Protecting your knees comes down to three things: keeping the muscles around them strong, managing the forces that pass through them, and avoiding the movement patterns that cause the most damage. Your knees absorb roughly 1.5 times your body weight with every step on flat ground, and two to three times your body weight when you climb or descend stairs. That load adds up over decades, but the choices you make now can dramatically slow cartilage wear and reduce your injury risk.
Why Knees Are So Vulnerable
The knee is the largest joint in the body, and it sits between two long levers (your thigh bone and shin bone) that amplify rotational and side-to-side forces. A thin layer of cartilage cushions the surfaces where these bones meet. That cartilage has no blood supply of its own, so once it starts breaking down, it regenerates poorly. Mechanical overload and repetitive stress are the primary drivers of cartilage degeneration, which is the hallmark of osteoarthritis.
Unlike a hip joint, which is a deep ball-and-socket, the knee depends heavily on soft tissue for stability: ligaments hold the bones together, and muscles control how the joint tracks during movement. When those muscles are weak or movement technique is off, the knee absorbs forces it wasn’t designed to handle alone.
Build Strength in the Right Muscles
The single most effective thing you can do for your knees is strengthen the muscles that stabilize them. Your quadriceps (front of the thigh), hamstrings (back of the thigh), and glutes all work together to keep the knee aligned and absorb shock before it reaches the joint. When any of these groups are weak, the knee shifts excessively during movement, and cartilage and ligaments take the hit.
A straightforward routine recommended by physical therapists at Hospital for Special Surgery covers all three muscle groups:
- Squats: Stand with feet shoulder-width apart, sit back and down while keeping your chest upright, then push through your feet to stand. Three sets of 8 to 15 reps.
- Deadlifts (hip hinge): Stand with feet hip-width apart, hinge at the hips with a flat back, lower until you feel tension in the hamstrings, then drive your hips forward to stand. Three sets of 8 to 12 reps.
- Monster walks: Place a resistance band around your ankles or just above your knees. With knees slightly bent, step sideways while keeping the band taut and your knees over your feet. Two to three sets of 10 to 15 steps in each direction.
- Heel raises: Stand facing a wall for balance, rise onto your toes slowly, then lower with control. Two to three sets of 12 to 20 reps.
Monster walks are particularly useful because they target the outer glutes, which control side-to-side knee motion. Weak glutes are one of the most common contributors to knee pain in runners and people who sit most of the day. You don’t need a gym for any of these exercises. Body weight alone is enough to start, and you can add resistance as you get stronger.
How You Land and Pivot Matters
Ligament tears, especially ACL injuries, often happen not from contact but from the way a person lands or changes direction. Research from Oregon State University found that people who tear their ACLs tend to land stiffly, tensing the muscles in the front of their thighs before their feet touch the ground. This creates a rigid leg that can’t absorb impact, sending all the force straight into the knee.
The other major risk factor is landing “knock-kneed,” where the knees collapse inward. Women are more likely to land in this position, which puts dangerous sideways stress on the knee. The fix is straightforward: when you jump, land with soft, bent knees and actively push your knees outward so they track over your toes rather than caving in. If you play sports that involve cutting, jumping, or sudden stops, practicing these landing mechanics in training is one of the highest-value things you can do for long-term knee health.
Manage Your Body Weight
Because the knee multiplies the forces of body weight, even small changes in weight have an outsized effect on your joints. Walking generates a force equal to about 1.5 times your body weight on each knee. Going up or down stairs pushes that to two to three times your body weight. So losing 10 pounds effectively removes 15 to 30 pounds of force from your knees with every step.
This works in the other direction too. Gaining weight doesn’t just add proportional stress; it compounds it. If you’re carrying extra weight and already feeling knee discomfort, even a modest reduction can produce noticeable relief because of this multiplier effect.
Move Throughout the Day
Sitting for long periods is surprisingly hard on your knees. When the joint stays bent in one position, blood flow to the surrounding tissues drops and stiffness builds. Cartilage relies on the compression and release cycle of movement to absorb nutrients from the surrounding fluid, so prolonged stillness essentially starves it.
If you work at a desk, set your chair height so your knees rest at a 90-degree angle with your feet flat on the floor. Then stand up and move every 30 to 60 minutes, even if it’s just a short walk to the kitchen or a few stretches. This restores blood flow, reduces stiffness, and keeps the joint lubricated. It doesn’t need to be a formal exercise break. Simply changing position regularly is enough to prevent the worst effects of prolonged sitting.
Choose the Right Shoes
The way your foot hits the ground directly affects the forces traveling up into your knee. Excessive foot pronation (where the ankle rolls inward with each step) increases rotational stress on the knee and can accelerate cartilage wear over time. Research shows that increased pronation on one side also changes trunk and hip mechanics, potentially overloading the knee and lower back.
If you overpronate, motion-control shoes can help. One study on female runners found that motion-control shoes prevented the spike in impact loading that normally occurs as muscles fatigue during a run, while neutral shoes did not. This matters because most knee injuries and pain flare-ups happen when you’re tired, not fresh. If you’re unsure about your foot mechanics, a running store with gait analysis or a physical therapist can tell you within minutes whether you need additional support.
For everyday wear, avoid completely flat, unsupportive shoes for long walks or standing. You don’t need expensive orthotics unless a specific problem has been identified, but a shoe with decent arch support and cushioning reduces the cumulative impact your knees absorb over a day.
What About Supplements?
Glucosamine and chondroitin are the most widely marketed joint supplements, but the evidence for them is genuinely mixed. A combined analysis of 29 studies with over 6,000 participants found that glucosamine and chondroitin taken separately showed some pain reduction for knee osteoarthritis, but the combination of the two did not. Individual studies have been wildly inconsistent, with some showing benefits and others showing none.
The American College of Rheumatology and the Arthritis Foundation both strongly recommend against using glucosamine or chondroitin for knee osteoarthritis, as does the Osteoarthritis Research Society International. The American Academy of Orthopaedic Surgeons takes a slightly softer position, listing them as possibly helpful for mild-to-moderate cases while noting the evidence is inconsistent. Whether these supplements affect actual joint structure (not just pain perception) remains uncertain. If you’ve been taking them and feel they help, they’re generally safe, but the data doesn’t support starting them as a preventive strategy.
When Knee Braces Help
Knee braces serve different purposes depending on the type, and wearing the wrong one (or wearing one unnecessarily) won’t do much good.
- Prophylactic braces are designed to protect healthy knees from side impacts during contact sports. Despite their popularity in football, both the American Academy of Orthopaedic Surgeons and the American Academy of Pediatrics have concluded there isn’t enough evidence that they actually reduce ligament injuries. Their routine use in athletics isn’t currently recommended.
- Functional braces are meant for people who already have ligament damage, particularly ACL injuries. They reduce abnormal movement in the joint and are commonly used after reconstructive surgery or for athletes returning to sports that involve cutting and pivoting.
- Patellofemoral braces (knee sleeves with a patellar cutout) help with kneecap tracking issues and anterior knee pain. They provide moderate subjective improvement for conditions like runner’s knee or patellar tendinitis.
For most people without an existing injury, a brace isn’t a substitute for strong muscles. Strengthening the muscles that control knee alignment does more to protect the joint than any external device. If you do have instability or a previous injury, a brace can provide useful additional support during demanding activities.