does that mean saddle and handlebar at same height ? Also is it a road bike?

I have a fitness bike it’s where comfortable , and handle bars are slightly below saddle

About 3 miles at a 3 mph pace. When I walk specifically for back rehab, I use a special motion, rotating each hip in a circle as best as I'm able. When I've been fixing a sciatica attack, that hurts like the devil for the first mile, then gets better. If you don't have pain while walking just a normal walk works fine. Oddly or perhaps not oddly at all, walking seems to be about the best core exercise, works everything. I guess that makes sense, after all we are bipeds and are supposed to be walking during many of our waking hours, but we don't do that much now that everything is mechanized - and the bike is also a machine. Thus many of our core muscles are activated specifically by walking - that's what they're for.

Now seeing downtube42's post, it's totally normal for muscle exercise to produce soreness about 48 hour later, known and DOMS - Delayed Onset Muscle Soreness. It's normal, just means you did something unusual or did it more than has been usual recently. Since pedaling activity varies with the individual, the amount of activation of the posterior chain also varies. Those who activate that muscle chain on the bike are more likely to get a sore lower back from greater than usual cycling activity. That's a decent theory anyway, not a proven result.

That said, I've found that strengthening my whole posterior chain reduces or eliminates my back pain after riding. My favorite over time has been the Romanian deadlift, relatively light weight, high reps, a full stop at the bottom, no jerking. For this old man, say 40 reps with 100 lbs. but start with way, way less.

This was my first thought in reading the original post. I've never had back pain from cycling, but a few days ago I strained my back from lifting something too heavy. It's not a bad strain, but I can feel it when I'm walking. I've been riding every day and don't notice the back pain when I'm riding, and it's not worse when I finish. From my experience, cycling should not cause back pain. Others may have different experiences, but my thought is that if you ride with good form (and the bike fits you), you shouldn't get back pain from riding.

I’d recheck the fit first by shortening the reach or raising the bars a bit. Strengthening my core and loosening tight hips and hamstrings made a big difference for me too.

I'm surprised that none have ask where the back pain is. Upper back between the shoulders. Lower back at your waistline? As well, how often and how long you ride your bike will be nice information. And even what type of bike it is can help us imagine how you fit to it.

Do you stay hydrated and drink plenty of fluid while you ride?

I gave up MTBing 10 years ago for several reasons, a minor one being that the upright position was causing lower back pain. Now, at 80 yrs I find the most comfortable position on a bike is in the drops and I have no back pain with 50 mile rides pretty normal at least once a week. Most averaging 20 6 days a week. Proper fit on a bike makes all the difference in the world.
I should be more specific about lower back pain, it was more like tail bone.

Zombie thread resurrected.

Well I for one, am embarrassed I failed to notice. I try to check the original post date.

Thanks for the warning... even if too late for me.

Lowered my bars to cm and started having lower back pain after the ride. Worked on core exercises and it disappeared. Unrelated to cycling, or so I think - since it’s been cronic, I have muscle related hip pain on one side. Am currently doing PT to strengthen my ‘very weak back’ according to the PT. I hate the exercises, but time will tell - he said my core is overcompensating for my back and time to get the two in balance. So strengthen both.

I see others have suggested "stronger core" muscles. It's common, Work on the strengthening. And work on "proper" pelvic and back position during riding. Get these "wrong" for you, or do it too long, and you might well ache later. It's common.

In my own case, I've got an old injury to muscles in one leg and hip. Muscles only. Lots of scar tissue. Big problem with remaining limber enough in a handful of muscle areas: hip flexors, groin, hamstrings, glutes, and low-back muscles. Invariably, if I find myself sitting too much and not paying enough attention to ensuring I remain flexible enough in those particular muscles, I find myself getting some low back pain. IMO, it has to do with the pelvic tilt, which those old injures seriously get in the way of maintaining during rides. But being flexible enough on those particular muscle areas really helps, in my case.

One more option, if you don't find the other things improve it.

Strengthen your core. Many years ago I had a similar experience and started doing core exercises, That fixed it. Full stop.

Good recs on core strengthening. I did a lot of core work and it helped a great deal for life in general. Lot’s of videos out there on core work for cyclists. However, I neglected doing back specific strengthening exercises which resulted in a super strong core (not six pack abs by any stretch of the imagination) but to the detriment of my back muscles which resulted in pain during prolonged standing in my glute region. So now I am doing PT to get my body back in balance. Morale to the story, do core AND back exercises. Another issue is having strong quads (an issue? Seriously? says backwards hat Dylan) which also threw my back out of balance. So my exercise should help with that imbalance as well.

I agee on the importance of core strength, and offer my experience. I've only been riding eight years (started at age 67) and my core strength has increased noticeably from cycling. I don't do any core exercises other than cycling. It's the cycling itself that has strengthened my core. I'm not saying you shouldn't do other core strengthening exercises--just saying that I'm too lazy to do them. And, observing that cycling alone with noticeably strengthen your core. I'll also add that prior to cycling I was a runner, so I was not out of shape when I started cycling. From my observation, cycling will do more to strengthen your core than running.

Fish on!