Anatomy TUESDAY – Cross Education of Strength

“I think the muscles on my left shoulder are getting bigger. Is that possible?” my patient asked. He is four weeks post-op rotator cuff repair and had been in a sling. We began “well arm” exercises almost immediately, incorporating weighted pulley punches and rows with his right arm.

A study involved immobilization of one arm for 8-hours a day. Subjects were divided into three groups: a control group (no exercise), an eccentric (ECC) exercise group and an concentric-eccentric (CON-ECC) exercise group. The exercise subjects performed 3-5 sets of 10 repetitions three times a week for four weeks. Arm circumference, 1-RM and maximum voluntary isometric contraction (MVIC) were then measured on the immobilized arm.

The control group demonstrated decreased strength (21.7% loss of MVIC). The CON-ECC and ECC groups demonstrated increased strength (0.29 v 0.47) with the ECC group demonstrating an average circumference increase of 2.9%. Eccentric only exercises appear to be the most effective way to attenuate weakness and atrophy of an immobilized arm.

Why does this matter?

Weeks of immobilization are protocol for post surgical rotator cuff repairs. Often patients are sent to PT where PROM only is prescribed until AAROM is allowed (4-6 weeks post-op). In the early phase of rehabilitation, incorporating hypertrophy training for the uninvolved arm may not only prevent atrophy of the involved arm but also give your patient a head start in strengthening once they are cleared to begin active movement.

Have you ever lifted weights, for example a barbell curl, to fatigue. Then someone helps you lift it a few more times and you work on lowering the weight independently for a few more repetitions? These are called negative reps or eccentric reps and are a real-life example of how much stronger you are eccentrically than concentrically. Eccentric only exercises are more effective in producing strength gains and muscle growth as you are stronger eccentrically than concentrically.

Maximize your patient’s post-op visits. Don’t let the restriction of PROM only limit your session. Work on improving thoracic mobility and activate muscles using the “good arm” and if you really want to help them out, be there to add some negative reps at the end of the set.

Because nobody has time to be in pain.

Until next time…