Bad Knees: Exercises to Avoid, Why They Hurt, and Safer Options

What exercises should you not do with bad knees?

If you're dealing with "bad knees," certain exercises that involve high impact, deep knee flexion, or excessive shear forces can exacerbate pain and potentially worsen existing conditions. Prioritizing joint health means understanding which movements to modify or avoid and why.

Understanding "Bad Knees"

The term "bad knees" is broad, encompassing various conditions such as osteoarthritis, patellofemoral pain syndrome (runner's knee), meniscal tears, chondromalacia patellae, or ligamentous instability. Each condition affects the knee joint's intricate structure differently, but the common goal is to minimize stress, reduce pain, and prevent further degradation while maintaining strength and mobility. Our focus here is on identifying movements that place undue stress on compromised knee structures.

General Principles for Knee Protection

Before diving into specific exercises, consider these foundational principles for safeguarding your knees:

• Avoid High-Impact Loading: Repetitive ground reaction forces can be detrimental to damaged cartilage and inflamed tissues.
• Minimize Deep Joint Flexion Under Load: Extreme bending of the knee, especially when weighted, significantly increases compressive forces on the patellofemoral joint and menisci.
• Control Movement Speed: Jerky, uncontrolled movements increase the risk of injury and apply sudden, high stresses.
• Listen to Your Body: Pain is a signal. If an exercise causes sharp pain, stop immediately. Distinguish between muscle fatigue and joint pain.

Exercises to Approach with Caution or Avoid

Based on biomechanical principles and common clinical observations, the following exercises often pose a risk for individuals with compromised knees:

• Deep Squats and Lunges:
  • Why avoid/modify: As the knee bends beyond 90 degrees, compressive forces on the patellofemoral joint dramatically increase. For those with osteoarthritis or patellofemoral pain, this can lead to significant pain and cartilage wear. Deep lunges also place considerable stress on the lead knee, especially if form falters.
  • Modification: Perform partial squats or lunges, limiting knee flexion to a comfortable range, typically above 90 degrees. Focus on hip hinge and glute activation.
• Plyometrics and Jumping Exercises:
  • Why avoid: Box jumps, jump squats, burpees, and any activity involving jumping or hopping create high impact forces upon landing. These forces are absorbed by the joints, and compromised knees may lack the shock-absorbing capacity, leading to pain and potential damage.
  • Modification: Replace with lower-impact power exercises like controlled step-ups onto a box, or focus on strength training with controlled eccentrics.
• High-Impact Cardio (Running, HIIT with Jumps):
  • Why avoid: Similar to plyometrics, repetitive high-impact activities like running can subject the knees to significant stress with each stride. High-Intensity Interval Training (HIIT) often incorporates jumping or explosive movements that are problematic.
  • Modification: Opt for low-impact cardio alternatives such as cycling, swimming, elliptical training, or brisk walking.
• Leg Press Machine (Deep Range of Motion):
  • Why avoid/modify: While seemingly supportive, allowing the knees to go into deep flexion (knees coming close to the chest) on a leg press can replicate the high patellofemoral compression seen in deep squats, potentially pushing the knee beyond its pain-free range.
  • Modification: Limit the range of motion to where your knees remain comfortable, typically stopping before your hips drop below your knees.
• Leg Extension Machine:
  • Why avoid: This exercise places significant isolated stress on the patellofemoral joint, particularly at the end range of extension. It creates a strong anterior shear force on the tibia, which can be problematic for those with ligamentous laxity or patellar tracking issues.
  • Modification: Focus on closed-chain exercises like squats, lunges, or step-ups that recruit multiple muscle groups and distribute forces more naturally across the joint. If using, limit range of motion and weight, avoiding full lockout.
• Leg Curl Machine (Full Range of Motion, Heavy):
  • Why avoid/modify: While generally safer than leg extensions, performing leg curls with excessive weight or forcing a full range of motion can place undue stress on the posterior knee joint capsule or exacerbate hamstring imbalances that affect knee mechanics.
  • Modification: Use controlled movements and avoid hyperextension at the top. Focus on moderate weights and controlled eccentrics.
• Certain Yoga or Pilates Poses (Deep Flexion/Twisting):
  • Why avoid/modify: Poses like Hero's Pose (Virasana), Lotus Pose (Padmasana), or deep kneeling poses can involve extreme knee flexion and internal/external rotation, which can be highly aggravating for meniscal tears or arthritic knees. Poses with significant twisting through the torso while grounded can also create torque on the knee.
  • Modification: Use props (blankets, blocks) to reduce joint angles, avoid pain, and choose modified versions of poses. Focus on gentle movements and maintain neutral knee alignment.

Understanding Why These Exercises Can Be Problematic

The common thread among these problematic exercises relates to specific biomechanical stresses:

• Increased Joint Compression: When the knee flexes deeply under load, the force pressing the kneecap (patella) against the thigh bone (femur) increases exponentially. This is particularly harmful for those with patellofemoral pain or cartilage degeneration.
• Shear Forces: Forces that act parallel to the joint surface, like those generated during the leg extension, can pull or push on structures that are not designed for such isolated stress, potentially compromising ligaments or joint stability.
• Impact Loading: High-impact activities transmit shock waves through the joint. While healthy cartilage can absorb some of this, damaged cartilage or inflamed synovial fluid cannot, leading to pain and further wear.
• Torque and Twisting: Movements that involve twisting the knee while the foot is planted (e.g., pivot movements in sports, certain yoga poses) place high stress on the menisci and ligaments, potentially leading to tears or sprains.

Empowering Your Movement: Safer Alternatives and Modifications

Instead of avoiding exercise entirely, focus on building strength and mobility through knee-friendly options:

• Low-Impact Cardio: Cycling (stationary or road), swimming, elliptical training, walking, and rowing are excellent choices.
• Strength Training Modifications:
  • Partial Range Squats/Lunges: Control the depth to a pain-free range.
  • Glute Bridges/Hip Thrusts: Excellent for glute and hamstring strength without direct knee stress.
  • Step-Ups: Use a low step, focusing on controlled movement up and down.
  • Leg Curls (prone or seated): Use moderate weight and controlled range.
  • Terminal Knee Extensions (TKEs): Light resistance band work to strengthen the last few degrees of knee extension, often beneficial for patellar tracking.
  • Hip Abduction/Adduction: Strengthens supporting muscles around the hip, which are crucial for knee stability.
• Focus on Core and Hip Strength: A strong core and stable hips are fundamental for proper lower limb mechanics and reduce compensatory stress on the knees.
• Warm-Up and Cool-Down: Always include dynamic warm-ups before exercise and static stretches afterward.
• Proper Footwear: Wear supportive shoes appropriate for your activity.

When to Consult a Professional

If you experience persistent knee pain, swelling, instability, or if pain worsens with specific movements, it is crucial to consult a healthcare professional. A physical therapist, orthopedic specialist, or sports medicine doctor can provide an accurate diagnosis, recommend appropriate exercises, and guide you on movements to avoid based on your specific condition. A personalized approach is always best for managing "bad knees" effectively.