Improving Core Strength in Tennis Players
Donald A. Chu, Ph.D., PT, ATC, CSCS

Everyone is searching for that tennis fitness edge? If you are making progress, but it doesn’t seem to be quickly enough, this article may have some answers for you. It describes plyometric exercises aimed at developing core strength. Trunk strength is the foundation of sports performance. Trunk positioning and stability directly affect all movement. While some weight routines may focus on “mirror” muscles, the exceptional tennis player doesn’t neglect those vital core stabilizers. It is the smart player who develops the ability to connect the top half of their bodies with the lower half.

Plyometric exercises are popular for “shock training” the muscles of the legs to increase vertical jump and power. Some athletes and coaches have extended plyometric training exercises to the upper body. Often neglected in the traditional strength training program is explosive training to develop power in the athlete's trunk. Plyometric exercises are perhaps the best method for just that. Plyometric exercises refer to the training method which exploits the muscles natural cycle of lengthening and shortening to increase power. These exercises start with rapid stretching of the muscle (eccentric contraction) followed by a shortening of the same muscle (concentric contraction). Plyometrics train the nervous system to react quickly to the lengthening of the muscle by rapidly shortening the same muscle with maximum force. This process is called the stretch-shortening cycle and is one of fastest reflexes in the human body.

First, let's define the trunk. The trunk includes the thorax (chest), rib cage, abdomen, spine, and shoulder and pelvic girdle. The trunk acts as a base for all movement. Looking at a physiological cross-section of the muscles that comprise the trunk area, the potential for the development of size is not obvious. These muscles are basically flat and thin in their overall shape and perform very specific functions in human movement. Although these muscles are often overlooked in training, trunk rotation is a primary and absolutely vital movement in tennis. Training the core area improves lumbar stability and increases the speed of trunk rotation, which leads to improved velocity and control of serves and groundstrokes.

Many plyometric trunk exercises utilize only the tennis players own body weight. These are known as “Body Weight Exercises”. Other plyometric exercises may utilize a medicine ball as a form of resistance. The resistance can be altered on an individual basis based on the weight of the ball. Because most medicine balls are relatively light (6-20 pounds), it is allowable to perform a high number of repetitions. Typically 25-30 repetitions per exercise are not unusual in the execution of a single set. A complete workout should last about 20-30 minutes and should be performed 3-4 times per week. One set of 25-30 repetitions are utilized to train strength-endurance. Strength-endurance is a desirable form of strength development for all tennis players. Choose 10-12 exercises and perform each one for one minute. Take a minute rest and repeat the sets. As with all plyometric training, it is necessary to have a substantial strength base and pain free range of motion prior to beginning a program. Remember that plyometric exercises depend on quick movements to be effective and the user must anticipate this and be reasonably fit before integrating these exercises into their training programs.

Plyometric exercises for the trunk may be grouped into three categories: trunk flexor exercises, trunk extensor exercises, and trunk rotation exercises.

Trunk Flexion Exercises
1. “Chinnies”
Start: Begin by assuming a sitting a position in which your upper body is inclined 45 degrees, place the medicine ball directly behind the low back for support, and lift the feet off the ground. This places the abdominal muscles “on stretch” by developing tension in the abdominal muscles prior to initiating movement.
Action: Straighten one leg and bend the other so that your knee comes close to your chest, alternate your legs in such a way that they cycle in and out.

2. “Pullover Crunches”
Start: Lie on your back with your knees bent, and hold the ball over your head at full arm extension.
Action: Bring the ball over your head to your chest while raising your trunk 45 degrees. Lower to the starting position in one fluid motion with the ball and your head touching the floor at the same time.

3. “Alternating Toe Touches”
Start: Lie on your back with your knees bent, and hold the ball over your head at full arm extension.
Action: Bring the ball over your head while raising one knee close to your chest. Raise your trunk to about 45 degrees touching the ball to your knee. Alternate your legs touching the ball to alternate knees as you raise your trunk. This exercise can be performed with a straight leg touching the ball to your toe.

4. “Hip Crunches”
Start: Sit with your back at a 45 degree angle to the floor, brace yourself with your hands behind your hips and hold the ball by squeezing it between your knees.
Action: Lift your feet off the floor and draw your knees toward your chest. You can also do this exercise off the end of a bench so that you can move the ball through a longer range of motion.

5. “Incline Chest Pass”
Start: This exercise requires a partner. Sit with your back at a 45 degree angle to the floor and hold the ball in front of your chest. Your partner can stand on your feet or move back five feet.
Action: Pass the ball back and forth. You should not move from the 45 degree angle during the exercise.

6. “Sit-Up Toss”
Start: This drill also requires a partner. Sit facing your partner two to three feet apart with your knees slightly bent.
Action: Your partner throws you the ball using a chest pass or overhead pass. Upon receiving the ball, quickly lower your torso to the ground. Then sit up and make a chest pass or overhead pass to your partner, who repeats the action.

7. “Throw Downs”
Start: This drill requires a partner. Lie on your back on the floor with your legs extended. Your partner stands facing you with one foot on either side of your head so that you can hold onto his or her ankles.
Action: As you raise your legs up to your partner's hands, he or she pushes them down forcefully. You should provide resistance to your partner, catching your legs before they reach the ground and returning them to the raised position. Your partner can push your legs in a variety of directions, ranging from straight forward to more lateral directions. Remember to keep the low back flat and pressed against the ground by contracting the lower abdominal muscles.

Trunk Extension Exercises
1. “Sitting Toe Touch”
Start: Sit on the floor with your legs extended in front of you holding the ball in both hand over your head.
Action: Keeping your arms straight, reach down with the ball and touch your toes. Return to the starting position. This action can also be performed while sitting in a “V” (legs apart in a “V”) sit position and alternating touching each toe.

2. “Bridging”
Start: Lie on your back, knees bent, arms out to your side for balance and place both feet on the ball.
Action: Lift your buttocks off the floor while squeezing your gluteal muscles. Hold the position up for a count of five or do five one inch bounces while in this position. This exercise can also be performed using a single leg balance on the ball.

3. “Superman Toss”
Start: This drill requires a partner. Lie on your stomach facing your partner, extending your torso backward so that your arms and legs are suspended and not touching the ground. There should be two feet of space between you with your arms fully extended.
Action: Keeping your arms and legs suspended, pass the ball to your partner from about chin level. Continue passing the ball 10-15 times.

4. “Reverse Hyperextension”
Start: This exercise requires a table with a level surface. Begin by lying on your stomach with your legs hanging off the end of the table. Grip the sides of the table firmly.
Action: Raise your legs, holding them straight until they are just above parallel to the floor. Lower your legs quickly and repeat the action.

5. “Rotation with Extension”
Start: This exercise is performed by starting in a “V” sit position with the medicine ball held behind the head.
Action: Rotate the trunk and drop your elbow on the right side to the left knee. Return to the sitting position by reversing the direction of movement. Alternate the right and left elbows and accelerate the return to the starting position.

6. “Backwards Toss”
Start: This drill can be performed using a partner or by throwing the ball against a solid wall. Hold the ball in front of you while standing.
Action: Drop into a squat position with the ball between the legs, reverse the squat and accelerate upward so that you throw the ball over your head to your partner or at the wall. Be careful to bend your knees, bend from your hips and keep your back straight throughout the motion.

7. “Over and Under”
Start: This drill requires a partner. Stand back to back with your partner with 18 inches between you. One person holds the ball over their head with both hands.
Action: Lower the ball between your legs and hand to your partner while bending over. Stand upright to take the ball with both hands and repeat the action for the prescribed number of repetitions.

Trunk Rotation Exercises
1. “Trunk Rotations”
Start: Sit with your legs extended out in front of you, holding the ball.
Action: Rotate your torso to the right and place the ball behind your back. Rotate your torso left and pick it up. Repeat in the other direction. This exercise can also be done with a partner. Sit back to back, twist and pass the ball in a circle. Increasing the distance between you and your partner requires more twisting of your upper body.

2. “Hip Rolls”
Start: Lie on your back with your knees at 90 degrees and hold the ball by squeezing it between your knees. Extend arms out to the sides for balance.
Action: Rotate your hips from left to right allowing your knees to lightly touch the floor on each side. A variation of this exercise is obtained by sitting with your back at 45 degrees and to the floor while you rotate your hips.

3. “Russian Twist”
Start: Sit with your back at a 45 degree angle to the floor, knees bent and together, and feet apart for balance.
Action: While holding the ball out in front of you with your arms fully extended, rotate your upper body and move the ball from side to side.

4. “Side Toss”
Start: This exercise requires a partner. Holding the ball on your right side, stand with your feet shoulder width apart.
Action: Swing the ball to your right and then forcefully reverse directions to your left and release it. You may toss the ball to a partner or throw it against a solid wall.

5. “Double Pump Toss”
Start: This exercise requires a partner or a solid wall. Stand so that you are facing in opposite directions of your partner.
Action: Perform as a motion similar to the Side Toss. However, this time you rotate to both sides (rotate over and back) prior to releasing the ball on the throw. Repeat the exercise on both sides.

6. “Wall Push-Off”
Start: Stand with your feet shoulder width apart and your back two feet from a wall.
Action: Without moving your feet, rotate your upper body to the right until you are able to reach the wall with your hands. Attempt to rotate so that your body is as close to parallel as possible. Push off the wall and twist your upper body left all the way around to reach the wall. Push off and repeat.

7. “Side-lying Leg Lifts”
Start: This exercise requires a Swiss ball or table. Begin by lying on your side with your legs hanging off the end of Swiss ball or table. Be sure to find something to grip to stabilize your upper body.
Action: Raise your legs until they are just above parallel to the floor. Let your legs fall towards the ground catching them right before they would hit the ground and snap them upwards to the starting position. Repeat the action. Do this on both sides.

Plyometric exercises can be performed in conjunction with resistance weight training to develop strength and power. An example of this is alternating sets of cable curls with pullover crunches or sit-up throws. Another is side bending with dumbbells intermixed with side throws or side-lying leg lifts. The combination of both resistance and plyometric exercise is a concept known has “complex training” and is very effective to bring the tennis player to a higher level of performance. Whether you are swinging a racket or just focusing on the weight room, plyometric training of your trunk will enhance lumbar stability, increase your core strength and power and give you that extra edge!

(Before beginning any exercise program consult with your physician.)

1. Chu, D.A., Plyometric Exercises with the Medicine Ball” 2nd Edition, Bittersweet Publishing 2003
2. Ebben, W.P. and Watts, P.B. A Review of Combined Weight Training and Plyometric Training Modes: Complex Training. Strength and Conditioning. 18-26. Oct. 1998.
3. O'Connor, D.P. Application of Plyometrics to the Trunk. Athletic Therapy Today.


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