Army crawling is EXCELLENT!!!!! It builds coordination and upper body strength (lower too - have you ever tried to do it? It's HARD!), and as odd and esoteric as it may sound, it grows the brain, or at least helps connections form in the brain that will give him a sounder foundation for later learning in all areas, especially physical and visual.
To take it another step further, you want to ideally see a cross-pattern when he crawls, both this way and when he eventually gets up on his hands and knees. In other words, when his right arm goes forward, his left leg should come forward too, and vice versa. This coordination is the foundation of the way we walk and run too, and the more he gets of that, the better-organized his brain will be in the long run. (Kids' brains is one of my passions!
Honestly, let him crawl this way as LONG and as MUCH as you can get him to! You can even help him along if he's struggling by putting a hand behind a foot so he can push off, although it sounds like he's got it down. Yeah, it might wreck his clothes, but it's a small price to pay. Target sells baby pants in 2-packs!
And if you're worried/curious about his progress to hands-and-knees crawling, Natalie did army crawling from about a month, by 5 months she was on her hands and knees, at 6 months she'd been pulling to standing for a while, and now at nearly 7 months she's also cruising a bit. Oh, and last week she finally learned to sit unassisted!
LOL Her strength, particularly in her upper body, is AMAZING: she can hang from my thumbs for a good 20 seconds (although I can barely hold HER any more!) and she constantly amazes the peds at her well-baby checks. When she got her first horrible cold a month ago and we spent nearly all day at the doctor's office trying to get her breathing back to normal, even though she was tight and croupy, her oxygen levels were at 100%, mostly (I suspect) because she gets so much exercise, especially crawling around.
Soooo....... let the army crawling continue!!!
