Also, it is also unclear what the dispersion of virus while deep breathing from exercise might look like. Anecdotal evidence from spreader events suggest continuous speaking and/or singing may further increase transmission by effect on dispersion profiles.
Like any infection, there is some dependency on the innoculum viral dose. So in general, exercising outdoors is terrific since virus disperses much more readily and inactivates in sunlight (not immediate, but likely in range of several minutes). But would give folks a bit more distance than typical guidelines, since so much is still unknown. Take a look at this provocative (though not definitive) modeling work:
Also, worth noting since the above modeling work, CDC has updated transmission not only from droplet, but also from airborne virusâ€”ie, smaller sized droplets and particles, which would adversely impact the distancing assumptions.
So still good to generously distance while exercising/training outdoors.