UPDATE: Having finally tried a real GHD, I have come to realize what a poor substitute this is for the real thing. I'm leaving the page up so as not to break links, but I can't recommend this approach. It was a better idea in theory than in practice.
The Crossfit folks love the Glute-Ham Raise, and it is one of the exercises featured in Infinite Intensity by Ross Enamait (my current program). So of course this warranted further investigation on my part. Really, you don't need to do any research beyond reading The Glute-Ham Developer (PDF, 787KB) by BFS, which is a description of the machine, includes a history of the exercise, a compelling list of benefits, and a variety of other exercises you can also perform on the apparatus (abbreviated "GHD"). The more you read, the more such a device seems like a must-have.
The problem is that GHDs are a bit pricey. Some Crossfitters recently shopped around, and there's always Froogle or eBay. Enamait's home-grown approach is to put a towel on the floor under his knees, secure his ankles, and do them that way. The pressure on my kneecaps scared me off trying them that way, so here's what I came up with:
I'm not recommending you build one of these, as it's surely structurally unsound, will break, and will maim or kill you. But here's how I did it just for curiosity's sake...
My Swiss Ball serves as the rounded pad. To anchor my feet I made two T-shaped attachments from 3/4" threaded galvanized pipe and screwed them to my basement door. Each T is composed of a floor flange, a 5" nipple, a T fitting, two 12" nipples, and pipe insulation for padding (make sure you buy the right size - the insulation should provide two measurements, one for the copper pipe it fits, and another for steel). To affix to the door I drilled all the way through and used bolts, washers, and wingnuts. The wingnuts make it easy to remove these or shift them to different positions. You might think you'd want to permanently affix the flanges to the door and just unscrew each T to move it, but you can't really do this as when you go to unscrew one T it will hit the other.
A couple assembly notes:
- You can just screw everything together by hand, leaving the flanges off. Then attach one flange to the door. Screw on the T assembly. You'll be able to use the "arms" of the T to get lots of leverage, making it really tight. Then get your feet in position to figure out where you want the other T to go, and affix the flange. Remove the tightened T via the wingnuts, and then screw the other T really tight. Reattach the initial T when you're done. One thing you might want to consider which I didn't do is epoxy the threads to make the assembly permanent (not the wingnut threads, of course).
- You might want to use smaller than a 5" nipple for the "upright" of the T. You'll want a fairly snug fit, and if your door has panels like the one above it can be tricky, as it's a squeeze to get your foot in, but then it's loose once it's in position because you're on a panel. I ended up screwing a couple boards onto my door to make the fit snug (not shown, as this was today, post-photo). Shorter than 12" nipples for the "arms" might solve this as well, as you wouldn't span different "depths" on the surface of the door.
So far using it is a mixed bag. It's great for back extensions and full range-of-motion situps. Jury is still out on the Glute-Ham Raise though. Part of the problem is that I'm not strong enough to do these under the best of circumstances, which makes other mechanical problems with my setup hard to diagnose. It seems hard to figure out where exactly to put the ball in relation to my hips and knees. I'm not sure if I'm going to be able to come up with a satisfactory solution, given that a proper GHD has a fixed pad you can push against, whereas the ball can roll/slide away from you if you try to replicate the mechanics demonstrated in the document above. The ball is also slippery when sweaty, although draping a towel over it seems like a workable cure.
In conclusion, I'm happy with it for some exercises, but not entirely for the exercise I was shooting for. I'm not sure if this will change with practice or not. I'll keep posting other notes on equipment, although between this and the medicine balls I'm not off to an auspicious start on the homemade front.