My GPS is confused, though. When I was running in Redondo Beach, I had maybe 40-50 feet of elevation change between the highest and lowest point, with lots of rolling hills. The GPS claims that my total ascent was 602 feet, and my total descent was 621 feet. That seems high but not unreasonable given the amount of up-and-down I was doing.
When I run at home, I have approximately ten feet of elevation change between the highest point and the lowest point on my route. The GPS claims I did 1098 feet of ascent and 1059 feet of descent tonight. That seems silly. In one "lap" of .21 miles it claims I did 250 feet of ascent and descent. Silly electronics.