Your thighs are the powerhouse of your body, so when half of it — the quadriceps muscles, a group of four muscles located on the front of your upper legs — isn't as strong as they should be, you suffer the consequences. From everyday activities such as climbing stairs to athletic pursuits like running, weak quads can make everything more difficult — and painful. In fact, quadricep weakness is linked to knee pain, according to a study published in 2014 in the journal Osteoarthritis and Cartilage.
In most cases, weak quads will simply be a result of a lack of muscle-building exercises. However, it could be caused by an injury or condition such as patellofemoral stress syndrome, iliotibial band friction syndrome or patellar tendinitis. To improve your quadriceps' strength, incorporate muscle-building exercises into your regular workouts.
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Read More: Rehab Exercises for the Quadriceps
If you have access to weight machines at the gym, leg extensions isolate the quadricep muscles to focus solely on building that particular muscle group. If you're a beginner, leg extensions can also help you learn proper form before moving onto more complex free-weight movements.
To do a leg extension, sit on the machine's chair and tuck your feet behind the bar below. Set the amount of weight being lifted to an appropriate amount for your fitness level. Engage your quads and lift the bar up until your legs are straight. Return it to the starting position.
Read More: Quadriceps Exercises Using Your Body Weight
Straight Leg Raises
For an exercise you can do at home, start with simple quadriceps-strengthening move that also works other muscle groups. To do straight leg raises, lie on your back on a flat surface. Bend one knee and place your foot flat on the floor, keeping the other leg straight. Contract the quad muscles and slowly lift the straight leg up 12 inches. Hold it raised for 5 seconds, and then release. Repeat 10 to 15 times, and then switch to the other leg.
Make this exercise more challenging by attaching a 2- to 3-pound cuff weight around your ankle.
This simple but effective exercise works all of your leg muscles, including the quadriceps. Start by standing with your back flat against a wall and your feet shoulder-width apart. Slide down the wall, bending your knees to a 45-degree angle. Hold for 5 seconds — or as long as you can without any pain — and then slowly straighten your legs to return to the start position. Repeat 10 times.