Types of Pain
Differentiating nerve pain from muscular pain can be tricky; there are similarities, but there are also key distinctions. Generally speaking, the causes of pain are multifactorial. The thing we perceive as pain is influenced by our anatomy, physical tissue damage, the activity of our nervous system, life stressors, socioeconomic status, access to healthcare, and other factors.
We classify pain in multiple categories:
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Nociceptive pain: This occurs from actual or threatened damage to the physical tissues of our body. Think muscle strain, rolled ankle, etc.
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Neuropathic pain: This is caused by a lesion or disease in our nervous system. Think sciatica (more on that later), shingles, or diabetic neuropathy.
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Nociplastic pain: This occurs from an altered pain perception with no identifiable tissue lesion. This occurs in people suffering from chronic low back pain, fibromyalgia, or chronic pelvic pain.
This article will focus on differentiating muscular pain, which typically falls into the nociceptive pain category, from nerve-related pain, which can be lumped into the neuropathic category. Important to note, complex pain syndromes such as those that fall into the nociplastic category result from our nervous system not working correctly. Nociplastic pain is especially complex, and I will forgo going into too much detail on it here. People have written textbooks on the topic, and there are great researchers such as Adrian Louw who explore the topic in sufficient depth.
Muscle Pain
Muscle pain can be caused by a plethora of things, including
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Muscle strain
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Delayed onset muscle soreness
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Tendinopathy: tendon pain/dysfunction between the muscle and the bone
Characteristics of muscle pain
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Localized to one area
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Bruising
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Swelling
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Tender to touch
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Pain with muscle contraction
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Pain with passive stretching
Muscle is highly vascularized. When there is a muscle strain or tear, it will bleed and cause swelling and bruising. Muscle is also heavily innervated by nerves, which means that muscle strains are normally quite painful.
Other Reasons for Muscle Soreness
Muscles can also become sore from exercising. Delayed-onset muscle soreness is the muscular soreness we feel in the days after a good workout, particularly if we have not done that activity in a long time. Interestingly, eccentric muscle contractions are more associated with muscle soreness than concentric exercises. This is the lengthening phase of a muscular contraction. An example of this occurs in our quad muscles as we run. Every time our foot strikes the ground, our knee flexes as it controls our impact with the ground. During this phase of the gait cycle, the quad lengthens. This mechanism makes us more sore than a concentric contraction. Using our running example, a concentric contraction would be our quads during the push-off phase of the gait cycle, when our knee is straightening.
This is why running leaves you more sore than biking. When running, you are repeatedly eccentrically contracting your muscles as you impact the ground. When biking, you are concentrically contracting your leg muscles with each pedal. The end result is more soreness after a run.
Nerve Pain
People often describe nerve pain as:
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numbness
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tingling
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shooting
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weird
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achy
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radiating
In order to better understand nerve pain, let’s use the term “sciatica” as an example. Colloquially, sciatica is typically used to describe pain that radiates down the leg. The sciatic nerve originates from the lumbar spine and traverses down the posterior leg. As it descends, it traverses around a plethora of structures and forms different branches that innervate our muscles, joints, and other tissues. The efferent nerves innervate the muscles and carry the signal to contract the muscle from the brain. The afferent nerves innervate our sensory structures, such as the skin, and form nerve endings in our joints, which facilitate proprioception, or our awareness of where we are in space. These nerves carry signals to our brain, which our brain interprets as different sensations.
The confusing part about the term sciatica is that radiating leg pain can be caused by nerve irritation at a multitude of locations. For example, one of the nerve roots of the sciatic nerve is irritated at the level of the spine, we would call this a radiculopathy. In this scenario, a medical provider might focus on the back for their treatment plan.
Further down the chain, the sciatic nerve runs near a muscle called the piriformis. You may have heard the term “piriformis syndrome.” This is a condition where the sciatic nerve is irritated by the piriformis muscle due to its anatomical proximity to the piriformis muscle. In some people, the sciatic nerve actually splits through this muscle, potentially increasing the chances of sciatic nerve irritation.
To complicate things even more, a nerve can become damaged after becoming pinched off for a long time. Our nervous system is greedy, consuming a great amount of energy, oxygen, and blood flow. If blood flow is restricted to the tissue, nerve damage can occur. Thankfully, our nerves have the capacity to heal after becoming damaged. The bad news is that nerves heal at a very slow rate. Nerves heal at about 1 millimeter per day. If you have radiating leg pain, down to your foot, it is understandable how this can take time to heal.
Treatment of Muscular Pain vs Nerve Pain
Similarities
The treatments for muscle pain are different than the treatments for nerve pain, though there is some overlap. For example, you don’t want to stretch a muscle strain, because this could make the strain worse and increase the tearing in the muscle belly.
For both types of pain, a doctor or other medical professional may recommend a combination of medications and lifestyle modifications in order to address the underlying dysfunction. Bonus points if they recommend seeing a physical therapist for a full evaluation to get a tailored exercise regimen (in many states, you can see a physical therapist direct access; meaning, you do not need a referral from a physician).
Differences
Managing muscular pain
There are some key differences in treating muscular pain. For example, for DOMS following a workout, static and dynamic stretching can be a great way to reduce soreness. Another way to reduce symptoms of muscular soreness is to do active recovery; going for a light jog, walk, or bike ride can all expedite the healing process. On top of that, manual techniques can be great as well. Using a tool like the QL Claw can target the hard-to-reach areas that are sore and provide pain relief to speed up recovery. There are some great resources on this site for specific protocols for targeting different muscle groups to reduce pain and improve function. Additionally, strengthening exercises work great for a swath of musculoskeletal conditions.
Managing nerve pain
The treatment of nerve pain is usually a bit more complex. It involves a more targeted, customized approach including education, exercises, and potentially medication. If you think you have more nerve-related pain, excessive stretching or self-massage can make symptoms worse.
One clinical example of this is when patients complain of having tight hamstrings. One thing many people do, as it makes intuitive sense, is to stretch something when it feels tight. Someone may come into a PT appointment and state that they have been stretching the crap out of their hamstrings, but their tightness seems to be getting worse. Oftentimes, the patient will have some nerve tightness, rather than muscular tightness. Different exercises are recommended for this type of pain, which normally include nerve flossing, going for walks, and other targeted strength exercises. This is something that a more targeted approach by a medical professional can help with if you are suspicious of an angry nerve
Muscular vs. Nerve Pain Conclusion
Now that we have discussed the types of pain, anatomy of the nervous system, and how to differentiate and treat different types of pain, you can be better equipped to use different strategies to reduce your symptoms and improve your function.
Until next time!
Sources:
[1] https://my.clevelandclinic.org/health/body/21202-nervous-system
[2] Davies, Clair, and Amber Davies. The Trigger Point Therapy Workbook: Your Self-Treatment Guide for Pain Relief. 3rd ed., New Harbinger Publications, Inc., 2013.