Getting to the core of it all

In a nutshell, I've been asked a couple times recently about what core exercises I do.  So, why not list them out here.

My routine admittedly varies from the "standard" core routine, in that I don't do crunches.  They're certainly not at all necessary for strength -- when I rode horses I had a ridiculously strong core despite never doing a crunch ever.  [Many people don't realize that much of controlling a horse at the higher levels is done via using your core to manage the distribution of your own weight in the saddle -- it's like planksx100.  Anyone who rides and shows horses regularly has an extremely strong core, plus inner thigh muscles].
 
Nor do I think that crunches are running specific -- the motion doesn't mimic anything we do while running.  Since the ultimate purpose of core work (for runners) is the maintenance of body stability even when you're extremely fatigued, I focus on exercises where I stabilize my core against different forces, be they rotational pull against my torso or movement of arms and legs in different ways.

So, here's my favorites:

• Planks.  
• These are a classic, but I like to do them with a special variation -- I place my toes on top of a medicine ball rather than on the ground, so that I have to stabilize my torso against my legs trying to fall to one side or another.  The smaller the ball, the harder this is.
  
• Headstand leg lift 
• I picked this one up when I was playing Capoeira a few years back.  This gets your lower back, and also your glutes and abs.  To do this one, get into headstand position, then lower your feet to the floor, keeping your legs straight, and raise them back into full headstand.   Better explanation here.  It's a similar exercise to back extensions, but targets the back and abs more and the glutes less, doesn't require access to a gym, and is much more fun.  I do these at least once a week.
• Balance on ball 
• This is a fun one.   Find an exercise ball (bigger is better here, and an under-inflated ball will make this significantly harder).  Then climb on top of the ball, first balancing on your hands and knees, then on just your knees.  
• Once you've got that down, practice balancing on the ball on your knees while swinging your arms in a motion that simulates running.
• When you've got that down, then add in light weights in your hands (5 pounds or less).  This isn't so much a strengthening exercise as a balance and coordination exercise.  Thus you want to keep the weights fairly light: just heavy enough that they disrupt your balance slightly when you swing them, and you have to focus to avoid falling.
• I like this one because it forces the glutes and abs to work together to stabilize you in the same way they do when running.
• You can actually integrate this into a solid routine with the following sequence: a) balance on balls and swing weights; b) put the weights down and walk your upper body out, so that you're now in plank position with your feet on the ball; c) do a set of push ups; d) walk your body back in. 
• Palloff Press
• Essentially, you use a cable machine with the cable pulley set at the level of your sternum.   The video linked here from Competitor magazine does a great job of explaining it, so I'll just send you there.
• Side Planks with Leg Lift and Marching Leg Bridge.
• My PT turned me on to both of these glute activation/core exercises, and I do them daily.  He explains them better than I could, so I'll refer you to his guide (go to pages 10 and 12).
• Single Leg Deadlifts
• Basically, you balance on one nearly straight leg, holding a weight in one hand, then lean forward (keeping torso square) while simultaneously lowering the hand with the weight to the floor in front of you and raising your other leg behind you.  Forces your core and glutes to work together, and also makes your feet and lower legs work some to stabilize you. 
• Here's a good description.  I like to modify by holding a dumbbell in only one hand, which makes me work a little harder to keep balance, since the single weight pulls me to the side.  I'll do this both with the weight in the same hand as the leg I'm balancing on (right hand, right leg) and opposite hand and leg.
• Classes.  
• Yup.  Those yoga/pilates/floor barre classes are great for core work/stability, with the added bonus of an instructor to correct those imbalances that you don't notice.  I try to fit in several classes per week.
• Everything.
• Seems like a truism, but really ALL exercises are (or should be) core exercises.  When I do my strides and drills, or pull-ups and squats in the gym, I try (as much as I can) to keep my torso properly engaged and active.  Even if that means that I have to lower the weights a bit to ensure that I don't lose form from fatigue.  It's not just about strength, but about the habit of USING that strength.  And every time you're not practicing something correctly, you're practicing it incorrectly.