If you have gone to a doctor, a trainer, or even another PT about back pain, there is a good chance you got some version of the same diagnosis: weak core. And there is a good chance the fix they gave you was a handful of ab exercises, maybe some crunches, maybe a plank progression, with the idea that stronger abs would solve the problem.
That diagnosis is not wrong. Core strength really does matter for back pain. But your core is a five-part system, not just your abs. It includes the diaphragm, pelvic floor, deep abdominal stabilizers, spinal muscles, and hip and glute muscles that work together to support the spine and control movement. Ab exercises address one-fifth of that system. When the other four-fifths are undertrained or not functioning well, back pain persists no matter how many planks you do. That is why so many people do their ab exercises diligently for months and still do not feel any different.
Here is what the other four-fifths actually are, and why each one matters.
Anatomically, the core is often described as a box. The abdominal muscles form the front and sides. The muscles along your spine and your glutes form the back wall. Your diaphragm forms the roof. And your pelvic floor forms the floor. All five work together to manage pressure and stability through your trunk. Train one wall of that box and leave the other four untouched, and the box still is not structurally sound.
Deep Abdominals (Transverse Abdominis)
Wraps the trunk like a corset to stabilize the spine during movement
Diaphragm
Creates intra-abdominal pressure that supports the spine from the inside
Pelvic Floor
Manages pressure at the base of the trunk and coordinates with the diaphragm
Multifidus and Spinal Muscles
Provide segmental stability along the spine
Glutes and Hip Muscles
Control pelvic position and transfer force between the trunk and legs
When people are told to strengthen their core, most of the attention lands on the front wall. That leaves four-fifths of the system untrained, which is exactly why back pain persists for so many people despite consistent effort.
Yes, but probably not in the way you have been told. When most people hear weak core, they picture a six-pack problem. In reality, core weakness that contributes to back pain is almost always a coordination and deep-stability issue, not a surface-strength issue. The spine needs internal pressure management and precise segmental control, and those come from the deeper layers of the system.
Research published in the Journal of Physical Therapy Science by Hlaing et al. compared exercise specifically targeting the deep stabilizers, including the transverse abdominis and multifidus, against general abdominal strengthening. The targeted group came out ahead on proprioception, balance, and muscle thickness. Even within core work, what you are training matters significantly more than how many reps you are doing.
Transverse Abdominis
The deepest abdominal muscle layer. It wraps around the trunk like a corset and helps stabilize the spine during movement.
Standard ab exercises like sit-ups and crunches mostly target the more superficial rectus abdominis, not this deeper stabilizing layer. That is one reason someone can have visible abs and still have a core that is not adequately supporting their spine.
Planks and crunches are not bad exercises. The issue is that they are being asked to solve a problem they were never designed to address in full. A plank trains the front wall of the core to resist extension. A crunch trains the superficial abdominals through flexion. Neither one meaningfully addresses your breathing mechanics, your pelvic floor, your deep spinal stabilizers, or your hip strength. Prescribing them as the complete fix for back pain is like strengthening one leg and expecting both to get faster.
When someone tells me they have been doing core work for months with no improvement, the first question I ask is which parts of the core have actually been trained and which have not. The answer is almost always the same. The front wall got plenty of attention. Everything else was left out of the conversation entirely. That is not a failure of effort. It is a failure of the plan.
Most people do not think of breathing as a core exercise, but the diaphragm is the roof of that box, and it does real mechanical work for your spine. Every time you breathe properly, the diaphragm flattens downward and the lower ribs expand outward. That builds intra-abdominal pressure, which acts like an internal air cushion that stiffens and supports the spine from the inside, the same way air pressure gives a tire its structure.
Diaphragmatic Breathing
A breathing pattern that engages the diaphragm and allows the lower ribs and abdomen to expand during inhalation, creating intra-abdominal pressure that supports spinal stability.
The research on this is striking. A study published in Respiratory Physiology and Neurobiology by Janssens et al. found that people with low back pain showed significantly greater susceptibility to diaphragm fatigue compared to healthy controls, with diaphragm fatigue present in 80 percent of the low back pain group. When the diaphragm fatigues, the supportive tension it provides to the spine drops along with it.
And the problem compounds. People with chronic back pain do not just have weaker diaphragms. They breathe differently. Research published in the European Spine Journal by Roussel et al. found that more than half of patients with chronic non-specific low back pain showed altered breathing patterns during movements that challenge trunk stability, shifting away from the diaphragmatic pattern that actually supports the spine.
The good news is that this is trainable, and the evidence supports it. A randomized controlled trial published in the Journal of Chiropractic Medicine by Veqar et al. found that adding diaphragmatic breathing exercises on top of standard core stabilization work produced greater improvements in pain, muscle activity, and sleep quality compared to core work alone.
This is part of why someone can do their planks every day and still feel unsupported through their trunk. If the breathing pattern underneath the plank is shallow and chest-driven, the roof of the box was never fully engaged in the first place.
The pelvic floor is the bottom of the same box, and it is almost never mentioned when someone gets handed a list of ab exercises. It works in coordination with the diaphragm, the deep abdominals, and the back muscles to manage that same internal pressure system. When the floor of the box is not doing its job, the rest of the system has to compensate.
Pelvic Floor
A group of muscles at the base of the pelvis that work with the diaphragm and abdominal muscles to support the spine and manage pressure inside the abdomen.
The connection to back pain is stronger than most people expect. Research has consistently found that pelvic floor dysfunction and lumbopelvic pain co-occur at high rates, even in people who are not presenting with obvious pelvic floor complaints. A systematic review published in Physical Therapy in Sport found a significant reduction in pain severity when pelvic floor muscle training was added to an exercise program for nonspecific low back pain, compared to exercise alone.
This connection is not limited to the populations most people associate with pelvic floor issues, like postpartum recovery. It shows up across a much broader range of people dealing with persistent low back pain, including men, athletes, and active adults who would never think to connect the two.
The back wall of the box is made up of your spinal muscles and your glutes, and this is where hip strength fits into the picture. Of everything in the five-part system, hip strength, especially through the side of the hip, is one of the clearest indicators of how someone's back is doing.
Research published in the European Spine Journal comparing 150 people with chronic low back pain against 75 matched controls without pain found that hip abductor weakness was significantly more common in the group with pain. A separate critically-appraised review found evidence supporting gluteus medius and hip abductor strengthening specifically to improve low back pain in adults aged 30 to 50.
The mechanical reason is straightforward. The muscle on the side of your hip is what keeps your pelvis level every time you are standing on one leg, which is most of what walking, running, and climbing stairs actually are. When that muscle is weak, the pelvis drops or shifts with every step, and the low back ends up absorbing stress that the hip muscles should have been handling instead.
This is also where people get tripped up doing exercises that look like hip work but are not quite reaching it. An informal way to build some awareness: lie on your side and lift your top leg, and notice where you actually feel it working. If it is mostly your hip flexor, your lower back, or the front of your thigh rather than the side of your hip and upper glute, that is worth paying attention to. It is not a diagnostic screen, but it can give you a starting sense of whether those muscles are showing up when you train.
If any of the following sound familiar, there is a good chance that the parts of your core that have not been trained are the ones driving the problem:
• Back pain persists despite consistent ab or core exercise
• You feel unstable or unsupported during lifting, even with good form
• Sitting for long periods consistently makes things worse
• You notice shallow, chest-driven breathing, especially under exertion
• You experience hip fatigue or soreness during walking or running
• Balance feels unreliable, particularly on one leg
• Flare-ups keep recurring even when you are doing everything you are told
None of these are a diagnosis on their own, but they are patterns worth paying attention to. When the same back pain keeps returning despite genuine effort, the missing piece is almost always something the current plan is not addressing.
When someone comes in with persistent back pain and tells me they have already been doing core work, the question I am asking is which walls of that box have actually been addressed and which have not. Most people have only ever touched the front.
At 901 Physical Therapy, we regularly evaluate patients throughout Memphis, including those coming from East Memphis, Germantown, Collierville, and Midtown, who have spent months doing core exercises without meaningful improvement. In many cases, the missing piece is not effort. It is the fact that the plan was only ever addressing one-fifth of the system.
A full hour, one-on-one evaluation gives us the time to assess all five parts of the core system, identify what has actually been trained and what has not, and build a plan that targets whatever has been missing. As treatment progresses, all five parts come into the conversation, not just the obvious one. The plan that comes out of that process addresses what is actually driving the pain, which is usually more than one thing.
I do planks and crunches every day. Why has my back pain not improved?
Planks and crunches primarily train the front wall of your core, specifically the rectus abdominis and, to some degree, the obliques. The full core system also includes your breathing mechanics, pelvic floor, deep spinal stabilizers, and hip and glute strength. If those other parts are underdeveloped or not functioning well, ab work alone is often not enough to resolve persistent back pain. The missing piece is usually not more reps. It is addressing the parts of the system that have not been trained.
Are planks good for back pain?
Planks are not a bad exercise for back pain, but they are an incomplete one. A plank trains the front wall of the core to resist extension, which is useful. But it does not meaningfully train the diaphragm, pelvic floor, deep spinal stabilizers, or hip muscles, all of which play critical roles in supporting the spine. Whether a plank is helpful for your specific back pain depends on whether abdominal endurance is actually the limiting factor, which it often is not.
Can weak hips cause lower back pain?
Yes, and it is one of the more common contributors we see. The gluteus medius, the muscle on the side of the hip, is responsible for keeping the pelvis level during single-leg activities like walking, running, and climbing stairs. When that muscle is weak, the pelvis drops or shifts with every step, and the lumbar spine absorbs compensatory stress. Research published in the European Spine Journal found that hip abductor weakness was significantly more common in people with chronic low back pain compared to matched controls without it.
Does breathing affect back pain?
Significantly. The diaphragm is the roof of the core system, and proper diaphragmatic breathing builds intra-abdominal pressure that stabilizes the spine from the inside. Research has shown that people with low back pain are significantly more susceptible to diaphragm fatigue, and that more than half of chronic low back pain patients show altered breathing patterns during movements requiring trunk stability. Adding diaphragmatic breathing to a core program has been shown to improve pain, muscle activity, and sleep quality beyond what core exercise alone achieves.
What muscles make up the core?
The core includes five interconnected components: the abdominal muscles, including the deep transverse abdominis and the more superficial rectus abdominis and obliques; the diaphragm, which forms the roof; the pelvic floor, which forms the base; the multifidus and spinal erector muscles along the back of the spine; and the gluteal and hip muscles that control pelvic position and force transfer. These five components work together as a pressure and stability system. Weakness or dysfunction in any one area affects how the entire system performs.
Why does my back still hurt after strengthening my abs?
Because abdominal strength is only one-fifth of the core system that supports your spine. If your breathing mechanics, pelvic floor function, deep spinal stabilizers, or hip strength have not been addressed, the underlying instability persists even though the front wall of the core is getting stronger. Persistent back pain despite consistent ab work is one of the most reliable signs that the other parts of the system need attention.
How is the pelvic floor connected to back pain?
The pelvic floor forms the base of the core system and works in coordination with the diaphragm and deep abdominals to manage intra-abdominal pressure. When the pelvic floor is not functioning well, the entire pressure management system is compromised, and the spine loses a layer of support. Research has found that adding pelvic floor training to a back pain exercise program significantly reduces pain severity compared to exercise alone. This connection exists well beyond populations typically associated with pelvic floor issues and shows up across a broad range of people with persistent low back pain.
How do I know if my hips are actually weak?
A proper hip strength assessment involves multiple clinical tests from several angles and positions. At home, an informal starting point is lying on your side and lifting your top leg while paying attention to where you feel it working. If the effort is mostly in your hip flexor, lower back, or the front of your thigh rather than the side of your hip and upper glute, that is worth noting. It is not a substitute for a clinical evaluation, but it can give you a starting sense of whether those muscles are contributing to your movement the way they should be.
If the patterns in this post sound familiar, here is the most direct path to figuring out what your plan has been missing.
If you have been doing core exercises for weeks or months without meaningful improvement, there may be more going on than abdominal weakness alone. A comprehensive physical therapy evaluation can identify whether breathing mechanics, hip strength, pelvic floor function, or movement patterns are contributing to your symptoms.
At 901 Physical Therapy, we help active adults throughout Memphis uncover the real drivers of persistent back pain and build individualized plans that address the entire system, not just the part that is easiest to train.
Curious which parts of your core have actually been trained and which have not?
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