New-to-me cross training meets skull crushers

As I mentioned earlier this week, the clock has been ticking on my March deadline to meet the (Just) Trying is for Little Girls new-to-me cross training challenge.

I received some excellent cross training suggestions:
Viper suggested jumping rope.
Jamoosh recommended rowing.
Sarah said cycling.
and
Kathy told me to go take a hike.

All of those are excellent recommendations, but part of the challenge is to get out of my comfort zone and "try something new." I have jumped rope, rowed, cycled, and hiked before... But I haven't been on a rowing machine in 2 years and I haven't jumped rope since grade school. Do those count as "new?"

I am quickly realizing that I have tried lots of cross training activities over the years, and am running out of "new" ideas. Can a blast from the past count as long as it's new to my current routine? I think I need a ruling from Kim on this topic... But in the meantime, I wanted to stick with the letter of the challenge. So I broke out the stability ball.

Hubby bought a stability ball when we moved to Florida. I often use the ball instead of a chair, but I have not used it for actual exercise. This morning I figured out why I have not used it for exercise... but we'll ge to that.

I decided to try two exercises: stability ball crunches and tricep extensions (an exercise sometimes referred to as "skull crushers" -- you can read that as none-too-subtle foreshadowing).

The crunches were a success. I will likely be adding those to my workout rotation. My abs could use a new challenge and the stability ball forced me to work minor muscles that get no action when I'm on a mat.

The tricep extensions, on the other hand, were a complete disaster. The exercise should look like this:

Image source

The picture makes it look easy, no?

Livestrong.com warns:

Remember to use some caution when exercising on a stability ball, as it can become unstable quickly if you don't maintain proper form. Keep your feet in a comfortable, stable position on the floor for most of the exercises and don't bounce around too much. Also, make sure the ball is inflated properly as per the manufacturer's instructions. It should have a slight bit of give as you sit or lie on it.

Let's just say: they're not kidding. I am pretty sure I had "proper form," feet flat on the floor, and wasn't bouncing. But when I was attempted the tricep exercise, the ball rolled out from under me and nearly dumped me on my head!

(Fortunately my butt hit the ground first, and through a combination of core strength and luck I managed to not crack my head on the tile floor or drop a weight on my skull...)

But imagine how ugly that could have been! I can just picture the fallout: "Sorry, I couldn't make it to class today. I broke my neck and my nose when I fell off a giant bouncy ball in my living room." I'm pretty sure my reputation (not to mention my spine) would suffer.

So the verdict on this one is: I like the crunches, but will not attempt any arm exercises on the stability ball again!

What's your favorite strength-training activity? Least favorite?