Kinetic Analysis of Instep and Side-foot Kick in Female and Male Soccer Players Academic research paper on "Agriculture, forestry, and fisheries"

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Procedía Engineering 147 (2016) 214 - 219

Procedía Engineering

www.elsevier.com/locate/procedia

11th conference of the International Sports Engineering Association, ISEA 2016

Kinetic Analysis of Instep and Side-foot Kick in Female and Male Soccer

Players

Keiko Sakamotoa, Naoki Numazub, Sungchan Hongc, Takeshi Asaib

a School of Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, UK b Institute of Health and Sport Science, University of Tsukuba, Ibaraki, Japan cSports R & D Core, University of Tsukuba Ibaraki, Japan

Abstract

The purpose of this study was to identify the kinetics of instep and side-foot kicks for female and male soccer players to understand the common and different mechanics underlying the two kicks. 6 female and 6 male soccer players performed maximal instep and side-foot kicks. Their motions and ground reaction forces were recorded by a motion capture system (250 Hz) and a force platform (1000 Hz). The ball velocity of the instep kick (22.5 ± 1.0 m/s for female players, 27.9 ± 1.3 m/s for male players) was significantly higher than that of the side-foot kick (21.5 ± 1.0 m/s for female players, 26.9 ± 1.3 m/s for male players ). Significant differences were also observed between the two kicks of female players for the value of hip flexion/extension torque. Moreover, significant differences were also observed between the female and male players for the value of hip adduction/abduction torque for side-foot kick. These results indicated that to enhance such hip torques is one of the technical elements that could be improved to increase ball velocity of side-foot kick in female players. © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/4.0/).

Peer-review under responsibilityoftheorganizingcommitteeofISEA2016

Keywords: Female soccer players, Instep kick, Side-foot kick;

1. Introduction

Recently, the competition level of female soccer has increased with the increasing player population. The game is also becoming more sophisticated, with demands for stronger shooting and faster passing. Therefore, a kicking technique for increasing the ball velocity is suggested to have become extremely important for achieving a high performance from female soccer players. The ball velocity of female players is considered to be slower than that of male players (Tant et al.,1991; Barfield et al., 2002). Physical factors such as the body frame or muscle strength can be cited as primary reasons for the slower ball velocity of female players, but other than that, we suggested that technical factors such as the swinging technique, ball impact technique, and others may be influencing the ball velocity. Many previous studies have been conducted on the kicking techniques of male players (Lees et al.,1998; Nunome et al., 2002), and only a very few studies have been performed using female players as participants (Shan, 2009; Orloff et al., 2008). However, no study has focused on the three-dimensional kinetics of these kicking techniques for female players. Thus, the kinetics of the instep and side-foot kicks have not been quantified appropriately. The joint torque for the swinging technique and kinetic chain technique are considered to be the most fundamental elements of the kicking technique. We suggest that comparing such technical elements between female and male players is critically important for revealing the characteristics and issues of the kicking technique of female players to improve their soccer performance.

This study examined the technical characteristics related to the swinging motions of female players by focusing on the instep kicking motions of university male and female soccer players.

* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000. E-mail address: author@institute.xxx

1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of the organizing committee of ISEA 2016

doi:10.1016/j.proeng.2016.06.216

2. Methods

2.1. Participants and Experimental Procedure

The participants were 12 players specializing in soccer at a university with a department of physical education (6 females, 158.7 ± 6.7 cm in height and 58.0 ± 5.7 kg in weight; 6 males, 175.0 ± 5.8 cm in height and 66.4 ± 6.8 kg in weight). Informed written consent was obtained from all the participants prior participation in this study. All procedures undertaken in this study were approved by the Ethics Committee for the Institute of Health and Sport Sciences, University of Tsukuba, Japan. The experimental task was to execute a kicking motion in which the ball is caught at the instep (Fig. 1a) and side-foot kicks (Fig. 1b). Each participant was asked to warm up, and then, with an ad libitum running start, to kick a soccer ball that had been set down towards a goal 10 m away, using the dominant leg at full force. Imaging was performed using 10 infrared cameras (Vicon Motion Systems, Oxford, UK); three-dimensional (3D) coordinate data for each body part (16 anthropometric points with reflective markers attached) during the kicking motion were collected at 250 Hz. The stationary coordinate system was defined as a right-handed system in which 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. The data, including the extrapolated points, were smoothed using a fourth-order phase-shift-free Butterworth digital filter to determine the optimum cut-off frequency (20 Hz) (Winter, 2004). A force platform (Kistler,Winterthur, Switzerland, Type 9287) 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 1000 Hz.

Fig. 1. Typical of kicks (a) instep kick ; (b) side-foot kick.

3. Results and Discussion

3.1. Average Velocities of Ball and Centre of Gravity of Foot

The average ball velocity for female players was 22.5 ± 1.0 m/s for instep kicks and 21.5 ± 1.0 m/s for side-foot kicks (Fig. 2a). In comparison, the average ball velocity for male players was 27.9 ± 1.3 m/s for instep kicks, 26.9 ± 1.3 m/s for side-foot kicks. Thus, the average ball velocities for two types of kicks were lower for female players than for male players, and the differences were statistically significant (p < 0.05). The average ball velocity of instep kick for female players (22.5 ± 1.0 m/s) was almost identical to the that reported in Orloff et al. (2008) (21.9 ± 3.5 m/s). Furthermore, the average ball velocity of instep kick for male players (27.9 ± 1.3 m/s) was higher than that for male players in Orloff et al. (2008) (22.7 ± 3.1 m/s). The average ball velocity of side-foot kick for male players (26.9 ± 1.3 m/s) was higher than that for male players in Nunome et al. (2002) (23.4 ± 1.7 m/s) and Levanon and Dapena (1998) (22.5 ± 1.8 m/s) (Fig. 2b). Various factors affect the ball velocity (e.g. foot velocity, place of impact, stiffness of the foot at point of impact, and mass of the kicking leg). Foot velocity in particular is considered to have the greatest impact on ball velocity. To increase ball velocity, techniques to increase the swing velocity before impact are considered to be important.

Fig. 2. Comparison of mean ball velocity and foot velocity before impact for female and male players: (a) instep kick; (b) side-foot kick.

The average foot velocity of instep kick for female players (17.8 ± 1.4 m/s) was higher than that reported in Barfield et al. (2002) (16.2 ± 2.3 m/s). The average foot velocity of instep kick for male players (21.2 ± 6.8 m/s) was higher than that for male players in Barfield et al. (2002) (19.7 ± 1.2 m/s). The average foot velocity for female players was lower than that for male players (p < 0.05). Horizontal velocities of hip, knee, and ankle joints in kicking leg during forward swing horizontal velocities of the hip, knee, and ankle joints in a forward swing were examined. For instep kick of females and males players, the hip joint velocity was the first to show a peak, followed by the knee joint velocity, and lastly the ankle joint velocity (Fig. 3a-c). Thus, for both kicks of female and male players, the proximal-to-distal energy transfer mechanism is apparently at work. Furthermore, the curve that describes the change in horizontal foot velocity is similar to that of side-foot kick (Fig. 3d-f). This suggests that the same mechanism is at work for the kicking action in both kicks for males and female players.

Fig. 3. Plots a, b, and c represent the average values obtained for joint horizontal velocities of the kicking leg for instep kick among the female and male players: (a) ankle velocity; (b) knee velocity; (c) hip velocity. Plots d, e, and f represent the average values obtained for joint horizontal velocities of the kicking leg of side-foot kick among the female and male players: (d) ankle velocity; (e) knee velocity; (f) hip velocity.

3.2. Hip Joint Torques in Kicking Leg

Figure 4a-c shows the average values of hip joint torque for instep kick of male and female players.

Fig.4. Plots a, b, and c represent the average values obtained for hip joint torque of the kicking leg for instep kick among the female and male players: (a) flexion/extension; (b) adducion/abduction; (c) internal/external rotation. Plots d, e, and f represent the average values obtained for hip joint torque of the kicking leg for side-foot kick among the female and male players: (d) flexion/extension; (e) adducion/abduction; (f) internal/external rotation.

Fig.5. Comparison of peak hip joint torque of kicking leg for female and male players: (a) instep kick; (b) side-foot kick.

The difference between the joint torques of the kicking leg for female and male players is presumably one factor that contributes to the difference in horizontal swing velocity. Among females, the average peak value was 196.5 ± 32.2 for flexion/extension, 76.8 ± 20.5 for adduction/abduction, and -10.9 ± 6.8 for internal/external rotation torques in the forward swing. For male players, the average peak value of instep kick was 250.1 ± 29.7 for flexion/extension, 109.5 ± 10.0 for adduction/abduction, and -13.8 ± 10.5 for internal/external rotation torques. The average peak values for the hip flexion/extension torques as well as the

adduction/abduction torques for instep kick of female players were smaller than those of male players (p < 0.05) (Fig. 5a). Therefore, to increase the foot velocity of instep kick in female players, increasing flexion/extension and adduction/abduction torque of hip joint may be assumed to increase the swing velocity. Figure 4d-f shows the average values of hip joint torque for side-foot kick of female and male players. Among females, the average peak value was 184.8 ± 31.4 for flexion/extension, 75.1 ± 17.3 for adduction/abduction, and -9.3 ± 6.4 for internal/external rotation torques in the forward swing (Fig. 5b). For male players, the average peak value of side-foot kick was 229.3 ± 44.1 for flexion/extension, 102.1 ± 10.9 for adduction/abduction, and -7.2 ± 18.8 for internal/external rotation torques. The adduction/abduction torque for side-foot kick of female players was smaller than those of male players (p < 0.05). For female players, to increase adduction/abduction torque of hip joint in side-foot kick may effectively increase their swing velocity. Moreover, statistically significant differences were observed between the two kicks of female players for the peak value of hip flexion/extension torque (p < 0.05) (Fig. 4a, d). This results suggest that to increasing flexion/extension torque of side-foot kick in female players may effectively increase their swing velocity. Otherwise, significant differences were also observed between the two kicks of male players for the peak value of hip adduction/abduction torque (p < 0.05) (Fig. 4b, e), increasing hip adduction/abduction torque of side-foot kick in male players may contribute to increase their swing velocity.

3.3. Knee Joint Torques in Kicking Leg

Figure 6a-c shows the average values of knee joint torque for instep kick of male and female players.

Fig.6. Plots a, b, and c represent the average values obtained for knee joint torque of the kicking leg for instep kick among the female and male players: (a) flexion/extension; (b) adducion/abduction; (c) internal/external rotation. Plots d, e, and f represent the average values obtained for knee joint torque of the kicking leg for side-foot kick among the female and male players: (d) flexion/extension; (e) adducion/abduction; (f) internal/external rotation.

Among females, the average peak value was 62.8 ± 28.2 for flexion/extension, 28.4 ± 8.1 for adduction/abduction, and 3.2 ± 1.5 for internal/external rotation torques in the forward swing (Fig. 7a). For male players, the average peak value of instep kick was 83.1 ± 18.1 for flexion/extension, 38.6 ± 10.8 for adduction/abduction, and 3.4 ± 3.4 for internal/external rotation torques. Figure 7d-f shows the average values of knee joint torque for side-foot kick of male and female players. Among females, the

average peak value was 56.4 ± 21.9 for flexion/extension, 28.6 ± 7.2 for adduction/abduction, and 3.2 ± 0.9 for internal/external rotation torques in the forward swing. For male players, the average peak value of side-foot kick was 66.8 ± 17.3 for flexion/extension, 35.3 ± 10.7 for adduction/abduction, and 2.8 ± 2.9 for internal/external rotation torques. Statistically significant differences were also observed between the two kicks of male players for the peak value of knee flexion/extension (p < 0.05) (Fig. 6a, d). For male players, to increase flexion/extension torque of knee joint in side-foot kick may effectively increase their swing velocity.

Fig.7. Comparison of peak knee joint torque of kicking leg for female and male players: (a) instep kick; (b) side-foot kick.

4. Conclusion

In this study, we investigated the difference in instep and side-foot kick for female and male players. The results showed that the average ball and foot velocities for both kicks in female players were significantly lower than those in male players (p < 0.05). Furthermore, the average peak values of the hip and knee joint torques for female players were also lower than those for male players (p < 0.05). The average peak values for the hip flexion/extension and the adduction/abduction torques for instep kick of female players were smaller than those of male players (p < 0.05). Therefore, to increase the foot velocity of instep kick in female players, increasing flexion/extension and adduction/abduction torque of hip joint may be assumed to increase the swing velocity. Moreover, the average peak values for the hip adduction/abduction torques for side-foot kick of female players were smaller than those of male players (p < 0.05). To increase the foot velocity of instep kick in female players, increasing adduction/abduction torque of hip joint may contribute to increase the swing velocity. In addition, statistically significant differences were observed between the two kicks of female players for the peak value of hip flexion/extension torque (p < 0.05). These results indicated that to increase the foot velocity of the side-foot kick in female players, investigating the factors that improve hip adduction/abduction and the knee flexion/extension and torque enhance techniques is important. Otherwise, statistically significant differences were observed between the two kicks of male players for the peak value of hip adduction/abduction and knee flexion/extension torque (p < 0.05). These results suggest that it is different the technical element to increase swing velocity in female and male players. This study analyzed only the kinetics. To investigate gender differences in more detail, it will be necessary to analyze the kinematic studies of gender differences.

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