core strengthening for weak lower back

Question

I have a weak L3 (the 3rd disc up from my pelvis) - that is, it is given to pressing against the nerve, causing discomfort (no actual pain, as yet) locally and, when I don't pay attention for long periods, further across the muscles in my back.

This has caused me to significantly reduce weight carrying and my physiotherapist has advised me with a couple of exercises to strengthen my "core".

Are there any exercises this community can recommend which I can use to strengthen the muscles around the lower back and "core" in general which will aid in supporting the problem area and (specifically) avoid putting undue load/stress on it?

Given my limited physiology knowledge, this supplemental question would seem to appropriate: Are the following good/advisable "core" strengthening exercises...

1. dead lifting
2. plank
3. back curl

I have consulted my GP and my physical therapist and will continue to do so. I ask here a knowledgeable and passionate community their advice and experience while not implying that I would discard input from medical professionals.

EDIT: The exercises I’ve been given are...

1. The bridge
2. Curl Up (opposite of the curl down)

Answer 1

It sounds to me as though you need to move beyond the standard gym exercises that you have listed and learn segmental stability exercises. Let me explain. I'm going to be quoting directly from this paper.

The lumbar extensors can be grouped into global and local muscles. The global muscles includes the longissimus thoracis. The local, or stabilizing muscles, are primarily the multifidus. "Persons with low back pain often have isolated atrophy of the multifidus without atrophy of the other extensors. Multifidus atrophy tends to be associated with the segmental region of pathology. Despite evidence that impairment of the multifidus is generally localized to a small region in the lower lumbar spine, exercises intended to restore normal function of the multifidus often produce similar levels of activation across the extensors. "

In other words, most exercises, such as the ones you have selected, activate your entire extensor musculature, but do not isolate the area of the multifidus where you have pathology and where you need additional stability.

"Exercises that promote targeted activation where the extensor impairment is greatest (ie, the deep multifidus) would seemingly result in more effective rehabilitation of extensor muscle function."

So, it is widely believed that you need to select exercises that are specific to the segment of your lumbar spine where your multifidus is atrophied.

Now, this is where the field of physical therapy really lets us down. You want exercises that will focus on the multifidus around L3-L4? However, I can't find any research that tells us what these exercises are. It is a real shortcoming of the research.

You best option is to go to an good (very good) physical therapist, and they should be able to manually and verbally facilitate your form to show you how to activate the desired local muscle. The above mentioned research paper shows that proper manual and verbal facilitation can train people to locally activate the multifidus.

Let me know if this makes sense.

Answer 2

I am answering this followup question: To my understanding, muscles can only pull, so that sounds like they ...putting more pressure on the disc."

You are right that muscles can only pull. And yes, any time the muscles connected to your spine pull, they increase the global pressure on your discs. However, it is much more complicated than this. First, the compressive forces on your disks should be distributed evenly over the area of that disc; you don't want the compressive force to be focussed on the front or back of a disc, or on one side of a disc. The muscles of your spine can help keep compressive forces distributed evenly over the area of your discs. Second, typically compressive forces are not the problem; rather the problem is shear forces and rotational shear forces (e.g. Russian Twists). The musculature of your core and back can help minimize shear forces on your discs. In summary, even if the muscles of your back increase the net compression on your discs, the benefit you get from better control over shear forces outweighs the cost of some increased compression. It comes down to a cost benefit ratio.

Getting back to the multifdus, it is the multifdus which serves the function of controlling and managing forces - also know as stability. Your global back muscles like the longisimus are very bad at giving you stability. Exercises like dead lifts will recruit your global muscles but are widely believed by researches to be a bad strategy for strengthening a weak multifidus. You really need to see a physical therapist for guidance on exactly how you can address an atrophied multifidus. However, as a suggestion, I found this paper and the exercise in figure 9 looks very good for your core and multifidus stability. Unfortunately, a typical gym isn't going to have the kind of specialized equipment in that figure.