Your core is more than just your abs.
Athletic definitions of the "core" often include muscles not only in your abdomen, but also your pelvis, hips, lower back, butt and beyond.
So although some of those muscles may be strong and functionally efficient, that doesn't necessarily mean you have a "strong core."
The Side Plank Test is one move that forced me to re-assess my own core strength:
I've always thought I had a pretty strong core, but I struggled to get to 10 lifts while bracing on my left side during this test.
When I switched to my right side, I only got two or three before I felt my form breaking down.
There was no doubt about it—my hips weren't very strong, and there was a big discrepancy in their strength from left to right.
Dr. Matt Stevens, a physical therapist and co-owner of Pure Physio (Strongsville, Ohio), frequently uses this test with runners, as weak and/or asymmetrical hips are a known cause of running injuries.
"We get a lot of runners who come in that complain of lateral hip pain when running long distances. So one thing we like to do to test if they have an imbalance from right to left is a Side Plank Test," says Stevens. "The test is going to be, can he lift up his leg for 10 repetitions. He's going to try to keep a nice straight line from his ankle all the way to his armpit. After 10 repetitions, he'll switch sides. He's going to compare how that feels from right to left. Often times, if we see a weakness on one side, that hip will start to drop within a couple repetitions."
If you have trouble achieving 10 repetitions on either or both sides or notice that one hip feels significantly weaker than the other, this "test" can be used as an exercise.
"So if you notice that one side is a little bit weaker than the other, you can use this test as an actual exercise. If doing if with the leg straight is very difficult, you can scale that by dropping down to the bottom knee, (keeping the) top leg straight, and you're just going to lift to shorten up that lever arm," Stevens says.
If you start with the scaled version, make it your goal to advance to the unscaled version. Aim to perform 3 sets of 15 on both sides, performing an extra set on the side you feel might be weaker. This is a fantastic move to have in your arsenal of core exercises.
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