This one is next because it combines where we've been (squat-type things) with where we're going (asanas that lift and engage the pelvic floor muscles). Also, I'll admit I've been shying away from this installment because I'm having problems finding pictures and explanations of exactly what I want to talk about.
I can find lots of pages that talk about the expression of the pose that's done in Bikram yoga. I'm personally more familiar with a two-footed version; however, my Google Fu is not helping me out in this respect.
Modified Padangustasana / Toe Stand
This is probably the best guideline picture since the body position will look basically the same -- except that both feet will be on the floor. Since this is a deep knee bending posture, be ready to modify if you feel any pinching in your knees.
- Stand in tadasana with your feet hip distance apart or maybe slightly closer. Rise onto the balls of your feet.
- Bend your knees, lowering down into a squat. You may find it helpful to keep your arms somewhere close in toward your torso, like in anjali mudra or at your hips. That said, some folks find straightening their arms out in front of them helps with balance here. If balance is still difficult, you may want to be arms' length away from a chair back or wall for support.
- Once you've lowered, engage your core to raise your torso to vertical. Lengthen down through the tailbone and up through the rest of the spine.
- Stay in the pose as long as is comfortable for you. To exit, either press through the balls of the feet to rise to standing or else lower so you're sitting on your bum.
Your pelvic floor muscles are part of that core engagement** that's supporting and lifting your torso. Exactly how much work your pelvic floor is doing will depend on your individual anatomy and body position. I find that bringing my thighs together (feet closer than hip distance) creates more lift in my torso, so there's more effort coming from my pelvis (lower abs and pelvic floor) and less from my thighs.
As you might guess, I'm having trouble finding videos of this. I did find a wide-knee version of toe stand on two feet:
The quality is not the greatest there, but I think seeing a candid shot of folks in asanas illustrates a good point to remember: falling is part of the practice.
Also, the one-footed expression with an entry from tree pose:
I haven't been able to get into this without a balance aid, but my hypothesis is that the one-footed version would require even more core strength than the two-footed expression, because the raised leg is now supported and no longer supporting. I'm still at the falling stage of this version, though, so I can't be sure. ;)
Next time, I promise, an easier-to-find pose!
**For reference, it may be helpful to think about your core this way, as a closed cylinder: Your abdominals, obliques, and back muscles are the walls of that cylinder. Your diaphragm (that breathing muscle) is the top, and your pelvic floor is the bottom. Pelvic floor strength is a part of core strength.