Understanding Knee Pain: Causes, Treatments, and Exercises That Can Help
- Justin Roth
- 4 hours ago
- 6 min read
Knee pain is one of the most common issues affecting people of all ages, whether you're a lifelong athlete, a weekend warrior, or someone just trying to stay active. According to the CDC, nearly 1 in 4 adults report chronic knee pain at some point in their lives1. For personal training clients, knee discomfort can interfere with workouts, daily movement, and long-term fitness goals.
In this post, we’ll break down what knee pain actually is, what causes it, how it’s treated, and most importantly, what exercises you can do to support your knees and reduce pain. This guide blends scientific research with real-world fitness strategies to help you or your clients move better—without pain.
What Is Knee Pain?
Knee pain refers to discomfort or inflammation in or around the knee joint. It can be acute (short-term), such as pain from a sprain or strain, or chronic (long-term), like in osteoarthritis or tendinopathy.
The knee is a complex hinge joint made up of:
Bones: Femur (thigh), tibia (shin), and patella (kneecap)
Cartilage: Articular cartilage cushions the bones; the meniscus acts like a shock absorber
Ligaments: ACL, PCL, MCL, and LCL provide stability
Tendons: Connect muscles to bones
Bursae: Fluid-filled sacs that reduce friction
When any of these structures are injured or inflamed, knee pain can occur.
Common Causes of Knee Pain
1. Osteoarthritis
Osteoarthritis (OA) is the most common cause of chronic knee pain, especially in older adults. OA is a degenerative joint disease where the cartilage wears down over time, causing bone-on-bone contact, swelling, and pain.
Research Insight: A 2020 meta-analysis in Osteoarthritis and Cartilage showed that strengthening exercises significantly reduce pain and improve function in patients with knee OA2.
2. Patellofemoral Pain Syndrome (Runner’s Knee)
This condition involves pain at the front of the knee around the kneecap. It’s often caused by muscle imbalances, poor movement mechanics, or overuse.
Risk Factors:
Weak quadriceps or glutes
Poor hip mobility
Misalignment of the kneecap
3. Meniscal Injuries
The meniscus is a C-shaped cartilage that helps absorb shock. Tears often happen with twisting motions or deep squats, especially under load.
Study Note: Research in The American Journal of Sports Medicine shows that non-surgical treatments, including physical therapy, can be just as effective as surgery for certain meniscus tears3.
4. Ligament Injuries
These include ACL, PCL, MCL, and LCL injuries—usually caused by trauma or sudden directional changes. While these often require surgical intervention, rehabilitation is crucial post-injury.
5. Tendinopathies (e.g., Jumper’s Knee)
Pain in the patellar tendon (just below the kneecap) is common in athletes and active individuals. It’s typically due to repetitive stress and insufficient recovery.
Risk Factors
Several factors increase the likelihood of developing knee pain:
Age – Joint tissues degenerate over time
Obesity – Every extra pound adds 3–5 pounds of pressure on the knee joint4
Previous Injury – Prior damage can change joint mechanics
Muscle Weakness – Especially in the quads, glutes, and hamstrings
Poor Movement Patterns – Knee valgus, overpronation, poor squatting form
Treatment Options for Knee Pain
1. Rest and Activity Modification
Sometimes, short-term rest is necessary, especially for acute injuries. However, complete immobilization should be avoided unless medically necessary, as it can lead to muscle atrophy and joint stiffness.
2. Ice, Compression, and Elevation (RICE)
For acute swelling and pain, RICE remains a go-to first response.
3. Physical Therapy, Personal Training and Exercise
A structured program from a certified personal trainer or physical therapist targeting strength, flexibility, and movement mechanics is often the most effective long-term treatment.
4. Anti-Inflammatory Medications
NSAIDs (like ibuprofen) can reduce pain and swelling but should be used sparingly due to long-term side effects.
5. Weight Management
Losing even 5–10% of body weight has been shown to reduce symptoms in those with knee OA5.
6. Injections and Surgery
Corticosteroid injections, hyaluronic acid, or platelet-rich plasma (PRP) are sometimes used. Surgery is considered for serious injuries or advanced arthritis.
Best Exercises to Help Relieve Knee Pain
Movement is medicine—when done correctly. Here are scientifically backed exercises that improve knee health and reduce pain.
1. Quadriceps Strengthening: Wall Sit (Isometric)
Why: Strong quads help absorb shock and stabilize the knee.
How: Stand against a wall, slide down into a 90° squat, and hold for 30–60 seconds.
Progression: Add weight or hold longer.
Study Support: A study in Clinical Rehabilitation found that isometric quad exercises reduce pain and improve knee joint function in those with patellofemoral pain6.
2. Glute Activation: Sidelying Clamshells
Why: Weak glutes contribute to knee valgus (inward collapse).
How: Lie on your side with knees bent, feet together. Keeping feet touching, lift the top knee without moving your hips.
Reps: 2–3 sets of 15 per side
3. Hamstring Strength: Glute Bridge
Why: Hamstrings stabilize the knee, especially during dynamic movement.
How: Lie on your back, knees bent. Squeeze your glutes and lift your hips until your body forms a straight line from shoulders to knees.
Progression: Single-leg glute bridge
4. Hip Mobility: 90/90 Hip Switches
Why: Limited hip mobility can affect knee alignment during squats and walking.
How: Sit with one leg in front at 90°, the other leg out to the side also at 90°. Rotate hips side to side while staying upright.
5. Controlled Squats: Box Squats
Why: Encourages proper mechanics and quad engagement without deep joint stress.
How: Use a box or bench behind you. Slowly sit back into the box, pause, then drive through the heels to stand.
Form Tips: Knees should track in line with toes; keep chest upright.
6. Step-Ups
Why: Functional, closed-chain exercise that builds strength and balance.
How: Step up onto a low box or step, focusing on control and keeping the knee aligned.
Variations: Add dumbbells or increase box height.
7. Calf Raises
Why: Often overlooked, the calf muscles (especially the soleus) support knee alignment during walking and running.
How: Stand tall, slowly rise onto the balls of your feet, then lower.
Mobility and Stretching
Tight tissues can change knee mechanics. Include the following:
Foam rolling the quads and IT band (not directly on the knee)
Hamstring stretches
Hip flexor stretches
Ankle dorsiflexion mobility drills (since poor ankle mobility can force the knee into compensatory patterns)
Tips for Exercising with Knee Pain
Warm up thoroughly: Increase synovial fluid for joint lubrication.
Avoid deep squats early on: Gradually build range.
Focus on form, not depth or weight
Use support if needed: Like resistance bands or TRX for balance
Don’t ignore pain: Discomfort is okay, sharp pain is not.
When to See a Doctor
If you experience any of the following, seek medical evaluation:
Sudden swelling
Inability to bear weight
Popping sounds followed by pain
Visible deformity
Severe limitation in range of motion
These could indicate ligament ruptures, fractures, or significant meniscal tears.
Final Thoughts
Knee pain doesn’t have to derail your fitness journey. With a structured, science-based approach to strengthening, mobility, and movement patterns, most people can recover or significantly reduce pain—and prevent it from returning.
As a personal trainer, integrating these principles can help clients regain function, stay active, and reach their goals safely. Every knee is different, so programs should be personalized based on each individual’s needs, history, and movement assessments.
The knee is a complex joint, but with smart programming and consistent attention to form, it can be one of your strongest assets.
Workouts & Fitness Tips @justinrothpt
Footnotes
Centers for Disease Control and Prevention (CDC). "Prevalence of doctor-diagnosed arthritis and arthritis-attributable activity limitation — United States, 2013–2015." MMWR (2017).
Fransen, M., et al. "Exercise for osteoarthritis of the knee." Cochrane Database of Systematic Reviews (2015).
Katz, J.N., et al. "Surgery versus physical therapy for a meniscal tear and osteoarthritis." New England Journal of Medicine (2013).
Messier, S.P., et al. "Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis." Arthritis & Rheumatism (2005).
Christensen, R., et al. "Effect of weight reduction in obese patients diagnosed with knee osteoarthritis: a systematic review and meta-analysis." Annals of the Rheumatic Diseases (2007).
Crossley, K.M., et al. "Physical therapy for patellofemoral pain: a randomized, double-blind, placebo-controlled trial." British Journal of Sports Medicine (2002).
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