1. Contents page
Signed word length and plagiarism declaration
List of tables and illustrative materials
Acknowledgements
Abstract
Introduction
Methods
Results
Discussion
References
Appendix

2. Plagiarism and Word Length Declaration
A copy of this form MUST be bound into the front of both copies of your project
DECLARATIONS ABOUT WORD LENGTH AND PLAGIARISM
WORD LENGTH
There is a maximum word length of 8000 words for the project, not including the Contents
page, Reference Section, Appendices, or any Tables, including titles, in your Results section.
Please note that 8000 (+10%) words is the maximum allowed, but this should in no way be
interpreted to mean that less than 8000 is undesirable. On the contrary we would encourage
you to be as succinct and economical as possible in your use of words, in order to achieve
clarity of expression. You must also e-mail an electronic copy of your project, plus your
SPSS data file, to your supervisor so that word length can be checked.
Take great care not to exceed this word length. The penalty for doing so will be a mark of
zero (0%).
WORD LENGTH DECLARATION:
I have checked the word length of this project, excluding the Reference Section, the
Appendices, and the Tables in the Results section and I declare that the word length does not
exceed 8000 (+10%).
I declare that the word length is __________ words (please state word count)
Signature:___________________________
PLAGIARISM:
Take great care not to plagiarise the work of another when writing your report. The penalties
are severe. Please sign the statement given below with regard to the work which you are
submitting. Please read it carefully before you sign.
PLAGIARISM DECLARATION:
“Apart from the contributions of my supervisor, the empirical work and its analysis
reported here were conducted entirely by myself. If there are occasions when I have
used the words of others I have acknowledged them by the use of quotation marks, and
I have cited the source; otherwise, the text of the report is written in my own words”.
Signature: ________________________________________________
Date: _____________________________________________________

3. List of tables and illustrative materials
Table 1 shows Approximate Gauge diameters
Table 2 – Incoming velocity, rebound speed and coefficient of restitution of soft string
Table 4 – Incoming velocity, rebound speed and coefficient of restitution of hard string
Table 5 – Descriptive statistics for soft, durable and hard strings, showing the mean incoming
velocity, rebound velocity and COR
Table 3 – Incoming velocity, rebound speed and coefficient of restitution of durable string
Table 6 – Tests of Between – Subjects Effects for incoming velocity, rebound velocity and
COR
Table 7 – Results from shots made by participant 1 in meters per second (M/S)
Table 8 – Results from shots made by participant 2 in meters per second (M/S)
Table 9 – Results from shots made by participant 1 in meters per second (M/S)
Table 10 – Results from shots made by participant 1 in meters per second (M/S)
Table 11 Comments made by participant 1 on the three different strings
Table 12 Comments made by participant 2 on the three different strings
Table 13 – Descriptive statistics for both participants for soft, durable and hard strings,
showing the mean rebound velocity
Table 14 – Tests of Between – Subjects Effects for both participant’s forehand and backhand
Figure 1 – Soft strings (Basic Nylon)
Figure 2 – Durable strings Yonex (Poly Tour Pro 130)
Figure 3 – Hard strings (Babolat RMB Blast)
Figure 4 – Prince Rebel racket
Figure 5 – Experiment set-up showing the position of the ball machine, the clamped racket
and the high speed camera. The red arrowed lines show the direction the ball travelled from
the ball machine, and the blue lines show the rebound velocity
Figure 6 – Direction of ball flight
Figure 7 – 500mm x 500mm calibration frame
Figure 8 – Racket when clamped

4. Figure 9 – Racket clamped at 90º
Figure 10 – Experiment set-up showing the position of the ball machine, the investigator and
the participant
Figure 11 – Shows both participants hitting Forehands
Figure 12 – Shows both participants hitting Backhands
Figure 13 – Soft string, ball 1 – Images from six frames from the high speed camera.
Figure 14 – Soft string, ball 2 – Images from six frames from the high speed camera
Figure 15 – Soft string, ball 3 – Images from six frames from the high speed camera
Figure 16 – Durable string, ball 1 – Images from six frames from the high speed camera
Figure 17 – Durable string, ball 2 – Images from six frames from the high speed camera
Figure 18 – Durable string, ball 3 – Images from six frames from the high speed camera
Figure 19 – Hard string, ball 1 – Images from six frames from the high speed camera
Figure 20 – Hard string, ball 2 – Images from six frames from the high speed camera
Figure 21 – Hard string, ball 3 – Images from six frames from the high speed camera
Acknowledgements
I have to acknowledge the two lecturers that helped me with my testing and analysing of the
results. My two participants for willing to be a part of my in investigation. Finally the
employees of Hit n Run sports for the string.

6. Introduction
Abstract
The main aims of this study were to determine whether there were major differences in
different string types from rebound velocity and coefficient of restitution (COR) during
laboratory and on court testing. Using three identical Prince EXO3 Rebel 95 rackets, tennis
balls were fired on separate occasions from a ball machine towards both stationary clamped
rackets, and participants, who attempted to hit shots down the line. The investigator recorded
the static testing using a high speed camera, with the speed of shots for the on court testing
recorded by radar gun. It was found that the soft string provided greater rebound velocity and
COR than the durable and hard string. It was also found that averagely soft strings provided
greater rebound velocity than the durable and hard strings for participant 1 forehand, and
participant 2 forehands and backhands. The findings were in line with previous research and
current information by tennis companies that softer strings provide more rebound velocity
than harder strings, due to their ability to elasticate more. It was concluded that the soft string
provided the most rebound velocity and COR in the laboratory. It also provided the greatest
rebound velocity from the on court test in forehands, and half the backhands, but the durable
strings were the preferred choice for both participants.
Key words: tennis, string, rebound velocity, coefficient or restitution.
‘The strings in a tennis racquet perform a number of functions. Their principle purpose is to
absorb the kinetic energy from the relative ball racquet velocity, turn it into potential energy,
and then give the energy back to the ball in the form of an outgoing ball velocity or kinetic
energy’ (Brody et al 2002). Tennis strings are a fundamental part of the game, especially if a
player wants to be successful in the sport. Selecting the right string is in many ways as
important as choosing the tennis racket itself. Like the tennis racket, selecting the right string
for you shouldn’t be determined by what the professional’s use, which are expensive and are
prone to breakage early on. ‘Up to about 1990 most professional players preferred natural gut
because they liked its feel and performance’ (Cross and Lindsey 2005). As the name suggests
natural gut comes from a natural product (e.g. cow/sheep intestines), however it is the most
expensive type of sting on the market, is prone to breakage and is not good when the strings
are wet. ‘For the last 40, plus years, most string types were made to mimic the characteristics
of natural gut, which is elastic, and power oriented’ (Amersports). For many years natural gut
string has been the bench mark for manufacturers, the principle aim was to provide the same
positive attributes as natural gut, e.g. power and feel, but without the negative factors, e.g.
lack of durability and high price. As a fellow tennis re-stringer, I am constantly asked by
fellow players, ‘what string should I put into my racket?’ With my answer being, ‘would you

7. like you tennis strokes to deliver more power, control or feel?’ Once the customer has
selected what they want in their game, the next dilemma is the price. This is almost the
pivotal factor in a player’s selection, if it’s over what they want to pay, and then they’ll
choose a cheaper string that can deliver their desired game. Which as a tennis re-stringer is a
shame as a tennis player should choose a string which is right for them, rather than letting the
price determine their final choice. Apart from the experience of tennis re-stringers, there is
not much information that tennis players can use, except for other players experiences. ‘For
example, players describe strings as having a `crisper' feel than old strings and they describe
old strings as being dead or lifeless or lacking the power of new strings’ (Cross 2000). There
are also tennis magazines, ‘the only guide to the properties of strings, apart from play test
reports in popular magazines and some early test results by Calder et al’ (Cross et al 2000).
Finally there is the manufacturer’s description which is usually always 10/10 and therefore
unreliable as this is a biased point of view. Or players can use strings which is currently the
string most used my professionals, ‘In recent times, most professionals have switched to
polyester strings. However the string used by most players is nylon string (Cross and Lindsey
2005). As there is a lot to think about for tennis players when selecting their next string for
their racket, an easy and simple way to decide is what you want your game to consist more
of, whether it’s more power (soft strings) or control (hard strings), or if that isn’t an issue to
the player, select a string that is robust (durable). ‘Hard strings will return a little less energy
to outgoing ball velocity. ‘Whereas soft strings will provide a little more power, but strings
that are too loose will dissipate energy’ (Brody et al 2002). Re-stringers can find out whether
a string is harder or softer from a gauge code, ‘the thickness of a string (its diameter) is
specified by a gauge number, where a higher gauge number means thinner string. The better
playing string (control, comfort, power) is usually the string which is thinnest, so it may
break sooner. If breaking strings is a problem, then a thicker string will often be
advantageous’ (Brody et al 2002). The thicker the stings mean that they’ll give you more
control and durability. The thinner the stings will give you more power, spin and do less
damage to the players elbow due the string stretching more than the thicker stings. This is
another important factor to players when selecting their next re-string is what damage could
occur to their elbow. This is especially key to the older tennis player who will be thinking of
limiting the damage as much as possible. So choosing a thinner/softer string will be a better
option which will elongate more than a harder string.

8. Table 1 shows Approximate Gauge diameters
Another way of how strings are determined to be softer or harder is a term known as the
modulus of elasticity. ‘All strings are elastic, they stretch, and absorbing energy, then return it
to the ball. Some string requires more force to elongate a certain amount. The ratio of the
incremental force required to increase the string length, a certain percentage is called the
modulus of elasticity. The smaller this number, the softer they play’ (Brody et al 2002).
Strings on a tennis racket can be compared to a trampoline, with the person bouncing on the
trampoline as a tennis ball bouncing off a racket. If the material on the trampoline is
firmer/harder than the person will bounce off at a lower and more controlled rate than if the
trampoline was more elastic which would elongate more. This is the same as the strings on a
tennis racket, if the strings are harder than the ball will travel at a more controlled rate than
softer strings which will elongate more. ‘Steel string (Kevlar) have a very high modulus of
elasticity, and even though they give back essentially all the energy they absorb, they hardly
stretch at all when impacted by a tennis ball. Nylon and gut have a low modulus of elasticity,
so they deform when a ball impacts and they play well.’ (Brody et al 2002). In order to find
out how strings that are soft, durable and hard compare against each other, and relate them
back to recreational and competitive tennis players, they would have to be tested in both a
laboratory and on the tennis court. Cross et al 2000 looked into testing 90 different tennis
strings in a laboratory; the aim was to compare the different strings from a controlled
environment. Lindsey 2011 performed an experiment that involved five different strings,
three of which were different types of string, gut, polyester and nylon. With one polyester (1
hour) and nylon string (1 month) strung at longer times than the others. Studying the
information from the two papers as well as my personal experience as a re-stringer, the types
of string selected for the investigation would be nylon, and two types of polyester strings.
‘Experiments were conducted to compare the spin generated by 16 different tennis strings,
using both clamped and hand held racquets. The ball was incident with backspin at speeds
around 23 m/s (51 mph), at an angle of incidence of 40º away from the normal’ (Rod Cross
2010). The study conducted by Cross et al 2000 showed how testing the strings from both a
controlled environment and on court play were beneficial as they were tested more
thoroughly than it would have been if they were tested in just the laboratory. To find out how
Gauge Diameter
15 1.43 mm
15L 1.38 mm
16 1.32 mm
16L 1.28 mm
17 1.25 mm
17L 1.20 mm
18 1.10 mm

9. best to analyse the data, previous studies that had been conducted on strings and identical
rackets. ‘The primary aim of this study was to determine whether variations in rebound speed
and accuracy of a tennis ball could be detected during game-simulated conditions when using
three rackets strung with three string tensions’ (String tension effects on tennis ball rebound
speed and accuracy during playing conditions) (Knudson 1993). He had also looked into the
rebound accuracy of tennis impacts was studied by measuring the vertical angles of approach
and rebound of tennis balls projected in a vertical plane at a clamped racket. Three identical
oversized tennis rackets were strung with nylon at 200, 267, and 334 N of tension. Ten
impacts were filmed at 200 Hz for each string tension with the ball impacting the strings
centrally and 8 cm off-centre (Knudson 1993). The first study to examine stringing and
rebound accuracy in tennis reported that string type, string tension, and the interaction
between the two have significant effects on ball rebound accuracy for midsized tennis rackets
(Knudson, 1993). The link between string material and tension is very strong from the
evidence of previous research. However different strings will perform differently under
different tensions, so selecting the string is more important initially. If players want to get
more accuracy on their shots they will need a high tension, so therefore a thicker string will
be beneficial as it won’t elasticate as much as thinner stings, and vice versa if you want
greater power then players would select a thinner sting with a lower tension. Going with the
power vs accuracy debate, it is important to illustrate what racket players these days are
using. ‘Frame technology has gone in a direction of power, so adding the softer strings only
serves to increase the home run average, which is not desirable for a tennis player. The poly
allows/ forces the player to swing a bit faster to get the ball deep in the court, and the lack of
string movement (at contact of the ball) provides a more predictable flight pattern off of the
string bed’ (Info@tennisnuts.com). ‘All other types of string move, and stick, at impact of the
ball, requiring the player to re-parallel the strings prior to the next point. If you think about it;
that is a considerable amount of energy lost, that could have been devoted to launching the
ball off the string bed in a more predictable manner. The lack of string movement also
enhances string life (less friction), and along with the other traits discussed, are the
favourable aspects of this string type’ (Info@tennisnuts.com). After examining the papers
which had looked at different strings and how their results were analysed. The way in which
this study would be conducted would be through a laboratory, where the environment would
be controlled; this is where the rackets were clamped. As one of the aims of this study is to
relate the findings to tennis players from recreational to competitive levels, a player based
test was also conducted, where the rackets where held and hit by university players. From the
information gathered from previous papers on this topic, the method of analysing the
laboratory data will be through the coefficient of restitution (COR) from the images produced
by the high speed camera. With the results from the on court test recorded by a radar gun and
player comments. The purpose of this study was to examine the effects of sort, durable and
hard strings on rebound velocity and COR in the laboratory, and rebound velocity on male
tennis players. It was hypothesized that softer strings would produce the greatest rebound
velocity as they are able to stretch further than the other strings. It was also hypothesized that
the hard string would provide the smallest rebound velocity as they are unable to stretch as
far. Another aim of the investigation was to see what the three different strings were like to

10. the two participating tennis players from the University of Central Lancashire, to find out
their personal opinion on each string.
Method
Tennis rackets
Three Prince Rebel 95 graphite rackets (tour/professional) were strung with three different
string types, deemed to be soft, durable and hard. All three rackets were strung at the same
tension of 55lbs, the middle of the manufactures range of between 50-60lbs so that it
wouldn’t favour a particular type of string. The strings were identifiable by the researcher as
it had been strung by the same person and so no marker was needed on the rackets to identify
them.
Prince Rebel 95 specifications
 Length 27 inches
 Head size 95 square inches
 Weight 349 grams
 String patter 18 mains / 20 mains
Mechanical test
A high speed camera, a Lobster ball machine and head radical tennis balls were used in the
experiment. The investigator controlled the ball machine to make sure the tennis balls were
released smoothly and were hitting the target area on the rackets, while an observer operated
the high speed camera and recorded the impact of the tennis balls. As no participants were
needed for this experiment no one had to be briefed prior the procedure and no Par Q or
informed consent forms had to be filled.
Figure 1 – Soft strings
(Basic Nylon)
Figure 2 – Durable strings
Yonex (Poly Tour Pro 130)
Figure 3 – Hard strings
(Babolat RMB Blast)
Figure 4 – Prince Rebel racket

11. Figure 5 – Experiment set-up showing the position of the ball machine, the clamped racket
and the high speed camera. The red arrowed lines show the direction the ball travelled from
the ball machine, and the blue lines show the rebound velocity.
Before beginning the official procedure, a test racket (Prince Rebel 95) was used; this was to
position the ball machine in the correct manor so when it came testing the three actual
rackets, there would be no mistakes. For the actual recorded testing a 500mm x 500mm
calibration frame was used before proceeding.
A total of three tennis balls were released from the machine towards the centre of each racket,
firstly beginning with the soft, then durable and finally hard string. Each impact was recorded
using the high speed camera at 500 Hz, and then analysed using the Human Movement of
Analysis software to measure the coefficient of restitution (COR).
Racket
Ball MachineClamp
High speed camera
Laptop
Figure 6 – Direction of ball flight
Figure 7 – 500mm x 500mm
calibration frame
Figure 8 – Racket when clamped Figure 9 – Racket clamped at 90º

12. Player based test
Participants
Two experienced university competitive tennis players (both males) agreed to the study. All
players read the protocol brief and signed an informed consent form and par-Q form.
Protocol
Permission was granted to use the indoor tennis facilities with the use of ball machine and
radar gun. The equipment was set up prior the participant’s arrival and was tested by the
investigator and observer so that no time was wasted during testing.
Target area for
forehand strokes
Target area for
backhand strokes
Ball Machine
Figure 10 – Experiment set-up
showing the position of the ball
machine, the investigator and
the participant.
Position of
investigator whilst
holding the radar gun
Participant

13. The Participants hit a total of ten balls, five for each stroke, forehand and backhand. The
groundstroke’s were hit down the line to the back target are of the singles court. The method
of analysing the speed would be from the radar gun, with the reviews of each string given by
the participant’s comments.
Figure 11 – Shows both participants hitting Forehands
Figure 12 – Shows both participants hitting Backhands

14. Results
Participant
1
Forehand
Shot
number 1 2 3 4 5 Average
Speed
M/S M/S M/S M/S M/S M/S
Soft
22.8 22.8 22.8 21.4 21 22.16
Durable
21 21 24.1 23.2 20.6 21.98
Hard
18.8 18.8 21.4 21.9 21.4 20.46
Participant
2
Forehand
Shot
number 1 2 3 4 5 Average
Speed
M/S M/S M/S M/S M/S M/S
Durable
15.2 19.7 19.2 24.1 -- 19.55
Hard 26.4 22.8 20.6 16.9 -- 21.68
Soft
28.6 23.2 19.2 20.6 21.9 22.76
Table 7 – Results from shots made by participant 1 in meters per second (M/S)
Table 8 – Results from shots made by participant 2 in meters per second (M/S)

15. Participant
1
Backhand
Shot
number 1 2 3 4 5 Average
Speed
M/S M/S M/S M/S M/S M/S
Soft
20.1 23.2 17.8 17.4 19.2 19.54
Durable
17.8 24.1 20.5 19.6 25.4 21.48
Hard
16.9 15.6 21 19.6 17.4 18.1
Participant
2
Backhand
Shot
number 1 2 3 4 5 Average
Speed
M/S M/S M/S M/S M/S M/S
Durable
21.1 23.2 26.8 24.5 18.3 22.78
Hard
14.7 21 23.2 24.5 15.6 19.8
Soft
22.7 29.9 22.3 22.3 21.4 23.72
Table 9 – Results from shots made by participant 1 in meters per second (M/S)
Table 10 – Results from shots made by participant 1 in meters per second (M/S)

16. String type Comment on string
Soft This racket felt the nicest when you hit the ball, but the end product
wasn’t the best.
Durable Best strings, all shots were hit well, good power and control at the same
time.
Hard Didn’t feel too good and definitely lacking in power.
String type Comment on string
Durable I felt that this string was good to hit with, offering plenty of give when
you hit the ball.
Hard Overall the racket felt rather stiff but offered a fair amount of power.
Soft I felt that the string in this racket preferred the most amount of power,
but were quite loose and lacked control.
Table 11 Comments made by participant 1 on the three different strings
Table 12 Comments made by participant 2 on the three different strings

17. Descriptive Statistics
String Mean Std. Deviation N
Player Soft 1.50 .527 10
Durable 1.50 .527 10
Hard 1.50 .527 10
Total 1.50 .509 30
Forehand Soft 22.430 2.4998 10
Durable 18.810 7.1167 10
Hard 18.900 7.1265 10
Total 20.047 6.0298 30
Backhand Soft 21.630 3.5553 10
Durable 22.130 3.1034 10
Hard 18.950 3.4125 10
Total 20.903 3.5415 30
Table 13 – Descriptive statistics for both participants for soft, durable and hard
strings, showing the mean rebound velocity

18. Discussion
The aims of the study were to find out the differences between three different types of strings.
The aims from the laboratory testing were to find out the differences in rebound velocity and
the coefficient of restitution (COR). The aims of the on court test was to find out again the
rebound velocity, but also to find out what the tennis participants thought of each of the three
strings after they had used each of them. It was hypothesised that the soft string would
provide the greater rebound velocity and COR as the strings was able to stretch farther than
the durable and hard strings. It was also hypothesised that the hard strings would provide the
least COR as the strings are designed to hold their tension better than the other two strings.
As durable strings are meant to provide a good mixture of control and feel, the theory was
that this string would be in the middle. As its main selling point to tennis players is durability,
we would have expected the string to last the longest, however as time was a limiting factor
in the investigation, this factor was not included. Previous studies and current tennis
companies have stated that softer strings provide tennis payers with greater power at the
expense of accuracy to their shots, whereas hard strings provide the opposite, with greater
ball control with less power. Researched gathered from Broody et al (2002) said that ‘hard
strings will return a little less energy to outgoing ball, with soft strings providing a little more
power’. Broody goes on to say that ‘high strings with a low modulus of elasticity will play
softer, such as nylon string. They deform when a ball impacts and they play well’. According
to the research from Broody et al (2002), they say that the better playing string (control,
comfort, power) is usually the string which is thinnest, so it may break sooner. Now that is
more opinion than fact, that thinner/softer strings can provide the three main points (control,
comfort, power) to a tennis player, which is why a on court test was conducted, to show some
real opinions to information from previous research. An email received from one of the
largest tennis companies in Europe (tennis-warehouse) had said that ‘frame technology has
gone in the direction of power, so adding the softer strings only serves to increase the home
run advantage’. So this could mean that softer stings could provide more of a power option to
players, or that the need for durability and control will be of even greater importance as the
racket will flex more.
‘The best string to use in a tennis racket is the one that the player likes best, but many of the
top professional players prefer natural gut. Gut is a highly elastic string and it maintains
tension better than most other strings’ (Lindsey and Andruczyk (2000). Natural gut is the
bench mark for other strings, which out of the soft, durable and hard strings provided the
results and satisfaction for participants. The results from the laboratory test show that the soft
strings produced this highest rebound velocity with an average of 8.156 M/S and COR with
an average of 0.413. The hard strings came second with an average of 8.013 M/S and COR
0.396. With the durable strings providing the least rebound velocity, with an average of 7.87
M/S and COR 0.386. The equation used to work out the COR was by dividing the incoming
velocity by the rebound velocity using the Human Movement of Analysis Software.

19. Where V is rebound velocity, U is incoming velocity, and Cr is coefficient of restitution.
As the clamp was not moved from its secured position throughout the testing, the contact
from the ball towards the centre of the rackets was very accurate. Tables 2, 3 and 4 show a
summary of the results for incoming velocity, rebound velocity and COR for each of the three
individual balls. Individual results do vary, however once averaged out, it shows that the soft
strings rebound the ball more than the durable and hard strings. The images from figure 13 –
21 show six shots from the high speed camera of the impact of the ball on the three rackets
for three shots. Even though it is not possible to see clearly how fast the ball is travelling
towards the racket, or how much the racket moves once the ball has struck the racket. It is
clear from the videos from the high speed camera that the racket with the soft strings was
wobbling more than the rackets that had durable and hard strings. The rate of which the
strings rebound are different under altering speeds, if a string is travelling at 10 M/S; it is
going to rebound far less than at 20 M/S. This is not surprising, but the faster the ball travels
through the air, the more the strings will elongate more. This is means that there will be a
greater difference between the three stings when it comes to rebound velocity. Cross et al
2000 found out that between impacts there is a slow recovery of tension in most strings. This
effect can be seen for the polyester string. Given that a decrease in tension can be explained
by the breaking of molecular bonds, then an increase in tension is presumably due to the
formation of new bonds. Cross et al 2000 also found the effect of a series of 10 hammer
impacts on string tension. The tension rises during each impact by an amount that depends on
the elasticity of the string. The decrease in tension after each impact therefore depends on the
previous history of the string, and it also depends on the magnitude of the impact. As basic
nylon is the string that represented the soft category, it produced more rebound velocity than
the two polyester strings. However the results only show three balls contacting the racket, so
we don’t know if nylon would have continued producing greater rebound velocity after 300
impacts plus. However Cross et al 2000 found that nylon string was tested with 200 impacts.
Despite a significant loss in tension after 200 impacts, the energy loss in the string during
each impact remained negligible, indicating no loss in resilience. So from their research we
could estimate that the softer nylon strings would have continued to produce more rebound
velocity and COR than the two polyester strings.
Before on court testing of each racket, the investigator chose the racket that they would be
using, beginning with soft, then durable and finally hard string for participant 1. With
Participant 2 starting with durable, then hard and ending with soft strings. This was in the
same order for both their forehands and backhands. Table’s 7 (participant 1) and 8
(participant) shows their forehands, giving the individual speed for the shots, and averaging
them out. Averagely the soft string produced greater rebound velocity for both participants
forehand. Table 7 shows the soft string producing 21.16 M/S, which is only 0.18 M/S more
than durable, but a more significant 1.7 M/S than the hard string. Table 8 shows that

20. averagely, the soft string is producing 22.76 M/S, which is 1.8 M/S more than hard string, but
a significant 3.21 M/S more than the durable string. Table’s 9 (participant 1) and 10
(participant 2) shows their backhands, giving the individual speed for the shots, and
averaging them out. Table 9 shows averagely that this time the durable string produced the
most rebound velocity with 21.48 M/S, which is 1.94 M/S more than the soft string, and a
significant 3.38 M/S more than the hard string. Table 10 shows that once again the soft string
was averagely producing the greatest rebound velocity with 23.72 M/S, which is only 0.94
M/S more than durable, but a notable 3.92 M/S more than durable. From the results, the soft
string was producing far greater rebound velocity in 3 of the four tables. Bower and Cross
2005 showed that a ‘repeated-measures ANOVA revealed significant differences (F = 20.7,
d.f. = 39, P50.05) in rebound velocity for varying string tensions. The effect size was large
(0.35), indicating that string tension is an important factor in determining rebound velocity’.
Participant 1 and 2 commented that the soft string lacked accuracy. They both agreed that the
durable string was their preferred choice as it offered them plenty of power and control.
Participant 1 comments that the hard string was definitely lacking in power and didn’t feel
good. Whereas participant 2 said that the hard string was rather stiff but offered a fair amount
of power. The results from the player based test obviously varied depending on the type of
player. Participant 1 is more of a controlled baseline player, who hits the ball very flat, so the
advice for these types of players would be to go for thinner/softer stings which provide that
extra bit of power they require. With participant 2 using a, very different style of play, with
far greater spin and aggression, so a firmer/harder string would be more beneficial.
Participant 1 did not prefer the hard string, which does not offer him the power he needed,
and therefore would not be beneficial to his game. Participant 2 said that the soft strings
lacked control, this given his aggressively spin generated game was not surprising, so the
advice to him would be to go for more durable/harder strings which can offer the control they
need.
It is clear from the results gathered from the investigation that the soft strings gave the
greatest rebound velocity and COR in the laboratory test. This has implications on the
players, as using a string which has a higher rebound velocity will result in more power but
less control, and vice versa if payers are using a string which has a lower rebound velocity.
The softer string also produced the highest rebound velocity for participant 1 forehands and
participant 2 forehands and backhands. The results are not surprising given that previous
research and current manufactures state that softer strings will elongate more than durable
and harder strings, which will give players greater power but with less ball control. The
limitations of the results from the investigation stretch to both laboratory and on court testing.
The issue early on was that only one type of racket (Prince EXO3 rebel 95) was used for the
whole study. Now the racket used was a thin framed, heavy racket, which has a low power
level. As all the strings were using the same model of racket it made the testing consistent,
however to make it fair for all three strings, a greater variety of rackets with larger head sizes
and lighter frames would have made the investigation fairer. Also only one string from each
type (soft, durable, hard) were used, again to make the results more credible more strings
could have been used. These limitations were down to a lack of money and equipment
availability. Only three balls were used to analyse the rebound velocity and COR in the
laboratory testing, and ten for the payer based test (5 forehands, 5 backhands). The players

21. and on-court environment was enabled to provide conditions for a training session, which
was important in providing results and comments that would be beneficial to other tennis
players. However the use of a ball machine used would not simulate exact training conditions
which could be used in match play.
Improvements
What could be done differently next time if the investigation was to be repeated would be to
use a greater variety or both rackets and strings that would give a much fairer set of results.
Also the amount of impacts recorded would be far greater as it would test the strings rebound
velocity from an early to a longer stage. Finally with on court testing, there should be more
shots hit by the participants, again to tell how well the strings would cope from a later stage,
but also as it would give the participants more shots and would therefore make the results
more reliable. The investigation could have done with some match play as this would have
shown how each string coped from training session to match play.
References
Bower, R and Cross, R. (2005). String tension effects on tennis ball rebound speed and
accuracy during playing conditions. Journal of Sports Sciences. P 1-6.
Brody, H. Cross, R and Crawford, L. (2002). The physics and technology of tennis. USRSA.
P 239-326.
Cross, R. (2000). Flexible beam analysis of the effects of string and frame stiffness on
racquet performance. Blackwell Sciences. P 111-122.
Cross, R. (2000). Effects of friction between the ball and the strings in tennis. Blackwell
Sciences. P 85-97.
Cross, R and Lindsey, C. (2005). Technical tennis. Racquets, strings, balls, courts, spin, and
bounce. Racquet Tech Publishing. P 59-86.
Cross, R and Lindsey, C. (2010). Which Tennis Strings Generate the Most spin? Tennis
Warehouse University.

22. Cross, R. Lindsey, C and Andruczyk, D. (2000). Laboratory testing of tennis strings.
Blackwell Sciences. P 219-230.
Haake, S.J and Coe, A.O. (2000). Tennis Science & Technology. Blackwell Sciences. P 119-
127.
Knudson, D. (1993). Effect of Tennis String Tension and Impact Location on Ball Rebound
Accuracy in Tennis Static Impacts. Journal of Applied Biomechanics. P 143-148.
Knudson, D. (2006). Biomechanical principles of tennis technique. Racquet Tech Publishing.
P34-37.
Lindsey, C. (2011). String Lubrication &Movement in Spin. Tennis Warehouse University.
Miller, S. (2003). Tennis Science & Technology 2. International Tennis Federation. P 17-31.
Miller, S and Davies, J.C. (2007). Tennis Science & Technology 3. International Tennis
Federation. P 1-21.
Pluim, B and Safran, M. (2004). From breakpoint to advantage. USRSA. P 29.
Customer.serviceuk@amersports.com
Info@tennisnuts.com
Info@tennis-warehouse.com
http://www.tennisnuts.com/shop/tennis/strings-stringing-machines.html