Strengthen and stabilize weak knees with this trainer's go-to lower-body workout

A common gripe among people when performing exercises like squats is that it hurts their knees, or that their knees are too weak. Often the issue is not the knee joint itself but the interconnected muscles, ligaments and tendons that enable it to function.

Squats alone won't remedy this, because they typically only target the quads muscles on the front of the thighs and, unless performed with exceptional form, rarely fully activate the hamstrings and glutes.

For a well-rounded workout to strengthen and stabilize the knees, you need to think 360˚. And that's exactly what trainer Rachael Penrose of fitness app WithU has done by recommending these three lower-body exercises for knee strength.

Yes, her routine involves a bodyweight squat (you can perform this with a chair behind you if you need additional support). It also incorporates a bridge exercise to activate the posterior chain muscles of the hamstrings, lower back and glute muscles.

It finishes with a lateral lunge, strengthening and stretching the adductors that run along the inside of the thigh while challenging your ability to move through a different plane of movement.

Three exercises to strengthen weak knees

These three exercises will get your lower body muscles working in harmony, building strength and stability that will keep your hips, pelvis and ankles in alignment while keeping your knees happy and injury-free.

Follow Penrose's video and use these form guides to perfect each exercise. You can then knit them together with the 150-rep, nine-minute workout I've outlined below. Trust me, you'll rattle through it in no time.

1 Bodyweight squat

• Stand with feet roughly shoulder-width apart, toes slightly turned out.
• Sit your hips back and bend your knees to lower into a squat. Keep your chest facing forward to keep your back flat.
• Lower until your thighs are parallel to the floor, then drive up to stand. Don't allow your knees to cave in—keep them wide as you lower and again as you drive up.

2 Glute bridge

• Lie on the floor with knees bent and feet flat. Keep your arms out wide for support and press your lower back into the floor.
• From here, drive through your heels to lift your hips high off the floor. Ensure your ankles, knees and hips are aligned to achieve full range of motion.
• Lower your bum to the floor under control and repeat.

3 Lateral lunges

• Start in a wide stance with feet more than double shoulder-width apart. Allow your toes to point out slightly.
• Sit your hips back and bend one leg to lower into a lunge on one side. Keep the other leg straight and your chest facing forward. Only lower as far as your inner-thigh flexibility allows.
• Drive back up by straightening your leg. As with the squat, don't let your bent knee cave in—keep it wide as you lower and drive up.
• Alternate sides and repeat.

Combine these moves for a comprehensive lower-body workout

Combining these three exercises in a pyramid EMOM format will provide an evenly balanced lower-body workout with some bonus cardiovascular pay-off.

A pyramid format means you'll gradually increase the number of reps (repetitions) for the first half of the session, then decrease them for the second.

EMOM stands for every minute on the minute. The goal is to complete a set number of reps at the start of each minute, resting for the remainder.

Here's how it works.

Start a timer and perform two reps of each exercise—so two squats, two glute bridges and one lateral lunge on each side—then rest the remainder of the minute.

• After one minute, perform four reps of each exercise, then rest.
• After two minutes, perform six reps of each exercise, then rest.
• After three minutes, perform eight reps of each exercise, then rest.
• After four minutes, perform 10 reps of each exercise, then rest.

Now work down the pyramid.

• After five minutes, perform eight reps.
• After six minutes, perform six reps.
• After seven minutes, perform four reps.
• After eight minutes, perform two reps.

And that's you done—in nine minutes and 150 reps flat.

Having tried this myself, you'll have to push to squeeze 30 reps in within 60 seconds, but make sure your form doesn't get sloppy. Don't worry if you don't get all 30 in. Do what you can, make a note of how many you missed, and try to improve your score next time you repeat the workout. Good luck.