Physical Training Oct 2008
 
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Relationship Between Muscular Strength and Kicking Performance

ANTHRAKIDIS N., SKOUFAS D., LAZARIDIS S., ZAGGELIDIS G.
Aristotle University of Thessaloniki, Greece
Department of Physical Education
Laboratory of Coaching and Sport Performance
Savvas Lazaridis
16 Giannakopoulou
56121 Ampelokipi
Thessaloniki
Hellas
Tel: (+30) 2310 720843
E-mail: sav200m@hotmail.com

ABSTRACT

Aim.The present study was carried out to examine the relationships between muscular strength, in terms of knee extension at two different angular velocities and kicking performance among soccer players of different skill levels.

Methods. Twenty four amateur soccer players (aged 21.50.7 years, body mass: 79.08 kg, height: 179.04cm) constituted the experimental group.They were divided into 2 groups, the superior group (n=12), the average group (n=12), and kicked the ball with maximal effort towards a target 15 m. away. Maximal ball velocity was recorded using a speed gun device and maximal isokinetic and concentric muscular strength was measured in terms of motion of the knee extensors using an isokinetic dynamometer.

Results. The results showed that the skilled group presented more powerful kicks than the untrained and demonstrated significantly greater peak torque values at concentric knee extension strength at both angular velocities. It was found that both groups presented positive correlation between peak torque values and kick velocity score. Also, the untrained group revealed greater correlation over the two knee extension conditions with the kick velocity.

Conclusions. Soccer trained players have more powerful instep kicks than untrained players and better knee extension concentric strength at slow and fast angular velocities. Possible explanations for the differences between the two groups could be the fact that skilled players are more experienced and adopt a different neuromuscular coordination compared to untrained ones. It is obvious that strength is not the only reason that allows players to perform powerful kicks as the untrained group presented better correlations (kicking score with knee extension peak torque) than the skilled group. On the other hand, trained soccer players have better kicking performance due to the fact that they use specific training methods (such as kicks) in their daily training course and increase this ability but not their isokinetic strength.

Key words
: soccer, strength, kicking, skilled



Introduction

Kicking is a very important factor in soccer and one of the most fundamentally used skills. It should be practiced from the early ages (Bloomfield et al..1979). It is the most widely studied soccer skill as many researches have examined kinematics, kinetics and EMG variables. It is a multijoint movement which depends on various factors such as the maximum strength and power of the muscles of the kicking and supporting leg that take part during the kicking action ((De Proft et al., 1988a, b; Isokawa & Lees, 1988; Weineck, 1992; Lees & Nolan, 1998; Dorge et al., 1999), the angle that the player approaches the ball and the speed that he has before the impact phase (Isokawa & Lees, 1988; Opavsky, 1988). It also, depends on the coordination between the agonist muscles (vastus lateralis and medialis, rectus femoris, tibialis anterior and m. iliopsoas) and the antagonists (gluteus maximus, biceps femoris and semitendinosus) during the kick (De Proft et al., 1988a, b; Isokawa & Lees, 1988; Lees & Nolan, 1998; Dorge et al., 1999).

During the game, muscle strength is required, because each player performs such dynamic movements as kicks, headers, tackling, and sprinting. So, power, endurance and muscle strength are needed to compete in the game (Cabri et al., 1988; Bangsbo, 1994). The relation between muscle strength and performance in the field is a subject of controversy in many research fields dealing with muscle power. Some articles have demonstrated positive correlations between force, measured in the laboratory and performance in the field. Perrine and Everton (1975) found high correlations between isokinetic strength (at a speed of: 6.29 rad/sec) and vertical jump and demonstrated improvements after fast isokinetic leg thrust exercises. Kanehisha and Myashita (1983) found significant relations between peak force (3.65 rad/sec) and 50m sprint velocity. Oberg et al. (1986) and Cabri et al. (1988) found that in general soccer players are stronger than non-soccer players and they perform more powerful instep kicks.

Many researchers have mentioned that the coordination between the agonist muscles (vastus lateralis and medialis, rectus femoris, tibialis anterior and m.iliopsoas) and the antagonists (gluteus maximus, biceps femoris and semitendinosus) during the kick and the maximum power of the lower limbs are very important factors for a strong instep kick (De Proft et al., 1988a, b; Isokawa & Lees, 1988; Lees & Nolan, 1998; Dorge et al., 1999). Also, studies with ball velocity and kicking distance (Cabri et al. 1988; Isokawa et al., 1988) have revealed that lower limb and/or toe velocity (Luhtanen et al.1988) and maximal strength of the knee extensor muscle (McLean et al., 1993; Mognoni et al. 1994) are important determinants of kick performance and muscle strength is directly responsible for increasing the speed of the foot.

The purpose of this study was to examine the relation between knee extension strength muscles and kicking performance at two different angular velocities and to investigate if trained soccer players have better relations than untrained subjects. A slow at 90 and a faster (more related to kicking) at 240 angular velocities were chosen according to Masuda et al 2004.


Methods

Participants

   
Twenty four amateur soccer players volunteered to participate in this study after signing informed consent forms, approved by the University ethical committee. They divided into two groups. Trained (n=12) and untrained (n=12).
The anthropometric variables of all the subjects are presented below:


n

24

age

21.50.7 years

Body mass

79.08 kg

height

179.04 cm.


Table1. Anthropometric variables of all subjects before dividing into untrained and skilled.

Procedures

Kick performance test. To evaluate kicking performance, subjects kicked the ball with maximal effort. Ball velocity was measured using a speed gun device (PSK Professional, Toa Sports Machine Co., Japan), located 1.22 m above the ground, behind the goal. The participants performed 10 full instep kicks in order to record their best kick. The approach to the stationary ball was free at 15m distance from the goal. The sports radar-gun was put back from the goal at 1,22m from the ground (Masuda et. al., 2004). All participants were asked to give their maximal effort.

Muscular strength test. Isokinetic concentric peak torque of the dominant leg was measured using an isokinetic dynamometer machine (cybex norm) at two different angular velocities, to find their knee extension concentric strength. The first angular velocity was slow, at 90 (1.57 rad/sec) and the second was faster at 240 (4.19 rad/sec). The number of repetitions was 3 for lower angular velocity movements and 5 for faster angular velocity movements. All the participants practiced isokinetic movements in order to familiarize themselves with the test protocol. Their best values were chosen for further statistical analysis.


Statistics

The Kolmogorov-Smirnov test of normality revealed that none of the studied variables required logarithmic transformation. Calculations were performed with a SPSS/PC 16 statistical package including mean, standard deviation of the mean and Student's t-test for independent samples. Spearman correlation coefficient was used to show the relationships and to quantify possible relationships between kick velocity release and knee extensors torque at the two angular velocities in the two groups. The level of statistical significance was set at P<0.05.


Results

The skilled group presented more powerful kicks than the untrained group. Those results agree with Cabri et al. (1988), who found a significant difference in kicking performance between soccer and non-soccer players. Table 2, presents the descriptive statistics for this parameter at which was found a statistically significant difference between the two groups t (22) =-7,420, p<0.001.



group

N

Mean

Std. Deviation

Std. Error Mean

t-value

p-value

kick

velocity

untrained

12

85,9

6,7

1,9402

-7,420

0,000 ***

skilled

12

106,0

6,5

1,8870

Table 2. Descriptive statistics for the parameter kick velocity in the two groups (untrained, skilled). Statistically significant differences between groups are presented with red font.

Also, the skilled group demonstrated significantly greater peak torque values at concentric knee extension strength at both examined velocities (90 or 240 rad/sec). In the table 3, are presented the descriptive statistics for the knee extensor torque values at both velocities in the two groups with the t- and p- values.



category

N

Mean

Std. Deviation

Std. Error Mean

t-value

p-value

extensor

90

untrained

12

177,000

10,3221

2,9797

-4,134

0,000***

skilled

12

211,417

26,9291

7,7737

extensor

240

untrained

12

127,000

9,6389

2,7825

-2,687

0,013 *

skilled

12

145,583

21,9315

6,3311

Table 3. Descriptive statistics and t-value for the knee extensor peak torque at two conditions (90/240 rad/sec) in the two groups (untrained, skilled). Statistical significant differences between groups are presented with red font.

Regarding the correlation between the kick velocity score and the knee extensors peak torque values at the two velocities (90 and 240 rad/sec) in the two groups it was found that: first of all, there was a positive correlation between the peak torque values at 90rad/sec velocity condition and 240rad/sec overall in the groups as it is presented in the table 4 below. The untrained group revealed greater correlation over the two knee extension conditions with the kick velocity as it is presented in the tables below (5,6) compared to skilled ones.


Correlations




extensor_90

extensor_240

Kendall's tau_b

extensor_90

Correlation Coefficient

1,000

,767**

Sig. (2-tailed)

.

,000

N

24

24

extensor_240

Correlation Coefficient

,767**

1,000

Sig. (2-tailed)

,000

.

N

24

24

Spearman's rho

extensor_90

Correlation Coefficient

1,000

,904**

Sig. (2-tailed)

.

,000

N

24

24

extensor_240

Correlation Coefficient

,904**

1,000

Sig. (2-tailed)

,000

.

N

24

24

**. Correlation is significant at the 0.01 level (2-tailed).




Table 4. Correlation between the two knee extensor velocity conditions in the groups together.

Untrained (12)

Kick velocity



Correlation

coefficient

p-value

Knee extensor_90

0,746

0,015**

Knee extensor_240

0,624

0,030*


Skilled (12)

Kick velocity



Correlation

coefficient

p-value

Knee extensor_90

0,541

0,069

Knee extensor_240

0,262

0,411


Table 5
Table 6

Tables 5,6. Correlations between the two condition velocities (90 and 240rad/sec) and kick velocity in the two groups. Statistically significant differences between groups are presented with red font.


Discussion


The current study revealed that trained soccer players presented higher levels of strength regarding kicking performance compared to untrained individuals. Both groups presented high values of correlation at the slower angular velocity (240ْ) which is reasonable, as kicking movement is a multijoint movement which depends on many joints, not only the knee joint (De Proft et al., 1988a, b; Isokawa & Lees, 1988). But untrained subjects seemed to have a better correlation on kicking performance and knee extensors muscle torque because the high kicking performance of trained players not only depends on strength parameters but also on coordination and technical parameters.

As is already known, professional soccer players should present high levels of strength and electromyography activation of their lower extremity muscles in order to perform a strong and powerful kick. But, this does not translate to the fact that muscle strength or torque is the main factor which affects a soccer kick, as kicking movement is a multijoint movement. For this reason, a trainer or a coach should use in his daily training program, a variety of training methods and specific soccer exercises in order to improve, apart from muscle strength, coordination and many technical kicking  parameters.

References

BANGSBO, J. (1994). Physical conditioning training in soccer: a scientific approach. Copenhagen, Denmark: University of Copenhagen

BLOOMFIELD, J., ELLIOTT, B.C. & DAVIES, C.M. (1979). Development of the punt kick: A cinematographical analysis. Journal of Human Movement Studies, 6, 142-150.

CABRI, J., DE PROFT, E., DUFOUR, W. & CLARYS, J. (1988). The relation between muscular strength and kick performance. In: Science and Football. Eds: Reilly, T., Lees, A., Davids, K. and Murphy, W. London: E & FN Spon. 186-193.

DE PROFT, E., CLARYS, J., BOLLENS, E., CABRI, J.& DUFOUR W. (1988b In: Science and Football. Eds: Reilly, T., Lees, A., Davids, K. and Murphy, W. London: E & FN Spon.434–440

DORGE, H., BULL-ANDERSEN, T., SORENSEN, H., SIMONSEN, E., AAGAARD, H., DYHRE POULSEN, P. & KLAUSEN, K. (1999). EMG activity of the iliopsoas muscle and leg kinetics during the soccer place kick. Scandinavian Journal of Medicine and Science in Sports, 9, 155-200

ISOKAWA, M. & LEES, A. (1988). A biomechanical analysis of the instep kick motion in soccer. In: Science and Football. Eds: Reilly, T., Lees, A., Davids, K. and Murphy, W. J. London: E & FN Spon. 449-455.

KANEHISHA, H. & MIYASHITA, M. (1983). Specificity of velocity in strength training. Eur. J. Appl. Physiol., 52, 104-106.

LEES, A. & NOLAN, L. (1998). The biomechanics of soccer; a review. Journal of sport science, 16: 211-234

LUHTANEN, P. (1988) Kinematics and kinetics of maximal instep kicking in junior soccer players. In: Science and Football. Eds: Reilly, T., Lees, A., Davids, K. and Murphy, W. J. London: E & FN Spon. 441-448.

MASUDA, K., KIKUHARA, N., DEMURA, S., KATSUTA, S. & YAMANAKA, K. (2005). Relationship between muscle strength in various isokinetic movements and kick performance among soccer players. J. sports med. Phys. fitness, 45, 44-52

MOGNONI, P., NARICI, V., SIRTORI, D. & LORENZELLI, F. (1994). Isokinetic torques and kicking maximal ball velocity in young soccer player. J. Sports Med. Phys. Fitnes, 34, 357-361.

MCLEAN, BD. & TUMILTY M. (1993). Left-right asymmetry in two types of soccer kick. Br. J. Sports Med., 27, 260-362.

OBERG, B., MOLLER, M., GILLQUIST, J. & EKSTRAND, J. (1986). Isokinetic torque levels for knee extensors and knee flexors in soccer players. Int. J. Sports Med; 7, 50-53.

OPAVSKY, P. (1988). An investigation of linear and angular kinematics of the leg during two types of soccer kick. In: Science and Football. Eds: Reilly, T., Lees, A., Davids, K. and Murphy, W.J. London: E & FN Spon. 456-459.

PERRINE, J.J., AND EDGERTON, V.R. (1975) Isokinetic anaerobic ergometry. (Abstr.) Med. Sci. Sports, 7, 78

WEINECK, J. (1992). Optimales Fu balltraining. Teil 1: Konditionstraining des Fussballspielers. Perimed-Spitta

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Physical Training Oct 2008