In our decision-making regarding return to sports after an injury, we try as much as possible to have objective criteria that are measurable and based on scientific evidence. A science-based RTS model for overhead athletes after a shoulder injury is still lacking, however at the level of ROM and strength, 2 major components of shoulder function, we do have some guidelines, and reference values.
ROM can easily be measured with an inclinometer on your smartphone. Measurements can be done in supine position, with the humerus in the frontal plane, and controlling scapular compensation through palpation of the coracoid and the spine of the scapula. Although normal values for external rotation, internal rotation, and total ROM vary very much from sport to sport, in general, IR ROM should be not more than 20° less on the dominant side, and the side-to-side differences for total ROM should not exceed 10°. ER ROM should be 5-10° more on the dominant side, but too much ER is also considered to be a risk factor for injury, so additional stretching should be avoided in these athletes, in particular towards ER.
Strength may be measured by a Hand-Held dynamometer in different positions. In general a minimum strength increase of 10% on the dominant side is recommended both for IR and ER, and focus should go specifically to the ER/IR ratio. Normal values for these ratios depend upon the shoulder position in which the strength was measured: 70-75% when measured in neutral, +/- 100% when measured in 90° of abduction and no rotation, between 60 and 85% when measured in the position of abduction/external rotation. These values are based on studies assessing elite athletes (smaller groups, but typical values for high level sports performance) or larger groups of recreational athletes.
Written by: Ann Cools
Cools AM, De Wilde L, Van Tongel A, Ceyssens C, Ryckewaert R, Cambier DC.
Measuring shoulder external and internal rotation strength and range of motion: comprehensive intra-rater and inter-rater reliability study of several testing protocols. J Shoulder Elbow Surg. 2014 Oct;23(10):1454-61. doi: 10.1016/j.jse.2014.01.006