Examining Muscle Activity Differences During Single and Dual Vector Elastic Resistance Exercises.
Ryan Wg Bench, Sydney E Thompson, Alan C Cudlip and 1 others
PMID 33842028WHAT IT FOUND
Dual vector elastic resistance increased muscle activation during shoulder abduction and flexion, but not during internal or external rotation.
This suggests dual vectors may be useful for specific strengthening phases, but are not universally beneficial for all shoulder exercises.
Key findings
01Dual vector exercises increased muscle activation in most muscles during abduction and flexion, with the dual vector abduction exercise generating the highest mean EMG in the deltoids, triceps, rotator cuff, and trapezius.
02Adding a dual vector to internal or external rotation exercises resulted in minimal changes to muscle activation, with significant increases only in the posterior deltoid and clavicular head of pectoralis major, both less than 4.1 %MVC.
03The study was conducted on healthy, right-handed male university students with no recent shoulder pain, limiting the generalizability of these activation patterns to injured or female populations.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study included only 16 healthy, right-handed male university students with no recent shoulder pain, so results may not apply to injured, female, or older populations. Only four specific exercises were tested, so findings may not generalize to other shoulder rehabilitation movements. The dual vector attachment point differed between exercises (hand vs. elbow), which may have influenced the resistance arm and load. Concentric and eccentric phases were not analyzed separately, so timing of muscle activation differences is unknown. Perceived exertion (RPE) was not collected, so variations in subjective intensity across participants could not be accounted for. The study used low resistance bands, so effects at higher intensities are unknown.
Declared interests
The authors declared no conflicts of interest related to the equipment, methods, or results.
The easy way to misread this
Do not assume that dual vector elastic resistance universally improves muscle activation for all shoulder exercises. The study found significant increases primarily during abduction and flexion, with minimal and potentially clinically insignificant changes during internal and external rotation.