Line Hops and Side Hold Rotation Tests Load Both Anterior and Posterior Shoulder: A Biomechanical Study.
Margie K Olds, Nicole Lemaster, Kelsey Picha and 3 others
PMID 33842043WHAT IT FOUND
Two shoulder tests place high load on posterior structures.
The Side Hold Rotation stresses anterior structures at end-range. The Line Hop is more dynamic, rapidly loading the shoulder. Both require handling nearly half bodyweight through one arm.
Key findings
01Both tests generated high posterior forces, with the Side Hold Rotation producing 4.84 N/kg and the Line Hop 4.25 N/kg.
02The Side Hold Rotation produced peak anterior forces (1.57 N/kg) and horizontal abduction moments at the end-range of horizontal abduction.
03The Line Hop test involved rapid loading and higher rates of force development compared to the Side Hold Rotation, simulating sport-specific demands like falling or blocking.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only 10 healthy, young participants, so findings may not apply to injured or older athletes. Participants were not instructed on landing technique for the Line Hop, leading to variability in elbow flexion and force absorption. Data were averaged from only five repetitions, not a full one-minute test, so fatigue effects are unknown. Inverse dynamics cannot isolate forces on specific ligaments or tendons, only net joint forces. The study did not measure actual sport impacts, so comparisons to game demands are estimates.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not interpret these force values as evidence that the tests predict injury or guarantee safe return to sport. The study describes biomechanical loads in healthy participants; it does not establish clinical outcomes or diagnostic accuracy for instability.