1. Power generated by a topspin vs. a slice
Ali Kazmi
April 30, 2012

2. Breaking Down a Shot
Every human motion is driven by the synergistic action of the basic biomechanical unit.
The basic biomechanical unit consists of a pair of mutually antagonistic muscles that produce a common muscular torque in the same joint
In tennis, the most obvious example is the biceps-triceps pair (pictured)
from Ivancevic et al. (2008)
An example of the basic mechanical unit

3. Breaking Down a Shot
The three components of the kinetic chain (nervous, muscular, and skeletal systems) all work together to produce movement.

4. Preparation or “Loading”
Breaking Down a Shot
The standard forehand has two main phases: (i) preparation or “loading,” and (ii) hitting the ball.
Preparation or “Loading”
Includes two simultaneous actions: stepping into the right position with the left leg forward (if right-handed) and lifting the racquet above the shoulders
Muscles involved: right deltoideus and biceps
Hitting the Ball
Includes three main movements:
Right hip rotation towards the ball with feet still on the ground (muscles involved: right gluteus maximus and medius muscles)
Arm swing of the racquet (Muscles involved: right pectoralis major, deltoideus, and biceps)
To create topsin, a slight twist of the wrist to brush over the ball (muscles involved: right palmar flexors)
Not pictured: gluteus maximus

5. Breaking Down a Shot
The topspin is a forehand shot generated hitting the ball with an up-and-forward force that causes the ball to drop.
What is “Topspin”?
“Topspin” refers to the property of a ball that rotates as if rolling in the same direction as its velocity.
Topspin inflicts a downward force that causes the ball to drop due to its interaction with the air (called the Magnus effect
Use in Tennis
Topspin provides the player an increased margin of error because the ball hits the ground quicker, and so can rise higher above the net
The racquet should face below the direction the ball is moving, and brush up against the back of the ball

6. Breaking Down a Shot
The splice is a forehand shot that utilizes “backspin” to cause an upward force that lifts the ball.
What is “Backspin”?
“Backspin” refers to the property of a ball that rotates as if rolling in a direction opposite to its velocity
An upward force is applied to the ball that lifts the ball (also due to the Magnus effect)
Use in Tennis
A splice is useful for defensive shots because the ball takes a longer time to reach the opponent, giving the player more time
Backspin shots also tend to bounce lower when the reach the opposite court.

7. Power Generation in a Topspin Stroke
Power Analysis
Power Generation in a Topspin Stroke
Instantaneous Power = Change in Energy
Initial Kinetic Energy
m= 0.057kg
X-velocity= 0.937m/s
Y-velocity = 0.912m/s
Overall velocity= 1.31m/s
g=10m/s2
h= m
KE= ½*m*v2 =0.050J
PE= mgh= 0.53
Total Energy= 0.58
Final Kinetic Energy
m= 0.057kg
X-velocity= m/s
Y-velocity = 2.517m/s
Overall velocity= 29.08m/s
g=10m/s2
h= .9213m
KE= ½*m*v2= 24.1J
PE=mgh= 0.53J
Total Energy= 24.6J
Power Generated= 24.02W

8. Power Generation in a Slice
Power Analysis
Power Generation in a Slice
Instantaneous Power = Change in Energy
Initial Kinetic Energy
m= 0.057kg
X-velocity= 0.863m/s
Y-velocity = 0.814m/s
Overall velocity= 1.19m/s
g=10m/s2
h= 1.051m
KE= ½*m*v2 =0.040J
PE= mgh= 0.60J
Total Energy= 0.64J
Final Kinetic Energy
m= 0.057kg
X-velocity= m/s
Y-velocity = 2.170m/s
Overall velocity= 24.2m/s
g=10m/s2
h= 1.051m
KE= ½*m*v2= 16.7J
PE=mgh= 0.60J
Total Energy= 17.3J
Power Generated= 16.66W

9. Future Directions
Further detailed analysis of impact rotation kinetic energy changes
Energy transfer measurements
Strategic considerations
Impact of elasticity of strings of racquet
Frequency of usage of different types of shots and success/failure ratios

10. References
Elliott, B. "Biomechanics and Tennis." British Journal of Sports Medicine 40.5 (2006): Print.
Ivancevic, T. “Biomechanical Analysis of Shots and Ball Motion in Tennis and the Analogy with Handball Throws.” Physical Education and Sport 6.1 (2008): Print