Let Me Ins

Question: How can I get better grip on the floor?
 * Wear sneakers
 * Use a yoga mat
 * More ideas here.

Question: If it really burns my thighs / quads, am I doing it wrong? Or are my thighs just that weak?  However, others say that learning back puts more work on the arms/back and allows the legs to rest a bit more.
 * Nope, seems normal (discussed here, here, here, here).
 * Take a look at Mark's answer to this exact question (on his site).
 * You're probably not used to the static half-squat hold required. It'll get easier. You can practice static full squats too to help.
 * Use some rope (see section below)
 * I noticed that I had the tendency to rock back on my heels, even every so slightly just shifting the weight. I felt less of that when I tried to keep my toes down and feet flat on the ground.
 * Trying extra hard not to lean my weight back helped a little.
 * Do lots of squats and lunges until the LMI feel okay.
 * Body weight by necessity involves many large muscle groups, even ones that aren't the primary focus of the exercise. Still, try really hard to focus on pinching your shoulder blades together at the top so that you get a lat burn too :) Control your descent as well so that you maintain a straight back.
 * I'm like 11 weeks into YAYOG stuff and those things still burn the hell out of my thighs.

Question: I felt like I might break the door. (discussed here, here, here)
 * Door knobs are hard to hang onto. Try wrapping an old towel around the knobs and holding onto the ends of the towel.
 * The doors always seem to hold up -- don't worry about the door unless/until it actually collapses. You'd be surprised how strong those things are, even when they feel like they're about to give.
 * Put some binders under the door for support. Might not need it but it's good insurance.
 * You can use other things besides doors (see below)

Question: Are pull ups a good replacement for let me ins?
 * Let me in's work different parts of the back than pull-ups. LMI are like a rowing exercise.
 * You can make the LMI harder by placing your feet further forward, and using the towel to extend yourself backwards and make your grip more difficult.
 * No. Pull ups would be a better replacement for Let Me Ups.

Alternatives to using a door
Keep in mind that it's important that the movement be a rowing motion, not a pull-up motion.
 * chin-up bar with a thick rope or old towel hanging down
 * mount a chin-up bar near hip-height and loop a towel around it
 * stairway railing
 * legs on a deck or porch
 * 2x4 stud or 4x4 support column in my basement (edges are sharp, so either wear gloves, grip with fingers vs. whole hand, or wrap a towel around and hold its ends)
 * post or pole outside
 * street sign poles
 * kids playgrounds

Use some rope
DustGod suggested a way (here) to modify this exercise that may make it easier on your quads:

Use some rope. Tie it on something sturdy and tall enough. For instance, if you have stairs outside your house, you can tie the rope on the handrails. With this little trick you could do your Let Me Ins with your legs straight. This approach has some other interesting advantages: it's much easier to change the difficulty of the exercise -- you just have to grab the rope at various lenghts. It also adds intense work on the forearms.

The height you anchor the rope determines the resistance -- it's all a lever trick:
 * longer rope, harder exercise
 * further feet, harder exercise
 * the taller you are, the harder the exercise is

Tie the rope so that, for the chosen rope length, your body and the rope form about a 90-degree angle in the starting position. With the rope tied higher or lower the work will be distributed differently:
 * with higher rope, emphasys on your lats and shoulders
 * with lower rope, emphasys on your biceps