where you train matters

The long runs that I do on Saturday typically takes place on environments similar to actual marathon trails (like Campbell Park, which the SV marathon route runs through for about 15 miles). On weekdays, the 4 miles that I run with my smaller group is at Rancho San Antonio, in Cupertino. This trail is not flat and is a real trail, not paved road. It is hard ground, with stones and pebbles and with a constantly undulating path. It is a lot harder to run 4 miles on this, than to run 4 miles on, say, the SV route. And this shows on the weekend runs when I have to typically run longer distances than I have ever done before.

If you are in NorCal and east of Redwood City, west of San Jose, I would recommend Rancho over any other place.