Technical Model

Technical Model

A technical model uses qualitative information to compare the performances of a literature model to the actions done by the performer. From this, we can identify what the performer is doing well, so these can be highlighted and keep the same, and also to find the weaknesses, which should be worked on to create a whole, fluid, perfect action. By using Kinovea, we can measure the technical aspects of the performance and compare this to the literature model to ensure maximum efficiency and consistency of the particular skill. Opposed to other quantitative methods of analysis, such as notational or numerical, this method is more subjective because it is focusing on opinion and descriptive methods, rather than statistical data. Although this may change from person to person slightly, this is similar to a coach’s environment because every sport coach will be different, and view a skill in slightly different ways. Therefore, this simulates a coaching situation more clearly.

The 4 components I looked at in the technical model were stride length, stride frequency, ball contact point and body position- two of which were strengths, the other two weaknesses.

Her first strength was Stride Length.
Stride Length

During the action of Charlotte’s kick, I measured the stride length of her final step before making contact with the ball, which is one of the most essential because it builds up power. This power however may have been stunted because of the many little steps she made prior to this, which could’ve changed her body position slightly. This leg angle is incredibly important because the pelvic rotation, from a Class 3 lever, allows for a greater range of movement, which provides a larger angle. A larger lever before the contact with the ball will give you a strength advantage, causing a more powerful shot, which may result in a more successful penalty kick. This is because the goalkeeper on the other side of the kick will have a shorter reaction time to respond to the direction of the ball, in order to move and potentially save it. Therefore, the more power and accuracy from the larger lever will impact the team (goal is scored), therefore the game. However, this would be different if Charlotte took less strides, or even none because not enough power is built up behind the shot.

'If the player hits the ball hard enough the goalkeeper has very little chance of saving it,' Professor of Sport and Learning at the University of Wolverhampton Andrew Lane told Mail Online.

This could result in a loss for the team, decreased statistics for the athlete, and may even affect the event results they're in. This could result in being knocked out of the cup, or dropping a place in the league; this could all be a result of one incorrect shot, therefore it is imperative that the technique is sound.

  But, this all depends on the run up to the ball, which according to A. Lees and Nolan (2002) “a larger last step length for two professional players performing a maximal instep kick (0.72 and 0.81 m)” is ideal.

Her last stride was 0.77m, making it right in the middle of the ‘desired’ maximal instep. This allows her to get the correct angle from the hip joint to perform a sharp, accurate shot.

Even though we can see stride length was a weakness, there may still be issues with the approach to the free kick. By conducting further analysis into the approach, we can see that there is a problem with Charlotte's stride frequency; a weakness to the overall motion.

Stride Frequency

As previously mentioned, Charlotte’s run up to the kick had an ideal maximal input step, however the steps previous to this were not preferable. Instead of being confident and taking two or three strides before the ball contact point, she took many more steps, which ultimately stunted her balance and core position, resulting in the ball contact point being incorrect, and the power and accuracy being deterred from the success that the above paragraph just stated.

Looking at the video, we can see that three small strides, barely the length of 30 cm are taken, before two larger strides complete the action. These steps will decrease the power taken because it can not be generated on the approach, which can give the goalkeeper the few milliseconds more that may be necessary for them to react and stop the ball from entering the net, which reduces the success of Charlotte as an individual and for her team.

The frequency of her steps, although may feel comfortable for her approach, may be too many. Kellis & Katis, 2007, Lees, Kershaw, & Moura, 2005 stated that “Players also prefer to use an approach distance that requires them to take a small number (2–4) of steps. An approach of this type generates a modest approach speed of around 3–4 m · s−1.” From this we can see that player’s preferences are to take as few steps as possible, around 2-4. Charlotte took 5 steps, which may be seen as too many, especially as she only travelled 1.68m from her start point to the end of her final stride. By making the strides less frequent, but together worked with the length of the strides, she could go on to develop a perfect approach to the ball before contact point.  This will reserve more energy for other aspects of the game, and will be less effort to provide a better strike on the ball. By reserving energy, she is increasing the chances of their team's success, and an increase in her shot success. This can effect her team positively in a numerous number of ways; these include winning the game, moving up the league, and being a team that others are nervous to encounter. Also, if she has developed the perfect combination of placement and power on the ball (due to the number of strides taken) she will give the goalkeeper a more difficult time at trying to save the ball. This means that she will have less time to react to the ball, and will have to travel a further distance to get to the ball (if Charlotte places it in the corner- the ideal location). By just taking two less strides, she can potentially change a weakness of her into a very strong, efficient positive. 
 However, some steps should still be taken to increase that power, even if they are over the ‘ideal’ amount stated by Kellis & Katis, 2007, Lees, Kershaw, & Moura, 2005.

Opavsky (1988) found that greater ball speeds were achieved (30.8 m.s-1) when a six to eight stride run-up was used compared to a stationary approach (23.5 m.s-1). This supports the fact that a run up approach is important to the flight of the ball.

According to sportsinjurybulliten.com, “At the point of impact 15% of the kinetic energy of the swinging limb is transferred to the ball. The rest is dissipated by the eccentric activity of the hamstring muscle group to slow the limb down”, so the more power created in the approach from the stride length and stride frequency, the more will be transferred into the shot.

Ball contact point

As seen on the above still image, Charlotte made initial contact with the ball on the side, and under the ball, which is important for height and accuracy. As she hit under the ball instead of centrally, the revolutions on the ball is increased, causing the Magnus effect on the ball and it’s flight path. Gustav Magnus (1853) said that as the spinning ball moves through the air, it will create a pressure difference between its two sides, according to the Bernoulli Effect. The interaction between the air layer on the side of the ball that rotates in the opposite direction of the ball movement and the surrounding air creates a low pressure area. This will “suck” the ball and curve its trajectory.

However, when the ball was struck under the ball, it is creating a backspin, which is not ideal. This will make the ball spin backwards, creating a higher pressure on top of the ball and a lower pressure under the ball, which will significantly shorten the distance of it’s flight. To correct this, Charlotte should make contact with the bottom of the ball yet on the side more so that the revolutions aren’t rotating backwards. This will increase the speed of her penalty kick, therefore making it more difficult for the ball to be saved.
If this is done, the power and speed of the ball will be increased, giving the goal keeper less time to react. It will also make the ball much more accurate. This will allow her to place the ball exactly where she wants it to go. "With goalkeepers naturally diving low to the right or left" (Telegraph, Mark Oliver and Steve Wilson, 2012), the preferable placement of the ball will be in the top left or right corners, making the ball as far away from the goalkeepers reach as she can. By contacting the ball at the perfect point, she can make that quick decision and place the bll in one of these areas.

Body Position

Above we see Cristiano Ronaldo, at the time playing for Manchester United, and Wayne Rooney, also playing for the same team, taking a shot at goal. As they are both elite players, both representing their country and other high profiled clubs, they have impeccable technique, and have had access to the highest of support and expertise, such as coaches and biomechanists. As a result, both of their upper bodies and lower bodies are the same, and both displaying the perfect technique to be taking a shot.

The ideal approach to a shot in the upper body is when “The non-kicking side arm is abducted and horizontally extended before support foot contact and then adducts and horizontally flexes to ball contact (Shan & Westerhoff, 2005), presented by both Ronaldo and Rooney.

They then went on to mention that the shoulder angle during  the kick stride should go through horizontal extension of 158°, and abduction to be 36° with the opposite arm, which have also been confirmed as the correct angles for the maximal instep by female participants (Shan, Daniels, Wang, Wutzke, & Lemire, 2005). These results make the data more applicable to Charlotte, a female participant.

Although the front face of Charlotte’s shot can not be seen, the angle of her shoulder is 53°, slightly too large for the recommended angle. This may throw Charlotte’s balance off, and the power from this larger angle may transfer to her upper body rather than her lower body, causing a decrease in speed and accuracy for her shot, maybe affecting the overall result of the game. The accuracy may also be affected because the body is twisting more (as seen by the increase in angle) so her foot may follow through at a skewed angle, directing the shot in a different direction.
Due to this, she may place the ball slightly too wide, or off target in the goal, giving the goalkeeper a much better chance of saving the goal. This may be a fatal mistake in a penalty shoot out, because they only have limited shots. This may cause them to lose the penalty shoot out, therefore the game, which impacts her whole team, more importantly herself, very negatively. They may lose the cup, decrease places in the league table etc.
Also, the goal keeper may be able to read her body position before the game much more- "Skilled goalkeepers apparently spend more time studying the face of the penalty taker and can fixate on the motion of a kicker’s legs moments before he touches the ball." (Daily Mail, 2014). This means she should make subtle movements to not give away where the ball is going because the keeper may be able to detect it, giving her a better chance of saving the ball.