My lower back locks up after a long day of dh, if I lie down it just locks and I can't move. If I try it feels like a sharp pain on a nerve, but once I'm standing it disappears, won't come back till I'm lying down for another 15 minutes. Seen doctors about it a fair bit but every time I get told 'it'll go away', pretty much dismissing me even after mentioning its been happening for last 18 months. Physio was more helpful, but couldn't quite figure it out, gotta go back soon.
Scares me, I'm only 20 and I'm having trouble getting out of bed after a day of riding.
Hey mate, don't know how bike fit you are; or what you do for work/ study but if you're like me (3 days gym minimal stretching/ half day trail riding a week/ 5 days predominantly sitting work) I'm going to give you my .02 cents worth of non-qualified but reasonably well read feedback.
I suffer/ used to suffer more with lower back stiffness/ pain- really reduced range of motion when leaning over, super stiff and tight when carrying anything and felt like it was pulling way too much when lifting loaded objects (Romanian Deadlifts in the gym for example).
Sore lower back, tends to not actually be your lower back but imbalances elsewhere. In my case, due to riding half a day and packing straight back into the car with minimal stretching, a few gym sessions on a sub par stretching routine and then sitting at a desk for 90% of a 50ish hour week. Basically, half of your hip is overstretched in a seated position (chair or bike) and the other half is loose, leading to imbalance in strength in your hips- ever noticed how the chiro or osteo doesn't only work on the point of pain during a session.
The ligaments and muscles that hold your hips in line connect in many directions, including from the pelvis around the leg bone opening, anchored onto the pelvis at the back. When these become unstable/ not used correctly (root cause could be a sore toe, bad arches, sore knees, tight calf) your body has to adopt a slightly altered posture to make up for this ailment which in turn can change how muscles in your pelvis and hips work... which in turn makes these muscles (as they are not being used correctly) become tight, over a short period of time you'll notice this into your lower back, leading to tightness there too.
I'm not about to get all hippy on you, but foam rolling has some seriously well documented recovery benefits. Word of warming: buy a good roller and use a good program. Numerous techniques (albeit poor ones) can potentially exacerbate injuries. NEVER roll your lower back to "release" your lower back- the muscles will try to protect the spine but constricting around it, increasing the existing stiffness and potentially injuring you. Do your reading and I can guarantee that this will provide relief- if not from what you've described above, from all the other tight spots you don't realise.
Here's 3 videos. If you haven't foam rolled or ball rolled before the pain will be seriously bad news; imagine biting really hard on a sore tooth. Or pushing on a really crappy bruise. I'd be interested to see how you find the exercises/ results. Also important is to roll the whole muscle slowly, in small sections. Don't only focus on painful areas.
Here goes, happy rolling and pressing!
Tail bone and hip release
https://www.youtube.com/watch?feature=player_embedded&v=JXr1C4bEOCc
Inner thigh release
https://www.youtube.com/watch?feature=player_embedded&v=apTRZOJlqqY
Outer thigh and leg release
https://www.youtube.com/watch?feature=player_embedded&v=mrC5-HN_S3c