We are in the age of high velocity fastballs in the major leagues. According to data from Fangraphs PitchF/X, the average velocity of a major league fastball in 2008 was 91.7mph. This year, it clocked in at 93.8mph.

One factor we’ve come to understand that is associated with pitch velocity is the ability to rotate the trunk quickly. In order to achieve this, hip and shoulder separation is needed. This is defined as the difference between the shoulder angle and hip angle in the transverse plane. Hip and shoulder separation is a key movement pattern for pitching and hitting. 

The ability to create hip and shoulder separation in combination with  producing maximum trunk rotation  has been strongly correlated with increased pitch velocity. (1, 4-6, 11-14, 19) Trunk rotation can provide up to 50% of the kinetic energy and momentum for pitching. (18) This separation creates and stores elastic energy in the muscles, tendons and fascial systems through what is called the stretch-shortening cycle (SSC). (5, 19) SSC refers to the muscle action when muscle lengthening is immediately followed by active muscle shortening. 

For pitchers, maximum hip and shoulder separation typically occurs at the foot plant.

In order to achieve this, the athlete needs: 

• Adequate shoulder, trunk/thoracic and hip mobility and stability.

• Ability to move through this movement pattern explosively (SSC).

One area we’re going to focus on today is the thoracic spine. The thoracic spine, also known as the mid-back, is composed of 12 vertebrae which are designed to flex, extend and rotate. Stiffness in this area can result in altered shoulder movement patterns and additional stress on the low back. Thoracic mobility is essential for shoulder and elbow health, scapular positioning, and the ability to transfer force from lower limb to upper limb. (2, 8, 9, 13-15)

Rotational athletes (golfers, pitchers, batters, etc.) need greater than 50-70 degrees of thoracic rotation for peak performance. Elite rotational athletes can achieve around 70-90 degrees of thoracic rotation. If a player lacks thoracic mobility, this can cause undue stress on the shoulder, elbow or low back through compensation. (2, 5, 7)

How do we assess this?

We first assess the active mobility - can the athlete get into the range of motion passively in a lumbar locked kneeling thoracic rotation?

Next we assess the passive mobility in the same position.

Can the athlete demonstrate the mobility explosively? Can the athlete be able to maximize the SSC and the length-tension relationship to increase and maximize power output?

Example of expressing the thoracic mobility explosively: 

If the athlete fails to demonstrate on any of these steps, it is crucial to identify the reason for the restriction and to address it appropriately with manual therapy, corrective mobility, strength training or workload management. It is also important to note that having more thoracic rotation does not necessarily mean greater throwing velocity, however it certainly allows for the potential to throw harder if the athlete can maximize the power output through that range. 

As always, assess, don’t guess. 

About the author:

Nick’s journey into physiotherapy started out as a student athletic therapist for the Western University (London, ON) Men’s Varsity Basketball Team where it fuelled his passion to further pursue physiotherapy. He then landed in Australia where he obtained his Master of Physiotherapy at the University of Sydney and continued to work with multiple renowned organizations. He became a physiotherapist in one of the busiest full-service medical centres in Western Sydney, and took the position of physiotherapist for the Sydney Blue Sox of the Australian Baseball League, a Major League Baseball (MLB) Winter League.

References: 

1. Bullock GS, Strahm J, Hulburt T, Beck EC, Waterman BR, Nicholson KF. The relationship of range of motion, hip shoulder separation, and pitching kinematics. International Journal of Sports Physical Therapy. 2020 Dec; 15(6): 1119–1128.

2. Cressey, Eric. (2013, November). Improving Thoracic Mobility in Throwers. https://ericcressey.com/thoracic-spine-mobility-drills-throwers

3. Dowling, Brittany, et al. "Relationship of pelvis and trunk kinematics to ball velocity in professional baseball pitchers." 40th American Society of Biomechanics (ASB) annual meeting. 2016. 

4. Erickson BJ, Sgori T, Chalmers PN, Vignona P, Lesniak M, Bush-Joseph CA, Verma NN, Romeo AA. Impact of Fatigue on Baseball Pitching Mechanics in Adolescent Male Pitchers. Arthroscopy. 2016 May; 32(5):762-71.

5. Fleisig GS, Hsu WK, Fortenbaugh D, Cordover A, Press JM. Trunk axial rotation in baseball pitching and batting. Sports Biomech. 2013 Nov; 12(4):324-33.

6. Fortenbaugh D, Fleisig GS, Andrews JR. Baseball pitching biomechanics in relation to injury risk and performance. Sports Health. 2009 Jul; 1(4):314-20.

7. Johnson, K D, Kim, K-M, Yu, B-K, Saliba, S A and Gridstaff, T L. Reliability of thoracic spine rotation range-of-motion measurements in healthy adults. Journal of Athletic Training, 47(1): 52-60. 2012.

8. Kebaetse, M., McClure, P., and Pratt, N. A. (1999). “Thoracic position effect on shoulder range of motion, strength, and three-dimensional scapular kinematics.” Archives of Physical Medicine and Rehabilitation, 80(8), 945–950.

9. Lintner D1, Noonan TJ, Kibler WB. – Injury patterns and biomechanics of the athlete’s shoulder. – Clin Sports Med. 2008 Oct;27(4):527-51.

10. Crosbie, J., Kilbreath, S. L., Hollmann, L., and York, S. (2008). “Scapulohumeral rhythm and associated spinal motion.” Clinical Biomechanics, 23(2), 184–192.

11. Oliver GD, Keeley DW. Pelvis and torso kinematics and their relationship to shoulder kinematics in high-school baseball pitchers. J Strength Cond Res. 2010 Dec; 24(12):3241-6.

12. Sgroi T, Chalmers PN, Riff AJ, Lesniak M, Sayegh ET, Wimmer MA, Verma NN, Cole BJ, Romeo AA. Predictors of throwing velocity in youth and adolescent pitchers. J Shoulder Elbow Surg. 2015 Sep; 24(9):1339-45.

13. Stodden DF, Campbell BM, Moyer TM. Comparison of trunk kinematics in trunk training exercises and throwing. J Strength Cond Res, 22(1):112-118, 2008. 

14. Stodden DF, Fleisig GS, McLean SP, Lyman SL, Andrews JR. Relationship of pelvis and upper torso kinematics to pitched baseball velocity. J Appl Biomech. 2001;17(2):164‐172.

15. Strunce Jb, et al. The immediate effects of thoracic spine and rib manipulation on subjects with primary complaints of shoulder pain. J Man Manip Ther. 17(4):230-6, 2009. 

16. Szymanski DJ, et. al. Effect of torso rotational strength on angular hip, angular shoulder, and linear bat velocities of high school baseball players. J Strength Cond Res, 21(4):1117-1125, 2007.

17. Talukdar K, et. al. The role of rotational mobility and power on throwing velocity. J Strength Cond Res. 29(4):905-911, 2015.

18. Toyoshima S, Hoshikawa T, Miyashita M, Oguri T. Contribution of the body parts to throwing performance. In: Biomechanics IV. Springer; 1974:169‐174.

19. Young JL, Herring SA, Press JM, Casazza BA. The influence of the spine on the shoulder in the throwing athlete. J Back Musculoskelet Rehabil. 1996 Jan 1; 7(1):5-17.

Pictures:

https://media.stack.com/stack-content/uploads/2018/05/11193350/Spine-Diagram-STACK.png

https://rocklandpeakperformance.com/pitching-biomechanics-hip-shoulder-separation/#)