1st IMACSSS International Conference - "Game, Drama, Ritual in Martial Arts and Combat Sports". Genova (Genoa, Italy) 8-10 June 2012. Speaker: Alessandro Timmi. Authors: Alessandro Timmi, Prof. Ettore Pennestrì, Prof. Pier Paolo Valentini (Dept. of Industrial Engineering, University of Rome Tor Vergata), Prof. Pierluigi Aschieri (coach of the Italian Karate Team, FIJLKAM). You will find the video of the presentation on: http://www.virtualsensei.it/imacsss-conference-presentation/ © 2012 Virtual Sensei

1. Biomechanical analysis of Karate techniques based
on the evaluation of the body kinetic energy from
3D mocap data
Eng. Alessandro Timmi, Prof. Ettore Pennestr` ı,
Prof. Pier Paolo Valentini and Prof. Pierluigi Aschieri
University of Rome Tor Vergata,
Dept. of Industrial Engineering,
in collaboration with the Italian National Karate Team
June 9, 2012
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

2. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

3. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

4. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

5. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

6. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

7. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

8. What is Virtual Sensei?
In-house developed software for instrumented and objective
3D biomechanical analysis of fast motions.
Performance parameters monitored:
velocities;
accelerations;
kinetic energy;
position of the body center
of mass (COM);
pelvis rotation axis.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

9. Project goals
Evaluation of the kinetic energy levels achieved in different
techniques (chosen index of performance).
Critical review and optimization of the body motions.
Recording of elite athletes’ performances.
Development of instruments for sports club coaches.
Prevention of athletes’ wear and injuries.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

10. Project goals
Evaluation of the kinetic energy levels achieved in different
techniques (chosen index of performance).
Critical review and optimization of the body motions.
Recording of elite athletes’ performances.
Development of instruments for sports club coaches.
Prevention of athletes’ wear and injuries.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

11. Project goals
Evaluation of the kinetic energy levels achieved in different
techniques (chosen index of performance).
Critical review and optimization of the body motions.
Recording of elite athletes’ performances.
Development of instruments for sports club coaches.
Prevention of athletes’ wear and injuries.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

12. Project goals
Evaluation of the kinetic energy levels achieved in different
techniques (chosen index of performance).
Critical review and optimization of the body motions.
Recording of elite athletes’ performances.
Development of instruments for sports club coaches.
Prevention of athletes’ wear and injuries.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

13. Project goals
Evaluation of the kinetic energy levels achieved in different
techniques (chosen index of performance).
Critical review and optimization of the body motions.
Recording of elite athletes’ performances.
Development of instruments for sports club coaches.
Prevention of athletes’ wear and injuries.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

14. Why Kinetic Energy?
Kinetic energy of a rigid body:
1 1
E = mvT v + ω T Jω (1)
2 2
where:
m = mass (kg );
v = velocity (m/s);
J = moment of inertia
tensor (kg · m2 );
ω = angular velocity (s −1 ).
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

15. Why Kinetic Energy?
Kinetic energy is an impartial parameter (not only velocity,
but also body mass and geometry).
Virtual Sensei calculates translational and rotational kinetic
energy of all body segments
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

16. Tools for sports club coaches
Virtual Sensei Lite is a free version of our software, based on
Microsoft Kinect sensor. It is a useful instrument for sports club
coaches (not part of this presentation!).
Free download on virtualsensei.it/lite
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

17. Experimental setup
Setup with 8 infrared high speed The athlete and the skeleton on
(100 fps) cameras the pc screen
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

18. 3D animated skeleton
Examples:
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

19. Case 1
Influence of target pad on gyaku tsuki kinetic energy levels
Click to play the video
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

20. Case 1: description
Figure: Michela Pezzetti, Italian National Karate Team
Method:
comparison of the gyaku tsuki in zenkutsu dachi performed
with and without the soft target pad.
Goal:
evaluation of the influence of the target pad on kinetic
energy released by the athlete.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

21. Case 1: description
Figure: Michela Pezzetti, Italian National Karate Team
Method:
comparison of the gyaku tsuki in zenkutsu dachi performed
with and without the soft target pad.
Goal:
evaluation of the influence of the target pad on kinetic
energy released by the athlete.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

22. Case 1: overall results
Data: 6 series (3 with and 3 without target pad) of gyaku tsuki +
tate shuto uke (required to return to the original position).
Results:
+9% average kinetic energy with the target pad;
constant hand speed in all the series (about 6 m/s);
the angular velocity of the pelvis is constant too
(9 − 10 rad/s).
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

23. Case 1: overall results
Data: 6 series (3 with and 3 without target pad) of gyaku tsuki +
tate shuto uke (required to return to the original position).
Results:
+9% average kinetic energy with the target pad;
constant hand speed in all the series (about 6 m/s);
the angular velocity of the pelvis is constant too
(9 − 10 rad/s).
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

24. Case 1: overall results
Data: 6 series (3 with and 3 without target pad) of gyaku tsuki +
tate shuto uke (required to return to the original position).
Results:
+9% average kinetic energy with the target pad;
constant hand speed in all the series (about 6 m/s);
the angular velocity of the pelvis is constant too
(9 − 10 rad/s).
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

25. Case 1: overall results
Data: 6 series (3 with and 3 without target pad) of gyaku tsuki +
tate shuto uke (required to return to the original position).
Results:
+9% average kinetic energy with the target pad;
constant hand speed in all the series (about 6 m/s);
the angular velocity of the pelvis is constant too
(9 − 10 rad/s).
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

26. Case 1: analysis of the single technique
Without target pad: over-rotation of the trunk due to inertia.
Counter-rotation required!
consistent negative angular velocity;
waste of rotational kinetic energy.
With target pad: sudden stop of the pelvis rotation:
optimized motion: reduction of the negative angular velocity;
rotational kinetic energy saving.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

27. Case 1: analysis of the single technique
Without target pad: over-rotation of the trunk due to inertia.
Counter-rotation required!
consistent negative angular velocity;
waste of rotational kinetic energy.
With target pad: sudden stop of the pelvis rotation:
optimized motion: reduction of the negative angular velocity;
rotational kinetic energy saving.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

28. Case 2
Biomechanical analysis of 2 variants of the gyaku tsuki
Click to play the video
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

29. Case 2: description
r3
returning arm (slow) returning arm (slow)
r1
trunk trunk
r2
r1
punching arm (fast) punching arm (fast)
1st variant: central axis 2nd variant: lateral axis
Method:
comparison of the 2 variants of gyaku tsuki in zenkutsu-dachi.
Goal:
evaluation of the influence of the rotation axis position on
kinetic energy released by the athlete.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

30. Case 2: overall results
Preliminary results of the analysis of 6 series of 11 gyaku tsuki
(blue circles) + 11 oi tsuki (required to return to the original
position):
+3% average kinetic energy in the lateral variant;
+9% punching hand speed in the lateral variant
(considering the most energetic punch for each series);
highest pelvis angular velocity in the central variant =
more punches in the same time.
Total kinetic energy (KE) − Entire body
Total kinetic energy (KE) − Entire body
60
Virtual Tk 60
Sensei Virtual peaks = 11, mean Tk = 46.75 J
X: 442 Sensei
Y: 56.84 Tt X: 298
50 Y: 57.08
Tr 50
peaks = 11, mean Tk = 39.57 J
40
Kinetic energy [J]
40
Kinetic energy [J]
30 30
20 20
VivianaBottaro Tk VivianaBottaro
10 sex: f 10 sex: f
48 kg Tt 48 kg
1.55 m 1.55 m
RGyakuCentral1 Tr
RGyakuLateral1
0 0
500 1000 1500 2000 0 500 1000 1500 2000 2500 3000
Time [s⋅10−2] Time [s⋅10−2]
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

31. Case 2: overall results
Preliminary results of the analysis of 6 series of 11 gyaku tsuki
(blue circles) + 11 oi tsuki (required to return to the original
position):
+3% average kinetic energy in the lateral variant;
+9% punching hand speed in the lateral variant
(considering the most energetic punch for each series);
highest pelvis angular velocity in the central variant =
more punches in the same time.
Total kinetic energy (KE) − Entire body
Total kinetic energy (KE) − Entire body
60
Virtual Tk 60
Sensei Virtual peaks = 11, mean Tk = 46.75 J
X: 442 Sensei
Y: 56.84 Tt X: 298
50 Y: 57.08
Tr 50
peaks = 11, mean Tk = 39.57 J
40
Kinetic energy [J]
40
Kinetic energy [J]
30 30
20 20
VivianaBottaro Tk VivianaBottaro
10 sex: f 10 sex: f
48 kg Tt 48 kg
1.55 m 1.55 m
RGyakuCentral1 Tr
RGyakuLateral1
0 0
500 1000 1500 2000 0 500 1000 1500 2000 2500 3000
Time [s⋅10−2] Time [s⋅10−2]
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

32. Case 2: overall results
Preliminary results of the analysis of 6 series of 11 gyaku tsuki
(blue circles) + 11 oi tsuki (required to return to the original
position):
+3% average kinetic energy in the lateral variant;
+9% punching hand speed in the lateral variant
(considering the most energetic punch for each series);
highest pelvis angular velocity in the central variant =
more punches in the same time.
Total kinetic energy (KE) − Entire body
Total kinetic energy (KE) − Entire body
60
Virtual Tk 60
Sensei Virtual peaks = 11, mean Tk = 46.75 J
X: 442 Sensei
Y: 56.84 Tt X: 298
50 Y: 57.08
Tr 50
peaks = 11, mean Tk = 39.57 J
40
Kinetic energy [J]
40
Kinetic energy [J]
30 30
20 20
VivianaBottaro Tk VivianaBottaro
10 sex: f 10 sex: f
48 kg Tt 48 kg
1.55 m 1.55 m
RGyakuCentral1 Tr
RGyakuLateral1
0 0
500 1000 1500 2000 0 500 1000 1500 2000 2500 3000
Time [s⋅10−2] Time [s⋅10−2]
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

33. Case 2: analysis of the single technique
Sample analysis of a single technique: most energetic gyaku
tsuki, lateral variant:
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

34. Case 3
Combination of kizami tsuki + gyaku tsuki
Click to play the video
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

35. Case 3: overall results
0.71 s 0.92 s 1.00 s 1.14 s
Total kinetic energy (KE) − Entire body
300
Virtual
Sensei
Tk
Best execution among 6 kizami
X: 92 Tt
250 Y: 273.8
Tr tsuki + gyaku tsuki:
200 high kinetic energy peak
Kinetic energy [J]
Sara Cardin (274 kJ), due to the body
150 sex: f
X: 100
Y: 111.9 X: 114
55 kg translation;
Y: 103.1 1.55 m
Kizami Gyaku
100 the sum of the two
50
X: 71
Y: 40.49
techniques produces a total
amount of 377 kJ.
0
0 50 100 150 ı, 200 250
Timmi, Pennestr` Valentini, Aschieri Virtual Sensei

36. Case 3: overall results
0.71 s 0.92 s 1.00 s 1.14 s
Total kinetic energy (KE) − Entire body
300
Virtual
Sensei
Tk
Best execution among 6 kizami
X: 92 Tt
250 Y: 273.8
Tr tsuki + gyaku tsuki:
200 high kinetic energy peak
Kinetic energy [J]
Sara Cardin (274 kJ), due to the body
150 sex: f
X: 100
Y: 111.9 X: 114
55 kg translation;
Y: 103.1 1.55 m
Kizami Gyaku
100 the sum of the two
50
X: 71
Y: 40.49
techniques produces a total
amount of 377 kJ.
0
0 50 100 150 ı, 200 250
Timmi, Pennestr` Valentini, Aschieri Virtual Sensei

37. Case 3: overall results
0.71 s 0.92 s 1.00 s 1.14 s
Total kinetic energy (KE) − Entire body
300
Virtual
Sensei
Tk
Best execution among 6 kizami
X: 92 Tt
250 Y: 273.8
Tr tsuki + gyaku tsuki:
200 high kinetic energy peak
Kinetic energy [J]
Sara Cardin (274 kJ), due to the body
150 sex: f
X: 100
Y: 111.9 X: 114
55 kg translation;
Y: 103.1 1.55 m
Kizami Gyaku
100 the sum of the two
50
X: 71
Y: 40.49
techniques produces a total
amount of 377 kJ.
0
0 50 100 150 ı, 200 250
Timmi, Pennestr` Valentini, Aschieri Virtual Sensei

38. Case 3: overall results
#1 Hips local Z angular velocity
12
Virtual
Sensei
10 X: 107
Y: 10.53
8
Sara Cardin
6 sex: f
Local ωz [rad/s]
55 kg
4 1.55 m
Kizami Gyaku
2
0
−2
−4
−6
0 50 100 150 200 250
1.07 s Time [s⋅10−2]
Max pelvis angular velocity: transition between kizami and
gyaku tsuki.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

39. Case 3: overall results
The hands
speed peaks
are synchro-
8
#5 Left Hand velocity norm
8
#7 Right Hand velocity norm nized with
Virtual Virtual
7
Sensei
X: 93
Y: 7.449
7
Sensei
X: 117
those of
Y: 7.245
6 6 body kinetic
5 Sara Cardin
sex: f
5
Sara Cardin
energy.
vG [m/s]
vG [m/s]
55 kg
1.55 m sex: f
4 4
Kizami Gyaku 55 kg
1.55 m
3 3 Kizami Gyaku
2 2
1 1
0 0
0 50 100 150 200 250 0 50 100 150 200 250
Time [s⋅10−2] Time [s⋅10−2]
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

40. Conclusions
Virtual Sensei software allows performing quantitative
biomechanical analysis of fast sports motions;
further studies on elite athletes required to confirm these
preliminary results.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei

41. Q/A
Thanks for your kind attention. Questions?
The authors wish to acknowledge the athletes of the Italian National
Karate Team for the fruitful collaboration during the experimental
sessions.
Timmi, Pennestr` Valentini, Aschieri
ı, Virtual Sensei