HOW: Get a band or cable anchored somewhere between waist and shoulder height. While standing perpendicular to the anchor and holding the handle with both hands, press your arms forward away from your chest until your elbows are fully straight. Hold that position for a moment while keeping your hips and shoulders square facing forward, then bring your arms in and repeat.
FEEL: You should feel your core and back muscles working as well as your arm muscles to maintain optimal position and form.
COMPENSATION: You should step away from the anchor until there is enough resistance that is challenging, but not too hard where you can't maintain optimal form. Do not let the band rotate your upper body, keep your arms straight and hips facing forward. Try to avoid twisting your back.