How to Tell if Hamstring “Tightness” is Nerve or Muscle Tension
How to Tell if Hamstring “Tightness” is Nerve or Muscle Tension
Riddle me this: When is a forward fold not a hamstring stretch?
. . . OK, the blog post title kind of gives the answer away to this one, but the answer is: when it puts your sciatic nerve on too much tension. (Although bonus points if you came up with the other acceptable answer “when you bend your knees a lot”)
If you have been trying to stretch your “tight” hamstrings but have seen limited progress, or if you often feel hamstring stretches in your calves or low back - it may not actually be your hamstring muscles that are the problem - it may be your sciatic nerve!
Last week I wrote about “Diagnosing” Muscle Tightness vs. Nerve Tension where I talked about the nervous system’s role in flexibility training and how to deal with “nerve tension” at a high level. This week we’ll specifically look at sciatic nerve tension and how to tell if the tightness you feel in a traditional hamstring stretch is actually muscle tightness or if it’s possibly coming from nerve tension (and how to adjust your training accordingly!).
(Friendly reminder - this post isn’t meant to diagnose any medical condition, such as sciatica, which is a whole different animal. If you have any form of chronic discomfort or pain you experience outside of stretching, see a medical professional!)
Sciatic Nerve Anatomy Overview
Our sciatic nerve runs from our skull, down our spinal cord, out some of the vertebrae in our lumbar and sacral spine, through the back of our hips, down the backside of our leg and calf, around our heel and the bottom of the foot all the way to our toes. It does branch out to several muscles on the way (not shown in the diagram - if you’d like to learn more this is a great 3 min video).
For the purposes of talking about nerve tension, it’s helpful to understand that it runs from your head to your toes, and it crosses several joints: the neck, back, hips, knee, and ankle. When we move those joints our sciatic nerve has to move too.
As discussed in last week’s post, nerves don’t stretch, but rather they slide back and forth through our soft tissue, much like how you could pull a piece of yarn through a straw. In situations where the nerve can’t slide back and forth comfortably (such as part of the nerve is being compressed by a tight muscle), this leads to nerve tension where the nerve is getting tugged too tight and can’t move. This can feel like an intense stretch, tingling, or other discomfort. In these situations, trying to push the stretch only increases the nerve tension, further aggravating the nerve, and tightens your muscles even more. Not helpful!
The most confusing (and frustrating) part for people trying to stretch is the fact that nerve tension can feel like an intense stretch, and the sensation alone may not feel any different from a muscle stretch. So it’s important to know how to evaluate whether they sensations you are feeling while doing a stretch like a forward fold are actually due to a muscle stretch (great! keep stretching!), or actually due to sciatic nerve tension (woah! dial it back! modify the stretch!).
How to Test for Sciatic Nerve Tension
There are a bunch of different ways you can do a quick self-test for sciatic nerve tension, I like doing this one sitting in a chair because anyone can do it, no matter how tight (or flexible) your hamstrings are.
1. Start in a pike position with feet flexed: Start sitting in a chair with your back flat (no slouching!) and your legs stretched straight out in front of you, feet flexed and heels about hip width apart on the floor. If you can comfortably do a pike stretch sitting on the floor, you can sit on the floor instead of a chair.
2. Forward fold (pike stretch): Keeping your back flat (don’t let it round), start to lean forwards, hinging at the the hips, until you start to feel a deep stretch. Notice:
What’s your range of motion? How far can you lean forwards maintaining that flat back? Where on your legs or the floor do your fingers touch?
What are you feeling? A gentle stretch? An intense stretch? Any pain or discomfort? Tingling?
Where are you feeling it? In the underside of your thighs (hamstrings)? Calves? Feet? Back? Neck? All of those places?
How intense are the sensations?
3a. Point/Flex Test: Keeping your back, pelvis, and legs in the same position, point your feet (this will reduce the amount of tension on the sciatic nerve). What do you notice? Do any of the sensations above change? Get easier/lighter/more comfortable? Can you reach your hands a teeny bit farther (without rounding your back)? You can even alternate pointing and flexing your feet a couple of times and noticing what (if any) sensations change in your forward fold
If the sensations in your body stay the same regardless of whether you point or flex your feet, then what you are feeling is likely not due to sciatic nerve tension (since pointing and flexing the feet or flexing or extending the neck both add and reduce tension, we’d expect the sensations to feel different). If this is the case - lucky you, you don’t need to worry about adding any nerve glides into your stretching routine
If the sensation in your hamstrings, back or neck gets more comfortable when you point your feet (which does absolutely nothing to change the muscle length of our hamstrings, back or neck muscles), then you’ve likely got a bit of nerve tension and you’re noticing it diminish when you put the nerve on slack by pointing your ankles
If the sensation in your feet or calves gets more comfortable when you point your feet - we don’t yet know if this is due to the changing the muscle length (since we just removed the calf and bottom of the foot stretch) or nerve tension, or something else.
3b. Forward Fold Test: Return to your flexed foot forward fold and note the sensations you feel in your forward fold. This time we’ll keep our foot and calf and foot muscles the same, but use a different way to reduce the nerve tension: Keeping your feet flexed, knees straight, and back flat, slowly lift and lower your torso. Do any of the sensations change?
When we lift our torso (tilt our pelvis back) we are lessen the hamstrings stretch, and when we lean forwards (tilt the pelvis forwards) we’re increasing the hamstrings stretch - so that’s an expected sensation change based on changing length of our hamstring muscles
But what about any sensations in your feet or calves? Hinging at the hips does nothing to change the length of those muscles, so if your calf or foot sensation all of the sudden lessens, it’s likely because we just put the sciatic nerve on a bit of slack by lifting our torso
The first time I did this test, my mind was totally blown. I notice a fairly large difference in what feels like a “calf stretch” when my feet are flexed, and I alternate leaning forwards and backwards. I always assumed it was because I had “tight” calves. But thinking about it logically, none of that torso leaning and lifting was altering my calf muscles in any way, so it makes sense some other structure (the sciatic nerve!) was likely at play.
So I’ve Got Some Nerve Tension - Now What?
If you are like me and have some sciatic nerve tension - this means keeping a couple of things in mind when you are training:
Avoid stretching in positions that maximize (aggravate) that nerve tension. Remember, nerves don’t respond well to being put under tension for a long time, and that can actually make you more tight as nerve tension increases and your nerves fire to increase muscle tone (the sensation of tightness). The stereotypical standing forward fold with straight legs where you round your back to reach your hands to your feet is literally the worst possible position (for people with sciatic nerve tension) because it maximizes the amount of tension on your sciatic nerve.
Modify your stretches to choose versions that minimize nerve tension. That means trying to find your hamstring stretch while adjusting your joints to put your sciatic nerve on a bit more slack:
Keeping your back flat
Bending your knees
Pointing your toes
Add in a gentle sciatic nerve glide to your warm up before stretching
Consider foam rolling or peanut-ing the affected area where you feel nerve tension before stretching. For example, if you generally feel the tension manifest in your calves, rolling out your calves or placing a lacrosse ball or peanut under your calves while you point and flex your feet can sometimes help.
Long-term solution: train your muscle engagement at end range so that both our big muscles (ex. hamstrings and hip flexors - like these drills) as well as our smaller stabilizing muscles (ex. our hip rotators - like these drills) can properly support the nervous system in positions that put the sciatic nerve on tension.
Tell Me How You Feel!
I’m always curious to hear from students what they feel in the sciatic nerve tension test exercise because lots of people feel nerve tension manifest in different places. For me, I notice a deep stretching feeling in my calves, and on days where I have a bit higher nerve tension, some tingling in my feet (both of which improve significantly after doing some nerve glides and tensioners). What do you feel? Let me know in the comments!
