HITTING
PHASES
Description:
In order to interpret the mechanics of a swing in more detail, the batting motion is commonly separated into phases. The key phases of a swing are: stance phase, stride phase, drive phase, acceleration phase, and follow-through phase. (Fleisig 2013).
The stance phase is started when the batter shifts his weight onto the back foot. It is important to note that foot and trunk position in this phase can vary among batters. The stance phase ends when the front foot is lifted off the ground (otherwise known as foot off). The stride phase is from front foot off to front foot contact. The drive phase refers to the time from foot contact to maximum bat lag, the minimum angle between the bat’s long axis and an imaginary line from the mid chest to hands. The acceleration phase is the time from maximum bat lag to ball contact. The follow-through phase is the completion of the swing after ball contact. (Fleisig 2013)
Common Mechanics at Each Phase:
The table below lists the general descriptions of each phase. Individual variations are expected.
Fleisig et al 2013, Monti et al 2015
HITTING METRICS
Biomechanics is used in many different fields and areas of study. In hitting, we as a group have defined metrics of interest when observing our hitters, also known as our KPI’s. Below you will find a list of lab metrics and Hawkeye in game metrics. Tap the learn more button below to review our metrics dictionary.
Key Performance Indicators
Stride Length
Stride length at footstrike describes the distance measured between the back ankle at setup and the lead ankle at footstrike.
Stride Horizontal Length
Stride horizontal angle at footstrike describes the angle formed by the line starting at the back ankle at setup in the direction of the mound and the line connecting the back ankle at set up with the lead ankle at footstrike. The further away from the reference line the lead foot lands, the greater the angle will be.
For hitters, a positive angle represents an open stride, and a negative angle represents a closed stride.
Pelvis Rotation at Footstrike
Pelvis rotation describes the pelvis orientation relative to the lab. Pelvis rotation at 90 degrees indicates the hips are facing the pitcher. Facing home plate is 0 degrees. A negative value indicate pelvis counter rotation.
Trunk Rotation at Footstrike
Trunk rotation describes the trunk orientation relative to the lab. Trunk rotation at 0 degree indicates the shoulders are facing home plate and 90 degrees indicates the shoulders are facing directly to the pitcher. Negative values indicate counter-rotation.
Hip-Shoulder Separation Angle
Hip shoulder separation describes the angular difference between the rotation of the trunk and pelvis. A negative value represents counter-rotation of the trunk relative to the pelvis, which is typically the case at all time points (leg lift through contact) for hitters.
Center of Mass Displacement (Sway)
Center of mass displacement describes the distance that the center of mass traveled toward the catcher from their load and initiation forward. Also referred to as backshift or sway.
