Could Weak Glutes Be the Hidden Cause of Your Hip, Knee or Back Pain? New Research Reveals the Best Way to Perform Clamshell Exercises
Written by Dr Julian Simpson — Chiropractor with 15+ years of experience, Board Member of the Chiropractic Australia Research Foundation, and author/reviewer of 800+ health articles.
Could Weak Glutes Be the Hidden Cause of Your Hip, Knee or Back Pain? New Research Reveals the Best Way to Perform Clamshell Exercises
If you've been doing clamshell exercises, are you getting the most out of them?
Have you ever been told to strengthen your glutes to help with knee pain, lower back pain or hip discomfort?
You're certainly not alone.
Whether you're commuting to Melbourne along the Calder Freeway, standing all day at work in Sunbury or Melton, enjoying a weekend walk with the family, or getting back into sport, weak hip muscles are one of the most common problems we see in the clinic.
One exercise that is frequently prescribed by chiropractors, physiotherapists and exercise professionals is the clamshell exercise. But new research suggests that a simple change in your knee position could make this exercise even more effective.
Let's take a closer look at what the latest science found—and what it means for your rehabilitation.
What is the Gluteus Medius, and Why Does It Matter?
The gluteus medius is one of the most important muscles in your body for everyday movement.
Located on the outside of your hip, it plays a major role in:
Keeping your pelvis level while walking
Supporting your lower back
Stabilising your hips
Controlling your knees during movement
Improving balance
Reducing unnecessary strain on your joints
When this muscle isn't working efficiently, other muscles often try to compensate, placing extra stress on your hips, knees and lower back.
This can contribute to conditions such as:
Patellofemoral (front of knee) pain
Hip pain
Iliotibial band syndrome
Lower back pain
Pelvic instability
Poor balance
Running injuries
What Did the Research Investigate?
Researchers from South Korea wanted to answer a surprisingly simple question:
Does changing the angle of your knees during a modified clamshell exercise affect how hard your glute muscles work?
To find out, they recruited:
30 healthy women
Aged 20–30 years
With no recent injuries or musculoskeletal conditions
Each participant performed the modified clamshell exercise with their knees bent at:
60°
90°
110°
Using specialised surface electromyography (EMG) equipment, researchers measured how much several important muscles were activated during each exercise.
These included:
Gluteus medius
Gluteus maximus
Tensor fasciae latae (TFL)
Quadratus lumborum
What Did the Study Find?
The results were clear.
Increasing the knee bend significantly changed which muscles were doing the work.
Researchers found:
Gluteus medius activation increased significantly as knee flexion increased (p < 0.001).
Gluteus maximus activation also increased significantly (p < 0.001).
Activity in the tensor fasciae latae (TFL) decreased significantly.
Activity in the quadratus lumborum, a lower back muscle that often compensates for weak hips, also decreased.
Importantly, there was no significant difference between 90° and 110°, suggesting that bending the knees beyond approximately 90 degrees provides little additional benefit.
In simple terms...
A knee bend of around 90 degrees appeared to activate the target glute muscles more effectively while reducing reliance on muscles that commonly compensate for weak hips.
Why Is This Important?
Many people unknowingly "cheat" when performing hip exercises.
Instead of the glute muscles doing the work, other muscles begin taking over.
One of the biggest culprits is the tensor fasciae latae (TFL).
When the TFL becomes overactive, it may contribute to:
Hip tightness
Outer hip pain
Knee discomfort
Altered walking patterns
Reduced pelvic stability
The study found that increasing knee flexion reduced TFL activation while encouraging the glute muscles to contribute more.
That's exactly what clinicians hope to achieve during early rehabilitation.
How to Perform the Modified Clamshell Exercise
The researchers used a carefully controlled version of the exercise.
Starting position
Lie on your side.
Keep your shoulders, hips and ankles aligned.
Bend your knees to approximately 90 degrees.
Keep your feet together.
Engage your abdominal muscles gently.
Movement
Slowly lift your top knee while keeping your feet touching.
Avoid rolling your pelvis backwards.
Pause briefly at the top.
Lower your knee under control.
The movement should come from your hip—not your lower back.
Quality is far more important than speed.
The Exercise Protocol Used in the Study
Participants completed:
Three repetitions at each knee angle
One minute of rest between repetitions
Ten minutes of rest before testing the next knee position
Randomised testing order to ensure fair comparisons
Although this was a laboratory study rather than a rehabilitation programme, it provides valuable information about how small changes in technique may influence muscle activation.
Does This Mean Everyone Should Perform Clamshells at 90 Degrees?
Not necessarily.
One of the strengths of this study is that it reminds us there is no one-size-fits-all exercise.
The participants were:
Healthy
Young adults
Women only
Free from pain
That means we can't automatically assume the exact same results apply to someone with:
Hip arthritis
Knee osteoarthritis
Persistent lower back pain
Hip bursitis
Pregnancy-related pelvic pain
Sports injuries
Your healthcare professional should always tailor exercises to your individual needs.
Why Glute Strength Matters Beyond Your Hips
Your glute muscles don't just help your hips—they help control movement throughout your entire body.
Strong, well-functioning glutes can assist with:
Better walking mechanics
Improved balance
More efficient stair climbing
Running performance
Reducing unnecessary stress on the knees
Supporting the lower back
Improving pelvic stability
That's why glute strengthening is commonly included in rehabilitation programmes for many different musculoskeletal conditions.
Why a Holistic Approach Delivers Better Results Exercises like clamshells are valuable, but they're only one piece of the puzzle. Research consistently shows that the best outcomes often come from combining targeted rehabilitation exercises with manual therapy where appropriate, movement retraining, strength and balance programmes, healthy sleep, regular physical activity and education. At Health Wise Chiropractic, we focus on improving the way your whole body moves—not just treating the painful area.
What Are the Study's Limitations?
Good research isn't just about what a study finds—it's also about understanding its limitations.
This study measured muscle activation, not pain or long-term recovery.
It also involved only 30 healthy young women, so we can't assume the findings will apply equally to men, older adults or people with existing hip or knee conditions.
The researchers also noted that the modified clamshell is a low-load exercise, making it ideal for improving muscle control in the early stages of rehabilitation rather than building significant strength on its own.
As rehabilitation progresses, additional strengthening exercises are usually needed to continue improving hip function.
How Can Chiropractic Care Help?
At Health Wise Chiropractic, we know that hip weakness is rarely just a hip problem.
During a comprehensive assessment, we look at how your:
Spine moves
Pelvis functions
Hips stabilise
Knees track during movement
Feet interact with the ground
Muscles work together
If clinically appropriate, your care may include:
Joint mobilisation or chiropractic adjustments
Soft tissue therapy
Individualised rehabilitation exercises
Glute strengthening programmes
Balance and movement retraining
Postural advice
Ergonomic recommendations
Guidance on safely returning to work, sport or exercise
While this study didn't investigate chiropractic care or spinal manipulation, its findings reinforce the importance of precise exercise prescription as part of a comprehensive rehabilitation programme.
Practical Tips You Can Start Today
If you're working on improving your hip strength, try these evidence-informed tips:
Focus on quality rather than quantity during exercises.
Keep your pelvis stable throughout each movement.
Perform clamshells with your knees bent to around 90 degrees, unless advised otherwise by your healthcare professional.
Avoid rushing through repetitions.
If you feel the exercise mainly in the front of your hip, check your technique.
Progress to more challenging weight-bearing exercises as your strength improves.
Stay consistent—small improvements over time often lead to meaningful results.
Seek professional advice if pain persists or exercises increase your symptoms.
How Chiropractic Care May Help
At Health Wise Chiropractic, we take a comprehensive approach to posture-related care.
Treatment may include:
We focus on addressing both the symptoms and the underlying biomechanical stress contributing to neck dysfunction.
About the Author
Dr Julian Simpson is an Australian chiropractor with over 15 years of experience in musculoskeletal healthcare and rehabilitation.
He is a Board Member of the Chiropractic Australia Research Foundation and has reviewed and written more than 800 evidence-based health articles focused on spinal health, rehabilitation, sports injuries and conservative care approaches.
His treatment focus includes:
Chiropractic adjustments
Sports chiropractic
Massage therapy
Shockwave therapy
Laser therapy
Non-surgical spinal decompression
Dr Simpson provides patient care through Healthwise Chiropractic, serving communities including Sunbury, Melton, Diggers Rest and surrounding regions.
Reference
Lee HY, Zhang YH, Kim KC, Lim HW. Effects of Knee Flexion Angle on Gluteus Medius Activation and Activation Ratios During the Modified Clamshell Exercise. Medicina (Kaunas). 2026 May 25;62(6):1025. doi: 10.3390/medicina62061025. PMID: 42356038; PMCID: PMC13303979.
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