Tennis players typically execute strength exercises that involve only one joint as, for example, the ankle in the heel raise, the elbow in the biceps curl, and the knee in the leg extension. They also do a few compound exercises such as the squat and overhead press. But most skills involve more than one joint action either simultaneously or in sequence or both.
Compound exercises such as the squat and bench press serve this purpose but they still lack sufficient involvement of other joints and muscles. Understand that the greater the number of joint actions involved, the greater the neuro-muscular and intra- and inter- muscular coordination needed to execute a skill well.
A good example of this is returning a shot. Execution of this skill may require only arm and shoulder rotation but most often it requires some leg action, hip and shoulder girdle rotation and shoulder and arm actions. Thus many seemingly simple skills require combinations of movements.
Other examples include jumping up and hitting overheads, hitting the ball while on the move, hitting the ball when reversing directions or when running backwards. These movements involve leg actions (which are also needed to get into position) hip, trunk and arm actions. Even a “simple” skill such as leaping up and hitting an overhead requires that you first jump up out of a semi- or quarter-squat and then raise the racket to execute the hit with the arm.
Your court movements and hitting skills can be improved by increasing your strength and coordination with exercises that more closely approximate or duplicate the movements that are involved. This requires doing combinational exercises for tennis, as for example: 2-3 repetitions of the good morning (as in reaching for the ball or preparing to leap), followed by 2-3 repetitions of the squat (for getting low or preparing to leap), followed by 2-3 repetitions of the overhead press (to get the arms overhead).
You can also do 2-3 squats, followed by 2-3 good mornings, followed by 2-3 upright rows or front arm raises. These exercises can be made very specific to the skills being worked on. For example, a combination squat/good morning, followed by an upright row or overhead press and then a heel raise for rising up as high as possible.
To develop speed and quickness, many combinational strength exercises for tennis can be modified for faster execution. For example, instead of using a barbell or dumbbells, use a medicine ball to do combinational strength exercises for tennis such as a few repetitions of the squat followed by a few deadlifts or good mornings and then an underhand throw forward and/or upward. The throw can be executed for height and/or distance.
Another combinational tennis exercise is the jump out of a squat with a simultaneous throw of a medicine ball upward-forward. This is useful in coordinating arm actions with an explosive jump. Even rotational movements can be added to combinational exercises. For example, as you execute the squat, raise the arms up, turn the shoulders 90 degrees to the right or left and then throw a medicine ball.
As you execute combinational tennis exercises, not only does your coordination improve, but you gain greater strength and quickness. However, before doing combinational exercises, you should be proficient in executing the one- and two-joint (individual) exercises. There must be adequate strength (and coordination) developed in each of the separate elements before they are united into a combinational exercise. Only then will you improve technique, perform better and prevent injury.
Understand that many injuries occur because of poor coordination in the transition from one movement (or joint action) to another, not lack of strength. Thus, when you execute combinational tennis exercises, the number of injuries can decrease greatly. Because of this, combinational tennis exercises should be included in your arsenal of exercises for improving your tennis playing.
See Biomechanics and Kinesiology of Exercise for more information on the different exercises. Also see Explosive Tennis: the Forehand and Backhand CD