If you have a Swiss ball, then it's probably about time you used it, and the "lying Swiss-ball row with external rotation" is a great exercise to try out. Men's Health gives you the lowdown on this arm workout. As with the incline bench row, you will work your back, biceps and forearm muscles.
Holding a light dumb-bell in each hand, lie face down on a Swiss ball with your chest off the ball so your body is inclined. Your arms should hang down in front of the ball, palms facing your feet.
Keeping your neck straight, slowly pull the weights up until your upper arms are parallel to the floor, then rotate your forearms forward until your palms face the floor. Pause, then reverse the motion to lower the weights to the starting position. We recommend that you first master this on a bench angled at 45º before progressing to the Swiss ball.
As with the incline bench row, you will work your back, biceps and forearms.
The rotation will help maintain a healthy shoulder joint, while the ball increases both the level of difficulty and the amount of stress placed on the core muscles. If you really struggle with balance, try placing your feet further apart. Breathe in as you lift and rotate, breathe out as you slowly return to the starting position.