Many pitchers are taught from a young age to “finish” their pitch by throwing their upper body towards home causing excessive trunk flexion resulting in the trunk getting stuck over their front leg – potentially impeding the front legs ability to brace up.

How does trunk flexion affect pitch delivery?

Based on preliminary data we have investigated in collaboration with ECU School of Physical Therapy we have found that there is an ideal range for pitchers trunk flexion.

When investigating the mechanics of 82 collegiate pitchers with over 400 (fastball) pitches analyzed using our Qualisys mocap system, Advanced Mechanical Technology, Inc. (AMTI) force plates, and C-Motion, Inc. analysis software, we found that there is an ideal range of 27 to 43 degrees of trunk flexion results in increased front leg GRF in the frontal plane (braking force).

With a quadratic R value of 0.702, we find these preliminary findings both significant and exciting as lead leg GRF in the frontal plane to be linked to increased ball velocity. (1, 2)

We are excited to keep digging into this data with ECU School of Physical Therapy.

(Skeletal image displayed excessive trunk tilt through ball release ~53.6 degrees)

1. Guido, John A. Jr1; Werner, Sherry L.2. Lower-Extremity Ground Reaction Forces in Collegiate Baseball Pitchers. Journal of Strength and Conditioning Research 26(7):p 1782-1785, July 2012. | DOI: 10.1519/JSC.0b013e31824e1211

2. McNally, Michael P.; Borstad, John D.; Oñate, James A.; Chaudhari, Ajit M.W.. Stride Leg Ground Reaction Forces Predict Throwing Velocity in Adult Recreational Baseball Pitchers. Journal of Strength and Conditioning Research 29(10):p 2708-2715, October 2015. | DOI: 10.1519/JSC.0000000000000937