Planks will forever be one of my go-to ab exercises because they can be modified for any fitness level, they can be done absolutely anywhere, and I feel them working instantly. Another reason I like the plank is because there are so many variations to do, which in my mind equates to so many new challenges.

One plank variation I almost forgot about until a few weeks ago is the plank with a side step. I like this variation because it really challenges my core strength. In a traditional plank, your body is learning how to avoid excessive arching of the lumbar spine (your lower back), which is pretty challenging in itself.

By adding a moving component (moving your legs in and out), you’re forced to use your abdominal muscles more to stabilize and prevent your spine from rounding or arching. I also like this move because the gluteus medius muscles (one of the three glute muscles located on the upper side of your buttocks) become activated, which help stabilize the hips and pelvis. As a result, stability in the core, pelvis, and hip regions can prevent lower back, hip, knee, and ankle problems. If the standard plank is beginning to feel easy and you want more of a challenge, give this move a shot.

• Start in an elbow plank.
• Extend your left leg out to the side, about eight inches, gently tapping your toes on the ground.
• Bring your foot back into a plank. Repeat the same movement with your right leg.
• Complete 10 reps on each leg.