Muscle weakness is not the cause of your pain in most cases

A theory

If you’ve been injured, you’ve likely had a physical therapist, athletic trainer, or doctor perform an isometric strength test on you. Example: Your shoulder hurts, so they have you try to raise each arm in front of you while they resist and compare the force exerted.

Your painful arm will test weaker. From there, the logic is that it hurts because it tests weaker. You will be prescribed exercises to strengthen your shoulder. I say it tests weaker because it hurts, and it hurts because you’ve lost proper range of motion (ROM).

Read this twitter thread to understand how losing proper ROM causes pain and injury.

In general, solely doing strength movements won’t help restore ROM. Breaking down muscles when strengthening makes them incrementally tighter. However, if you are using light weight (likely the case) and not working the muscles very hard, you are essentially dynamic stretching. In this case, the exercises meant to strengthen could actually be restoring ROM and may accidentally fix the issue.

Let’s say that the pain goes away 2 weeks after starting these exercises. You will test stronger, and its easy to conclude that this is a result of an increase in strength from the doing exercises. But, using light weight over such a short amount of time will not cause a big enough increase in strength to account for the increase in force output measured in the test.

Here’s what’s happened: Your muscles, tendons, and joints aren’t aggravated anymore because they have proper ROM. So now, they can exert full force. Newton’s third law states: For every action, in this case a force, there is an equal and opposite reaction. In order for your muscles to be able to exert a certain force on an object, they also have to be able to withstand that force. During an isometric strength test involving healthy muscles, the limiting factor is the strength of those muscles. However, during an isometric strength test involving sufficiently injured muscles, the limiting factor becomes how much force your injured parts can withstand. The more injured, the lower the force.

One factor to consider is the degree to which your muscles are locked up. This is determined by:

1. How much ROM you are missing. More ROM missing = muscles more locked up.
2. How long the ROM has been missing. Missing ROM for longer amounts of time = more locked up.

If your muscles aren’t majorly locked up, you don’t NEED to use a static stretching technique to loosen back up. You might ‘accidentally’ loosen up the muscles through exercise or movement in everyday life. However, when your muscles are locked up past a critical point, you will need to use a form of static stretching to successfully restore your ROM.

When you are locked up past this critical point, your muscles require the time and control that static stretching provides to lengthen. If you do strength exercises or dynamic stretching, your muscles and joints will be aggravated faster than those exercises can restore enough ROM.

Muscles lock up to protect the joints they interact with from damage. Aggravating your joints will only cause the muscles to lock up more. You might then take time off from the exercises and try again. Time off will not increase ROM (once you are locked up past the critical point), so the cycle continues without resolution.

The solution is to coax your muscles back open by using static stretching techniques.

If the front of your shoulder hurts, your biceps tendons, anterior delt, and/or pec is too tight. When you restore proper ROM to these muscles, the front of your shoulder wont hurt anymore.

To make sure it doesn’t start hurting again, you have to maintain your ROM (which takes A LOT less time than restoring it does).

To maintain ROM, you must integrate a small amount of flexibility work into your lifestyle and training to counteract gradual losses over time. You must also avoid incidents that cause your muscles to lock up again. There are many reasons your muscles can lock up. Common ones are lack of strength (trying to bench press too much weight), lack of conditioning (trying to do too many reps without rest), overuse (too much volume throughout the week or no rest days, and impact injury (car accident).

Summary:

Your pain is likely due inflexible muscles, not weak muscles.

To get rid of the pain: restore flexibility.

To prevent it from coming back: maintain flexibility, which often involves building more strength.