Scapular kinematics during supraspinatus rehabilitation exercise: a comparison of full-can versus empty-can techniques.
Level 3 - non-randomized controlled study
Non-randomized within-subject comparative laboratory study
PubMed 16282575 · doi:10.1177/0363546505281797
What was done
Twenty participants performed both full-can and empty-can exercises while three-dimensional scapular kinematics were measured using an electromagnetic tracking system. Scapular angles at 30 degrees, 60 degrees, and 90 degrees during the ascending and descending phases of humeral elevation were compared using two-way repeated measures ANOVA.
What was found
The empty-can exercise resulted in significantly more scapular anterior tipping and internal rotation compared to the full-can exercise across all sampled humeral elevation angles, except at 30 degrees of the descending phase for anterior/posterior tipping (P < .05). Scapular upward rotation did not differ between exercises. Exact numerical angles were not reported in the abstract.
Why it matters
Because scapular internal rotation and anterior tipping are thought to decrease supraspinatus outlet volume, the full-can exercise may be more appropriate than the empty-can exercise when preserving subacromial space is desired during rotator cuff rehabilitation.
Limits
The sample size was small (n = 20), participant health status (healthy vs. symptomatic) was not specified in the abstract, subacromial space dimensions were inferred rather than directly imaged, and exact kinematic values were omitted from the abstract.