Scholarly article on topic 'Difference in Kicking Motion between Female and Male Soccer Players'

Difference in Kicking Motion between Female and Male Soccer Players Academic research paper on "Animal and dairy science"

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Abstract of research paper on Animal and dairy science, author of scientific article — Keiko Sakamoto, Yutaka Shimizu, Eiko Yamada, Sungchan Hong, Takeshi Asai

Abstract This study was designed to compare the kicking motion between female and male soccer players to determine the mechanical and technical characteristics of the kick by female players. A motion capture system (250Hz) was used to compare ball velocity, foot velocity, mean peak knee joint torques, angle of the thigh and shank, and mean thigh-to- shank energy ratio between female and male soccer players to elucidate the mechanical and technical characteristics of the kick by female players before ball impact. The values for ball velocity, foot velocity immediately before impact, mean peak knee joint torques, and mean thigh-to-shank energy ratio were smaller for the female players than for the male players (p < 0.05).

Academic research paper on topic "Difference in Kicking Motion between Female and Male Soccer Players"

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Procedía Engineering

ELSEVIER

Procedía Engineering 60 (2013) 255 - 261

www.elsevier.com/locate/proeedia

6th Asia-Pacific Congress on Sports Technology (APCST)

Difference in kicking motion between female and male soccer

players

Keiko Sakamotoa*, Yutaka Shimizua , Eiko Yamadab, Sungchan Hongc, Takeshi

aGraduate school, Institute of Health and Sport Science, University of Tsukuba, Tennoudai 1-1-1, Ibaraki, 305-8574, Japan bInstitute of Health and Sport Science, University of Tsukuba, Tennoudai 1-1-1, Ibaraki, 305-8574, Japan cSports R & D Core, University of Tsukuba, Tennoudai 1-1-1, Ibaraki, 305-8574, Japan

This study was designed to compare the kicking motion between female and male soccer players to determine the mechanical and technical characteristics of the kick by female players. A motion capture system (250 Hz) was used to compare ball velocity, foot velocity, mean peak knee joint torques, angle of the thigh and shank, and mean thigh-to-shank energy ratio between female and male soccer players to elucidate the mechanical and technical characteristics of the kick by female players before ball impact. The values for ball velocity, foot velocity immediately before impact, mean peak knee joint torques, and mean thigh-to-shank energy ratio were smaller for the female players than for the male players (p < 0.05). © 2013 The Authors. Published by Elsevier Ltd.

Selection andpeer-review underresponsibilityoftheSchoolofAerospace,Mechanicaland ManufacturingEngineering, RMIT University

Keywords: Female players; kicking leg; energy

1. Introduction

In a kick motion in soccer, obtaining a high ball velocity is an important technical task. The reported determining factors for ball velocity include the important kick elements, namely, swing velocity [1], reduced mass of the kicking leg, the position at which the ball is impacted, and the posture of the ankle joints [2]. However, little research has been conducted to analyse kicking techniques in female soccer players [3-5] in comparison with male soccer players. Despite the known sex-based differences in

* Corresponding author. Tel.: +81-029-853-2711; fax: +81-029-853-2711. E-mail address: s0930492@u.tsukuba.ac.jp

Received 20 March 2013; revised 6 May 2013; accepted 9 May 2013

Abstract

1877-7058 © 2013 The Authors. Published by Elsevier Ltd.

Selection and peer-review under responsibility of the School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University doi: 10. 1016/j .proeng.2013.07.009

skeletal, muscular, and flexibility-related aspects between male and female players [6, 7], the technical characteristics of the kick by female players have not been elucidated; thus, the technical coaching given to soccer players has not been adapted to female players. Hence, this study aimed to use a 3-dimensional motion-capture system to compare swing velocities and joint torques between male and female players to better understand the features of the kicking motions by female soccer players.

2. Methods

2.1. Participants and experimental procedure

The participants consisted of 13 male soccer players (height, 174.3 ± 4.7 cm; weight, 66.8 ± 4.9 kg) and 13 female soccer players (height, 160.4 ± 4.9 cm; weight, 57.1 ± 5.7 kg). In total, 26 athletes specializing in soccer at a university with a department of physical education participated in this study. Written informed consent was obtained from all the subjects before participation in the study. All the procedures undertaken in the study were approved by the ethics committee of the Institute of Health and Sport Sciences, University of Tsukuba, Japan. All the participants' dominant leg was the right leg.

The experimental task was a kicking motion in which the ball is caught at the instep (the portion centred on the dorsum of the foot leading to the ankle). Each participant was asked to warm up and then, with an ad libitum running start, kick a soccer ball that had been set down, toward a goal 10 m away, using the dominant leg at full force. Two trials were performed by each participant; a trial was deemed to be a success if the kick hit a 2-m square in the centre of the goal. To minimize the impact on the mechanical interaction between the foot and the ball during ball impact at the soccer shoes, all the subjects wore different sizes of the same model of indoor soccer shoes (DESTAQUE 2 J, Asics Corporation). Imaging was performed using 10 infrared cameras (Vicon Motion Systems); 3-dimensional coordinate data of each part of the body (16 anthropometric points with reflective markers attached) during the kicking motion were collected at 250 Hz (Fig. 1). A stationary coordinate system was defined as a right-handed coordinate system where the x-axis is the direction orthogonal to the horizontal kicking direction at the start of the task, the y-axis is the horizontal kick direction at the start of the task, and the z-axis is the vertical direction.

Raw data was calculated for every kinematic variable, and 20 points of post-impact data were extrapolated by reflection [8]. The data, including the extrapolated points, were smoothed by using a fourth-order phase-shift-free Butterworth digital filter to determine the optimum cut-off frequency (5-47.5 Hz) [9]. A force platform (Kistler) was installed beside the ball, and the ground reaction force at the point of contact with the supporting leg was measured at a sampling frequency of 1,000 Hz [4].

Fig 1. (a) Location of the markers for the lower limbs; (b) Fig. 2. Experiment setup.

2.2. Data analysis and calculated parameters

In this study, to analyse differences between females and males, the following parameters were calculated. Ball velocity was determined by calculating the ball velocity in the horizontal left-right (x-axis), horizontal front-rear (y-axis), and vertical up-down (z-axis) directions and resultant velocity (composition of x, y and z direction velocity). The foot centre of gravity was identified by using body part inertia coefficients for Japanese athletes [10] to geometrically calculate the raw data for the coordinates of the foot centre of gravity, which was then differentiated by time to thereby calculate the velocity of the foot centre of gravity in the horizontal left-right (x-axis), horizontal front-rear (y-axis), and vertical up-down (z-axis) directions, and then resultant velocity. The joint centre for the hip joint was calculated using the estimation method of the Clinical Gait Analysis Forum of Japan. The knee joint and ankle joint centres were taken to be the midpoint of the internal and external condyles in each respective joint. The raw data of the coordinates for the resulting midpoints were differentiated by time to thereby calculate the midpoint velocity. The knee joint and hip joint midpoint velocities were determined by calculating the midpoint in the horizontal left-right (x-axis), horizontal front-rear (y-axis), and vertical up-down (z-axis) directions and then resultant velocity.

In the present study, the whole body was modelled using a segment model of 15 rigid bodies connected by 14 joints with 3 degrees of motion freedom. A moving coordinate system was set for every degree of motion freedom from the 3-dimensional coordinates of each site on the body to calculate the joint angle, joint angular velocity during the kicking motion (Fig. 2). Inverse dynamics calculation was adopted for reaction force data to calculate the joint torque. To evaluate the extent to which energy from the thigh to the shank is transferred, the energy transfer ratio in the leg was also determined by calculating the thigh and shank energy in the kicking leg. The shank-to-thigh energy ratio was calculated for the point of contact between the kicking leg and the ball, following the point of contact between the support leg and the ground, by dividing the integral value of the shank energy during a later stage by the integral value of thigh energy. The early stage was defined as the time from the point of contact between the support leg and the ground until the peak value of thigh energy in the kicking leg, whereas the late stage was defined as the time from the peak value of the thigh energy in the kicking leg until the point of contact between the kicking leg and the ball (Eq.1).

xSHA sSHA

ZhIE XhFE

ZkI XkFE

Knee and Ankle

Fig. 2. (a) Definition of the segment coordinate systems fixed at the thigh, shank, and foot segments used in the calculation of the angular velocity of each segment; (b) Definition of the joint coordinate systems fixed at the centre of the hip, knee, and ankle joints to express the anatomical joint rotations.

Thigh — to — shank energy ratio =

Integrated value of shank Integrated value of thigh

3. Results and discussion

3.1. Data analysis and calculated parameters

Fig. 3(a) depicts the horizontal velocity of the foot, knee, and hip of the kicking leg from the landing of the plantar leg until its impact on a global coordinate system.

The initial peak hip velocity, the peak knee velocity, and finally, the peak foot velocity were observed at impact. The female and male players effectively generated foot velocity using the kinetic chain mechanism. The mean ball velocity for the female players' instep kick was 22.0 ± 1.4 m/s, compared with the male players' 26.4 ± 2.0 m/s (Fig. 3(b)). Thus, the mean ball velocity for the instep kick was 17% lower in the female players than in the male players (p < 0.05). The female players' mean foot velocity just before impact for the instep kick was 17.4 ± 1.0 m/s, compared with the male players' 19.9 ± 1.2 m/s. The foot velocity immediately before impact for the instep kick in the female players was approximately 13% lower than that in the male players (p < 0.05).

Fig. 3. (a) Examples of horizontal velocity of the hip, knee, and ankle (kicking leg) of the female and male players (a, female players; b, male players); (b) Comparison of the ball and foot velocities before impact. The bars and asterisks represent significant differences between females and males (*p < 0.05).

3.2. Knee joint torque

Fig. 4(a) shows the knee joint torque of the kicking leg from the landing of the plantar leg until impact. Overall, the magnitude of the knee joint torque transitioned to lower values in the female players than in the male players.

Fig. 4(b) shows the mean peak torque in the knee of the kicking leg from the landing of the plantar leg until impact. The mean peak flexion/extension torques of the knee joint of the female players' instep kick was 41.0 ± 2.6 N/m, compared with the male players' 60.6 ± 2.6 N/m (Fig. 3(b)). Thus, the mean peak flexion/extension torques in the knee joint of the female players was 22% lower than that of the male players for the instep kick (p < 0.05). For the female players, the mean peak adduction/abduction torques in the knee joint was 16.0 ± 1.8 N/m for the instep kick, compared with the male players' 25.6 ± 2.6 N/m. The mean peak adduction/abduction torques in the knee joint of the female players immediately before impact was approximately 37% lower than that of the males for the instep kick (p < 0.05). The difference in the mean peak internal/external rotation torques of the knee joint between the female and male players were not significant.

100 80 r 60

40 U 20 : 0 K -20

-40 -60 a)

100 80 60 40 20 0 -20 -40

Time (%)

-Flexion/

Extension

-----Adduction/

Abduction

'•........Internal/

External rotation

20 40 60 80\ 100

Time (%)

80 70 60 50 40 30 20 10 0 -10

flexion/ adduction/ internal/ extension abduction external rotation

Fig. 4(a). Examples of knee joint torques of the kicking leg of the female and male players (a, female players; b, male players); (b) Comparison of the peak knee joint torques of the kicking leg. The bars and asterisks represent significant differences between females and males (*p < 0.05).

3.3. Angle of thigh and shank

Fig. 5 shows the horizontal angle of the thigh and shank of the kicking leg from the landing of the plantar leg until impact. Female and male players exhibited positive values for thigh angle from the latter half to impact. Shank angular velocity, however, showed a tendency towards a greater increase than thigh angle.

40 20 0 -20 -40

ro -100

ra -120 < -140 -160 -180

Time (%)

„ 0 «

t -40 ö -60 o

£ -80 n -100

ra-120 < -140 -160 -180

— Thigh

— Shank

Time (%)

Fig. 5. Examples of thigh and shank angle (kicking leg) for the female and male players (a, female players; b, male players).

3.4. Energy of the thigh and shank of the kicking leg

Fig. 6(a) shows the horizontal energy of the thigh and shank of kicking leg from the landing of the plantar leg until impact. The overall torque magnitude in the female players had the tendency to be smaller than that in the male players. Energy exerted by the thigh was presumably transferred to the shank by the linked motion and contributed to the translational motion of the kicking leg (Fig. 5). To illustrate the extent to which thigh motion impacts shank motion, Fig. 6(b) shows the mean shank-to-thigh energy ratio. The female players showed a significant value for the mean shank-to-thigh energy ratio in

comparison with the male players (p < 0.05). This suggests the possibility that the thigh-to-shank energy ratio is lower in the female players than in the male players.

350 300 2 250

w 100 50 0

40 60 Time (%)

80 100

ra150 a3

w 100 50 0

40 60 Time (%)

80 100

Energy

Fig. 6(a). Examples of the energy of the thigh and shank (kicking leg) in the female and male players (a, female players; b, male players); (b) Comparison of the energy ratio. The bars and asterisks represent significant differences between females and males (*p < 0.05).

4. Conclusion

This study was designed to compare the swing motion between female and male soccer players to determine the mechanical and technical characteristics of the kick by female players. The values for ball velocity, foot velocity immediately before impact, mean peak knee joint torques, and mean thigh-to-shank energy ratio were lower in the female players than in the male players (p < 0.05).

Female and male players' swing motions presumably include energy transfer by means of a kinetic chain technique between the thigh and shank; however, our results suggest that female players may have a lower thigh-to-shank energy ratio than male players. Furthermore, given that the hip joint also contributes significantly to shank acceleration, we suggest that future research not only on knee joint motion but also on hip joint motion be conducted.

References

[1] Lees, A., Asai, T., Andersen, TB., Nunome, H. and Sterzing, T., The Biomechanics of Kicking in Soccer: A Review, Journal of Sports Sciences, 2010, 28(8), 805-817.

[2] Nunome, H., Lake, M., Georgakis, A. and Stergioulas, LK., Impact phase kinematics of instep kicking in soccer, Journal of Sports Sciences, 2006, 24(1), 11-22.

[3] Clagg, SE., Warnock, A., and Thomas, JS. Kinetic analyses of maximal effort soccer kicks in female collegiate athletes. Sports Biomechanics, 2009, 8(2), 141-153.

[4] Heidi, O et al. Ground reaction forces and kinematics of plant leg position during instep kicking in male and female collegiate soccer players. Sports Biomechanics, 2008, 7(2) , p. 238-247

[5] William, RB., Donald TK., Bing Y. Kinematics instep kicking differences between elite female and male soccer players. Journal of Sports Science & Medicine, 2002, 1, p.72-79.

[6] Wojtys, EM., Ashton-Miller, JA., Huston, LJ. A gender-related difference in the contribution of the knee musculature to sagittal-plane shear stiffness in subjects with similar knee laxity. Journal of Bone Joint Surg Am, 2002, 84-A, p. 10-16.

[7] Wilkerson, RD., Mason, MA. Differences in men's and women's mean ankle ligamentous laxity. Journal of Iowa Orthop, 2000, 20, p. 46-48.

[8] Smith, G. Padding point extrapolation techniques for the Butterworth digital-filter. Journal of Biomechanics, 1989, 22, p. 967-971.

[9] Abdel-Aziz, YI., & Karara, HM. Direct linear transformation from comparator coordinates into object space coordinates in close-range photogrammetry. Proceedings of the Symposium on Close-Range Photogrammetry, 1971, pp. 1-18.

[10] Ae, M., Tang, H. and Yokoi, T., Estimation of inertial properties of the body segments in Japanese athletes, in: The Society of Biomechanisms, ed., Biomechanisms 11: Form, Motion, and Function in Humans, The University of Tokyo Press, Tokyo, 1992, 23-33.