I find it easier to explain lordosis than to simply tell you "do this, don't do that," because understanding the condition will help you a lot better than me listing off some exercises which you might do poorly, resulting in continuation of the condition. That said, I will get to some exercise prescription, I just need to cover the basics first. Please note that the following is looking at things from a rehabilitative perspective, and that all my study and personal experience indicates to me that attempts to improve general strength may at this stage make it harder for you to correct your posture (as will be explained throughout the post).
Lumbar lordosis can be causd by any of the following 4 muscular imbalances:
- Hip flexors too tight
- Lower spinal erectors too tight
- Hip extensors too weak
- Lower abs too weak
Lumbar lordosis also often occurs relative to thoracic kyphosis, as a way of evening out the gravitational forces on the spine. Thoracic kyphosis often occurs as a result of the following muscle imbalances (but is much more structurally based and thus harder to treat):
- Weak upper spinal erectors
- Weak lower trapezius
- Tight pecs
- Tight upper abs
Treating either/both issues is not as simple as elimination or modification, because if you look at the way the body moves as a unit, one part that is too weak often works with one part that may be too tight.
If a muscle is particularly tight or overstrong, it will tend to take over the movement. So, in the case of normal sit-ups, tight hip flexors will take over for the abs, especially if the lower abs are also weak. So before you can do much about improving the weak muscles, you will most probably have to deal with the overstrong muscles. The best thing you can do with minimal/no assistance is stretching the overstrong muscles daily (preferably several times a day). Expect it to take about 6 weeks to see improvements.
Once you've made some progress with deactivating the overstrong muscles (through regular stretching, and probably with the assistance of physiotherapy techniques such as trigger point release), you'll be far more productive at learning to use the weak muscles, as the overstrong muscles are less likely to get in the way. At that point, the following low-level exercises may come in quite handy:
- Pelvic Tilt (for abs): Stand with the back of your hips, head and shoulders against a wall. Activate your abs by drawing your navel inward, and tilt your pelvis backwards, drawing your lower back towards the wall.
- Glute Raises (for hip extensors): Lying face-down with your legs hanging over the edge of the bench, raise one leg at a time up to horizontal. Lift with your gluts, keeping your lower back relaxed.
- DB Straight Arm Extension (for lower traps/thoracic extensors): Lying face-down, with your arms straight and at your side, hold a light DB in each hand, activting your lower trapezius muscles to hold the weight.
- Practice standing with good posture. Imagine a string pulling you up through the back of your head, and lightly tighten your gluts and core to get that posterior pelvic tilt (in actuality, you don't want a posterior tilt which results in flat-back, but you need to activate the muscles as if you're trying for it to reduce the anterior tilt which promotes lordosis).
These of course are very basic exercises, but if you want to correct your posture, you gotta master these before you move on. You should be ready to progress in 3-6 weeks. Progressive exercises will include horse stance, bridge/hip thrusts, and light deadlifts/rowing. After another 6-12 weeks, with continued stretching and strengthening, you should be about ready for normal strength training. Pay close attention to technique, make sure that your muscles are activating the way they should, and you should be right. Once you have good posture, it's not so difficult to maintain it, as all you need to do is make sure you have good, strong posture in every exercise, use properly balanced functional routines, and keep checking posture outside of the gym. Master technique in exercises at low weights (by which I don't mean high reps; I mean that if you want to do 10 rep sets (for example), start learning exercises at a weight that is easy to do for 10 reps, do 10 reps per set, and progress up in weight until it becomes hard to do 10 reps), and make sure technique is correct for every rep, no matter how heavy you go. If it's too heavy to do with perfect form, then it's too heavy.