How can I eliminate leg soreness/fatigue in a standing desk setup?

First, I'm glad you love your standup desk! I am a big fan of them. But standing for hours can indeed make your legs tired. Here are suggestions to try : Get your circulation flowing. Walk to the water cooler. Use stairs. That sort of thing. Sit down part of the time. Try resting your feet on a footstool, box or crate. It will feel good! Stand with your feet in the "at ease" position. That means with position them shoulder's width distance apart. Then try shifting your weight from side to side. Reverse your blood flow and restore your energy with this easy yoga pose: This pose excellent for people who spend lots of time of their feet.

I typically start to feel fatigue in my feet first when standing at my height-adjustable desk. Instead of sitting down, I've learned a simple technique that's easy to do and helps to regain my strength. Position your chair (or stool) behind you, lift one of your legs to a 90 degree angle, and rest it on the seat of the chair (or spindle/top) while keeping your other leg on the floor. This action relieves soreness after you've alternated between feet. Not to mention, your back and overall balance will benefit as well.

You need a standing support to "perch".  Its inteersting that one of the most essential elements that being left out of much of the standing vs. sitting desk debate is how to stand. Static standing is no better for your body than sitting.  It results in a whole host of different problems relating to posture, the spine, as well as problems with the veins and muscles of the legs. Long term static standing is just as bad as long term sitting.  One way to counter the detrimental effects of long term standing at a stand desk is more frequent periodic switching between the two positions OR a  standing support like a MOVE stool to allow safe healthy extended periods of standing.  MOVE by Varier has been endorsed in Germany by the Federal Institute for Occupational Safety and Health (BAuA) as the most effective device to reduce workplace related injuries related to long term standing. Here is some good reading on the subject http://varierusa.com/ergonomics-in-the-work-place/to-stand-or-to-sit-at-work-that-is-the-current-question-what-is-being-left-out-of-the-current-%E2%80%9Cstanding-versus-sitting%E2%80%9D-debate/

Use a Wurf Board.  If you've stood on an inflatable stand up paddle board, it feels like that...firm yet bouncy. https://www.kickstarter.com/projects/wurf/wurf-board-by-jumpsport-weve-reinvented-standingtm?ref=nav_search

I think the single biggest thing is movement. That's really what all these answers get at. The box provides support for different postures you can move between. The mat is just soft enough to require subtle micro movements for balance. Put them both together, and you get this beauty: Plus you can reposition it easily with just your foot, because it's designed to easily move in/out for a sit/stand desk. Check it out: http://ergodriven.com/topo/

I've been using a standing desk for almost 10 years and I learned the hard way. For a few years I had soreness and fatigue, while rationalizing it away, but then I read a book about skeletal alignment and discovered I just didn't know how to stand. You just have to learn how to stand and you can retrain your feet muscles and work your way up to the neck to have perfect posture and stand for hours with no discomfort. It might take a year or two of diligent effort, but you'll regain the great posture and body mechanics you had when you were a kid and lost by wearing shoes and imitating people around you with bad posture. The book I first read is [i]Ageless Spine, Lasting Health[/i] by Kathleen Porter, which I strongly recommend, but if you want only one book, the more recent and thorough book [i]8 Steps to a Pain-Free Back[/i] by Esther Gokhale has mostly the same information and is absolutely essential. Porter also has a newer book I haven't read yet, and much of the same information can be obtained from channels like Alexander Technique, Feldenkrais, Rolfing, etc. Of course, even if you stand with perfect alignment, intermittently moving around and entirely switching activities is vastly superior in almost every way. Of course this topic is very complicated and there are issues with keyboards and so on that make it an unsolved problem for everyone in the world right now to some extent, but the posture aspect is the first and biggest thing to tackle.

You could always try regular bouts of MyoFascial Release (or rolling out) tight areas. Kelly Starretts' http://MobilityWOD.com is a fantastic resource. While standing is considerably better for you, i believe you can still run into just being locked in a position too long. How long do you stand? And are you actively engaged?

Check out this 3 position seating product https://healthpostures.com/products/coming-soon-new-stance-angle-chair/ at http://www.healthpostures.com. I use it everyday and it helps me move between several different healthy postures while working. As I write this I am in the Kneeling position. I just transferred to kneeling from standing about 20 minutes ago.

When I made the switch I would get a pain in the heel of my foot. Probably had something to do with how I stand. I tried the box thing, but getting a mat was the thing that helped me the most. http://standingdeskmat.com has a bunch of reviews.