Introduction
The tennis serve is an important aspect in the game as it is the start
of all points, and provides the opportunity to gain a tactical advantage over
an opponent. When analysing the tennis serve from a biomechanical perspective
there are a range of factors that influence both the speed at which the ball is
served and also how accurate that serve is. If the tennis serve is viewed as a
tactical advantage it would make sense that the higher the speed of the ball,
the harder it is for an opponent to return, however this is also determined by
position in which it is served. This blog will discuss the biomechanics behind
speed and accuracy in the tennis serve and determine what this means for a tennis
player in relation to the first and second serve. For the purposes of this blog, a research question has been formulated and will provide a base in which knowledge can start to be constructed in relation to the tennis serve.
What biomechanical factors influence speed and accuracy in the tennis serve?
Hypothesis:
Speed will have a correlation with the
accuracy of serve. The greater the speed the less accurate the serve will
become.
Aim:
This experiment aims to compare the
speeds of a tennis serve and discover the relationship this has with accuracy.
The rules of tennis stipulate that a player can have two attempts at the serve,
therefore creating a tactical dilemma for the player; this experiment will seek
to understand the relationship between speed and accuracy and provide the basis
for further biomechanical discussion.
Method:
Ten balls were served, both at a high
pace (a first serve equivalent), and ten at a slower pace (a second serve
equivalent). Video footage was taken so that speed could be calculated. A
points system where the serves box was dived up into different sections was
used to gauge how accurate the serve was, as can be seen in diagram 1.1. All
serves were served from the same court position and were serve “flat” (without
any spin), this allowed for a controlled experiment. Limiting factors were the
variability in compression of balls, difference in technique between serves and
environmental factors such as wind.
diagram 1.1
Results:
fast
serve
|
||
speed
(m/S)
|
accuracy
|
|
24.24
|
1
|
|
25.75
|
3
|
|
28.78
|
0
|
|
30.3
|
1
|
|
28.78
|
5
|
|
33.33
|
2
|
|
28.78
|
0
|
|
33.33
|
4
|
|
30.3
|
5
|
|
34.8
|
0
|
|
average/
total
|
29.839
|
21
|
Slow
Serve
|
||
speed
(m/S)
|
accuracy
|
|
22.72
|
5
|
|
24.24
|
2
|
|
18.18
|
4
|
|
21.21
|
3
|
|
16.66
|
4
|
|
21.21
|
1
|
|
19.69
|
5
|
|
15.15
|
5
|
|
22.72
|
3
|
|
25.75
|
0
|
|
average/total
|
20.753
|
32
|
Discussion and analysis of
biomechanical factors
As seen in the results, there is a notable difference in the average
speed of serve, and also accuracy. It is clear that there is a correlation
between speed and accuracy, as the serve becomes slower the accuracy is
increased. In a professional tennis game this difference is also notable
and is a tactical focus of many players. There is generally an aim to produce
maximum speed from the first serve, and if unsuccessful the speed is reduced to
produce a more accurate second serve. There are a range of biomechanical
factors which influence an individual’s ability to produce a successful serve,
some of which are:
·
Coefficient
of restitution
·
Newton’s
second law (f=ma)
·
Newton’s
third law , Action –Reaction
·
The throw
like movement pattern and the summation of forces
·
Projection
angle
·
Forward
momentum
·
Lever
length/ grip
Newtons second law states that “the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object: (F = ma). When looking at the speed of the tennis serve, the speed that the ball travels is determined by the force placed on the ball at the time of impact with the racquet. Put simply the harder the ball is hit, the greater the acceleration. The force is also determined on the mass of the object, however in tennis; the mass of the object remains a constant and does not vary.
An efficient tennis serve is different than most projectile motions in that it will usually have no vertical motion, it does not travel up before coming down as it is hit in a downward angle from a high point. Because once again a tactical advantage is trying to be gained over an opponent, minimal air time and the quicker the ball bounces, the greater the advantage for the server. This biomechanical factor has an influence over both how quickly the ball reaches an opponent and also where the ball bounces on the court. Diagram 1.2 demonstrates the tactical advantage of downward projectile angle and a higher contact point. Obviously there are other factors such as spin and kick which also influence the serve direction and impact on an opponents ability to return the serve.
Having identified that racquet speed is a crucial aspect when transferring speed into the ball, there is the need to look at how this is achieved. In other word how the body moves in preparation for the point of impact. The tennis serve is a throw like movement pattern which means that the body moves in a sequence to produce and overall action. For example, the tennis serve movement pattern begins in the feet and legs while simultaneously the arms are preparing and then in succession these different movements come together to produce a summation of forces or a full tennis serve action. This succession or movement pattern allows for momentum to be transferred through different segments in the body which then finally results in a high speed at the point of impact with the tennis ball (De Subijana & Navarro, 2010). Although everybody has different techniques and there is no one prescribed “textbook” technique, this basic pattern is the basis of the tennis serve.
Newtons third law also applies to the upward force
generated by the feet and legs, and states that “for every action, there is an
equal and opposite reaction.” Through the feet and legs force is applied into
the ground while the ground provides a resistance. The equal and opposite
reaction results in an upward motion, this enables a higher contact point with
the ball which has beneficial links with projection angle. Depending on
individual technique the upward reaction is often coupled with a slight forward
reaction which is the start of forward momentum. An effective serve requires a
transfer of linear and angular momentum through the body, this stems from
Newton’s law of action reaction (Groppel,1992 as cited in Bahamonde,
2010). The actions and movements of the body react to provide to
create linear and also angular momentum.
As well as looking at the body it is important to
consider the impact the tennis racquet has on the production of speed. Looking
at the throw like movement again, the racquet can be viewed as another segment
in the sequence that produces high speeds. This being the last segment in the
summation of forces, the speed at which the racquet is travelling is directly
linked with the speed of the ball (Blazevich, 2010). In saying this, where the
racquet is held also affects the speed how fast the racquet is travelling and
time of contact. Put simply, the longer the lever, or the further down the
handle the racquet is held, the greater the speed produced. The racquet could
be viewed as the last link in a chain, when a chain is whipped the end of the
chain will be travelling at a higher velocity than the end closest to the hand.
The same principle is applied in the tennis serve, the further from the hand,
the greater the velocity when the ball is struck.
From viewing the video footage it can be seen that there are notable differences between serving technique. In video one while the serving technique was exaggerated to be non effective, it highlights some key areas that contribute to speed and accuracy in the serve. Firstly there is a clear difference in the summation of forces within the serves. In video one there is little evidence of summation or a throw like movement pattern and consists mainly of just arm movements, this therefore limiting the amount of speed generated and transfer of speed into the ball. Another difference was in the length of the lever and the height at which the ball is struck, in the second video it can be seen that the ball is struck at the highest point and makes full use of the momentum travelling through the different segments. Once again this action and throw like movement creates a greater racquet speed and energy transferred into the ball, thus achieving a greater serve speed. The YouTube links also provides an example of what an effective serve should look and provides a further comparison of two athlete who have different serving techniques but still achieve success. While the two techniques look quite different, there are still the obvious biomechanical factors which were looked at previously.
How else can we use this information?
The biomechanics involved with the tennis serve can be applied to many
different physical actions. The basic principles provide an understanding in
which to analyse an athlete’s performance and then make improvements. The
principles relating specifically to the tennis serve have links with various
different actions, for example throwing, kicking and other sports that use
implements such as bats and racquets. Biomechanical principles all interact
with each other to produce an overall action that is technically sound and
efficient, therefore when teaching or coaching it is important to consider the
biomechanical aspects and how this impacts on performance. In this case, what
are biomechanical principles that influence speed and accuracy in the tennis
serve.
Conclusion
In conclusion, it is clear that there is a strong correlation between
speed and accuracy, however there is a range of biomechanical factors which
influence the tennis serve. Through research of the tennis serve and
biomechanical factors it is clear that these different factors all interact and
rely on each other to produce a high speed serve. In answer to the original research question, there is a multitude of biomechanical factors that influence speed and accuracy, as can be seen in the discussion section. From comparison of both
higher speed serves and lower speed serves it can be assumed that the tactical
focus when serving should be an “all out” approach for the first serve and if
unsuccessful a more conservative second serve that focuses on accuracy. A
highly proficient tennis player would have little biomechanical differences
between the first and second serve, except the serving action would be slower.
Reference list
Blazevich, A.J. (2010), Sports Biomechanics:
The Basics, Optimising Human Performance, A&C
Black Publishers, 2nd edition.
De Subijana, C.L. & Navarro, E.
(2010), Kinetic
energy transfer during the tennis serve, Biology
of Sport, 27(4), p.279.
Groppel, 1992 as cited in
Bahamonde, R. E. (2010), Changes in angular
momentum during the tennis serve, Journal
of Sport Science, 18(8), pp. 579-592.
Web Resources
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