Looking for something more aerobic? Consider the more than 150 parks and parkways and 15,000 acres of greenland. Milwaukee [1] has more park area per person than any metropolitan city in the United States. The place to inquire first is the Milwaukee County Parks System (414/257-6100, www.countyparks.com [2]).
Links:
[1] http://www.moon.com/destinations/wisconsin/milwaukee
[2] http://www.countyparks.com