Photo: Thomas Schönenborn|
The second part of the series was about the stride. Part two deals with hip rotation.
Hip rotation
The rotation phase overlaps with the stride phase and the blocking phase. Its main component is hip rotation.
Interestingly, maximum hip rotation speed is not related to ball speed – at least for more advanced pitchers. However, the timing of the maximum rotation speed is much more important. It should be reached after the footplant but as long as possible before the highest rotation speed of the upper body.
The highest rotation speed can hardly be seen with the naked eye, even on high-speed videos. A good indication that the timing is good is if the hip remains closed for a long time, opens shortly before footplant, and is open approx. 45 degrees at footplant. If the hip opens much earlier (an indication of inefficient hip-shoulder separation), or if it is still closed at footplant (making it difficult to perform an optimal lead-leg block), the timing can usually still be improved.
This delay can support hip-shoulder separation. In an in-house study by Driveline, pitchers who throw harder (>88mph) open the hip earlier than pitchers who throw less hard (<76mph)(https://www.drivelinebaseball.com/2019/09/full-signal-analyses-the-next-step-in-biomechanical-analysis/).
In order for the lead leg block to work well, the hips should be open approx. 45 degrees and tilted forwards in footplant. The tilt initiates the flexion of the upper body.
Good exercises to improve hip rotation and timing are roll-ins and drop-step-throws.
The fourth and final part deals with the blocking phase and the lead-leg block.
