What is kinetic chain and why is it so important for efficient serving in tennis??!!
Optimal performance during the serve involves co-ordinated motion between leg, trunk, shoulder girdle and upper limb which, in summation provide for the force generation needed to hit the ball with maximal efficiency. This force system is called as the kinetic chain.
The lower extremities and core provide a stable base and are responsible for the maximum amount of force generation. The scapula acts as a funnel for force transmission and serves as a fulcrum for stability throughout the rapid arm sequence.
Uncoupling at any time during the serve cycle initiates compensatory mechanics and increased load on the remaining segments, predisposing to injury and impaired performance.
SICK scapula
S – Scapular mal-position
I – Inferior medial border prominence
C – Coracoid pain and mal-position
K – Scapular dyskinesis during movement
SICK scapula syndrome is a consequence of scapular dyskinesis (i.e. abnormal voluntary movement) caused by overuse fatigue muscles. There is scapular asymmetry when observed at rest and while throwing/serving; there is difficulty in scapular movement.
To recognise the compensatory mechanism throughout the kinetic/force chain, observation of following key checkpoints (aka nodes) is required:
| Checkpoints | Proper position |
| Foot position | Back foot behind the lead foot |
| Knee motion | Adequate knee flexion in cocking followed by extension at ball impact |
| Hip motion | Counter rotation away from the court in cocking phase |
| Trunk motion | Counter rotation away from the court in cocking phase |
| Scapular position and motion and Shoulder motion | The scapula and subsequently the shoulder act as a funnel for force regulation to allow the upper extremity to transmit energy through the racket with long axis rotation during the follow-through phase |
| Shoulder over shoulder and long axis rotation | A coupled scapular retraction/arm rotation with proper technique allows the player to achieve cocking in the scapular plane with a back leg to front leg motion to create a “shoulder over shoulder” motion at ball impact and long axis rotation into ball impact/follow-through. |
CONDITIONING PROGRAM TO IMPROVE SERVICE VELOCITY
The program is approximately 60-70min in duration, performed 3 times a week for 6 weeks.
Each training consists of 10min of warm ups and 50min of strength training (combining core, elastic tubing and medicine ball exercises)
Warm ups – arm circles in multiple directions, side stretch to the right and left, forearm supination and pronation, and wrist flexion and extension
The next 10-15 min consisted of basic core training exercises (i.e., crunches, reverse crunches, oblique crunches, plank, side – plank). Two sets of 20 repetitions for the first three exercises, and two sets of 20 s for the last two exercises.
The subsequent 25 minutes of the program consists of using elastic tubing for nine upper extremity strength exercises.
Exercises are performed for 2 sets of 20 repetitions, with 45 s rest between exercises, and included the following: (a) triceps (elbow extension); (b) rowing; (c) external rotation with shoulder flexed 90°; (d) external rotation with shoulder abducted 90°; (e) shoulder abduction to 90°; (f) diagonal pattern flexion; (g) reverse throw; (h) standard forward throw; and (i) wrist flexion-extension. Each exercise is performed in a 3-s repetition (1 s for the concentric phase and 2 s for the eccentric phase).
The next 20 minutes consisted of a medicine ball-throw (e.g., 2 kg) training program consisted of seven exercises, which were performed for two sets of 8 repetitions (i.e., each side if the exercise was performed with just one arm), with ~1 min rest between exercises, including the following: (a) Chest pass; (b) Overhead throw; (c) Ear throw; (d) Squat to thrust; (e) Overhead slam; (f) diagonal wood-chop; and (g) close-stance throw.
Cool down – bilateral quadriceps stretch, hamstring stretch, and trunk twists. Unilateral (racket side) stretches are performed for the latissimus dorsi, pectoralis major, triceps brachii, wrist flexors, and shoulder (i.e., sleeper stretch & horizontal adduction cross-body stretch). Stretches are held just ‘‘before the point of discomfort’’ with approximately 10 s between repetitions.
During the tennis serve, rotation of the trunk is an integral part of the development of power and transfer of energy up to the kinetic chain from the lower to upper extremities.
Due to the importance of the tennis serve, as the most powerful and potentially dominant shot in tennis, these strength-focused training interventions, especially in developmental players, can be helpful to increase performance levels.
GROUNDSTROKE
The groundstroke is a forehand and backhand which is typically hit standing a few feet behind the baseline and is the most commonly associated shot in tennis.
Backhand and forehand tennis strokes, along with movements on the tennis court, incorporate use of the core and the transfer of energy from the ground up throughout the kinetic chain. A weak core could be detrimental to the performance of an athlete if not addressed in their workout program. Stabilization of core muscles, as well as power production throughout these muscles; need to be trained to improve groundstroke performance.
Backhand and forehand strokes, along with movements on tennis court, incorporate use of core and transfer of energy from the ground up throughout the kinetic chain.
Below are some drills for stabilization and power production by the core:
- Transition movement progression
- Hitting medicine ball
- Resistance with bungee rope
- Working on absorbing the deep ball
Dr. Brinda Bharati (MPT)
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