Mobility= the ability to move freely without restriction
Stability= the ability to maintain adequate posture
Imagine you are 5 years old, you are trying to catapult an object on a rubber band to smack your older brother while he is looking the other way. You stretch out the band to find it has knots in it- it is impossible to get that band to stretch out to its full length and “sigh” you won’t be able to produce as much force to get that object to startle him. Take a second rubber band without knots which stretches to its full length, and you have a powerful weapon!
The same analogy works with your muscles. Having adequate mobility is having muscles without “knots” in- you can freely move without restriction to achieve maximal force capacity. No matter how strong that “band” is, if it cannot move freely, it will never be able to reach its true capabilities.
That is why one of the first things I do in a client assessment is measure range of motion with a goniometer aka human protractor. This tells us your passive range of motion and highlights any imbalances. These mobility discrepancies go hand in hand with stability imbalances.
Take the example of creaky knees. I recently had a client visit a doctor for pain in his knees. He is dealing with arthritis and a decline of cartilage in his knees. The doctor advised gluteus and core strengthening after utilizing a gluteus medius manual muscle test. This client has excellent gluteus and core stability but due to recent inconsistency in his training has developed mobility restrictions.
The phrase “tight” is subjective and is a feeling, but when he comes in after 2 weeks of travelling without any deliberate movement that's how he feels. What is happening is restricted range of motion disabling his stability. After opening his joints and going through loaded movement training (combining weight with mobility) he has no problems stabilizing his gluteus and passes the manual muscle test with flying colors. This is why we often feel better after we exercise- blood flow and enhanced ability to move increase our ability to stabilize.
Once our stability muscles are firing there is enhanced muscular coordination and multiple body parts can work together to achieve the desired motion. Think of this like a train travelling on tracks, it is smooth and efficient, if the train goes off the track, that's when things break down. Whether that's walking, squatting or resisting a fall, maintaining muscular coordination prevents injuries and promotes performance. This is why we train movements not muscles. Regional interdependence is the relationship of mobile and stable joints within the body. An example of regional interdependence is lower back pain. The spine is supposed to a stable joint but in the absence of mobile hips, the spine will sacrifice stability and be vulnerable to injury.
Use the below progression to achieve range of motion in your thoracic spine (the T shape in your upper back) which will allow you to achieve adequate shoulder stability. When doing these exercises, it is important to not only going through the motions (pun intended ;)) but to really increase the range, holding at the end range for a couple of second and breathing deeply. With the stability exercises, it is open to continue to open and then activate by really engaging and firing up the region you are activating.
Mobility: 10 x Thread the needle to T-spine twists
Activation: 10 x Band W with 2-3 second hold (use a resistance band to increase strength in the scapular region)
Stability: 5 reps each side x Shoulder clock