The Bosque da Barra is a good running spot in Rio, especially as a shade option on a hot day. This nature preserve features ~5 km of walking & jogging trails, all underneath a dense, lush canopy. There’s a lake and many species of plants.

Google Street View

From the parking lot at the south end of the Preserve, there’s a 3 km outer loop, much of it around the lake at the northern end. Add with a 1.8 loop around the more interior paths. The trails are a dirt surface, fairly wide with good footing. A combination of open and shaded.

Note: From a map, it looks tempting to combine this with the Barra Beach route just to the south, but unfortunately there’s no good pedestrian connection.