I found this on the T-mag site:
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Glute/Ham Raise — While I reported on how this exercise was used by physiologists to lengthen the sarcomeres in the hamstrings and thereby reduce the incidence of hamstring injuries, strength coaches like John Davies and Dave Tate have been using them for a long time.
While there probably isn’t a specific "Glute/Ham Raise Machine," you can duplicate the movement easily enough by using either one of those old-fashioned straight sit-up boards with the Velcro straps, or even the traditional family couch. Alternately, you can use sandbags, or have your training partner hold your ankles down.
You simply stand on your knees away from the anchor (either the couch or the Velcro straps), and slowly lower your body to the ground while keeping your back straight and focusing on the hamstrings. If you’re like most people, you’ll need to keep your hands out in front of you to catch yourself, just in case you can’t do the movement and you end up kissing pavement.
If, initially, you need assistance from your hands, fine. Place them in front of you on the ground, and slowly lower yourself, just using enough pressure from your hands and arms to allow you do a slow, controlled rep.
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