Every morning you have to sit for a while after getting up before you can bend forward. The band of muscle on the right side of your lower back has been stiff since you slipped in the bathroom last year. Back then the sharp pain lasted a few weeks and then eased, and the scans showed nothing worrying. Now, after more than half an hour of driving, that band of muscle is as tight as a guitar string. Rubbing in liniment, a warm compress or stretching softens it for half a day, and the next time you walk down the stairs it clenches up again. A neck after one sudden braking, or an ankle after one bad roll, often leaves this kind of pain too, and people tend to hold back from mentioning it because every place they have been checked says it has healed.
The injured spot has healed, but the signals from it have not
Tendons, ligaments, joint capsules and the belly of each muscle contain a great many tiny nerve endings, called sensory receptors. Some report how stretched a muscle is, some report the angle of a joint, and some report pressure or pain. Thanks to them, the brain knows how far your back is bending, or whether your foot has touched the step, without having to look. Right after an injury, signals from that area pour in, and the brain switches the whole area into protection mode: the muscles around it brace and movement becomes guarded. In some people that mode keeps running after the tissue has healed, and the receptors in that area go on sending the old signals.
In people with long-lasting neck pain of no clear cause, a review by Stanton and colleagues (2016) pooled 10 studies and found that they brought the head back to an upright position less accurately than healthy people. Sensing the position of the head is the job of the proprioceptors in the neck (the receptors that tell the body where its parts are), so that result suggests these receptors are sending back distorted signals.
Some people hurt far more than the damage that can be found. Long-lasting pain trains the spinal cord and brain to amplify pain signals, as our article when old emotions help keep pain going describes. Fitzcharles and colleagues (2021) place pain like this in a group of its own, called nociplastic pain (pain from altered pain processing), and note that this group responds poorly to approaches that target only the painful spot.
The muscle never gets the signal to rest
When you bend your elbow to lift a glass of water, the biceps at the front of the upper arm contracts, and at the same moment the nervous system tells the triceps at the back to let go a little so the movement runs smoothly. In Applied Kinesiology (AK), a muscle is called hyper-reactive when it does not let go when it should. That muscle works all day, even while you lie resting. It feels harder than the area around it, sometimes lumpy with small knots. Over time it pulls your posture out of line and makes other muscles carry extra load.
The source is sometimes far away. One leg that is shorter than the other can tilt the neck, so the neck muscles on the opposite side have to stay tense all day to keep the head balanced. That person goes to get treatment for a tired neck, when sometimes the part that needs a second look is the legs.
Beyond structure, a micronutrient shortage or the side effects of a medicine you are taking can also keep a muscle clenched, and so can long-lasting stress. In some people, muscle testing also points to an imbalance that the clinic places in the energy layer (the chakras, the aura field and the meridians), and the doctor checks this part gently along with the others.
When an old pain needs to be checked again soon
Pain after an old injury usually stays in one place and goes up and down with what you do during the day. Pain that gets worse at night, pain with fever or unexplained weight loss, and numbness or weakness in the arms or legs that keeps getting worse are signs you need to be seen soon, before thinking about receptors. Our article an overview of back pain explains why a back can still hurt when the scans are clear, and lists the signs that call for further imaging or tests.
After an injury to the neck area, such as a sudden braking or a fall where you hit your head, dizziness, double vision or numbness in the arms means you need to see a neurologist first. If one side of your body has become weak after a fall, see also our article on shoulder pain after a fall.
Tracking down receptors that still misreport, with P-DTR
Dr. Dinh Ngoc Duc (MD, MSc in Traditional Medicine) usually starts with a list of your old injuries, including that sprain back in your school days, and then asks when the muscle feels tightest and after which movement. The once-injured areas on that list are the places to search first, even when they lie far from where it hurts now.
The doctor uses muscle testing on a muscle that is currently strong as a reference, called an indicator muscle. A stimulus fed into the nervous system can make the muscle stronger (facilitation) or weaker (inhibition), and manual muscle testing picks up that change (Schmitt and Yanuck, 1999). The doctor asks you to place your hand on the ankle you once rolled, or on the spot in your lower back that once hit the floor (therapy localization). If the indicator muscle loses strength while your hand is there, that area is still sending unusual signals.
P-DTR (Proprioceptive Deep Tendon Reflex) is a branch of AK in the direction of functional neurology, developed by José Palomar, that focuses on finding which type of receptor is misreporting. The doctor tries each kind of stimulus on the suspect area: a very light touch, deep pressure, stretching the skin, moving a joint to a particular angle. Whichever stimulus changes the indicator muscle tells the doctor which type of receptor needs attention. While you hold the stimulus just found, the doctor taps a tendon reflex, like the small hammer tap below the kneecap in a neurological exam. As P-DTR explains it, that reflex helps the nervous system read the signals from that area correctly again.
After that step, the doctor touches the old area once more to compare it with the start. Then you bend forward, or step down a stair the way that used to hurt, and feel for yourself whether the movement is easier. The whole procedure consists only of short touches, presses and taps, much like a neurological exam.
If muscle testing also points to a micronutrient shortage, the doctor adjusts the nutrition side. When a muscle has been clenched for many years and the pulse shows that the qi and blood in the meridian running through that area are stagnant (气血瘀滞 / 氣血瘀滯, qì xuè yū zhì), the doctor adds a few acupuncture points along that meridian. You will also be shown a few exercises to do on your own, so the once-injured area gets used to moving normally again.
Worth keeping
- Write down your old injuries, including a sprain or a slip that seemed minor, with when it happened and which way you fell;
- Notice when in the day the muscle is tightest and after which movement, so you can tell the doctor;
- Bring a list of the medicines and micronutrients you are taking, since they can also keep a muscle braced;
- If the pain gets worse at night, or comes with fever, weight loss or numbness and weakness that keep increasing, get checked soon;
- If you have dizziness, double vision or numb arms after a neck injury, see a neurologist first.
References
- Stanton TR, Leake HB, Chalmers KJ, Moseley GL (2016). Evidence of Impaired Proprioception in Chronic, Idiopathic Neck Pain: Systematic Review and Meta-Analysis. Phys Ther 96(6):876-87. https://doi.org/10.2522/ptj.20150241
- Fitzcharles MA, Cohen SP, Clauw DJ, Littlejohn G, Usui C, Häuser W (2021). Nociplastic pain: towards an understanding of prevalent pain conditions. Lancet 397(10289):2098-2110. https://doi.org/10.1016/S0140-6736(21)00392-5
- Schmitt WH, Yanuck SF (1999). Expanding the neurological examination using functional neurologic assessment: part II neurologic basis of applied kinesiology. Int J Neurosci 97(1-2):77-108. https://doi.org/10.3109/00207459908994304
