Recently I've been looking everywhere for a program or something that can give me an accurate elevation profile that also tells me how many feet I ascended and descended during a race. I find this bit of information extremely interesting as well useful in seeing how your race compares against, say, another 10k with 500 feet of elevation gain. But I couldn't find anything!
I use my Garmin and the elevation ascent/descent is always wrong. I could be standing still at sea level (the SF marathon for example) and it fluctuates up and down from -100 to 200 feet within a matter of 30 seconds. Or I run around a track and it says I ran 1,000 feet of elevation gain! This irked me some, so I called Garmin to see if there was a software update or something. Nope, there wasn't. Apparently the Forerunner 205 is based off of GPS, which has some god awful margin of error, so much so that it isn't really accurate at all. The 305, though, is based off of an altimeter (sp?) and is much more accurate, although still with a big margin of error.
So I searched the web and looked high and low. Found a National Geographic software called GPS USA that claims to do elevation profiles, yet it isn't compatible with anything higher than the 201 or 301 and you can't even zoom in enough for you to plot the course! So you can pay more money to plot the course on more specific software, but it still isn't compatible with the 205 or 305. So I found a plugin for Google Earth called Wikiloc that gives the profile, but it takes whatever your GPS device says and plops out some number.
For example, my Garmin said that I ascended something like 10,000 feet in my last Half Marathon (actual was around 1,600 ft). The Wikiloc plugin says that I ascended 6,600 feet. So better, but still way off. So I tried plotting it myself, but I come up with 2,400. Much better, but still no cigar.
Finally, and completely by accident, I came across MapMyRun. Absolutely amazing. Exactly what I have been looking for for weeks. You can plot your own run and it will give you an accurate elevation profile. But even better, you can download directly into it from the Garmin and it will take the coordinates and plot it on a map (you can view in map, satellite, or hybrid) and it discards the accompanied elevation figures, as well as discards the random 100, 200, and 300 foot shifts in elevation that the Garmin has when standing still. Its algorithm filters this out and, voila! An accurate elevation profile. Amazing. Even better is that you can then share it with the public and you can also look for other race profiles and/or find other trails and routes around where you run. And its free!
I can't toot MapMyRun's horn enough. This was certainly made by outdoor adventurers for outdoor adventurers with a mind for the data that we typically look for and like. Give it a try.
PS It says it has the capability of uploading GPX files into it but I have not been able to get this to work. This sucks because I've deleted all of the races and courses off my Garmin and so am unable to plot a profile. I have an email placed in to MapMyRun and will let everyone know when they respond. Otherwise, the only method of getting your information into the system to plot the profiles would be to do it manually or upload it via a GPS device.