Straight leg raises are a staple in many core-strengthening routines. They’re simple, effective, and don’t require any equipment, making them a go-to for anyone looking to build lower abdominal strength and hip flexor control. But like many bodyweight movements, the effectiveness of straight leg raises depends on your form.
Done incorrectly, this seemingly easy exercise can lead to wasted effort, poor results, or even lower back discomfort. In this article, we’ll explore the three most common mistakes people make during straight leg raises—and how to fix them for maximum benefit.
Mistake 1: Arching the Lower Back
One of the biggest mistakes in straight leg raises is allowing the lower back to arch off the floor. While lifting both legs may feel effective, it often shifts the focus from your core to your lower back, reducing the impact of the exercise and increasing the risk of injury.
Why It’s a Problem
When your lower back lifts off the mat, it breaks core engagement. Instead of your abdominals bearing the load, the pressure moves to your spine. Over time, this can cause lower back pain or strain, especially if you’re doing high reps or adding resistance.
How to Fix It
Before lifting your legs, press your lower back flat into the floor. You can do this by engaging your core and slightly tucking your pelvis. Maintain this position throughout the movement. If keeping your back flat is difficult, try bent-knee leg raises until your core is strong enough to support the straight-leg version.
Training Tip: Place your hands underneath your glutes or lower back for support as you build strength. This can help you maintain spinal alignment during the lift.
Mistake 2: Using Momentum Instead of Control
Another common error is using speed or momentum to complete each rep instead of controlled, deliberate motion. This often shows up as swinging the legs up and down quickly or bouncing at the top or bottom of the movement.
Why It’s a Problem
Using momentum takes the work away from your abs and shifts it to other parts of the body. It also increases the risk of strain in the hip flexors and lower back. This approach may help you do more reps, but it doesn’t improve strength or stability where it counts.
How to Fix It
Slow down. Perform each leg raise with a two-second lift and a two-to-three-second descent. Pause briefly at the top and bottom of each rep to reinforce control. Controlled movement keeps tension on your abdominal muscles and helps improve your strength over time.
Training Tip: Think of raising your legs with your core, not your hips. Imagine your abs actively pulling your legs off the ground with each rep.
Mistake 3: Incomplete Range of Motion
Some people perform leg raises with too short a range, either not lifting their legs high enough or not lowering them close to the floor. While this may feel easier, it limits muscle activation and reduces the overall benefits of the exercise.
Why It’s a Problem
When you skip the full range of motion, you cheat your muscles out of the time under tension needed to grow stronger. Lifting your legs only halfway works your hip flexors more than your abs, and failing to lower them near the ground avoids the hardest part of the exercise.
How to Fix It
Raise your legs until they’re perpendicular to the floor, and lower them until they’re just a few inches above the ground—without touching. Ensure that your lower back stays pressed into the mat the entire time. If you can’t control the descent, reduce your range slightly and build up over time.
Training Tip: Start with slow negatives (lowering phase only) to build control at the bottom of the movement, which is the most challenging portion for many people.
Bonus Tips for Safer, More Effective Leg Raises
- Warm Up Properly: Engage your core with basic movements like dead bugs or bird dogs before jumping into leg raises.
- Breathe with Intention: Inhale before lifting, exhale as you raise your legs, and inhale again as you lower with control.
- Use Variations as Needed: If straight leg raises are too difficult, try single-leg raises or bent-knee versions to build core strength gradually.
Final Thoughts: Quality Over Quantity
Straight leg raises are a powerful tool for building core strength, but only if performed with proper form. Arching your back, rushing through reps, or cutting the range of motion may make the movement easier, but they also make it less effective.
Fixing these three common mistakes will help you get more out of every rep while reducing the risk of injury. Focus on control, form, and progression. Your abs will thank you.
