Think of your shoulder like a finely tuned sports car. It’s built for performance and flexibility, but when you push it too hard—whether from overuse, poor posture, or injury—it can exceed its functional capacity and break down. In the shoulder, this means the structures that keep everything running smoothly become irritated, inflamed, and start to slow you down.

The functional threshold is essentially the limit of what your shoulder can handle before it starts to protest. Just like a car engine running too hot, when your shoulder goes beyond its threshold, it leads to inflammation in the tissues, causing pain and restricted movement. Understanding this concept can help you avoid pushing past that limit and keep your shoulder from “breaking down.”

Here are the five most common structures in your shoulder that can get inflamed when you push too far past that functional threshold:

1. Rotator Cuff Tendons – The Shoulder’s Supporting Cast

Imagine your rotator cuff as the backstage crew of a theatre production. They’re not in the spotlight, but without them, nothing would work. The rotator cuff includes four muscles and their tendons that stabilize and move the shoulder. When you overload them—by lifting heavy weights or performing repetitive overhead motions—you push past their functional threshold, causing rotator cuff tendonitis. This is like asking the crew to work overtime without rest—they get worn out and start to throw tantrums!

Signs your rotator cuff is overwhelmed:

• Pain when raising your arm (like reaching for something high but hitting a wall)
• Tenderness around the shoulder joint (like a bruised spot that just won’t go away)
• Weakness in overhead movements (like your arm gets “stuck” during a routine action)

2. Bursa – The Cushion That’s Had Enough

The bursa in your shoulder is like a shock absorber in your car—it cushions the bones and reduces friction to keep everything moving smoothly. But when the bursa gets overloaded or irritated (think about driving over too many speed bumps), it becomes inflamed, causing bursitis. This is the point where the cushion can't absorb any more shock, and every movement becomes painful.

How to spot bursitis when it’s overworked:

• Swelling or warmth over the shoulder (like driving with your brakes on)
• Pain when moving your arm, especially overhead (feels like you’re trying to move through thick mud)
• Tenderness in the front or top of the shoulder (even light pressure feels like a bruise)

3. Long Head of the Biceps Tendon – The Overzealous Helper

Your biceps tendon is the helpful assistant who wants to do everything for you—sometimes, too much. The long head of the biceps tendon stabilizes the shoulder during movement, but when overused, it’s like a helper trying to carry all the heavy boxes alone. It gets strained, leading to bicipital tendinitis, and you end up with an inflamed tendon that’s no longer as cooperative.

What bicipital tendinitis feels like when you push too far:

• Pain in the front of the shoulder (like someone pressing on your biceps)
• Tenderness near the bicep area (feels like overdoing it at the gym)
• Weakness in the arm (like you’ve lifted one too many heavy bags)

4. Acromioclavicular (AC) Joint – The Broken Bridge

Think of the AC joint as a bridge between your collarbone and shoulder blade. When this bridge gets overworked—maybe from an injury or repetitive motion—it can break down, leading to AC joint arthritis or inflammation. This is like driving over a bridge that’s starting to crumble—it can no longer handle the traffic and starts to cause discomfort.

Signs of AC joint issues:

• Pain at the top of the shoulder (where the “bridge” connects)
• Tenderness over the AC joint (feels sore to the touch, like it’s been knocked around)
• Pain that gets worse with arm movements (like trying to cross a wobbly bridge)

5. Glenohumeral Joint Capsule – The Shoulder’s Tight Hoodie

Your glenohumeral joint is the ball-and-socket joint of the shoulder, and the joint capsule is like a hoodie that keeps everything snug and stable. When the capsule becomes inflamed—due to overuse or injury—it can tighten up, restricting your shoulder movement, leading to frozen shoulder. It’s like trying to wear a hoodie that’s too small for you—it just doesn’t fit, and movement feels restricted.

Frozen shoulder symptoms when the joint “hoodie” gets too tight:

• Pain and stiffness (feels like your shoulder is in a straitjacket)
• Limited range of motion (you can’t raise your arm the way you’d like)
• Pain that gets worse at night (like trying to sleep in an uncomfortable position)

At Movement Therapy, we’re all about helping you understand your body’s functional threshold and keeping you in the safe zone. Whether it’s rotator cuff tendonitis, bursitis, or frozen shoulder, we can help you find the right balance, so your shoulder doesn’t break down. Our team will guide you through exercises and treatments designed to reduce inflammation, restore mobility, and strengthen the muscles that keep everything running smoothly.

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