You've probably heard about how important it is to keep your core strong — fitness magazines, personal trainers, yoga teachers and even Michelle Obama all tout the benefits of a strong center. Many people think that doing zillions of sit-ups or crunches is how to get there, but that's old thinking and could possibly even lead to injury if you do too many. 

"Performing the 'sit-up' movement actually can produce 'Hunchback Posture' when done in high volume. Why? Hands behind the head, cause neck muscles to tighten, resulting in a forward tilt. This causes pressure on the lumbar spine. Instead, opt for Isometric Plank Exercises," Jay Cardiello, a celebrity trainer and owner of JCore, told Men's Fitness

In fact, to get great core strength, you need to build and tone many muscles in the trunk and pelvis, which include your back muscles, butt muscles, stomach muscles and even chest and upper thigh muscles. "[Core exercises] lead to better balance and stability, whether on the playing field or in daily activities. In fact, most sports and other physical activities depend on stable core muscles," advises the Mayo Clinic staff.

Below find seven simple exercises you can do sans equipment (you just need your body weight for resistance), so you can get a strong core even if you can't afford the time or money to get to the gym. These are easy to do at home.  

Bird dog

This move is a classic core exercise that works on the abs, lower back and stability. And the video above includes a couple variations if you're ready for something a little more challenging than the basic bird dog. 

Reverse crunches 

This exercise is a great abs workout, but instead of bringing the upper body up (and potentially straining the neck), you are bringing the lower body up, for a smaller — and more effective — movement that will strengthen the lower abdominals.

Magic carpet plank slides

This is a slightly more advanced set of moves, but is a great way to get several muscle groups working at once and together. As with all tough, complex moves, it's best to start out doing a few reps, ensuring that your form is as close to perfect as you can than it is to try to do many reps but get sloppy. 

Barre plie move

This simple move has plenty of variations (as demonstrated above), and the idea is to keep going for a defined period of time and to increase that over time. This really strengthens the butt and upper thighs, which gives your lower trunk plenty of strength and stability for whatever sports you engage in (or will just lift your butt and streamline legs). 

Russian twist 

This twist needs a bit of weight to work, but you can use anything you find around the house. It works to strengthen the side abdominal muscles that define your waist. 

Rotational lunge

A great move that stretches and strengthens hips, thighs and the thoracic spine at the same time. 

Pilates 100s

Pilates is all about the core, so most exercises from the discipline will strengthen the midsection, but the 100s exercise might be the most well-known and it's incredibly easy to start doing. This video shows all three levels, so you can work toward the next level as you build up strength. 

You'll notice that over time core exercise supports almost any other sport you engage in, whether you run, lift weights, play tennis or hike with a pack. It's especially great for snowboarding, skiing and any kind of rowing. 

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Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.