The phrase "at one's elbow" means to be very close by, often in a position of assistance or support. It is derived from the idea that one's elbow is a convenient and accessible part of one's body, from which to offer help or advice.
Sentences with «at one's elbow»
Grab a dumbbell or kettlebell with both hands and hold it in front of your body with the arms bent at the elbows. (fitnessandpower.com)
Keeping the body straight, lower body to the ground by bending arms at the elbows. (hundredpushups.com)
I've been looking for a version that ends at the elbow so I can avoid all of that. (whenthegirlsrule.com)