4. Crunches
Several studies have shown that crunches just don’t get the job done when it comes to making your abs stronger. What’s more, you can easily hurt your lower back during this type of workout.
A much more effective alternative to crunches is planks. This isometric exercise (with all its possible variations) can also help you work out your back safely, along with your shoulders and arms. It can even allow you to reduce your waistline and improve your overall posture, as you’re required to stabilize the spine.