Kettlebells are awesome, as are the swings you perform using them. Kettlebell swings have become very popular, and for good reason. They are great to enhance general athletic performance, and can be used for rehabilitation purposes. Regular kettlebell swings can even enhance your 1RM-max in compound exercises like the squat.
Another thing you can do with kettlebells is train your core musculature. Swinging a kettlebell (or two!) targets your entire core. This includes your erector spinae, your rectus abdominis, and your external oblique muscles.
Does performing one-armed swings differ from two-armed when it comes to activating your core muscles?
A study from earlier this year had 15 resistance-trained men perform 10 reps of both one-armed and two-armed kettlebell swings. During the movements, the researchers used electromyography to measure the muscle activity of the erector spinae, rectus abdominis, and external oblique muscles of the subjects.
The Swinging in Action
Analyzing the results, they found significantly different activation patterns of the trunk muscles when the participants performed one-armed swings compared to two-armed. For example, the two-armed swing activated the rectus abdominis, the abs, more when using both arms to perform it. On the other hand, the one-armed swing activated the erector spinae muscles on the opposite side of the kettlebell up to 25% more compared to the same side. This was likely due to the rotation of the trunk when performing the movement using just one arm.
The results suggest that to target your erector spinae muscles, performing kettlebell swings using one arm at a time is the best option. For the rectus abdominis, two-armed swings seem to be superior.
However, for a complete core workout, you should consider using both one-armed and two-armed kettlebell swings to target your entire trunk.