Throwing sports, racquet sports, swimming, bowling and other activities that repeatedly strain the rotor cuff muscles can weaken the shoulder tendons and lead to injury and inflammation. Charles Poliquin, Australian coach for Olympic medal winners in 12 sports, recommends eccentric weightlifting exercise for strengthening tendons. Concentric exercise shortens muscles when you push weight up, while eccentric exercise lengthens muscles when you lower weight back down.
Eccentric Shoulder Press
Perform the shoulder press with a count of one on your uplift and a count of four when you bring the weight down to strengthen your shoulder tendons by increasing the duration of the eccentric motion. Stand with your feet slightly more than shoulder-width apart. With palms facing forward, hold a bar or barbells in both hands just above chest height with your elbows pointing down. Your hands should be slightly more than shoulder-width apart at a distance that feels comfortable. Fully extend your arms as you push the bar straight up above your head for a count of one, and then slowly lower the bar back down to the starting position while counting to four. Do three sets of 10 to 15 repetitions once or twice a week if you are under 50, or do this once a week if you are over 50. Use weight heavy enough to feel resistance but not complete cause muscle fatigue after one complete set.