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Pain Library/Knee pain

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Knee pain. Strengthened.

Knee pain is the most common musculoskeletal complaint in adults. Whether it is patellofemoral pain, osteoarthritis, or tendinopathy, strengthening the muscles around the knee is the most effective long-term solution.

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Person performing a step-down single-leg exercise on a step box for knee rehabilitation

Quick facts

  • Knee pain affects up to 25% of adults
  • Patellofemoral pain syndrome is the most common cause in younger adults
  • Knee osteoarthritis affects 10% of adults over 55

Pain Library

Understanding knee pain

The knee is the largest joint in the body and bears significant load during everyday activities. Pain can arise from the joint itself (osteoarthritis, meniscal tears), the surrounding soft tissues (patellar tendinopathy, IT band syndrome, bursitis), or be referred from the hip or lumbar spine.

Patellofemoral pain syndrome — pain around or behind the kneecap — is the most common knee complaint in younger adults and is strongly associated with quadriceps weakness, hip abductor weakness, and altered movement patterns. It responds very well to targeted NASM corrective exercise.

Knee osteoarthritis is characterized by cartilage loss and joint space narrowing. Despite common belief, exercise does not accelerate cartilage loss and is the most evidence-supported treatment. Strengthening the quadriceps reduces joint loading and significantly improves pain and function.

Important: Red flags: knee pain following significant trauma (possible fracture or ligament rupture), sudden severe swelling, inability to bear weight, or a locked knee. These require urgent medical assessment.

NASM-based corrective exercises

Movements that help.

  • Integrate — Functional Strength

    Step-Down Exercise

    The step-down is a NASM-recommended integration exercise that trains single-leg eccentric quadriceps control — the most important factor in patellofemoral pain and knee OA management. It also challenges hip abductor stability, addressing the common hip-knee relationship in lower extremity dysfunction.

    • Stand on a step or low box on the affected leg, with the other foot hanging free
    • Slowly lower the opposite heel toward the floor by bending the standing knee
    • Keep the standing knee tracking directly over your second toe — do not let it cave inward
    • 10 repetitions, 3 sets — focus on a slow, 3 to 4 second descent for maximum benefit
    See full exercise guide

  • Activate — VMO

    Terminal Knee Extension

    Terminal knee extension (TKE) isolates the VMO (vastus medialis oblique) — the inner quadriceps muscle that is most commonly inhibited in patellofemoral pain and knee instability. NASM identifies VMO activation as a priority in knee corrective programming.

    • Stand with a resistance band looped behind the knee, attached to a fixed point in front of you
    • Begin with a slight knee bend, then straighten the knee fully against the band resistance
    • Focus on the inner quad contracting at full extension — you should feel it just above and inside the kneecap
    • 15 repetitions, 3 sets — progress band resistance gradually as strength improves
    See full exercise guide

  • Lengthen — Hamstrings

    Supine Hamstring Stretch

    Tight hamstrings increase posterior knee tension and alter patellar tracking. NASM includes hamstring lengthening as part of the corrective protocol for knee pain, particularly for patellofemoral syndrome and popliteal tightness. The supine position allows a controlled, gravity-assisted stretch.

    • Lie on your back and loop a towel or strap around the sole of one foot
    • Straighten the knee as much as comfortable, then gently pull the leg toward you
    • You should feel a stretch in the back of the thigh — not behind the knee
    • Hold 30 seconds, 3 repetitions per side — perform after exercise when muscles are warm
    See full exercise guide

Physical therapy equipment

Tools that support your recovery

Affiliate disclosure: links below go to Amazon. If you purchase through them, we may earn a small commission at no extra cost to you. We only recommend equipment used in physical therapy practice.

Support & Proprioception$15 – $40

Knee Compression Sleeve

Graduated compression knee sleeve for patellofemoral pain and mild OA. Compression improves proprioception and reduces swelling during activity — not a substitute for strengthening, but a useful adjunct.

Why it helps: Enhances joint position sense and reduces pain during the step-down and TKE exercises, allowing better form and higher training volume.

VMO Activation$10 – $25

Resistance Band (Loop, Medium)

Medium-resistance loop band for terminal knee extension (TKE) and lateral band walks. The TKE is the primary VMO activation exercise and requires a band anchored at knee height.

Why it helps: Provides the resistance needed for TKE — the most targeted VMO activation exercise for patellofemoral pain and knee instability.

Functional Training$30 – $70

Step Platform (Adjustable)

Adjustable aerobic step platform for step-down eccentric training. The step-down exercise requires a 4-8 inch elevated surface — a dedicated step platform allows consistent height and safe footing.

Why it helps: Provides the controlled elevation needed for eccentric step-down training — the most effective exercise for patellofemoral pain and quad strength.

Flexibility$8 – $20

Hamstring Stretching Strap

Yoga strap or physical therapy stretching belt for supine hamstring stretching. Allows the leg to be held at full extension without gripping, enabling a relaxed, sustained stretch.

Why it helps: Reduces posterior knee tension from tight hamstrings that alter patellar tracking and increase patellofemoral joint stress.

Common questions

Common questions.

Answers to the questions we hear most often about knee pain.

  • Yes — for most knee conditions, exercise is not only safe but essential. The key is to work within a tolerable pain range (0 to 4 out of 10) and choose exercises that do not significantly aggravate symptoms. High-impact activities like running may need to be temporarily modified, but low-impact exercise like cycling, swimming, and walking is generally well-tolerated.

    Pain during exercise that settles within 24 hours is generally acceptable. Pain that is significantly worse the next day suggests the load was too high.

  • Knee braces can provide short-term pain relief and confidence for some people, but they do not address the underlying weakness and movement dysfunction. They are best used as a temporary support while building strength, not as a long-term solution. Patellar taping (McConnell taping) has good evidence for patellofemoral pain and can be taught by a physical therapist.

  • Knee osteoarthritis typically affects adults over 50, causes diffuse joint pain and stiffness, and is associated with joint space narrowing on X-ray. Patellofemoral pain syndrome typically affects younger adults and athletes, causes pain around or behind the kneecap, and is associated with quadriceps weakness and altered movement patterns. Both respond well to corrective exercise, though the specific exercises differ.

  • Knee replacement is typically considered when: pain significantly limits daily activities, conservative management has been tried for at least 3 to 6 months without adequate relief, and quality of life is substantially affected. Evidence shows that corrective exercise therapy is as effective as surgery for many knee conditions, including meniscal tears and mild-to-moderate osteoarthritis.

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Medical disclaimer: The information on this page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any exercise program, particularly if you have a medical condition or have recently been injured. Read our full disclaimer.