Internal Rotation Strength
Why it matters, how it’s analyzed and what the research says
Internal Rotation Strength
Why it matters, how it’s analyzed and what the research says
Why it matters
Internal rotation strength is an important performance metric as it’s related directly to the throwing motion. The strength of your internal rotator helps to accelerate the arm during throwing but also helps to maintain shoulder stability, which is vital for throwing at high-velocities.

Research has shown that internal rotation strength is one of the biggest influencers of throwing performance. Both velocity and accuracy decrease when the internal rotators become fatigued.

Analyzing Internal

Rotation Strength

There are three ways that the app
compares internal rotation strength:

1. Percentile

Percentile compares your internal rotation strength to other players your age. If you are in the lower third for players your age, you know that this is an area that you need to improve.

2. Symmetry

Symmetry compares the internal rotation strength of your throwing side to your non-throwing side, in which most players are stronger on their throwing arm.

2. Symmetry

Symmetry compares the internal rotation strength of your throwing side to your non-throwing side, in which most players are stronger on their throwing arm.

3. Trend

Trend analyzes how your strength has changed compared to previous tests. It’s normal for a player’s strength to fluctuate throughout the season, but these changes should be monitored and addressed.

If the strength score has decreased by 10% or more, the app will automatically modify your arm care to a recovery-based program that reduces training loads & volume. Along with your symmetry score, the trend score is an excellent marker to identify arm fatigue.
Summary of Research
  • Internal rotation strength is shown to be one of the biggest influencers of throwing performance (Clements, 2001).

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  • In a study comparing professional to amateur pitchers, the pro guys were much better at recruiting the internal rotators of the shoulder during the acceleration phase of throwing (Gowan, 1987).

 

  • Throwing puts a lot of stress on the internal rotators, so it shouldn’t be surprising that pitchers lose an average of 17% of their internal rotation strength following a start (Mullany, 2005).

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  • Spotting these drops is crucial because we know that both velocity and accuracy both decrease when the internal rotators become fatigued (Erickson, 2016). It’s also shown that players who pitch when tired are 36x more likely to get injured (Flessig, 2011).

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  • A decrease in rotator cuff strength may be a sign of an injury to the arm as well. A 2015 study showed that players with UCL tears had more significant reductions in strength in both their throwing and non-throwing arms when compared to uninjured players. (Garrision, 2015.)
Research
Research
Toyoshima S., Hoshikawa T., Miyashita M., Oguri T. (1974) Contribution of the body parts to throwing performance. In: Nelson R.C., Morehouse C.A. (eds) Biomechanics IV. International Series on Sport Sciences. Palgrave, London.

Gowan ID, Jobe FW, Tibone JE, Perry J, Moynes DR. A comparative electromyographic analysis of the shoulder during pitching. Professional versus amateur pitchers. Am J Sports Med. 1987 Nov-Dec;15(6):586-90.

Mullaney MJ, McHugh MP, Donofrio TM, Nicholas SJ. Upper and lower extremity muscle fatigue after a baseball pitching performance. Am J Sports Med. 2005 Jan;33(1):108-13.

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

Fleisig GS, Andrews JR, Cutter GR, Weber A, Loftice J, McMichael C, Hassell N, Lyman S. Risk of serious injury for young baseball pitchers: a 10-year prospective study. Am J Sports Med. 2011 Feb;39(2):253-7.

Garrison, J Craig et al. “Baseball players with ulnar collateral ligament tears demonstrate decreased rotator cuff strength compared to healthy controls. International journal of sports physical therapy vol. 10,4 (2015): 476-81.