Stand tall with a neutral spine and your feet slightly wider than shouder width apart. Hold either end of a long resistance band in your hands. Extend your arms up and out directly in front of you, until they level with your shoulders, with your hands almost touching. This is your start position. Keeping your core braced and hips still, drive your hands apart, resisting against the band until each hand is almost parallel to your shoulders. Exhale as you do so. Pause at full extension before returning to the start position. Repeat for the required number of reps (or time).