Chronic Low-Back Pain? Build Core Strength Without Repeatedly Bending Your Spine
- drjoeferetdc
- 5 days ago
- 13 min read
Many people with chronic low-back pain are told that they need a stronger core.
That advice sounds simple—but what should you actually do?
Traditional sit-ups and crunches repeatedly bend the lower back. For some people, especially those recovering from certain disc injuries or flexion-sensitive back pain, repeatedly moving through that position may feel uncomfortable or aggravating.
The McGill Modified Curl-Up takes a different approach.
Instead of repeatedly rounding the lower back, the exercise asks your abdominal muscles to brace and stabilize your spine while you gently lift your head and shoulders.
It is not about completing hundreds of repetitions or chasing a burning sensation in your abs.
It is about developing controlled core endurance while maintaining a comfortable spinal position.
Watch Dr. Joe Demonstrate the McGill Modified Curl-Up
In the video below, Dr. Joe demonstrates the setup, movement, and important details of the modified curl-up.
The movement should be small.
You are not trying to sit all the way up. You are lifting the head and shoulders just enough to create tension through the abdominal muscles without excessively rounding the lower back.
What Is the McGill Modified Curl-Up?
The McGill Modified Curl-Up is a core-stability exercise performed while lying on your back.
One knee is bent while the opposite leg remains straight. The hands are positioned underneath the natural curve of the lower back to help maintain a relatively neutral spinal position.
From there, the abdominal muscles are gently braced while the head and shoulders lift slightly from the floor.
Unlike a traditional sit-up, the lower back does not repeatedly flatten, round, and lift away from the ground.
The goal is to create abdominal tension while limiting unnecessary movement through the lumbar spine.
Why Is One Knee Bent and the Other Leg Straight?
The split-leg position helps maintain the natural curve of the lower back and may reduce the tendency to flatten or flex the lumbar spine.
It also helps create a more stable starting position.
The bent leg does not need to be pulled tightly toward the body. Place the foot comfortably on the floor while allowing the opposite leg to remain relaxed and straight.
You can switch which leg is bent between sets.
What Muscles Does the Modified Curl-Up Work?
The exercise primarily challenges the muscles that help stabilize the trunk, including the:
Rectus abdominis
Internal obliques
External obliques
Transverse abdominis
Deep spinal stabilizers
Diaphragm
Pelvic-floor muscles
The neck muscles may also work slightly to support the head, but the movement should not feel like a neck exercise.
The goal is to create coordinated abdominal tension rather than aggressively shortening or bending the trunk.
How Is the Modified Curl-Up Different From a Sit-Up?
A traditional sit-up involves moving the trunk through a relatively large range of spinal flexion while the hip flexors help pull the torso upward.
The modified curl-up uses:
A much smaller range of motion
Less movement through the lower back
A controlled abdominal brace
Short holds rather than rapid repetitions
A focus on spinal stability rather than trunk bending
Neither exercise is automatically good or bad for everyone.
The better choice depends on the person’s goals, symptoms, training history, and current tolerance.
For someone rebuilding core endurance after chronic low-back pain, the modified curl-up may offer a more comfortable starting point.
How to Perform the McGill Modified Curl-Up
Lie on your back on a comfortable surface.
Keep one leg straight and bend the opposite knee so the foot rests on the floor.
Place your hands underneath the natural curve of your lower back. Your hands are there to help you monitor and maintain the curve—not to forcefully press your back upward.
From this position:
Gently tighten your abdominal muscles.
Keep your ribs from flaring upward.
Maintain the natural curve of your lower back.
Lift your head and shoulders slightly from the floor.
Keep your head, neck, and upper back moving together.
Pause briefly while continuing to breathe.
Lower slowly and relax before the next repetition.
The shoulder blades may lift only slightly.
You should not attempt to sit all the way upright.
The Most Important Form Cue
Brace your core and lift your upper body as one controlled unit.
Avoid pulling the chin aggressively toward the chest or curling one spinal segment at a time.
Imagine that your head, neck, and upper back are gently connected.
The movement comes from lifting the upper torso rather than repeatedly rounding the lower back.
Should You Flatten Your Lower Back?
No.
The purpose of placing the hands underneath the lower back is to help preserve a comfortable, natural lumbar curve.
Do not aggressively press the spine into the floor.
You should feel your abdominal muscles working while the shape of the lower back remains relatively unchanged.
Some people have a larger natural curve than others. The goal is not to create a perfect universal position—it is to avoid excessive movement during the exercise.
How High Should You Lift?
Only lift high enough for the shoulder blades to begin clearing the floor.
A larger movement does not necessarily create a better core exercise.
Lifting too high may cause you to:
Round the lower back
Pull through the neck
Use excessive hip-flexor tension
Hold your breath
Lose abdominal control
Think about creating tension rather than creating height.
How Long Should You Hold the Modified Curl-Up?
A useful starting point is a hold of approximately five to ten seconds.
During the hold:
Keep breathing
Maintain abdominal tension
Avoid shaking excessively
Keep the neck relaxed
Preserve the lower-back position
Longer holds are not automatically better.
Several shorter, high-quality holds are often preferable to one prolonged hold performed with deteriorating form.
How Many Modified Curl-Ups Should You Do?
A general starting point may be:
Five repetitions with a five- to ten-second hold
Rest briefly between repetitions
Complete two or three sets
Switch which knee is bent between sets
Another option is to use a descending sequence, such as:
Six repetitions
Four repetitions
Two repetitions
The correct amount depends on your current symptoms, endurance, and rehabilitation plan.
Stop before fatigue causes your lower back, neck, or breathing pattern to change.
Is the Modified Curl-Up Good for Chronic Low-Back Pain?
It may be helpful for some people with chronic low-back pain because it trains core endurance without requiring a large amount of lumbar movement.
However, chronic low-back pain is not one single condition.
It can be influenced by:
Disc irritation
Joint sensitivity
Nerve involvement
Muscle weakness
Reduced endurance
Fear of movement
Hip limitations
Previous injury
Training overload
Poor sleep or recovery
Prolonged sitting
Repetitive lifting
The modified curl-up should be viewed as one possible part of a complete rehabilitation program—not a cure for every type of back pain.
Is the Modified Curl-Up Good for a Disc Herniation?
It may be appropriate for some people recovering from a lumbar disc herniation because it can train abdominal endurance while limiting repeated spinal flexion.
However, disc herniations vary considerably.
Some people tolerate this movement well. Others may experience increased back pain, leg pain, numbness, tingling, or nerve-related symptoms.
The exercise should not be performed simply because an MRI showed a disc herniation.
The decision should be based on:
Current symptoms
Neurological findings
Which movements improve or worsen symptoms
Stage of recovery
Strength and endurance
Individual movement tolerance
If the exercise causes pain to travel farther into the buttock or leg, stop and seek professional guidance.
Can the Modified Curl-Up Push a Disc Back Into Place?
No.
An exercise does not physically push a herniated disc back into position.
Exercise may help improve strength, confidence, load tolerance, and function while the body recovers, but it should not be described as mechanically repositioning a disc.
Many disc herniations improve over time with appropriate conservative care, activity modification, progressive exercise, and symptom management.
Is the Modified Curl-Up Safe During an Acute Back-Pain Flare?
It depends on the person and the nature of the flare.
During a highly sensitive phase, even a small abdominal contraction may feel uncomfortable.
Other people may tolerate a gentle brace without lifting the shoulders.
Possible starting options include:
Gentle abdominal bracing
Short walks
Comfortable breathing exercises
Changing positions regularly
An unloaded Bird Dog progression
A modified side plank
Only the pain-free portion of the curl-up
Do not force the exercise during an acute flare because it is considered a “back exercise.”
The appropriate starting point should match the current level of irritability.
What Should the Exercise Feel Like?
You should generally feel controlled muscular tension through the abdominal wall.
You may also feel mild fatigue through the front and sides of the torso.
You should not experience:
Sharp lower-back pain
Increasing leg pain
Numbness or tingling
Burning pain traveling below the knee
Sudden weakness
Significant neck strain
Groin pain
Loss of bladder or bowel control
Stop if symptoms worsen or begin traveling farther away from the lower back.
Why Does My Neck Hurt During the Modified Curl-Up?
Neck discomfort may occur when:
You pull your chin toward your chest
You lead the movement with your head
You hold the position too long
Your neck muscles fatigue
You lift too high
You hold your breath
Keep your neck in a comfortable neutral position.
Imagine gently holding an apple between your chin and chest rather than crushing the chin downward.
You may also shorten the hold or perform only a very small lift.
Why Do I Feel the Exercise in My Hip Flexors?
Hip-flexor involvement may increase when:
You lift too high
Both knees are deeply bent
You attempt to sit upright
Your abdominal brace is lost
You complete too many repetitions
You move rapidly
Return to the small curl-up position and focus on bracing rather than lifting.
Why Does My Lower Back Hurt During the Exercise?
Lower-back discomfort may occur when:
You flatten or round the spine
You lift too far
You brace too aggressively
The exercise is not appropriate for your current symptoms
You hold your breath
Your back is currently highly sensitive
Reduce the range or try bracing without lifting.
Persistent or increasing pain is a reason to stop and be evaluated.
Should You Hold Your Breath?
No.
You should be able to maintain abdominal tension while continuing to breathe.
Holding your breath may make the exercise feel stronger temporarily, but it does not teach the trunk to maintain stability during normal breathing and movement.
Try taking small, controlled breaths while keeping the abdominal wall firm.
Is This Exercise Part of the McGill Big Three?
Yes.
The commonly referenced McGill Big Three exercises are:
Modified Curl-Up
Side Plank or Side Bridge
Bird Dog
Each exercise challenges the core in a different direction.
The modified curl-up trains the front of the trunk, the side plank emphasizes lateral stability, and the Bird Dog challenges cross-body control.
Together, they may provide a balanced foundation for spinal endurance.
Do You Need to Perform All Three Exercises?
Not necessarily.
Some people benefit from all three, while others need modifications or different exercises.
For example:
Someone with shoulder pain may struggle with side planks.
Someone with knee pain may need a modified Bird Dog position.
Someone who is sensitive to abdominal pressure may need a different curl-up variation.
An athlete may need more advanced loaded exercises.
A person in an acute flare may need simpler movements.
A program should be individualized rather than copied blindly.
Can Beginners Perform the Modified Curl-Up?
Yes.
Beginners can start with a gentle abdominal brace without lifting the shoulders.
Once that feels comfortable, add a very small lift and a short hold.
A beginner progression may include:
Practice breathing while maintaining a neutral spine.
Add a gentle abdominal brace.
Lift only the head slightly.
Lift the head and shoulders together.
Add a five-second pause.
Gradually add repetitions.
There is no need to rush to longer holds.
How Can You Make the Modified Curl-Up Easier?
To reduce the difficulty:
Use a smaller lift
Shorten the hold
Perform fewer repetitions
Brace without lifting
Support the head lightly with a folded towel
Rest longer between repetitions
Use less abdominal tension
The easiest version that you can perform without pain is often the best starting point.
How Can You Make the Modified Curl-Up Harder?
Once the basic exercise feels controlled, progress by:
Extending the hold slightly
Increasing repetitions
Reducing rest between repetitions
Adding a gentle arm lift
Increasing abdominal tension
Combining it with side planks and Bird Dogs
Progressing to carries or anti-rotation exercises
Do not place a heavy weight behind the head.
The goal is spinal endurance and control—not maximizing resistance at any cost.
Is the Modified Curl-Up Good for Runners?
Runners need enough trunk endurance to control the spine and pelvis while the arms and legs move repeatedly.
The modified curl-up may help runners build a foundation of anterior core endurance.
It should be combined with exercises for:
Hip strength
Single-leg control
Calf strength
Lateral core endurance
Running-specific load tolerance
Is the Modified Curl-Up Good for Golfers?
Golf requires rapid rotation while the trunk controls the forces created by the swing.
The modified curl-up may help golfers improve abdominal endurance and the ability to maintain trunk position.
Golfers also need:
Thoracic rotation
Hip mobility
Rotational power
Side-plank strength
Balance
Swing-specific coordination
The curl-up builds stability, but it does not replace rotational training.
Is the Modified Curl-Up Good for Skiers and Snowboarders?
Skiers and snowboarders need core endurance to maintain an athletic stance while the legs react to changing terrain.
The exercise may help build foundational trunk control, especially when combined with:
Side planks
Bird Dogs
Squats
Hinges
Single-leg strength
Anti-rotation exercises
Is the Modified Curl-Up Good for Cyclists?
Cyclists spend long periods in a flexed position and need enough trunk endurance to support the upper body.
The modified curl-up may improve abdominal endurance without requiring repeated trunk bending.
Cyclists should also consider:
Bike fit
Hip mobility
Upper-back endurance
Glute strength
Changing hand and trunk positions
Is the Exercise Helpful for Desk Workers and Commuters?
Yes, it may help desk workers and drivers build core endurance after spending long periods sitting.
However, it should be combined with:
Regular standing and walking breaks
Hip mobility
Upper-back movement
Appropriate workstation setup
Gradual general strength training
No core exercise completely offsets sitting in one position for several hours.
Movement variety remains important.
Is the Modified Curl-Up Good for Older Adults?
It can be modified for older adults who can comfortably get to and from the floor.
The exercise may support trunk endurance for:
Walking
Lifting
Carrying
Household tasks
Balance
Getting out of bed
People who have difficulty getting onto the floor may need a bed-based, seated, or standing core exercise instead.
Can You Do Modified Curl-Ups Every Day?
Low-volume practice may be appropriate for some people, particularly during rehabilitation.
However, frequency depends on:
Current symptoms
Exercise volume
Hold duration
Other training
Recovery
Stage of rehabilitation
Daily exercise is not required to make progress.
Two to four sessions per week may be sufficient for many people.
Are Curl-Ups Better Than Planks?
They train the trunk differently.
The modified curl-up emphasizes anterior core endurance while preserving a relatively stable lumbar position.
A front plank creates a longer lever and may place greater demand on the shoulders and entire trunk.
Neither is universally superior.
The best exercise is the one that matches your goals and can be performed with good control.
Can Core Strength Cure Low-Back Pain?
Core training may be helpful, but low-back pain is rarely caused by one weak muscle.
Recovery may also require:
Gradual return to activity
Improved hip and spinal movement
Better load management
Walking
General strength training
Sleep and recovery
Addressing fear of movement
Ergonomic changes
Manual treatment when appropriate
A strong core is useful, but it is only one part of a resilient back.
Should You Wear a Back Brace While Exercising?
Most people should learn to create their own muscular brace during low-level rehabilitation exercises.
A medical brace may be appropriate in specific circumstances, such as after surgery, fracture, or under the direction of a healthcare provider.
Do not rely on a brace solely because your back feels weak.
When Should Someone With Back Pain Seek Immediate Care?
Seek urgent medical evaluation for symptoms such as:
New loss of bladder or bowel control
Numbness around the groin or saddle region
Rapidly worsening leg weakness
Severe pain following significant trauma
Fever combined with severe back pain
Unexplained weight loss
A history of cancer with new severe back pain
Progressive neurological symptoms
These symptoms require more than an exercise recommendation.
Frequently Asked Questions About the McGill Modified Curl-Up
What is the McGill Modified Curl-Up good for?
It is used to build abdominal and spinal endurance while limiting repeated movement through the lower back.
Is the McGill Curl-Up good for low-back pain?
It may help some people with chronic low-back pain, but its suitability depends on symptoms, diagnosis, and movement tolerance.
Can I do the exercise with a herniated disc?
Some people with disc-related back pain tolerate it well, while others do not. Stop if it increases back pain, leg pain, numbness, or tingling.
Is it safer than a sit-up?
It uses less spinal movement than a traditional sit-up, which may make it more comfortable for certain people. No exercise is universally safe for everyone.
Should my lower back stay curved?
Maintain a comfortable natural curve rather than forcefully flattening the back into the floor.
How far should I lift?
Lift only until the head and upper shoulders slightly clear the floor.
How long should I hold?
Begin with approximately five seconds and progress toward ten seconds if you can maintain good form and normal breathing.
How many repetitions should I perform?
Start with approximately five controlled repetitions and gradually increase based on tolerance.
Should I switch which knee is bent?
Yes. You can switch the bent leg between sets to avoid always using the same setup.
Why are the hands placed under the lower back?
The hands help preserve and monitor the natural lumbar curve during the exercise.
Should I feel the exercise in my abs?
Yes. You should generally feel controlled tension through the abdominal wall rather than pain in the back or neck.
Why does my neck get tired?
You may be lifting too high, holding too long, or leading with the head instead of lifting the head and shoulders together.
Is it part of the McGill Big Three?
Yes. The modified curl-up, side plank, and Bird Dog are commonly referred to as the McGill Big Three.
Will the McGill Big Three fix every back injury?
No. They are foundational stability exercises, but rehabilitation should be individualized to the injury, symptoms, and functional goals.
Can athletes benefit from modified curl-ups?
Yes. Runners, golfers, cyclists, skiers, lifters, and field athletes may use them to develop foundational trunk endurance.
Can I perform the exercise during a painful flare?
Possibly, but it should not worsen symptoms. Some people need to begin with gentle bracing or walking instead.
A Strong Core Is About Endurance and Control
Core strength is not measured only by how many sit-ups you can complete.
Your core must repeatedly stabilize your spine while you walk, run, lift, golf, ski, work, and perform daily activities.
The McGill Modified Curl-Up trains that ability using a small, controlled movement and a stable spinal position.
Start with short holds. Continue breathing. Stop before your form changes.
Most importantly, remember that chronic low-back pain and disc injuries require an individualized approach.
At Performance & Recovery Clinic in Basalt, Colorado, we evaluate how the spine, hips, core, and nervous system respond to movement and loading.
An assessment for chronic low-back pain may include:
Neurological screening
Spinal movement tolerance
Hip mobility
Core endurance
Leg strength
Balance and coordination
Lifting mechanics
Sitting and driving tolerance
Previous injuries
Athletic and work demands
Care may include chiropractic adjustments, targeted manual therapy, movement-based rehabilitation, progressive core strengthening, mechanical traction when appropriate, and modern recovery technology.
If chronic low-back pain, a previous disc injury, or recurring flare-ups are keeping you from exercising, working, skiing, running, golfing, or enjoying daily life, schedule an evaluation and let’s build a plan that matches your body and goals.
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