P

- landing.

Table 2: Velocity (m/s) of upper limbs in key points of stepping over the hurdle.

Segment Lead arm Trial arm Lead forearm Trial forearm Lead hand Trial hand

Lead leg worse better worse better worse better worse better worse better worse better

Athlete 1

1.2 1.6 0.9 1.3 1.3 1.6 0.9 1.3 1.2 1.5 1.2 1.6

1.8 1.6 2.3 2.3 1.9 1.7 2.3 2.4 2.1 2.2 2.2 2.6

1.7 2.0 2.3 3.1 2.2 2.5 2.6 3.7 2.9 3.5 2.6 4.2

Athlete 2

0.9 1.7 0.7 1.9 1.2 1.6 0.9 2.1 1.1 1.2 1.2 2.5

2.0 2.3 2.5 2.4 2.3 3.1 2.9 1.6 2.8 4.1 2.7 1.4

3.9 3.7 3.8 4.6 4.9 4.8 4.0 5.4 5.8 6.3 4.0 6.0

movement during the exercise is the velocity of the

trail hand motion in P

. This is the element that train-

ers pay attention to (McFarlane, 2000). For athlete 1

the velocity difference for the trail hand was 1.6 m/s,

while for athlete 2 it was 2 m/s. In this point (landing)

the big differences were also seen between the com-

petitors. Athlete 2 made considerably faster trail arm

movements than athlete 1.

Another element of the analysis was to determine

the trajectory of selected segments of the upper limbs.

Figures 4 and 5 show arm and hand movement in

space (height and distance). Analysis of the graphs

indicates that the greater difﬁculty in stepping over

the hurdle is more related to lead upper limb move-

ment than to the trail upper limb. In particular, the

biggest differences are noted for the lead hand (Figure

4(c) and 5(c)). Both athletes display a lack of sym-

metry of movement between the better and worse leg.

However, in the analysed points, the lead and trail arm

movement of athlete 1 shows some similarities (Fig-

ure 4(a, b) as opposed to athlete 2 (Figure 5(a, b)).

Analysing the trail hand (Figure 4(d) and 5(d)) it

was noted that both athletes ﬁnish the move faster

when clearing the hurdle with the better leg. This may

suggest individual conditioning of the arms while

clearing the hurdle with the better and worse attack-

ing leg, which is consistent with the basic principles

of the technique and the recommendations of trainers.

4 CONCLUSIONS

The paper presents the analysis of kinematic param-

eters of the upper limbs in stepping over the hurdle.

The research used IMU-based motion capture system.

The results for the considered points show that, in

most cases, higher velocities were achieved with the

better leg. Moreover, the analysis shows that atten-

tion should be paid to the trail arm movement in the

landing. Difﬁculties in stepping over the hurdle (in-

cluding those with the upper limbs) mainly concern

movements of the trail arm performed during exer-

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(a) lead arm

attempt 1 − better leg attempt 2 − worse leg

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(b) trial arm

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(d) trial hand

Figure 4: Movement trajectory of athlete 1. The symbols + and × mark the points P

–P

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(a) lead arm

attempt 1 − better leg attempt 2 − worse leg

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(b) trial arm

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

−1.5 −1 −0.5 0 0.5 1 1.5

0.8

1.2

1.4

1.6

1.8

distance [m]

height [m]

(d) trial hand

Figure 5: Movement trajectory of athlete 2. The symbols + and × mark the points P

–P

cises with the ’worse’ leg.

Future work will focus on a comparison of the

movement of the arms during other special exercises.

Moreover, the number of athletes will be increased in

order to draw more detailed conclusions on the move-

ment investigated.

ACKNOWLEDGEMENTS

This work has been supported by the Polish Min-

istry of Science and Higher Education within the re-

search project ”Development of Academic Sport” in

the years 2016-2018, project No. N RSA4 00554.

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