Building the muscles around your knees is one of the most effective ways to protect the joint, reduce pain, and improve how you move. The knee itself is a hinge held together by ligaments and cartilage, but it’s the surrounding muscles that do the heavy lifting of absorbing force and keeping everything tracking properly. Strengthening those muscles requires targeted exercises, the right training volume, and enough protein to support growth.
The Muscles That Support Your Knee
Two main muscle groups control the knee. The quadriceps, a group of four muscles on the front of your thigh, straighten your leg. The hamstrings, three muscles on the back of your thigh, bend it. Both groups attach across the knee joint, and an imbalance between them is one of the most common reasons people develop knee pain.
Your calves also play a role. The larger calf muscle crosses behind the knee and helps with bending, while a small deep muscle called the popliteus helps “unlock” the knee from a fully straight position. When people talk about “knee muscles,” they really mean all of these groups working together. A good program trains them all, not just the quads.
How Much Training You Actually Need
The most current guidelines from the American College of Sports Medicine recommend training each major muscle group at least twice per week and aiming for roughly 10 sets per muscle group per week to drive muscle growth. That’s less daunting than it sounds. You could hit your quads and hamstrings in two sessions of five sets each, spread across the week.
Research published in Frontiers in Physiology compared doing all six sets in one weekly session versus splitting the same volume into three sessions of two sets. Both groups did the same total work, but the group training three times per week gained more strength. The takeaway: spreading your sets across more days works better than cramming them into one leg day, even when total volume is equal. For most people, two to three sessions per week with moderate volume per session is the sweet spot.
The well-established rep range for muscle growth is 8 to 12 repetitions per set at a weight that feels challenging by the final two reps. Rest about two minutes between sets. If you can easily finish all 12 reps, increase the weight next session.
Best Exercises for Knee Strength
Closed-Chain Exercises
Closed-chain exercises are movements where your feet stay planted on the ground or a platform. Squats, lunges, step-ups, and leg presses all fall into this category. These distribute force across the entire leg and load the knee joint more evenly through the range of motion. During a squat, compression on the kneecap increases with depth, peaking around 90 degrees of bend. This gradual loading is generally well tolerated because the force is shared between multiple muscles and joints.
For squats, keep your knees tracking in the same direction as your toes and avoid letting them drift far past your toes at the bottom of the movement. Both cues reduce unnecessary rotational and shear forces on the joint. You don’t need to squat with a barbell to build knee muscles. Goblet squats with a dumbbell or kettlebell, wall sits, and bodyweight squats all work, especially when you’re starting out.
Step-downs are another excellent option. Stand on a low step, slowly lower one foot toward the ground by bending the standing leg, then push back up. This loads the quads through a controlled range while also training balance.
Open-Chain Exercises
Open-chain exercises, like seated leg extensions and hamstring curls, isolate individual muscle groups. Leg extensions put the highest compression on the kneecap between 20 and 30 degrees of bend (the early part of the movement), with forces decreasing as the leg straightens. This makes them useful for targeted quad work, but people with kneecap pain sometimes find the early range uncomfortable. If that’s the case, you can limit the range of motion to the top half of the movement where stress is lower, then gradually work deeper as your muscles and tendons adapt.
Hamstring curls (seated or lying) are the simplest way to strengthen the back of the thigh. Strong hamstrings counterbalance the pull of the quads and protect the ACL. Don’t skip them.
Eccentric Training
Eccentric training focuses on the lowering phase of a movement, when the muscle lengthens under load. This type of training builds muscle and also strengthens tendons, which matters because tendons adapt more slowly than muscle and are often the weak link in the chain.
A classic eccentric exercise for the knee is the decline squat, performed on a board angled at about 25 degrees. The decline shifts more work onto the quads and patellar tendon by relaxing the calf. You lower yourself slowly on one leg, bending to about 70 degrees, then use both legs to stand back up. Clinical protocols typically start at around 70% of your max capacity and progress gradually over weeks to full load. Decline squats have been used successfully in rehabilitation settings to improve tendon strength and reduce pain in people with patellar tendon issues.
You can apply the eccentric principle to any exercise. On a leg press, push up with both legs, then lower the weight slowly with one. On a step-down, spend three to four seconds on the lowering phase. The key is controlling the descent rather than dropping quickly.
A Simple Weekly Structure
Here’s what a practical week could look like, hitting each muscle group with enough volume to grow:
- Day 1: Squats (3 sets of 10), hamstring curls (3 sets of 10), calf raises (2 sets of 15)
- Day 2: Leg press (3 sets of 10), leg extensions (2 sets of 12), step-downs (2 sets of 10 per leg)
- Day 3 (optional): Walking lunges (2 sets of 12 per leg), decline squats (3 sets of 10), hamstring curls (2 sets of 10)
That gives you roughly 10 to 14 sets per week for the quads and 5 to 7 for the hamstrings, right in line with evidence-based recommendations. Start with weights that let you finish every rep with good form, and add load by small increments week to week.
What to Eat to Support Muscle Growth
Training provides the stimulus, but protein provides the raw material. To trigger the muscle-building process after a workout, each meal needs to contain enough of the amino acid leucine, which acts as a molecular switch for muscle protein synthesis. Research suggests about 2.5 to 3 grams of leucine per meal is the threshold for a strong response, which corresponds to roughly 25 to 30 grams of high-quality protein. Younger adults can get away with slightly less (around 20 grams per meal), while adults over 60 benefit from hitting the higher end.
In practical terms, that’s a chicken breast, a cup of Greek yogurt with a scoop of whey, or a can of tuna. Spreading protein across three to four meals per day keeps the muscle-building signal elevated throughout the day rather than relying on one large serving at dinner.
Protecting Your Knees While Building Them
Building knee muscles and protecting knee joints aren’t separate goals. They’re the same goal, as long as you follow a few principles. Progress gradually: your muscles may be ready to lift heavier before your tendons are, and tendon injuries take far longer to heal than muscle strains. A 10% increase in weight per week is a reasonable ceiling for most people.
Keep your knee aligned with your toes during all pressing and squatting movements. Internal collapse (the knee caving inward) increases rotational stress on the ligaments and cartilage. If your knee drifts inward, the fix is usually weak hip muscles rather than weak quads, so adding side-lying leg raises or banded lateral walks to your warmup helps.
Moderate discomfort during exercise is normal, especially if you’re coming back from an injury or starting from zero. Pain that is sharp, localized to one spot, or that makes you change your movement pattern is a signal to reduce the load or range of motion. Building muscle around the knee is a months-long project, not a weeks-long one. Consistency at a tolerable intensity will always outperform aggressive training you can’t sustain.