What muscles are primarily worked during a bent knee raise?

The bent knee raise primarily engages the rectus abdominis (especially its lower fibers), obliques, iliopsoas, rectus femoris, and sartorius muscles.

What are the main benefits of doing bent knee raises?

Incorporating bent knee raises strengthens lower abdominals and hip flexors, enhances core stability, supports spinal health by strengthening core muscles, and is a versatile exercise accessible to many.

How can I ensure proper form and avoid common mistakes during a bent knee raise?

To ensure proper form, avoid arching your lower back, using momentum, hyperextending your neck, or relying only on hip flexors; focus on controlled movement and maintaining core engagement throughout.

Who should perform bent knee raises?

The bent knee raise is suitable for beginners building foundational core strength, fitness enthusiasts, athletes, and individuals with lower back pain (with caution and professional consultation).

Are there different variations of the bent knee raise to increase difficulty?

Yes, variations include the standard lying bent knee raise, hanging, incline, weighted, and seated bent knee raises, allowing for increased challenge and different angles of engagement.

How to do a bent knee raise?

The bent knee raise is a foundational core exercise primarily targeting the lower abdominal muscles and hip flexors, performed by lifting the knees towards the chest while maintaining a stable torso.

What is the Bent Knee Raise?

The bent knee raise is a highly effective exercise designed to strengthen the abdominal wall, particularly the lower rectus abdominis, and the hip flexor muscles (iliopsoas, rectus femoris, sartorius). It is a versatile movement that can be performed in various positions, including lying on the floor, seated, or hanging from a bar, making it adaptable for different fitness levels and equipment availability. Its focus on controlled movement and core engagement makes it an excellent choice for improving core stability, posture, and athletic performance.

Benefits of the Bent Knee Raise

Incorporating the bent knee raise into your routine offers several key benefits:

Strengthens Lower Abdominals: Specifically targets the often-neglected lower region of the rectus abdominis, contributing to a stronger and more defined core.
Enhances Hip Flexor Strength: Develops strength in the muscles responsible for bringing the knees towards the torso, crucial for walking, running, and jumping.
Improves Core Stability: A strong core is fundamental for all movements, providing a stable base for the spine and protecting against injury.
Supports Spinal Health: By strengthening the core, the exercise helps to support the lumbar spine, potentially reducing lower back pain and improving posture.
Accessible and Versatile: Can be performed virtually anywhere with minimal or no equipment, making it suitable for home workouts or gym settings.

Muscles Worked

The primary muscles engaged during a bent knee raise include:

Rectus Abdominis: The "six-pack" muscle, particularly its lower fibers, responsible for spinal flexion.
Obliques (Internal and External): Assist in stabilizing the trunk and may contribute to slight rotational stability, especially during variations.
Iliopsoas: A major hip flexor group (composed of the iliacus and psoas major), responsible for flexing the hip joint.
Rectus Femoris: One of the quadriceps muscles that also acts as a hip flexor.
Sartorius: A long, thin muscle that assists in hip flexion and external rotation.

Step-by-Step Guide: Performing the Bent Knee Raise

The following instructions detail the lying bent knee raise, a common and accessible starting point.

Starting Position: Lie flat on your back on a mat or comfortable surface. Place your hands lightly by your sides, palms down, or under your glutes for lower back support. Ensure your lower back is pressed gently into the floor. Your legs should be extended straight.
Engage Core: Take a deep breath, and as you exhale, draw your navel towards your spine, bracing your core as if preparing for a gentle punch to the stomach. This creates intra-abdominal pressure and protects your spine.
Initiate Movement: Keeping your knees bent at approximately a 90-degree angle, slowly and deliberately lift your knees towards your chest. The movement should be initiated by your abdominal muscles, not by momentum or pulling with your hands.
Concentric Phase (Lift): Continue lifting until your knees are directly over your hips, or slightly closer to your chest, ensuring your lower back remains in contact with the floor. Avoid lifting your hips excessively off the ground; the focus is on abdominal contraction.
Peak Contraction: At the top of the movement, pause briefly and squeeze your abdominal muscles, feeling the contraction in your lower core.
Eccentric Phase (Lower): Slowly and with control, lower your legs back to the starting position. Resist the urge to let your legs drop quickly. Maintain core engagement throughout the entire descent.
Repetition: Once your feet lightly touch the floor (or hover just above it for increased challenge), immediately begin the next repetition.

Key Points for Proper Form:

Controlled Movement: Avoid swinging or using momentum. The entire movement should be slow and controlled, emphasizing muscle contraction.
Spinal Stability: Keep your lower back pressed into the floor throughout the exercise. If your back arches, you may be lowering your legs too far or need to improve core strength.
Breath Control: Exhale as you lift your knees (exertion phase) and inhale as you lower them.
Mind-Muscle Connection: Focus on feeling the contraction in your lower abdominal muscles.

Common Mistakes to Avoid

To maximize effectiveness and prevent injury, be mindful of these common errors:

Arching the Lower Back: This indicates a lack of core engagement or lowering the legs too far, putting undue stress on the lumbar spine. Focus on keeping the lower back glued to the mat.
Using Momentum: Swinging the legs up rather than lifting them with controlled abdominal contraction reduces the exercise's effectiveness and increases injury risk.
Hyperextending the Neck: Cranking the neck forward or backward can strain the cervical spine. Keep the neck neutral and relaxed.
Relying on Hip Flexors Only: While hip flexors are involved, the primary target is the lower abs. If you feel it mostly in your hips, focus on initiating the lift by "curling" your pelvis slightly and engaging your core more actively.
Rushing the Movement: The slower the movement, especially the eccentric (lowering) phase, the greater the muscle engagement and time under tension.

Variations and Progressions

Once you've mastered the basic bent knee raise, consider these variations to increase challenge or target different aspects of core strength:

Lying Bent Knee Raise (Standard): As described above, excellent for beginners and focusing on lower abdominal control.
Hanging Bent Knee Raise: Performed while hanging from a pull-up bar. This variation significantly increases the challenge due to gravity and requires greater upper body and grip strength for stability.
Incline Bent Knee Raise: Performed on an incline bench, with your head higher than your feet. This increases the range of motion and gravity's resistance, making the exercise more challenging.
Weighted Bent Knee Raise: For advanced individuals, a light dumbbell or medicine ball can be held between the knees or ankles to increase resistance. Start with very light weight and prioritize form.
Seated Bent Knee Raise: Sitting on the edge of a bench or chair, lean back slightly, and lift your bent knees towards your chest. This offers a different angle of engagement and can be a good option for those who find lying flat uncomfortable.

Who Should Do Bent Knee Raises?

The bent knee raise is a versatile exercise suitable for a wide range of individuals:

Beginners: It's an excellent starting point for building foundational core strength.
Fitness Enthusiasts: Can be integrated into various workout routines for core development.
Athletes: Improves hip flexor strength and core stability, benefiting sports performance.
Individuals with Lower Back Pain (with caution): When performed correctly with a focus on spinal stability, it can help strengthen supporting core muscles. Always consult a healthcare professional before starting new exercises if you have pre-existing conditions.

Safety and Considerations

While generally safe, keep the following in mind:

Listen to Your Body: Stop immediately if you experience any sharp pain, especially in your lower back or hips.
Consult a Professional: If you have chronic lower back pain, hip issues, or are recovering from an injury, consult a physician or physical therapist before attempting this exercise.
Progress Gradually: Do not attempt advanced variations like hanging or weighted knee raises until you have mastered the basic lying version with perfect form.
Proper Warm-up: Always perform a light warm-up before engaging in core exercises to prepare your muscles and joints.

Bent Knee Raise: Benefits, Muscles Worked, and Step-by-Step Guide