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  3. Exercises
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  5. Core & Abs
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  7. Weighted Lying Supine Straight Knee Raise

Exercise guide

Weighted Lying Supine Straight Knee Raise

  • Beginner
  • Isolation
  • Rep-based
  • Upper legs
  • Waist

This isolation exercise targets the quadriceps, specifically the rectus femoris, by performing hip flexion while the knee remains locked. It is an effective way to build knee stability and quad strength with minimal joint impact.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Weighted Lying Supine Straight Knee Raise demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Quadriceps

Secondary

  • Abs
  • Hip flexors

Equipment

  • Body weight

Setup

  1. Lie flat on your back on an exercise mat with your legs extended.
  2. Bend the non-working knee and place that foot flat on the floor to stabilize your pelvis and protect your lower back.
  3. Straighten the working leg completely, pulling your toes toward your shin to engage the anterior chain.

How to do it

  1. Contract your quadriceps to lock the knee of the straight leg firmly.
  2. Exhale as you lift the straight leg upward until it is roughly level with the thigh of the opposite bent leg.
  3. Inhale as you slowly lower the leg back toward the floor using a controlled 2-second tempo.
  4. Stop just before your heel touches the ground to maintain tension, then repeat for the desired reps before switching sides.

Form checklist

  • Keep your lower back pressed firmly into the mat throughout the movement.
  • Ensure the knee of the lifting leg stays perfectly straight; do not allow it to bend.
  • Avoid using momentum or swinging the leg upward.
  • Keep your core braced to prevent your hips from tilting or rocking.

Pro tips

  • Focus on 'squeezing' the quad as hard as possible before starting the lift to ensure the muscle is fully recruited.
  • Turn your toes slightly outward (external rotation) to increase the engagement of the vastus medialis (teardrop muscle).

Make it harder

  • Add ankle weights to increase the resistance against hip flexion.
  • Slow the eccentric phase to 4 seconds to maximize time under tension for the quadriceps.

Frequently asked

What muscles does the weighted lying supine straight knee raise work?
The weighted lying supine straight knee raise primarily targets the quadriceps, and also works the abs and hip flexors as secondary muscles.
What equipment do you need for the weighted lying supine straight knee raise?
The weighted lying supine straight knee raise requires no equipment — just your body weight.
Is the weighted lying supine straight knee raise good for beginners?
Yes. The weighted lying supine straight knee raise is a beginner-friendly movement and a strong foundation to build on.

Related exercises

  • 90 To 90Beginner · abs, glutes, obliques, and quadriceps
  • 90 To 90 SwitchIntermediate · abs, glutes, obliques, and quadriceps
  • Air Punches MarchBeginner · calves, pectorals, and quadriceps
  • All Fours Squat StretchBeginner · quadriceps

Train it with Crucible Fit.

Every movement in this library is in the app with video and instructions, ready for your own sessions on the days between Crucibles. Your first Crucible is on us.

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