Sports and Ergonomics Lecture

1. APPLICATION OF ERGONOMICS
IN THE DESIGN OF EQUIPMENT
AND PLAYING SURFACE FOR
RACQUET SPORTS.
PRESENTED BY: VRUNDA R MAKWANA
MODERATED BY : ASHISH JOHN PRABHAKAR

2. INTRODUCTION
• Racket sports have a wide appeal to a large population due to its
unique attributes.
• There are four major racket sports includes tennis, badminton, table
tennis and squash with some other racket sports being played to a
lesser extent.
• The development and increasing popularity of racket sports in recent
years has led to more scientific disciplines involved to understand all
aspects of racket sports.

3. • Sports engineering is a field of engineering that involves the design,
development and testing of sports equipment.
• Consideration of the characteristics of the equipment used in sport is
an important aspect of interfacing the performer with the sporting
environment.
• Racket characteristics have changed markedly in recent years, largely
as a result of the development of new materials
• The modern racket can be made lighter, stronger, stiffer and yield
greater power than the one manufactured 20 years ago.

4. • In this sports, appropriate shoes, clothing and footwear have been
fabricated to promote the safety and efficiency of performance.
• As competition in top-flight sport has grown increasingly intense,
much creativity has been applied by engineers in attempting to launch
new artefacts to be used by the champion performers.

5. BIOMECHANICS CONSIDERATION
• While hitting the ball it generated an angular inertia which is affected
by the mass of an object.
• If you consider the tools used in sports game; you will note that the
heavier the implements are more difficult to start swinging or stop
swinging.
• So, a heavier bat is harder to swing than a lighter bat.

6. • It has already been remarked that the hand can generate higher
velocities than the foot, and this is because of the greater number of
segments involved in the sequential build-up of velocity. With an
implement extended to the arm as an extra segment the velocities
generated are potentially even greater.
• Such high velocity impacts would produce enormous forces and
torques on the musculature of the body if it were not for the mass of
the ball being kept low.
• Thus in golf, squash, racquetball, badminton and tennis (0.06 kg) the
ball mass is considerably lower than in hand or foot sports.

7. • In the case of baseball and cricket, the mass of the ball is higher (0.16
kg) but the striking action is two-handed and the length of the bat is
restricted.
• In games where the ball mass or projectile is extremely light (table
tennis and the shuttlecock in badminton) the forces and torques
generated on the body are considerably reduced, but, as a
consequence, both games are dominated by the aerodynamic forces
acting on the ball when in the air. The performance characteristics in
these cases are a direct result of the materials used for their
manufacture.

8. • The effectiveness of the striking implement depends on its design and
the properties of the materials from which it is constructed as well as
the skill of the user.
• Characteristics of design are initially determined by the general
requirements of the game – for example, in tennis a racquet head of
reasonable dimensions is required in order to make successful hits;
this in turn put limitations on the construction of the racquet head in
order not to make it too heavy for one handed use.

9. EQUIPMENT DESIGNING
TENNIS
• 1] Rackets:
• We have to consider the tennis terminologies
before designing of its rackets like;
A]head size
B] string pattern
C] balance
D]weight
E]stiffness
F]string tension

10. A] head size:
• Head size generally range from 80sq.in to 130 sq. in.
• Centre of percussion , power region , nodal region
• Usually racket head size is in proportional to level of player for
whom the racket is design for. Keyword being usually used for.

11. B] String patterns:
• Within the racket head there are various string patterns are there. In which two
commonest string patterns well take in consideration which are 16*19 and 18*20.
• The few amount of strings in racket equals more spin due to the limited amount of
surface area touching the ball. A more amount of string in racket equals more
control due to the more amount of surface area touching to the ball.

12. C]Weight
• Light weight rackets <10.5 oz.
• Intermediate player typically picks rackets of 10.6 to 11.6 oz.
• Strong =Advanced players 11.5 oz. or more than that rackets.
• Generally , lighter racquets are easier to swing and maneuver, but tend to
provide less stability and control when hitting. As a result, these racquets
can be great options for beginners or players who weigh less and have less
strength.
• On the other hand, heavier racquets will typically provide you with more
control and help reduce vibration or shock when hitting. However, by their
very nature, heavier racquets tend to be more difficult to maneuver and
harder on your wrist and arm.

13. D]Balance:
• The balance of the racket refers
to the where the weight of the
rackets are located.as most of
the weight is found in the head
of the racket it is considered as a
head heavy [harder to swing].
• Conversely this weight is located
over the handle it will consider
as head light [easier to swing].
• Where the racket is perfectly
balanced will considered as even.

14. E] stiffness:
• Like swing weight stiffness is also measure on number scale of 0 to
100.the majority of rackets will fall between in 50 to 80 range. Just
like it that the stiffness is the measure of how stiff the racket is.
• The stiffer the racket the more powerful it is.at the same time is can
potentially it can be less comfortable. Especially if player’s having an
arm issues , should not take stiff racket.
• Rackets with low stiffness will provide control and feel.This type of
rackets make it the great options for precision players.

15. F] string tension:
• String tension is the pressure at which the strings are secured to the
racket’s frame and is performed in either lbs. or kg. Typical tensions
range from around 40-65lbs.
• LOW STRING TENSION
• Stringing your racket at a low tension will give you:
• MORE Power
• MORE SPIN
• LESS Control
• MORE Durability
• MORE FEEL
• MORE COMFORT

16. • HIGH STRING TENSION
• A high string tension would be anything from around 55lbs to 65lbs.
• Generally speaking, between 55lbs and 60lbs would be an excellent
choice of higher tension. This will still give you access to power but
will also supply a lot of control.
• LESS Power
• LESS Spin
• MORE Control
• LESS Durability
• LESS Feel
• LESS Comfort

17. 2] BALL:
• Lift force due to the Magnus effect is responsible for the curved flights of
balls observed in a variety of sports. Backspin will keep a ball aloft longer,
whereas topspin will cause a ball to drop to the ground sooner. Sidespin will
cause a ball to swerve right or left.

18. • Air can be thought of as a fluid, in the sense that it flows like other liquids.
When an object, such as a ball, moves through the air, the air tries to resist
or block the motion of the ball. This resistance is a force known as
aerodynamic drag. If the ball has a smooth surface, there is very little
friction between the surface of the ball and the surrounding air. This is why
smooth balls can travel much faster through the air.
• On the other hand, if a ball has a rough surface, like the nap on a tennis
ball, every fiber on that nap is like a hurdle that air must get through. That
is why air moves more slowly over the nap. This leads to increased friction
between the ball and the air, causing the ball to lose momentum and slow
down. This kind of drag force is known as skin friction drag.

19. • Also, as the ball cuts through air, it is essentially trying to knock the air out
of its way. This creates turbulent swirls of air behind the ball. These swirls
are known as a wake.
• A turbulent wake forms a region of low pressure behind the ball. The larger
the size of the wake, the greater the area of low pressure. The front of the
ball, however, is still experiencing a higher pressure, and this pressure
difference causes the ball to experience ‘drag force’ in the direction opposite
to which it is moving, causing the ball to slow down.
• This drag force arising from the low-pressure region essentially tries to
‘suck’ the ball in. This sucking action curves the trajectory of the ball and
imparts a spin to it.

20. • Tennis balls are made up of rubber and covered with nylon type of material. Tennis
ball changes as playing surfaces changes. Tennis ball is always design for one type of
court.
So there are mainly 3 types of tennis balls are used:
1] Championship
2] Professional
3] Recreational
• Professional balls are used in tournaments like Wimbledon and Australian open.
championship balls are used for local games. recreational balls are used as practice
ball, used in tennis camps and schools.
• Playing tennis in clay courts causes more slides that makes the ball more absorb
more clay. But regular duty ball doesn’t absorb and gives the best shot as they have
tighter weave and less fluff. This ball fluffs a little, that makes ball give better and
faster shot.

21. 3] FOOTWEAR
• Tennis shoes are by far the most important item in a player’s dress. They must be
heelless and it is preferable that they should have a toecap. Sorbo is now a common
type of pad inside the shoe.it is wise as well to have an arch support. This will
support and strength the instep.
• Shoe manufacturers generally designed a full range of predominantly white shoe for
different court surfaces: indoor carpet, clay, grass etc.
• Generally slip proof and hard wearing pair of shoes are suitable for a tennis player
which gives him / her plenty of ankle support, good fit and is specific to the surface
in which the game is playing on.
• Traction is an important criterion for tennis players, and contemporary tennis shoes
are a major advance on the tractional “pumps” with canvas uppers.

22. BIOMECHANICS CONSIDERATION
Player Adaptation and
Manipulation of Tractional
Forces.
Comparing available and
utilized traction yields
important information. Too
much available traction can
lead to joint overloading and
too little can result in
slipping, each of which may
contribute to injury and limit
performance

23. • The classic example of player adaption and manipulation of available
traction is how players slide on clay. Even though clay is softer and
has a lower available friction than hard courts, players experience
higher shear forces on clay because they go into their deceleration
slide at a higher speed and lower angle, knowing that the forces
probably will not become dangerous. In doing so, they utilize more of
the available traction.
• Hard court players do the opposite — they decelerate more by running
through the deceleration with a higher center of mass and with more
knee and ankle bend in order to lessen the joint stresses. The
coefficient of traction for clay courts is typically reported to be about
0.5-0.7 and 0.8-1.2 for acrylic hard courts.

24. SHOES INTERACTTION ON DIFFERENT PLAY
SURFACE
• A change in surface has a greater effect on plantar pressures than a change in shoe.
The higher pressures on a hard court support an association for increased levels of
overuse injuries. On clay, limiting areas of high pressure and a longer braking step
could facilitate sliding by preventing sticking. Unloading episodes could also be part
of the strategy aiming at sliding on clay.
• Theoretically a shoe or surface that grips more will allow higher pressures to be
generated prior to reaching the ‘slipping point’ when grip is lost and the player lose
their footing. By extension when a rotational force is also applied this can lead to
increased torque in the lower limb which may translate to an increased risk of injury
in the lower limb especially when rotation is combined with supination or pronation
of the forefoot.

25. • Some studies exploring the role of the playing surface as an extrinsic factor
have found that artificial turf results in significantly higher torques than
natural grass. Ford et al. comparison of artificial turf and natural grass
established no significant difference in total force time integral between the
two surfaces.
• However, when regional pressures were analyzed they discovered that
synthetic turf produced significantly higher forces in the central forefoot and
lesser toes, while natural grass produced significantly higher forces in the
medial forefoot and lateral midfoot.
• Others suggest that there is an increased risk of overuse injury for players
who switch frequently between playing surfaces compared to those who
train and play on a consistent surface.

26. 4] PLAYING SURFACE
• Tennis was traditionally played on lawns, a fact that contributed to its
formal name (lawn tennis). The game is now played year-round given the
widespread availability of synthetic courts in indoor facilities. Outdoors,
the game is played on clay, synthetic courts, and grass.
• Among the major tennis championships, only the Wimbledon event is now
played on grass and only the French championship is played on clay.
• Changes in surface characteristics cause players to adopt different
strategies, and athletes playing mainly on one type of surface may find it
difficult to play on another.

27. O’Donoghue and Liddle
(1998) compared
performances in women’s
singles on clay and on
grass, finding more points
won on serve and at the net
on grass than on clay and
more baseline rallies on
clay-court competition

28. • Hard courts (H), clay and grass are the most common surfaces on which professional
and leisure tennis is played today.
Grass court
• On grass court, there is less loss of horizontal velocity during the ball rebound since
the COF [Coefficient of friction] of this surface is low. As a consequence, the player
will have less time to get to the ball and prepare their shot than on clay court.
Clay Courts
• Clay court is considered as the slower surface than faster surfaces. This results in a
high and relatively gentle bounce and slows down the ball. On clay, the ball may
pick up bits of clay or moisture and become heavier. This phenomenon slows down
the game more on clay courts because a heavier ball comes off the racket with
slightly lesser speed.
Hard Courts
• H courts, like Rebound Ace in the Australian Open and Deco turf in the US Open,
are usually considered as medium surfaces.

29. • Comparison:
• On clay courts, the friction and coefficient of restitution are higher
than on hard courts, resulting in a high and relatively moderate
bouncing of the ball, which gives the player more time to prepare to
hit the ball than hard surfaces do.
• From a biomechanical point of view, the higher and slower ball bounce
on clay entails a more difficult power production and therefore a lower
ball velocity. On the other hand, the longer time needed to prepare
allows a longer acceleration movement resulting in a faster racket
velocity at the hitting point on clay. In comparison, on carpet, there is
a flatter hitting point and the oncoming ball speed is higher, which
allows a better power production, but the shorter movement leads to a
decrease in racket acceleration.

30. BADMINTON
• 1] Shoe:
• In badminton, lunging is essential and frequently performed,
accounting for approximately 15 per cent of all badminton movements
in a competitive game.
• In competitive badminton game situations, players often performed
powerful and long distance lunges, having larger shoe-ground landing
angle that may result in greater impact force and joint loading than
less extreme lunges.
• During the heel impact phase of a lunge step, the geometry of a
badminton shoe heel may have a great influence to the biomechanical
responses such as loading and movement characteristics of the foot
and knee joints.

31. RECENT EVIDENCE
• An experimental study done by ki-kwang lee in which they have studies 3 pairs of
tests shoe. The pairs of 3 shoes were identical except their heels. They had done heel
modifications.
• In which they have studies the rounded heel[RH], square heel [SH] and regular heel
for the performance of the players.

32. • The rounded heel shoe was associated with longer time from heel contact to
peak vertical ground reaction force that might reduce impact shock. Also, the
increased heel curvature showed less slippery phenomenon, which might be
associated with better traction during initial contact phase. These results
might affect the reduced dorsiflexion moment of ankle joint just after initial
heel contact with the rounded heel shoe compared to the square shape shoe.
Although it was expected that rounded heel shape induced greater shoe sole
angle at heel contact, there was no heel modification effect.
• In conclusion, the rounded heel shoe demonstrated superior impact
attenuation compared to regular and square-type shoes

33. 2]Racket:
• A] Weight:
• The weight of a racket is normally marked
on the shaft with unit ‘gram’.
• It is also marked in another international
format ‘U’:
• U: 95-100g; 2U: 90-94g; 3U: 85-89g; 4U:
80-84g; 5U: 75-79g.
• Suppose all other variables remain same,
the more weight, the more power player
will get. In another words, it is easier to hit
shuttlecocks far with heavier rackets in
condition of all other factors are same.

34. • B] Racket Balance
• The balance of a racket is
measured by a balance board. It
is presented in unit ‘mm’, which
describes the distance between
bottom and the balance point of
a racket.
• Normal range: 280-300mm
• Head heavy: >288mm
• Head light: <288mm
• C] Racket Length
• The length of a modern racket is
675mm.
• There is measurement tells that 5%
more racket length will increase 30%
more hitting area.
• Normal range: 664-680mm
• A long badminton racket: 675mm
• Offensive: 675-680mm
• Defensive: 665-670mm

35. • D] stiffness:
• Stiffness: 8.0: hard
• 8.5: moderate hard
• 9.0: moderate
• 9.5: moderate soft
• Since the duration of a shuttlecock
stays on rackets when smashing is
0.004-0.006 second, it is a must to
make a very stiff frame so that it
recovers as fast as possible right
after every hit.
• E] Shapes of Frames
• There are three shapes of racket
frames in the market, as follow:
• Traditional: 330 cm2 (51 in2)
• ISO: 340 cm2 (53 in2)
• Extra-ISO: 370 cm2 (57 in2)
• The direct influence of racket frame
is to sweet spots.

36. • 3]shuttlecock:
• The shuttle may be made from natural or
synthetic materials. Nylon and feathered
shuttles come in designated speeds.
• The speed of nylon shuttles are usually
designated by the color of the band around the
head of the shuttle. Red indicates fast, blue is
medium, and green is slow.
• The feathered shuttle must have 16 feathers
attached to its base and must weigh between
4.74 and 5.50 grams.
• The weight of the feathered shuttle determines its speed. The lighter shuttle is
designed for play in higher elevations, such as Mexico City.
• The heavier shuttle is for play in hotter, more humid climates nearer sea level.

37. SURFACES
Synthetic surface – PVC/
PU Wooden surface

38. Acrylic surface Cement surface

39. TABLE TENNIS
• The designing of a bats needs
careful consideration as there
are a number of important
factors to take into account.
Basically there are 3 different
types of bats:
• Defensive {slow}
• All round {medium}
• Offensive {fast}

40. • Type of Woods: Defensive , All round and Offensive
• Types of Sponge: Soft and Hard
• Type of Rubber: pimple in and pimple out
• HANDLES:
• A handle should feel comfortable in the player’s hand during a game.
Some people perspire very easily and if the perspiration contacts the
racket handle then the racket could slip out. A dovetail shaped handle
or the use of towel grip on a blade like, will help in solving the
problem.

41. RECENT EVIDENCE

42. SQUASH
• 1] Courts:
• A squash court is much
different as players play in
a closed area in which they
hit the ball off of the walls.
• Squash court surfaces are
typically wood or rubber.
The size of a squash court is
much smaller than a tennis
court. A court’s length is 32
feet long and 21 feet wide.

43. Balls
Shoes
Rackets

44. REFERENCES:
• 1. Adrian Lees (2003) Science and the major racket sports: a review, Journal of
Sports Sciences, 21:9, 707-732.
• 2. Ergonomics in Sport and Physical Activity Enhancing Performance and
Improving Safety.Thomas Reilly Director, Research Institute for Sport and Exercise
Sciences Liverpool John Moores University.
• 3. Magee DJ, Zachazewaski JE, Manske RC. Athletic and sport issues in
musculoskeletal rehabilitation. Elsevier Saunders;2011.
• 4. Youlian Hong. ROUTLEDGE HANDBOOK OF ERGONOMICS IN SPORT AND
EXERCISE.Taylor & Francis; 2014.
• 5. D.J. Stefanyshyn and J.W. Wannop, “Biomechanics research and sport equipment
development,” Sports Engineering 18, 191-202 (2015).
• 6. I.C. Wright, R.R. Neptune, A.J. van ben Bogert, and B.M. Nigg, “Passive
regulation of impact forces in heel-toe running,” Clinical Biomechanics 13, 521-531
(1998).

45. FIN.