The Use of IMU-based Human Motion Capture to Assess Kinematic

Parameters of Specific Exercises Performed by 400 M Hurdlers

Janusz Iskra

, Michał Pietrzak

and Krzysztof Przednowek

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

Faculty of Physical Education, University of Physical Education in Katowice, Katowice, Poland

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

Keywords: 400 M Hurdles, Hurdle Clearance, Kinematic Analysis, Technique Preparation.

Abstract: The 400 m hurdles is a difficult track and field event, in which the hurdle clearing technique is of crucial

importance. In this work, we analyse hurdle clearance while performing two specific exercises: marching and

running. We evaluated the kinematic parameters (bending angle and movement speed) of the knee joint and

movement trajectory (of the thigh and shank) when performing exercises with the left (“stronger”) and right

(“weaker”) lead leg. Two 400 m hurdlers of the Polish National Athletic Team participated in the analysis.

The exercises were performed on five 91 cm high hurdles; the third hurdle was filmed using a Motion Capture

(Perception Neuron) system with Axis Neuron Pro software consisting of 18 IMU sensors operating at a

frequency of 120 Hz. The analysis demonstrated significant difference in the angle parameters of the “stronger”

and “weaker” trail leg knee (1), no differences in the movement speed during exercises performed with

alternate legs (2) and individual characteristics of movement trajectory in both exercises (3). The results may

be used to optimise of the hurdle training process.

1 INTRODUCTION

The hurdles (at sprinting distances – 100/110 m and

at a distance of 400 m) is a complex athletic event in

which technique and motor preparation are equally

important. (Boyd, 2000, McFarlane, 2000).

The technique used to clear hurdles is an

important element of preparation for athletes

competing in hurdle events (Iskra, 2012b). Research

on clearing obstacles concerns not only the typical

hurdle distances (100/110 and 400 m), but also the

steeplechase (Hunter et al., 2008), clearing high

obstacles by fitness enthusiasts (Mauroy et al., 2014)

and running through very low obstacles by general

population (Austin et al., 1999). The hurdles is a

difficult athletic event, in which the technique of

clearing standard obstacles at a height (depending on

the distance) of 0.84-1.067 m is essential. These

events mostly involve the movement of the lower

limbs, referred to in the literature as the “lead leg”

(the leg first approaching the hurdle) and “trail leg”

(the leg opposite the lead leg) – see the Appendix.

https://orcid.org/0000-0001-8626-8881

https://orcid.org/0000-0002-2128-4116

Thus, the movements of the lower limbs are a basic

subject for biomechanical analyses (kinematic and

dynamic) in hurdling, as evidenced by numerous

scientific publications (Salo, 2002, Coh et al., 2004,

Krzeszowski et al., 2015). The evaluation of hurdle

technique focuses mainly at the assessment of the

individual phases of hurdle clearing (Krzeszowski et

al., 2016). These phases constitute a complex form of

dynamic movement.

The 400 m hurdles kinematic is difficult to

analyse in terms of movement structure. Running the

straight parts and the turns, changing the lead leg and

unpredictable changes in the manner of hurdle

clearing resulting from increasing fatigue demand

certain indirect (non-competitive) means for

movement analysis.

Researchers have mostly focused on changes in

the centre of gravity during hurdles (Przednowek et

al., 2016). An important elements in understanding

the technique in 400 m hurdles are the specific

marching exercises (Iskra, 2008). Kinematic analyses

most often concern the competitive conditions and

less frequently the specific exercises carried out dur-

Iskra, J., Pietrzak, M. and Przednowek, K.

The Use of IMU-based Human Motion Capture to Assess Kinematic Parameters of Speciﬁc Exercises Performed by 400 M Hurdlers.

DOI: 10.5220/0008363602090216

In Proceedings of the 7th International Conference on Sport Sciences Research and Technology Support (icSPORTS 2019), pages 209-216

ISBN: 978-989-758-383-4

209

Figure 1: Analyzed moments of overcoming the hurdle in the march.

a) b) c)

Figure 2: Analyzed moments of overcoming the hurdle on the run.

ing the preparation period (Grimshaw, 1995, Iskra et

al., 2000, Przednowek et al., 2016).

The most prominent kinematic analyses concern

the running strategy, taking into account the “stride

pattern” and “split times” (Guex, 2012). In the current

literature on the subject, there are no works dealing

with the analysis of the movements performed by 400

m hurdlers during specific exercises taking kinematic

measurements into consideration.

The aim of this work is to evaluate the course of

movement and selected kinematic parameters, known

as the “hurdle step”, performed using the dominant

(stronger) and the opposite (weaker) lead leg by

highly skilled athletes.

2 MATERIAL AND METHODS

The analysis involved two highly skilled 400 m

hurdlers who have competed in the World and

European Championships and the Olympic Games.

Both athletes indicated the left leg as their

“stronger” lead leg (the one they use more often

during a 400 m hurdle race). The basic characteristics

of the athletes are presented in Table 1. Written

informed consent was obtained from all athletes. The

research was conducted according to the guidelines

laid down in the Declaration of Helsinki.

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Table 1: Study subject characteristics.

Age

[years]

Height

[cm]

Weight

[kg]

Training experience

[years]

Personal best in 400

m hurdles [s]

Stride

pattern*

Stronger

leg

Athlete 1 26 181 73 10 51.00 7/3 Left

Athlete 2 28 185 80 15 50.84 6/4 Left

* – in the course of a 400 m hurdle race the athlete cleared the hurdles 7 (6) times with the left (= “dominant”) lead leg and 3 (4) times with

the right (= “opposite”) lead leg.

The kinematic analysis included specific

exercises performed while marching and running.

These are basic exercises for hurdle training at any

distance, and are used throughout the annual training

cycle (Arnold, 1992, McFarlane, 2000, Husbands,

2006). Both athletes made two attempts to march over

the hurdles and two attempts to run over the hurdles.

Five hurdles were cleared in each of the marching and

running exercises, and their movement at the third

(middle) hurdle was analysed (filmed). In the

marching exercise, the distance between the hurdles

was 100 cm, while in the running exercise it was 8.50

m – a distance chosen for specific exercises

performed by 400 m hurdlers during technical

training by the best coaches (McFarlane, 2000, Iskra,

2012a). In both types of exercise, the first attempt of

hurdle clearing was performed with the “stronger”

lead leg and the second with the “weaker” one.

During the exercise, the competitors were able to

clear hurdles with a height of 91 cm (standard height

in this event). Both marching attempts were carried

out in such a way that the hurdle was cleared with

only the trail leg while the lead leg was placed beside

the hurdle (trail leg march). This is the most

frequently used exercise in hurdle technical training

(McFarlane, 2000).

Three essential time points were designated for

marching over the hurdle (Figure 1). The first point

was the take-off, which is the moment when the

athlete performs the take-off in order to clear the

hurdle. The second point was the moment when the

knee joint of the trail leg was located over the hurdle.

The third point was the landing, determined by the

moment when the player put the lead leg behind the

hurdle and the knee joint of the trail leg was drawn up

to the chest. This division of the movement phases in

hurdling is consistent with many previous

publications (Iskra and Przednowek, 2016,

Krzeszowski et al., 2016). Analogous points were

determined for the running exercises (Figure 2).

The analysis included the movement of the lower

limb, i.e. the thigh and shank, the speed of the point

determined by the location of the knee joint and the

angle of its bending. These parameters have been

particularly emphasized by many authors. The

analysis of changes regarding the angle of the knee

joint is justified by the frequent use of this parameter

in the kinematic structure of the hurdle clearing

movement and taking into account the relatively

small coefficient of multiple repetition variation over

time (Salo and Grimshaw, 1998).

The acquisition of the kinematic parameters was

carried out using the inertial Motion Capture system.

The Perception Neuron system with AxisNeurono

Pro software (Noitom Technology, 2017) was used in

the study. The system consisted of 18 IMU sensors

operating at 120 Hz. Each sensor included an

accelerometer, a gyroscope and a magnetometer.

According to the manufacturer, the accuracy of the

system is determined by the accuracy of the

individual sensors (Static accuracy: Roll:<1 deg,

Pitch:<1 deg, Yaw angle:<2 deg). The data were

captured wirelessly using a WiFi network. The device

was calibrated before each sequence. The analysis

was carried out using Matlab software and the BoB

Biomechanics package. The data generated by the

motion capture system (.calc file with global

coordinates xyz of segments) were processed. A

script was developed that transformed the data into

the common coordinate system and calculate the

resultant linear velocities. In addition to the parameter

values for individual points, the mean values (M),

standard deviation (sd) for the parameter during the

entire movement were taken into account in the

analysis. The statistical significance of differences

between mean values was determined using the U

Mann-Whitney test.

3 RESULTS

Analysis of the knee joint bending angle showed

significant differences between the “stronger” and

“weaker” leg only in the case of the trail leg (Table 2).

Angular values (in all phases of movement) were

different

for exercises performed with the “stronger”

and “weaker” lead leg. It should be pointed out that the

differences observed in the analysis were of an

individual character. During the running exercise, the

differences in both subjects (Athlete 1 and Athlete 2)

were significant (p<001). During the marching exerci-

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Table 2: The knee joint bending angle [

Athlete Athlete 1 Athlete 2

Trail Lead Trail Lead

Side L R L R L R L R

Marching

P1 59 65 139 137 64 75 151 133

P2 157 159 52 69 169 139 43 59

P3 166 152 65 59 172 133 82 70

M 139 144 104 113 146 138 105 104

29 27 46 35 28 19 40 33

D -5 -9 8 1

0.2699 0.6479 0.0001* 0.1402

Running

P1 71 78 144 145 91 71 160 170

P2 144 157 51 104 152 120 41 83

P3 163 169 85 79 165 116 82 59

M 142 149 83 97 147 113 79 81

23 24 45 46 19 12 39 51

D -7 -14 34 -2

0.0021* 0.1049 0.0001* 0.6651

P1, P2, P3 – time points; M – mean value; sd – standard deviation; D – difference between left and right leg; p – probability of U Mann-

Whitney test; L – left leg; R – right leg.

Table 3: The knee joint speed [m/s].

Athlete Athlete 1 Athlete 2

Trail Lead Trail Lead

Side L R L R L R L R

Marching

P1 5.3 3.8 0.7 0.9 0.9 1.7 0.7 1.0

P2 0.9 0.3 4.4 5.7 1.1 1.4 4.1 3.9

P3 0.4 1.3 2.7 2.4 0.8 0.6 2.5 3.0

M 1.6 1.9 3.0 2.7 1.6 1.3 2.2 2.2

0.9 1.0 1.5 1.7 1.7 0.8 1.6 1.4

D -0.3 0.3 0.3 0.0

0.1192 0.2018 0.9663 0.3767

Running

P1 5.8 7.5 2.3 1.8 5.0 5.1 1.3 1.7

P2 4.2 4.4 6.1 5.4 3.9 4.2 6.1 2.8

P3 4.8 3.8 5.5 8.2 1.8 3.9 6.2 4.2

M 4.8 4.5 5.7 6.0 3.7 3.8 4.8 4.6

1.5 1.0 2.4 2.5 1.7 0.9 1.3 2.5

D 0.3 -0.3 -0.1 0.2

0.5517 0.3686 0.1131 0.0915

P1, P2, P3 – time points; M – mean value; sd – standard deviation; D – difference between left and right leg; p – probability of U Mann-

Whitney test; L – left leg; R – right leg.

cise, the differences concerned only Athlete 1 (p<01).

The analysis did not reveal differences between

knee bending of the lead leg in the case of exercises

performed using the left and right leg (both while

marching and running). Further information on the

differences in hurdle clearing was provided by

movement trajectory analysis (Figure 3 and 4).

During specific exercises performed while

marching the “weaker” leg's thigh movement was

ahead of the same movement performed with the

“stronger” lead leg. The hurdle was cleared from a

farther distance and the movement ended closer to the

hurdle. This applied to both athletes.

The movement of the trail leg was more individual

– the above mentioned aspect applied only to Athlete

When marching over the hurdle, the shank of the

“stronger” leg made the movement more smoothly

(“round” on the chart); the movement of the “weaker”

limb was more ragged (“peak” on the chart). This

applied to both the lead leg and the trail leg.

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Athlete 1

Athlete 2

Figure 3: Trajectory of the march (UpLeg – Thigh, Leg – shank).

The Use of IMU-based Human Motion Capture to Assess Kinematic Parameters of Speciﬁc Exercises Performed by 400 M Hurdlers

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Athlete 1

Athlete 2

Figure 4: Trajectory of the running (UpLeg – Thigh, Leg – shank).

During specific exercises performed while

running, the course of movement while clearing the

hurdle was very diverse and individual. In the case of

Athlete 1, the movement performed with the

“stronger” leg occurred earlier than with the “weaker”

leg. In the case of Athlete 2, the situation was

reversed. The movement profiles for both athletes

were incomparable, which indicated the individual

nature of hurdle clearing techniques by the best

athletes. The analysis of knee joint speed (resultant)

did not show any significant differences between

exercises performed with the “stronger” and

“weaker” leg (Table 3).

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4 CONCLUSIONS

The analysis of hurdle clearing in the course of a 400

m hurdle race requires the consideration of multiple

methodological issues (research needs) and aspects

strictly related to the competition rules (Iskra and Coh

2011). The primary issue is being able to organize the

research work in a way that allows the evaluation of

the running technique with respect to both legs (as

lead legs), “stronger” and “weaker”. To reconcile

both positions (scientific and training), certain basic

specific exercises were selected for the analysis. The

analysis allowed the following conclusions to be

drawn from the analysis:

1. During a hurdle race, the knee joint bending angle

was significant in differentiating between the

technique of hurdle clearing using the “stronger”

and “weaker” trail leg. Such differences were not

observed in the case of the lead leg.

2. The resultant knee joint speeds cannot be

differentiated between exercises (marching and

running) performed with either leg.

3. In the case of 400 m hurdlers, the assessment of

the technique of performing specific exercises

refers to spatial (knee joint bending angle) and not

temporal (in this case knee speed) parameters.

4. The leg movement trajectory for marching and

running was completely different. In view of the

above, the use of both forms of technical training

for hurdling are of different significance in the

organization of the training.

The presented paper has potential limitations. Study

limitations are related to the number of athletes. The

conclusions being drawn may be potentially not

precise. Other limitations are related to the IMU

mocap suits. Sensors placed on the athlete's body can

move gently, which affects the accuracy of the

measurement.

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APPENDIX – GLOSSARY

Lead Leg – the leg that approaches the hurdle first.

Trail Leg – the leg that is bent at the knee joint and

positioned sideways behind the lead leg

Dominant Leg – the preferred (most frequently used)

lead leg during a 400 m hurdle race

Opposite Leg – the leg that is used as lead leg in 400

m hurdle race only in the case of a change in the

“stride pattern”.

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