The McGill Big 3—the modified curl-up, side bridge and bird dog—are three well-known exercises used to build strength and endurance around the spine. They can be a useful starting point for some people with low back pain, particularly when performed comfortably and progressed appropriately.
But they aren't a one-stop solution for back pain, and they aren't necessarily better than other types of exercise.
In my practice, I often use the McGill Big 3 as part of a broader exercise program. They can provide a simple way to begin loading and challenging the muscles around the spine while keeping the lower back relatively neutral. As someone progresses, however, I generally want to build strength and capacity in other positions and movements too. After all, our spines don't stay perfectly neutral throughout everyday life—and they aren't supposed to.
The goal isn't simply to create a spine that can resist movement. It's to develop a back that is strong, adaptable and capable of handling the activities you want it to do.
What Are the McGill Big 3?
The McGill Big 3 are a group of exercises popularized by Canadian spine researcher Dr. Stuart McGill. They are:
- Modified curl-up
- Side bridge
- Bird dog
Rather than repeatedly bending and extending the lower back, these exercises challenge the muscles surrounding the trunk while maintaining a relatively neutral lumbar spine.
That can make them a practical starting point for building trunk endurance and control.
Modified Curl-Up
Lie on your back with one knee bent and the other leg straight. Place your hands underneath the natural curve of your lower back.
Gently brace your abdominal muscles and raise your head and shoulders slightly from the floor without rounding significantly through your lower back. Keep your neck comfortable and avoid pulling your chin toward your chest.
Lower yourself under control and repeat.
The goal isn't to perform a large abdominal crunch. You're creating muscular tension while minimizing movement through the lumbar spine.
Side Bridge
Lie on your side with your forearm supported on the floor and your elbow approximately underneath your shoulder.
A beginner can perform the exercise from bent knees. As strength improves, it can be progressed to straight legs with the feet supporting the body.
Raise your hips from the floor and maintain a comfortable position through your trunk while continuing to breathe normally.
Lower yourself under control and repeat on both sides.
Bird Dog
Begin on your hands and knees with your hands underneath your shoulders and knees underneath your hips.
Brace comfortably through your trunk and extend one leg behind you while reaching the opposite arm forward. Try to keep your pelvis relatively level rather than twisting as you move.
Return to the starting position and repeat on the opposite side.
As with the other Big 3 exercises, the goal isn't to see how high you can lift your arm or leg. The challenge comes from controlling the trunk while your arms and legs move around it.
Do the McGill Big 3 Actually Help Low Back Pain?
They can, but the evidence requires some context.
Research supports exercise in general as part of the management of persistent low back pain. Stabilization and motor-control exercises can improve pain and function, but they are only some of many forms of exercise that can be effective.
There is much less research specifically investigating the McGill Big 3 as a unique exercise program.
One small randomized trial compared McGill stabilization exercises with a conventional physiotherapy exercise program in 34 people with chronic nonspecific low back pain. Both groups improved over six weeks. Although the McGill group demonstrated somewhat greater improvements in some outcomes, the study was small and does not establish that the Big 3 are superior to other exercise programs.
More recent research examining stabilization exercises more broadly continues to find improvements in pain and disability among people with chronic low back pain.
So the takeaway isn't that the Big 3 are ineffective. Far from it.
They're good exercises. We just shouldn't confuse "good exercises" with "the best exercises for everyone with back pain."
Are the McGill Big 3 Better Than Other Core Exercises?
We don't have good evidence that they are.
Research comparing different approaches to exercise for chronic low back pain generally finds that several types of exercise can be beneficial.
These can include:
- stabilization and motor-control exercises
- resistance training
- general strengthening
- aerobic exercise
- mobility exercises
- Pilates and other structured exercise programs
- combinations of different exercise approaches
Current clinical guidelines similarly recommend several forms of exercise rather than identifying one particular exercise program that everyone with low back pain should perform.
A 2026 network meta-analysis comparing different exercise approaches found improvements in pain across stabilization, resistance, traditional, combined and motor-control exercise programs.
That fits well with what we see clinically: there are many ways to build a healthier, more capable back.
Choosing exercises someone can tolerate, progressively challenge and actually continue doing may ultimately be more useful than searching for three universally "perfect" exercises.
Who Might Benefit From the McGill Big 3?
The Big 3 can be particularly useful as an introduction to trunk strengthening.
For example, I may consider them when someone:
- is beginning a rehabilitation or strengthening program
- has difficulty tolerating larger spinal movements initially
- wants a simple home program that requires little or no equipment
- needs to develop trunk endurance and control
- tolerates the exercises comfortably
- needs a foundation before progressing toward more demanding activities
The important phrase here is "tolerates the exercises comfortably."
Low back pain doesn't present identically from person to person. Two people with seemingly similar back pain may respond quite differently to the same exercise.
That's one reason individualized exercise prescription can be helpful.
Who Might Find the McGill Big 3 Uncomfortable?
Not every exercise feels good for every back.
Someone whose symptoms are aggravated by flexion may initially dislike the modified curl-up. Another person might find the position used for the bird dog uncomfortable. Someone with shoulder problems may have difficulty supporting themselves during a side bridge.
This doesn't necessarily mean an exercise is dangerous or that something is being damaged.
It may simply mean we need to change the exercise, modify the range or difficulty, choose a different variation, or temporarily use another exercise.
Your symptoms and response to an exercise matter.
How Often Should You Do the McGill Big 3?
There isn't a scientifically established "perfect dose" of the McGill Big 3 that applies to everyone.
Exercise studies investigating low back pain use widely varying frequencies, durations and programs.
Rather than focusing on a magic number of repetitions, I generally think about whether the exercise provides an appropriate challenge without repeatedly causing a significant or lasting increase in symptoms.
For someone beginning rehabilitation, relatively short sessions performed regularly may be enough to start building capacity. From there, the exercise can be progressed as strength, endurance and confidence improve.
Is It Okay to Do the McGill Big 3 Every Day?
For many people, yes—but you don't necessarily need to.
The Big 3 are generally relatively low-load exercises, and some people tolerate performing them frequently. But frequency should still depend on the difficulty of the exercises, your overall exercise program and how your body responds.
More isn't automatically better.
If you're performing more challenging variations or combining them with resistance training and other activities, recovery becomes part of the equation too.
Consistency over time is generally more important than trying to complete a specific routine every single day.
Does Everyone With Back Pain Need to Strengthen Their Core?
No.
Strengthening can certainly be helpful, and current clinical guidelines recommend trunk strengthening and endurance exercises as options for chronic low back pain.
But that doesn't mean everyone with back pain has a deficient core.
Depending on the person, rehabilitation might include some combination of strengthening, walking, aerobic exercise, mobility work, resistance training, returning gradually to meaningful activities and addressing other factors that influence pain and recovery.
The appropriate program depends on the individual.
Is a "Weak Core" Actually the Cause of Low Back Pain?
This is one of the biggest misconceptions surrounding core exercises.
Low back pain doesn't usually have one simple cause, and having pain doesn't automatically mean your core is weak.
Strength, endurance and physical capacity can certainly be relevant. If someone has difficulty tolerating the demands placed on their back, improving those qualities can be useful.
But low back pain is influenced by many interacting factors, which can include physical loading, previous injury, activity levels, sleep, stress, health conditions, work demands and individual pain sensitivity.
Telling someone, "Your back hurts because your core is weak," can therefore be both inaccurate and unnecessarily alarming.
A better question is:
What physical qualities could we improve to help this person do more comfortably and confidently?
Sometimes trunk strength is part of that answer. Sometimes other things deserve just as much attention.
Does My Spine Need to Stay Neutral When I Exercise?
This is where I think an important distinction needs to be made.
Neutral spine is a useful exercise strategy. It isn't a rule that your spine must follow at all times.
The Big 3 deliberately challenge the trunk while minimizing movement through the lumbar spine. For someone with an irritable back, this can provide a useful way to begin exercising.
But human spines bend.
We flex when putting on our shoes. We extend and rotate during sports. We bend, reach, twist and lift throughout everyday life.
Research has not established lumbar flexion itself as something that must universally be avoided. In fact, a systematic review examining lumbar flexion during lifting found low-quality evidence that greater lumbar flexion was not a risk factor for developing or persisting low back pain.
This doesn't mean technique and load don't matter. They do. Lifting something extremely heavy while fatigued is very different from bending down to pick up your shoes.
It means that movement itself shouldn't automatically be treated as damage.
For many people, the longer-term goal of rehabilitation should include gradually building the ability to tolerate different movements, positions and loads—not indefinitely protecting the back from leaving neutral.
The Big 3 Can Be the Beginning, Not the End
This is perhaps the most important thing I tell patients about these exercises.
The McGill Big 3 can make an excellent foundation for a back exercise program.
But once someone can comfortably perform a bird dog, side bridge and modified curl-up, we need to ask:
What does this person actually need their back to do?
For one person, that might mean comfortably carrying groceries.
For another, it's working at a desk and then playing with their children.
For someone else, it might mean running, gardening, deadlifting, golfing, curling or returning to a physically demanding occupation.
Those activities require more than the ability to hold the lumbar spine still.
Recent research supports resistance training as an effective option for people with chronic nonspecific low back pain. Importantly, that doesn't mean everyone needs to start lifting heavy weights. It means progressively loading the body can be part of a well-rounded rehabilitation program.
The amount and type of load should match the individual.
How Should the McGill Big 3 Be Progressed?
Progression doesn't simply mean doing more and more repetitions forever.
Depending on the individual, progression might involve:
1. Improving technique and tolerance
First, learn to perform the exercise comfortably while breathing normally and maintaining control.
2. Increasing endurance
Gradually increase the number of repetitions, duration or total work performed.
3. Increasing the challenge
Progress from easier to more demanding variations—for example, moving from a bent-knee side bridge toward a full side bridge.
4. Adding resistance
Eventually, some people benefit from exercises that challenge the trunk and the rest of the body with progressively greater resistance.
5. Introducing different movements and positions
Depending on someone's symptoms and goals, rehabilitation can include controlled flexion, extension, rotation, lifting, carrying, hinging, squatting and other movements.
6. Making exercise specific to real life
Ultimately, rehabilitation should help prepare you for the things you actually want and need to do.
Someone returning to heavy lifting at work needs a different end-stage program from someone whose primary goal is comfortably walking and gardening.
When Should You Stop or Modify an Exercise?
Pain during exercise doesn't always mean you've harmed your back, but symptoms shouldn't simply be ignored either.
Consider reducing the range, resistance, repetitions or difficulty if an exercise produces a substantial increase in your symptoms or repeatedly leaves you feeling significantly worse afterward.
Sometimes changing the exercise is all that's necessary.
An assessment is more appropriate if your back pain is severe or progressively worsening, follows significant trauma, or is accompanied by concerning symptoms such as progressive weakness or numbness, changes in bowel or bladder control, numbness around the groin or saddle region, unexplained fever or weight loss, or other symptoms suggesting that something beyond routine mechanical back pain may be occurring.
So, Should You Do the McGill Big 3 for Low Back Pain?
If they feel comfortable and appropriately challenging, the McGill Big 3 can be a very useful part of a low back rehabilitation program.
They provide a simple, accessible way to work on trunk endurance and control and may be particularly useful as an entry point into exercise.
But there's nothing magical about these three exercises.
Current research supports many forms of exercise for low back pain, and we don't have convincing evidence that the McGill Big 3 are universally superior to other appropriate exercises.
My preference is therefore to think of the Big 3 as tools rather than rules.
They may provide a great place to start. From there, rehabilitation can progress toward building the strength, movement tolerance and physical capacity required for your work, sport and everyday life.
If you're having difficulty determining which exercises are appropriate for your particular pattern of low back pain, an assessment can help identify movements you currently tolerate well and develop a progressive exercise program based on your symptoms and goals.
About Dr. Matthew Serrick
Dr. Matthew Serrick is a chiropractor and Clinical Director at Back In Balance Clinic with over 16 years of experience treating low back and spine-related conditions. He is also an Advanced Practice Provider with Ontario's Rapid Access Clinics for Low Back Pain, where he assesses and manages patients with persistent and complex low back pain.
References
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