Effects of Hip Range of Motion and Isometric Strength on Energy Flow during Windmill Softball Pitching

Context: Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility.

Objective: To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed.

Design: Descriptive laboratory study.

Setting: University research laboratory.

Participants: A sample of 29 youth softball pitchers (11.2±1.3 yrs.; 155.0±10.4 cm; 53.2±12.6 kg).

Main outcome measure(s): Bilateral hip internal rotation (IR) and external rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured.

Results: Regression analysis revealed a significant effect of drive hip ER ISO on the net energy flow out of the distal ends of the trunk (p=0.045) and humerus (p=0.002). Specifically, increased drive hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to also achieve higher pitch speeds.

Conclusions: There is an association between drive hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in the execution of the whole-body windmill pitch. Overall, energy flow analysis is an interesting new way to analyze pitching mechanics and will aid in further understanding of performance and injury risk in windmill softball pitching.