Trunk lean at release

A trunk angle is only comparable when “release” means the same event each time. Choosing the frame where the whole body is highest can be misleading because the delivery bound may lift both the shoulder and wrist before the ball is released. FastBowlingLab anchors release to the bowling wrist relative to its own shoulder and returns the selected frame with the measurement.

With the camera square to the crease, the line of the torso can be compared with a stable vertical reference at release. Repeating that setup allows an athlete to see whether the forward position is broadly stable across deliveries and re-tests.

• Keep both hips and shoulders visible.
• Avoid a handheld camera that rotates with the bowler.
• Compare the same delivery phase and similar bowling intensity.
• Use multiple deliveries before interpreting a change as a new pattern.

A side-on image cannot completely separate rotation and lateral flexion occurring out of the image plane. It also does not measure spinal loading. Trunk position can be a useful coaching observation, but pain, injury risk and rehabilitation require an appropriately qualified clinician rather than an angle from a phone video.

Laboratory research treats bowling trunk motion as multi-planar and can calculate loads using measurements that a side-on phone does not provide. A prospective study of 50 elite male fast bowlers also reported differences in several lumbopelvic and trunk-motion variables between groups, but it does not validate diagnosis from one video. See the study abstract and post-print.