I'm having trouble doing the arch body hold as described. I'm a big guy: 250 lb olympic weightlifter, 520 high bar squat and 30" thighs. If I try to keep my feet together, I can't flex my hamstrings and get my feet off the ground at all due to the pressure on the muscle. To put it another way, I can easily hold the position with six inches between my feet, but once elevated I can't bring my feet together despite squeezing with all my strength. Note that I'm not talking about losing the position after moving my feet together; I mean that once my hams are engaged, I cannot get my feet to touch, period. I even tried having a friend push them together and tried to hold, but they just bounced back.
Some of this mass is fat which I'm on my way to losing (down from 300 lbs 16 weeks ago) and that should help, but for the time is it "ok" to do the hold with my feet as close as I can get them instead of touching?