Kitesurfing is a relatively recent phenomenon with raising popularity worldwide – a recently developed extreme water sport considered a high-risk injury sport. It combines elements of several other sports, in particular sailing, surfing, windsurfing, wakeboarding, and snowboarding. The main purpose of authors’ research in the present paper is to use a vision system technique for measuring a kitesurfer’s body movements in order to analyze group of activated muscles during take-off and handle pass maneuver reproduced in the laboratory conditions

Anna Grzeczka

Edmund Wittbrodt

Maciej Kłaczyński

Piotr Kohut

Tadeusz Uhl

English

Vibroengineering PROCEDIA

 302 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533  
Vision-based motion analysis of a kitesurfer 
Anna Grzeczka1, Piotr Kohut2, Maciej Kłaczyński3, Edmund Wittbrodt4, Tadeusz Uhl5 
1, 4Gdansk University of Technology, Department of Mechanics and Mechatronics, Gdansk, Poland 
2, 5AGH University of Science and Technology, Department of Robotics and Mechatronics,  
Krakow, Poland 
3AGH University of Science and Technology, Department of Mechanics and Vibroacoustics,  
Krakow, Poland 
1Corresponding author 
E-mail: 1annagrzeczka@gmail.com, 2pko@agh.edu.pl, 3maciej.klaczynski@agh.edu.pl, 
4e.wittbrodt@pg.gda.pl, 5tuhl@agh.edu.pl 
(Accepted 30 September 2015) 
Abstract. Kitesurfing is a relatively recent phenomenon with raising popularity worldwide – a 
recently developed extreme water sport considered a high-risk injury sport. It combines elements 
of several other sports, in particular sailing, surfing, windsurfing, wakeboarding, and 
snowboarding. The main purpose of authors’ research in the present paper is to use a vision system 
technique for measuring a kitesurfer’s body movements in order to analyze group of activated 
muscles during take-off and handle pass maneuver reproduced in the laboratory conditions. 
Keywords: kite-surfing, shoulder injury, vision systems, motion analysis, training plan. 
1. Introduction  
Like any sport discipline kitesurfing involves risk of injury. Freestyle kitesurfing is one of the 
most traumatic sports -disciplines and, at the same time, the most popular one in Poland [1]. 
Freestyle competitions are held in strong winds, with small, fast kites and without high waves. 
Heats consist in making better tricks than competitors, which leads to generating newer and newer 
and more difficult maneuvers. Unfortunately, it often leads to injuries. The authors of this article 
analyzed various freestyle maneuvers and followed injury statistics among Polish top kitesurfers. 
Thanks to the analyses and further investigation of the most critical maneuvers we can better 
customize the training plan, modify certain behaviors or deliberately avoid the manoeuvres 
causing most injuries. Before proposing a hypothesis on which behaviors and which maneuvers 
are destructive to human body structures, the authors selected two movements that were then 
examined in connection with injuries of the rotator cuff area. The first is the take-off maneuver. It 
is a basic maneuver requiring no special skills from the surfer [2]. As a basic trick, it serves as a 
reference for subsequent measurements. Handlepass was the second examined freestyle trick. It is 
an advanced trick, which is a base for a number of maneuvers performed during the competitions. 
The main difficulty of this maneuver is to put the control bar (a bar a kitesurfer holds and with 
which he/she controls the kite) behind his/her back during a jump. It is a complex maneuver to 
perform, involving many upper body muscles (abdominals, back muscles, shoulder girdle and 
arms). Fig. 1 presents four most important phases of the maneuver. A surfer starts the take-off 
trick by unfastening chicken-loop (a part attaching the main flying lines to the trapeze, that is to 
the pelvic harness of the surfer) from the harness hook. In this situation the entire energy generated 
by the kite is transferred through the control bar to the shoulders of the surfer. The surfer performs 
a rotated jump as illustrated in the first part of the figure. During the flight, with continuous 
rotation of the body, the kitesurfer puts the control bar behind his back from one hand to the other 
as shown in the middle part of the figure. The last step is landing on the front edge of the board. 
After fastening the chicken-loop back to the harness hook, the surfer continues sailing on the tack, 
or performs another jump. While putting the control bar from one hand to another behind the back, 
the surfer often suffers a rotator cuff injury. It is a group of tendons attached to muscles covering 
most of the surface of the shoulder joint [3]. 
The authors reproduced in laboratory conditions the movement performed during putting the 
control bar, which is under load, behind the back. The vision-based technique of computing the 
VISION-BASED MOTION ANALYSIS OF A KITESURFER.  
ANNA GRZECZKA, PIOTR KOHUT, MACIEJ KŁACZYŃSKI, EDMUND WITTBRODT, TADEUSZ UHL 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533 303 
trajectory of selected points on the kitesurfer’s body was conducted. These points were responsible 
the location of, respectively: 1 – elbow appendix, 2 – further attachment of arm triceps muscle,  
3 – closer attachment the lateral head of triceps muscle, 4 – base of humerus, 5 – the place of the 
trapezius muscle fiber intermediates, 6 – trailers trapezius muscle for teenagers squamous spine. 
The aim of the study was to record the work of individual muscle structures during take-off and 
handlepass maneuver with handling the control bar by a kitesurfer and to assess their repeatability 
employing a vision system based on high-speed cameras. 
 
Fig. 1. Selected stages recorded during the performance of handlepass trick [4] 
2. Description of the experiment 
The measurement setup consisted of a control bar attached to the ceiling in order to retain the 
angle of deflection from the vertical line, observed while swimming. The load the loose ends of 
the flying lines imitated the thrust of the kite during swimming on the tack. 
 
a) Experimental setup and markers placements  
over competitor’s body 
 
b) Vision-based measurements system:  
HSC – high speed cameras, HL – halogen lamps 
Fig. 2. View of the measurement setup and the markers location on the body of the surfer 
In order to determine parameters needed to describe the competitor’s body motion (related to 
the activated groups of muscles) laboratory tests were conducted. Vision-based experimental setup 
(Fig. 2(b)) was composed of two Phantom v9.1 high speed camera with 2MPix resolution 
equipped with Carl Zeiss 35 mm lenses, a lighting system (set of halogen lamps) and TEMA 
Automotive motion analysis software. The software is equipped with tools to track markers and 
advanced post-processing tools. The developed vision system was calibrated (internally and 
VISION-BASED MOTION ANALYSIS OF A KITESURFER.  
ANNA GRZECZKA, PIOTR KOHUT, MACIEJ KŁACZYŃSKI, EDMUND WITTBRODT, TADEUSZ UHL 
304 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533  
externally) in compliance with procedures of Tema software. Image sequences were acquired with 
the frequency of 300 Hz, recording time 10.5 sec. Homemade ball-shaped markers were stuck on 
selected group of muscles of competitor body on skin (Fig. 2(a)). These places corresponded to 
activated group of muscles. The image correlation method was employed to track markers. As a 
result of tracking process displacement and trajectory motion of characteristic kitesutrfer’s points 
were investigated. As a result of multiple repetition of the manoeuvre, functioning of individual 
muscle structures could be observed. The same change of distance between markers was noted at 
each iteration of the maneuvers, which corresponded to the function of the observed muscles. 
Fig. 3 shows the change of distance between the two markers corresponding to the attachments of 
the triceps arm muscle during three muscular contractions caused by triple repetition of the 
maneuver of putting the control bar behind the back of the surfer. The averaged pick to pick value 
of displacement was about 30 mm. Fig. 4 shows the change of distance between markers 
describing the observed head of the quadriceps during the same maneuver recorded relative to the 
reference system on the left camera. The averaged pick to pick value of displacement was about 
120 mm. The shapes function presented at Fig. 3 and 4 of the displacement points are similar to 
the course of periodic function, which testifies achieved good repeatability of measurement. 
 
Fig. 3. The recorded repeatable change of distance between the points 2-3  
(lateral head of the triceps of the forearm) recorded relative to the reference system on the left camera 
 
Fig. 4. The recorded repeatable change of distance between the points 5-6  
(trapezius muscle fiber intermediates) during three consecutive movements  
recorded relative to the reference system on the left camera 
VISION-BASED MOTION ANALYSIS OF A KITESURFER.  
ANNA GRZECZKA, PIOTR KOHUT, MACIEJ KŁACZYŃSKI, EDMUND WITTBRODT, TADEUSZ UHL 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533 305 
3. Summary 
Repeatable results reproducing the complex movement of a kitesurfer performing freestyle 
tricks were obtained by use of the presented post. In order to achieve high measurement resolution, 
the vision system architecture was developed and its configuration was arranged. In the literature, 
there are no reported uses of a vision system for measuring kitesurfer body to analyze group of 
activated muscles [5-9]. For this reason, the measurement method presented in this paper can be 
regarded as a new approach for estimating kitesurfer body movements. Thanks to the developed 
vision system, by correlating the collected material describing the work force measurement of 
individual muscles by the use of EMG, the authors will propose a modification of the movement 
in order to change the angle of the force likely to endanger the correct work of muscles. Using the 
available models of distribution of forces in the selected areas of the upper limb and creating their 
own models for an unusual position of the body during performing the described tricks, the authors 
will be able to pass the obtained knowledge to the coaches and therapists who care about the health 
of top kitesurfers. 
References 
[1] Grzeczka A. Experimental modal analysis of kitesurf boards. 1st Conference – Achievements of 
Students’ Scientific Technical Universities, STUKNUT, 2015, (in Polish). 
[2] Grzeczka A. The theory and technique of sailing on kitesurfing. Conference on Technical and 
Scientific Issues in Competitive Sailing Sports, 2013, (in Polish). 
[3] Sobotta – Atlas Anatomii Człowieka. Elsevier Urban and Partner, Vol. 4, Wrocław, 2012. 
[4] http://www.www.flickr.co, 2015. 
[5] Nebas Tim, Heller Ben A smartphone based system for kite and board measurements in kitesurfing, 
Conference of the International Sports Engineering Association, Procedia Engineering, Vol. 72, 2014, 
p. 477-482. 
[6] Lundgren L., Brorsson S., Osvalder A. L. Injuries related to kitesurfing. Waset, Vol. 53, 2011, 
p. 1132-1136. 
[7] Lundgren L., Olandersson S., Hilliges M., Osvalder A. L. Biomechanics of extreme sports – a kite 
surfing scenario. 39th Nordic Ergonomic Society (NES) Conference, Lysekil, Sweden, 2011. 
[8] Valsecchi M., Saggin B., Tarabini M. Whole Body Vibration in Kitesurfing. Master’s Thesis, 
Politecnico di Milano, Milan, Italy, 2010. 
[9] Bourgois Jan G., Boone Jan, Callewaert Margot, Tipton Michael J., Tallir Isabel B. 
Biomechanical and physiological demands of kitesurfing and epidemiology of injury among 
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Vision-based motion analysis of a kitesurfer

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Vision-based motion analysis of a kitesurfer

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