Christopher Johnston

Tennis Serve Analysis

Introduction

I started playing tennis in high school. I tried out for the varsity team with no

experience and as expected, I did not make the cut to play in any actual games. This did

not make me lose my hopes of learning the sport and I have continued to play ever since.

Over my last three semesters in college I have taken tennis for my required sports classes.

I have continued to play tennis outside of class and can now play at a rather average level

consistently. My ambitions for this activity are to make it a lifelong sport that I participate

in. I plan on playing for the rest of my life whether it is recreationally or competitively.

Skill wise I hope to be able to improve all aspects of my game. I currently have been

working on my serve so I thought that this project would be the perfect opportunity to

help with the learning process. My long term skill goals are to be able to play the game

with all different styles; whether it is a strong forehand game, strong serve, or the ability

to make the opponent run around the court. In order to perfect the different aspects of

the game I need to hone in on many aspects of the game.

A powerful shot can blow the opponent out of the water, but accuracy is the key

to winning a match when it comes to tennis. It doesn’t matter if your shot is powerful if

you can’t place a shot in the court or away from your opponent. A well placed drop shot

can leave your opponent stunned with nowhere to go. The major force that determines if

a shot is a top spin shot or the previously mention drop shot, is lift force. Due to the

magnus effect a top spin shot will drop faster and a backspin shot will make the ball be in

the air for a longer time. These two spin shots are a key to success when facing an

opponent in tennis

Prepatory Phase

For my prepatory phase I think that the shoulder, shoulder girdle, elbow and radio

– ulnar, knee, and hip joint are the most important. Without strength and mobility in the

shoulder girdle the prepatory phase would be almost nonexistent and a powerful serve

cannot be had. Extension at the elbow and radio-ulnar join is crucial during the prepatory

phase because it readies the player to extend their elbow to hit the ball during the

propulsive phase. Knee and hip join flexion are important because it preps the player for

triple extension during the propulsion phase. The following table shows the joints,

actions, and muscles used in the prepatory phase.

Table 1. Joints, actions, and muscles used during the prepatory phase of the tennis serve

Propulsion Phase

The most important joints in the propulsion phase are the same as the prepatory

phase: shoulder, shoulder girdle, elbow and radio – ulnar, knee, and hip joint. The same

joints are being used but they are doing completely opposite actions than in the

prepatory phase. Thanks to the prepatory phase, these joints primed to extend and hit the

ball with great speed. The more mobile the shoulder girdle and shoulder joint are the

better extension at contact can be had which would increase the speed at which the

Prepatory Phase

Joints Action Muscles

Shoulder Joint Extension Deltoid, Posterior | Pectoralis major, sternal | Latissimus dorsi | Teres major | Triceps, long head

Shoulder girdle Downward rotation and Retraction Pectoralis minor | Rhomboid | Trapezius II,III,IV

Elbow/radio-ulnar joint Flexion Biceps brachii | Brachialis | Brachioradialis | Pronator teres

Knee joint Flexion Semitendinosus | Semimembranosus | Biceps femoris | Sartorius | Gracilis | Gastrocnemius

Hip Joint Flexion Iliopsoas | Sartorius | Rectus Femoris | Pectineus | Tensor fasciae latae

projectile is hit. The transverse movement in the shoulder and shoulder girdle is seen in

more skilled players.The radio-ulnar join extension is needed in order to increase the

extension at contact of the projectile. The triple extension used to generate power during

the propulsive phase includes the knee, hip, and ankle joint. The ankle joint was not

included because I believe that the other joints are more important during this phase.

The following table shows the joints, actions, and muscles used in the propulsion phase.

Table 2. Joints, actions, and muscles used during the propulsion phase of the tennis serve

Post-Propulsion Phase

The post propulsion phase is important because it allows the player do get ready

for the next shot if they execute it well. When I serve I tend to rotate my whole body to

the left. My right leg swings over the left. Unfortunately this is not the best form because

I may cross my feet up and trip on them. The joints I chose for this phase are the

shoulder, shoulder girdle, thoracic and lumbar spine, ankle, and hip. I chose the shoulder

girdle and shoulder because a follow through must be executed in order to not put too

much eccentric muscle strain on the shoulder. The thoracic and lumbar spine and the hip

must move almost simultaneously in order to reduce stress between the two systems. If

the ankle does not dorsiflex on landing then the server will land on their toes and have a

small base of support which could cause them to fall. The following table shows the

joints, actions, and muscles used in the post-propulsive phase.

Propulsive Phase

Joints Action Muscles

Shoulder Joint Transverse Adduction Deltoid Anterior | Pectoralis Major Clavicular | Pectoralis major, sternal | Coracobrachialis | Biceps, short head

Shoulder Girdle Protraction Pectoralis Minor | Serratus Anterior

Elbow/radio-ulnar joint Extension Triceps brachii | Anconeus

Knee Joint Extension Rectus Femoris | Vastus group

Hip Joint Extension Gluteus maximus | Biceps femoris | Semitendinosus | Semimembranosus

Figure 3. Joints, actions, and muscles used during the post-propulsion phase of the tennis

serve

Important Muscles

Some of the primary muscles used during these three phases are the deltoid

anterior, biceps femoris, tibialis anterior, semitendinosus, and the triceps brachii. I chose

these muscles because a lot of them are used in multiple actions.

The semitendinosus is used at the hip joint during medial rotation and extension,

and at the knee joint during extension. To improve functional strength in the

semitendinosus, medial rotation and extension exercises must be done. One exercise that

can be done for both extensions at the hip at the knee join is a standard squat. The squat

is a perfect exercise for a tennis player because it mimics both the prepatory phase and

propulsion phase. The squat should be done at a low weight and high volume in order to

be specific to the needs of a tennis player. The tennis player is moving their legs fast in a

match so there is no need to max out weight while performing squatting. The low amount

of weight and high amount of reps will be sport specific for the tennis player. There is

going to be a little amount of weight on the bar which means that the repetitions are

going to be high. Safety concerns come into play with a high amount of repetitions

because form can break down. If the athlete’s form breaks down and he/she cannot safely

Post Propulsive Phase

Joints Action Muscles

Shoulder Joint Transverse Adduction Deltoid Anterior | Pectoralis Major Clavicular | Pectoralis major, sternal | Coracobrachialis | Biceps, short head

Shoulder Girdle Protraction Pectoralis Minor | Serratus Anterior

Thoracic and Lumbar Spine Rot. to L. R. External Oblique | L. Internal Oblique | L. Erector Spinae

Ankle Joint Dorsiflexion Tibialis anterior | Extensor digitorum longus | Peroneus tertius

Hip Joint Medial Rot. Tensor fasciae latae | Gluteus Maximus |Semitendinosus | Semimembranosus | Gracilis

perform a free weight squat then I think it would be a good idea to make them use a

squat machine. An exercise that could be used for semitendinosus medial rotation is a

static band hold. The athlete would lie on their stomach with a band around their ankles,

flex their knees, and then medially rotate their hips and hold it. This exercise is rather

safe because they can control the resistance and it is easy to release the tension once the

exercise is over. To improve the functional length of the semitendinosus I would tell my

athlete to foam roll. Foam rolling is easy because it can be done on the ground. Another

reason I think foam rolling would be a good idea is because when foam rolling it is easy to

not contract the hamstring while the athlete is doing it. I believe that when doing a

stretch such as a hip hinge it is easy for the athlete to contract their hamstring. The

muscle that is being stretched should not be contracted.

The next muscle I chose is the biceps femoris because of its involvement in knee

flexion in the prepatory phase and hip extension in the propulsive phase. The squat is also

good for strengthening the biceps femoris. Light weight and high reps should be used

when performing the squat because tennis is not a maximal effort sport. If form starts to

break down then the athlete should use a squat machine in order to be safe and not hurt

themselves. A good exercise to lengthen the biceps femoris is to foam roll it.

The last muscle in the legs that I chose is the tibialis anterior because it is needed

to land properly in the post-propulsion phase. The tibialis anterior is activated during

dorsiflexion. One exercise that can be done to strengthen it is to sit down on a chair and

just dorsiflex the ankle. This should be done with minimal to no weight due to the natural

strength of the tibialis anterior being weak. The only safety concern I have is that athletes

sometimes feel the need to use a lot of weight when doing an exercise. It would be easy to

overload the tibialis anterior and injure it due to in not being a strong muscle. A good

way to stretch the tibialis anterior would be to foam roll it. The athlete could place their

shins on the foam roller and then sit on their ankles and then roll out the tender spots.

I talked a lot about the squat for all three muscles because I think that it is the best

exercise for all three. The serve is essentially a squat so the best way to improve this

movement is to do it over and over again. This is the meaning behind sports specific

training. I mentioned foam rolling a lot because I think it is one of the safest stretch

lengthening exercises for the legs. It does not require the athlete to curve their spine in

order to stretch their legs like a hang stretch would. This allows people with immobile

spins to stretch their hamstring. Foam rolling also allows the athlete to pin point tender

spots and apply pressure to them in order for pain relief.

The first muscle in the upper body that I think is important is the triceps brachii.

The triceps brachii is activated when the elbow and radio-ulnar joint extends. This is

important when the athlete is trying to hit the ball at its apex during the serve. A good

exercise to increase triceps brachii strength is tricep extension. This would be done with

low weight and at a fast speed in order to develop power. In theory this power should

transfer to the serve since it is a sports specific exercise. In order to perform the exercise

safely the athlete needs to makes sure the weight is far enough away from their head so

they do no accidentally hit it on their way down or on the way up. If the user is unable to

do this exercise safely with free weights then they could do tricep extension exercises with

cables. A good lengthening exercise for the tricep is to put it behind your head by placing

the same side hand on the same side scapula and hold this position for sixty seconds.

One of the most important muscles for the tennis serve is the deltoid anterior. It is

involved in the transverse adduction of the arm during the propulsion and post-

propulsion phase. A good exercise for increasing deltoid anterior strength is a cable cross

over. The athlete stands next to the cable machine, grips it at about elbow height, and

then pulls it across their body. This would be at a light weight and high reps in order to

replicate the intensity of a tennis serve. I can see no danger in doing this exercise besides

adding too much weight to the machine which could result in a shoulder injury. A good

lengthening stretch for deltoid anterior would be to cross the shoulder over the arm and

hold it. This would be a good way to static stretch the deltoid anterior.

POSSUM Scale

The tennis serve is light and fast so I am going to want a large back swing and my

swing should be sequential. The effort of intensity is maximum so I am going to want to

increase my number of segments, increase my transverse action, increase compactness,

have a large extension at contact, and have max speed and rage of motion. I will want to

be rather mobile during the serve so my line of gravity will be outside of my base of

support. I want the ball to go in a downward path which means I want to hit it at an angle

below the horizon. I have a power serve so I am going to want to have maximum

translation by hitting the ball through the center of gravity.

Quantitative Assessment

My first qualitative assessment was hip height during the start of the start of the

prepatory, end of the prepatory/start of the propulsion phase, and end of the propulsion

phase. I used hip height to relatively judge my waist center of gravity to my shank and

thigh center of gravity. In general, the close these three centers of gravities are to each

other the more compact I am. I included the prepatory phase because compactness

during this phase determines the amount of extension at the hips and knee joints during

the propulsive phase. Between the start of the prep and the end of the prepatory phase I

squatted down 4.86 inches. From the beginning of the propulsive phase I rose 10.58

inches. These calculations can be seen in figures 1 through 4. I believe that if I was more

compact during the prepatory phase it would all me to extend more during the propulsive

phase and hit the ball at a greater speed.

My next qualitative assessment was taken at the end of the propulsion phase. I

assessed the angle my elbow was at during contact in order to determine the extent of my

extension at release. I determined that my elbow was at a 160 degree angle when it came

in contact with the ball. During this assessment I also noticed that more forearm was out

of line with my spine because I was reaching out in order to make contact with the ball.

This qualitative assessment can been seen in figure 4.

The last qualitative assessment I took was the path of projection. In order to do

this I translated the location of the ball at the start of the post-propulsive phase onto the

picture at the end of the propulsion phase. I found that my path of projection was at

about 6 degrees below the horizon. I believe that this serve is the only one that made it

on to the other side of the court. My other shots had a greater angle which made it hit the

net and not go over. This qualitative assessment can be seen in figures 4-5.

Core Concept Performance

One core concept I feel that I have almost perfected with the tennis serve is the

number if segments. I am using my ankles, knees, and hips to explode out of the squat

position and up towards the ball, while almost simultaneously I am extending my

shoulder and elbow to make contact with the ball. I believe that this core concept is

advanced enough that an expert level me would not be able to tweak anything without

further evaluation. However, my nature of these segments could use a little work. My

trunk and shoulder do go through the transverse plane but not to the extent that they

should. I believe that an expert version of me would finish with the racquet across the

body instead of the same said that it started at. Naturally my spine would follow this

shoulder rotation because it is influence by shoulder girdle rotation; this would cause my

trunk to have more transverse rotation.

The next core concept I want to address is extension at contact. A tennis serve is a

max intensity effort so my extension at contact should be as long as possible. My

extension at contact was not as long as it could be because when I throw the ball out too

far in front of me it forces me to reach out for it. Since I have to translate my arm forward

I am not able to extend it vertically as much as needed. An expert version of me would

throw the ball closer to myself so I would not have to reach out for the ball and I could

have max extension at contact.

Compactness during the prepatory phase is essential because it allows for fast

movement up toward the ball during the propulsion phase. At the start of my propulsion

phase my knee angle is rather large which means I am not compact so I will have

decreased speed towards the ball. I believe that an expert version of me would be more

compact and squat lower during the prepatory phase in order to allow them to be faster

at the start of the propulsive phase.

The purpose of the serve is to have the ball’s initial path to be downward. The

tricky part here is that the angle cannot be too sharp or else the ball will hit the net. The

path of the ball that I hit was six degrees. I believe that this angle is decent but nowhere

near an expert level. I believe I was able to have a successful serve with such a small angle

because I hit the ball too late and it was rather low when I struck it. I believe that an

expert version of me would hit the ball with a higher degree below the horizontal. They

would hit the ball when it is higher in the air which would allow them to make a

successful serve with the increased angle.

Approach to Improvement

My approach to improvement would be to address compactness. I would first

address compactness because I believe that it has a large effect on other core concepts as

well. Currently I am not compact enough during my serve and I do not get that low in the

prepatory phase. I believe that being more compact and increasing my speed during the

start of propulsion phase will make my nature of segments more transverse. The high

speed at which im starting the serve will force my trunk and shoulder to move through

the transverse plane in order to slow them down without too much eccentric muscle

strain. A good sports specific exercise to prescribe to this athlete would be to toss the ball

up while getting into a compact squat position and then stop the exercise there. This

exercise would be repeated until the athlete is comfortable with getting into a compact

position during the prepatory phase. Once the athlete is comfortable with the first phase

of the serve then they can spring back up an actually hit the ball.

Modification of movement

The easiest modification that I could make is to throw the ball closer to me during

the prepatory phase. This would make it so I have less horizontal translation when hitting

the ball. I would not have to extend my arm forward as much and I can have more vertical

extension of my arm at time of contact with the ball. My prepatory phase needs to be

more compact in order for me to generate more speed at the start of the propulsive phase.

This greater speed will lead to a more transverse movement which is essential for speed. I

believe that I need to work on my shoulder mobility so I can have a greater range of

motion throughout the whole movement and it will also make it easier for me to have a

long extension at contact. If my changes work I will practice doing “perfect” form on a

consistent basis. Once you get form down that does not mean the work stops. The next

step is to be consistent and gain strength so form does not break down over time in a

game.

Commercial for Myself

I didn’t have perfect attendance but I did only miss one day of lecture and I still

find that rather impressive. I often came to open lab hours to not only get help with

assignments but on a couple occasions I came to talk about career options within

biomechanics and outside of biomechanics. When I first saw that I had to take

biomechanics I had no interest in it and was nervous about taking it because I heard it

was hard. I’m glad that I took it and actively participated in this class. This class had made

me question my daily activities and I even sometimes evaluate others. Just the other day I

informed my roommates that if they have to do the walking test with a cop that they

should do it fast in order to have better balance. This class has allowed me to explore an

area of interest that I thought never existed and I think that is what college is all about.

Figure 1. Start of Prepatory Phase

Figure 2. End of Prepatory Phase

Figure 3. Start of Figure 3. EnPPropulsive Phase

Figure 4. End of Propulsive Phase

Figure 5. Start of Post-Propulsive Phase

Figure 6. End of Post-Propulsive Phase