Shoulder impingement syndrome is pain caused when a bone in the shoulder rubs against and irritates the rotator cuff tendon (which joins shoulder muscles to the top of the arm) or the bursa, the fluid-filled sac that cushions the tendon from the bone.
It can result from a heavy fall onto the shoulder or from repeatedly raising the arm above the shoulder – so triathletes can experience it after long stints of cycling on the tri bars or repeated heavy front crawl-only sessions in the pool.
Like most conditions, the degree of impingement varies. Grade 1 is a bursitis or tendinitis (inflammation of the bursa or tendon), while grade 3 denotes a complete tear in the rotator cuff, the group of muscles and tendons attaching shoulder to arm. More often than not, conservative rehabilitation involving rest, ice and non-steroidal anti-inflammatories such as ibuprofen will do the trick, though rehabilitation time can range from a few days to several months. In some cases an arthroscopy (keyhole surgery) is required.
If your impingement is manageable, and you have a sensible approach, you can continue training. Concentrate your efforts on stabilising your shoulder with warm-up, flexibility and strengthening exercises. Avoid too much impact running, prolonged swim sets of front crawl or heavy biking on tri-bars.
I’d suggest trying indoor rowing, a good all-over aerobic workout that avoids too much stress on the shoulders – get technique advice from a trainer. Also try spinning classes (avoid dropping down onto the tri-bars); the elliptical trainer is good, but only use your legs. With all aerobic activities, if you start to feel discomfort or pain in the shoulder area either dial down or stop the session.
Probably the most important focus will be to stabilise the shoulder and rotator cuff muscles (subscapularis, supraspinatus, infraspinatus and teres minor), anterior and posterior. Perform shoulder-strengthening exercises at least three times a week: for example, a shoulder-blade squeeze, shoulder-blade shrug and static rotator-cuff contractions. When you begin to find these simple exercises too easy, move on to resistance-band training: external and internal rotation of the shoulder, combined with some rotator-cuff stretches. You’ll find instructions for these strength and flexibility exercises at most sports centres or gyms; alternatively, ask a personal trainer or enrol in a specific body-stretch/conditioning class.
If you can’t do these, I’d recommend The Anatomy of Stretching by Brad Allen (Lotus, 2011), a self-explanatory and easy-to-follow book. Persevere with the stretching and strengthening, and work on the flexibility of your shoulder muscles, and you should see improvements.