: If my lower back feels tired after squats, am I doing something wrong? When I squat, I tend to squat very deeply. Lately I've been noticing that my lower back feels a bit worn out afterwards. It doesn't hurt - I don't feel

Lower back soreness can be indicative of bad form or it can be indicative of heavy barbell squats. It's impossible to tell which from just the information that it makes you sore.

This is because heavy squats are not a leg exercise: they are a legs, butt, lower back, and upper back exercise. The lower back is generally the point of failure in maximally loaded barbell back squats, and so often is the most sore.

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As commented by others, without seeing a video of your form or knowing a bit more information it is hard to say if you are doing proper form 100%. Even then, sometimes what one person feels is proper form and causes 0 pain, someone else might have a different reaction. I find this true especially with squats.

You might want to pay attention to how straight your back is, the direction of your legs / knees, and how low you go before you might feel the discomfort.

I found an article which elaborates on this:

The simplest way to fix lower back rounding on the Squat is to push
your knees out harder on the way up and down. If your knees point
forward or in, your lower back will usually round. So Squat with your
heels shoulder-width apart, toes out 30° and push your knees to the
side as hard as you can.

Next don’t Squat lower than parallel. Many people lack the flexibility
to Squat ATG (“ass-to-grass”). If you lack the flexibility to Squat
all the way down, until your butt touches your ankles, your lower back
will have to compensate by rounding at the bottom. This can result in
lower back pain.

Read the full article here

Also give front squats a try. I wouldn't replace regular squats with them, but alternating might give your lower back a break and let you get more insight on whether it is the muscle that isn't adapting or your form that is causing the issue.

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Reason 1 - you got weak low back. That is why better for you to start do exercises for your low-back separately. Don't do squats with a bar on your shoulders, move it on your chest (google front squats) or do squats at Smith, but don't put leg right under the bar - your coccyx should be right under the bar, put legs forward for this, and of course your back should be straight.
Reason 2 - your legs. Maybe the proportion between your femur and shin is special, and makes angel between your body and legs too small. That is why you feel strain in your low back. There are 2 ways to solve this problem - again, put the bar at front of you, on your chest, or don't do full squats, just do it until you feel strain in you femur.
Reason 3 - you got problems with your low back. Visit your doctor!
Reason 4 - the weight is too big for you or your femurs are not stretched enough. So spend more time with stretching. And do squats using low weights in superset with dumbbell stiff legged deadlift
Reason 5 - wrong technics. To check it use an exercise - squats with hands on the wall. (youtube video with an example -

If you feel too much strain in you femurs, that probably means that your technics is not correct.
Sorry for my English - it's not my native

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You should also look at doing some mobility work. There's a "Limber 11" video by a guy called Joe DeFranco on youtube. i started doing this a few times a week and my back feels much better on leg days.

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