I received an email yesterday asking if tennis players are so fit, why are there so many hip and knee injuries in tennis? This is a good question! To help me explain, take a lookat the training video I found on YouTube of world number 39, Marta Kostyuk of the Ukraine. Marta is one of the young bright stars of the WTA tour who has an excellent off court workout routine, All of her routines place a strong emphasis on dorsiflexion and plantar flexion. These movements are crucial for the recruitment of the kinetic chain for the alignment of all your joints in your lower extremities. Her muscles, joints, and ligaments are all synchronized which is one of the reasons Marta is such a great athlete.
With synchronization and a great workout routine, then why is it Marta has suffered from sever lower extremity injuries? It is her on-court footwork and hitting technique which has caused all of her lower extremity injuries. Marta rotates her hips. As a result, her knees, ankles and feet are also rotating.
In her workouts, she works with the muscles and ligaments in the sagittal plane, which is how they were designed. On court though, Marta immediately rotates which is causes hyperextension; damaging her joints and ligaments.
This is a real simple answer. Our bodies are designed to move primarily in the sagittal plane. Tennis players have a technique that forces them to use the transverse, or rotational plane. This damages the joints and ligaments of our lower extremities.