Hi Core Warriors...
If you don't mind me rambling again I wanted to make a few key points about the exercises (especially the abdominal series!). I think you'll be happy with some of what I say...
1. You never have to lift higher than off the tips of your shoulder blades. You want to maintain your core connection, and lifting too high up causes you to lose that connection. So just off those shoulder blades is perfect!
2. Try hard to focus on relaxing your shoulders. As we work hard the tendency is to draw the shoulders up toward the ears and "shrug" a bit. This causes neck and shoulder tension which nobody needs

. We get enough of that from daily stress. So really focus on keeping those shoulders down!
3. Repetitions: Only 8-10 sets of EACH exercise in the abdominal series. If you can move from one exercise to the next without resting that will really fire your core. But if you are feeling any tension in the neck..lower your head between each set and take a few moments to relax before beginning the next set. The idea is that you want to do 8 QUALITY repetitions....focus on doing them slowly and precisely. Do not swing the legs, but instead focus on using your core muscles to bring them into your center and then lengthen them away. Make the last exercise as precise as the first! Only do one of each in the ab series plus plank. That's all you need. I promise!
4. Spine: If you find you are ARCHING your back at any time, during any exercise, you need to reevaluate what's going on. For instance...if in lower leg lifts you find your back lifting off the mat, then you may want to first support your back by placing hands under tailbone! Sometimes it's a matter of how much you are lowering your legs, etc. Focus on keeping a healthy spine, we never want to load the lower lumbar!
Here are some key points for each exercise:
Plank, Forearm Plank, Bird Dog: Check to make sure your shoulders are aligned with your wrists and that your back is nice and straight (have someone check for you)!
Single Leg Stretch: Focus on keeping your upper body/torso "stable" throughout the entire exercise. Allow only the arms and legs to move smoothly and precisely. Try to draw the knee into the chest while the opposite leg lengthens away. Focus on the opposition and using the core muscles to draw the legs inward. Make sure you are breathing in a rhythmic pattern.
Double Leg Stretch: Exhale as the knees are pulled into the chest, head neck and shoulders are lifted, then INHALE as you lenghten the arms and legs away in opposite directions. Repeat that action, keeping the torso fully stable. Imagine that your upper body is in cement and that the only things which can move are your arms and legs. Don't bob the upper body up and down...keep it solid as a rock the entire time!
Scissors: Be careful not to "swing" the legs rapidly. Make the motion fluid but controlled. Don't "pull" on the legs so much (keep the elbows soft) but instead really tighten your core muscles to help draw the leg into your center as the other lengthens away.
Lower Lift: Only lower the legs to 45 degrees. If you allow them to go too low you may cause the back to arch. And just as importantly, once the legs go exceptionally low to the floor the stronger muscle group invariably takes over....the leg muscles. As endurance athletes we all have very strong hip flexors, glutes and thighs. We can do those lower lifts until the cows come home using just the leg muscles. However, if we only go to 45 degrees we are not getting into the hip flexor muscle. With that in mind...try to lengthen the legs during this exercise but don't TENSE them b/c that activates the wrong muscle group. Really focus on using the abdominals to draw the legs back up. Again...fluid movement...3 counts lower down to 45 degrees and one fluid movement back up. Imagine your feet and abdominals are attached to via a string...when you want to bring the legs back up, you have to pull the belly button in tighter to retract that string.
Criss-Cross: This is the most difficult exercise to teach. Here is how I'd love for you guys to do it. Try just 8 like this and see if you don't really feel the difference. Bring legs into table top (shins parallel to the ceiling). Keep your elbows wide. Lift up in the center. While maintaing that lift twist to the right and pause. Now twist a little deeper to the right. Then come back to center a little higher. Now twist to the left (are those elbows still wide)...twist a little deeper. Now back to center. Repeat this without the knees for 4 sets. THEN bring the knees into the action but still maintain that wide elbow. Focus more on bringing your armpit to the knee as opposed to elbow to the knee. Go SLOWLY.....twist...go a little deeper....go a little further. THEN go back to the start staying lifted if you can. It only takes 8-10 sets to REALLY feel these. You should feel those obliques!
Sorry to ramble but my main concern is that you guys are working out safely as to not injure the neck or back.

And THANK YOU for saying such kind words. I truly appreciate it!