Why Your Whole Body Can Feel Turned Down When One Spot Hurts: A Muscle IQ Hypothesis

You have had the pain long enough that it stopped being just a spot. The knee, or the low back, or the neck is where it started. But lately everything feels a little heavier. Carrying groceries across the parking lot at University Place takes more attention than it should. Getting out of a chair feels like a decision.

If you have mentioned this to anyone, you were probably told you are deconditioned. Sometimes that is true. But there is another explanation worth knowing about. Dr. Chris Knudsen, a physical therapist at Muscle IQ in Orem, has written it up as a formal hypothesis paper because it fits what our therapists feel with their hands more often than "out of shape" does.

Your body has an idle speed

Even when you are doing nothing, your muscles are not doing nothing. The muscles that hold you upright against gravity — along your spine, across the backs of your hips, down the front of your thighs — keep a low, steady hum of activity all day. Neuroscientists call it extensor tone.

That hum is not set by the muscles. It is set from above, by a region at the base of your brain called the brainstem. The brainstem sends a continuous "stay ready" signal down the spinal cord to those antigravity muscles, adjusting it moment to moment based on how alert you are, what your senses are reporting, and what your posture demands (Cacciatore and colleagues, 2024). The same brainstem neighborhood also runs your alertness system, and alertness and muscle tone are known to move together (Garcia-Rill, 2012). This is the muscle tone dial we have written about before.

When the dial is up, you feel solid and connected. When it is turned down, you do not feel weak in one place. You feel heavier everywhere.

What pain may do to the dial

Cacciatore's paper notes that in people with musculoskeletal pain, disruption of these brainstem pathways frequently shows up as altered muscle tone and poorer motor performance. Dr. Knudsen's hypothesis takes the next step: in a subset of people with long-standing pain, the brainstem's regulatory state may shift, turning global extensor tone down across the whole body — not just near the injury.

We have written before about how pain turns the dial down and muscles go offline, and about the brainstem's own pain brakes. That story is usually local — a sore knee quiets the quad. This hypothesis proposes a second, body-wide version, run from the brainstem. It also fits what we see when a muscle tests strong but the body still does not feel right.

What a therapist can feel

The paper proposes a simple observation. You lie on your back and hold an arm or leg firm while the therapist gently tries to lift it. It is not a strength contest.

What we are feeling for is quality, not pounds. A limb with normal tone engages immediately and feels connected to your trunk. A limb with reduced tone engages late, feels like only the local muscles are working, and gives a different amount of resistance each try. The paper calls this the Limb Extension Resistance Assessment and uses it as test, treat, test again. What changes within a single visit is the interesting part.

What this hypothesis is — and what it is not

This is a hypothesis paper. It has not been tested in a controlled study, and the paper says so plainly. It lists the other reasons a limb might feel weaker on that test: you were not trying as hard, you learned the test, pain quieted the muscle locally, you were guarding, you were tired, the muscle itself was weak, you expected it to be weak, or the examiner lifted differently. The test is an observation, not a diagnosis. It does not measure your brainstem directly, and it sits alongside — not in place of — the established science on chronic pain, such as central sensitization and an over-revved stress system.

The paper also lays out what would have to be true for the idea to hold up: two therapists should feel the same thing, the result should be stable within a visit, and it should track with nervous-system measures like heart-rate variability. In Dr. Knudsen's words, this paper is the starting point, not the finish line.

One safety note. Weakness that comes on suddenly, affects one side of the body, or arrives with numbness, trouble speaking, or a severe headache is a medical emergency. Call 911 or see a physician first.

Why "get stronger" may be the wrong first step

If your pain has outlasted the injury and your whole body feels turned down, "get stronger" may be the wrong first instruction. Exercise builds muscle, but it may not by itself reset a dial the brainstem has turned down — and a program pushed onto a body running at low idle can feel like more fatigue. The order we work in at Muscle IQ is different: find what is turning the dial down, treat it, confirm with our hands that tone came back up, and then load the muscle. Pain causes muscle weakness, and muscle weakness causes pain. The key to long-term relief is finding the weakness and fixing its cause.

We can help. Strength is coming.

Take control of your health today by calling Muscle IQ at (801) 310-0851 to schedule your first appointment.

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