Effect of altered carrying angle on the medial-to-lateral activation ratio in the biceps brachii and triceps brachii.
Ga-Hee Kim, A-Young Lee, So-Young Park and 2 others
PMID 30154580WHAT IT FOUND
Straightening the forearm during biceps and triceps dumbbell exercises did not show a difference in overall muscle activation in 35 healthy adults.
The medial side showed greater activation than the lateral side in the resting and straight positions.
Key findings
01Straightening the forearm during biceps or triceps dumbbell exercises did not show a difference in overall muscle activation compared with the resting forearm position.
02The medial side of the biceps and triceps showed greater activation than the lateral side in the resting and straight positions.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was done in 35 healthy adults with no current upper extremity trauma or pain and normal shoulder, elbow, and forearm range of motion, so it does not show what happens in patients with elbow pain or injury. The main comparison found no difference between the resting and straight forearm positions, so the study does not support changing the carrying angle to alter overall muscle activation. The authors note a measurement limitation: the standard deviation between raters was large for carrying angle measurements obtained with a digital inclinometer. The outcomes were surface electromyography activation ratios during a single exercise session. Only selected heads of the biceps and triceps were measured, not all elbow flexors and extensors.
Declared interests
The authors declared no conflicts of interest.
The easy way to misread this
Do not conclude that straightening the forearm during biceps or triceps exercises makes activation more symmetrical. The study found no difference between positions, and it measured only muscle electrical activity in 35 healthy adults.