POSTERIOR DELTOIDS
WHAT IS IT?
The deltoid is a large, triangular muscle that surrounds the shoulder. It consists of three sets of muscle fibres, known as heads: the anterior (front), the mid (lateral) and the posterior (rear).
WHAT DOES IT DO?
Each of these heads produces a different movement of the shoulder. The posterior deltoid extends, externally rotates and retracts the shoulder joint.
WHAT HAPPENS WHEN IT GOES WRONG?
During cycling your upper back is often in a flexed position with the shoulders rolled forwards. This places your shoulders in an internally rotated position, causing your chest and anterior deltoid muscles to become tight. Over time, this can cause your posterior deltoids to become chronically lengthened, reducing their strength and function. Exercises such as press-ups and shoulder presses work the anterior deltoids, which can cause a strength imbalance between the anterior and posterior deltoids.
HOW TO FIX IT?
Strengthening exercises for the posterior deltoids and supporting upper back muscles should be performed at least twice a week. Before performing strength exercises it’s a good idea to mobilise your shoulders by slowly swinging your arms in a circular motion, 20 times forwards and backwards. Following this, a light chest stretch should be performed for 20-30 seconds, as relaxing your pectoral muscles makes it easier for you to retract your shoulder blades (pull them back).