I started building up base mileage in early January, and am still running base mileage now. I'm training for a marathon in November. Currently at about 35 mpw (eventually get to 80-100 mpw by November). I haven't started speedwork yet, and I'd like to, but without rushing it into injury. How soon would I be able to start speed sessions on the track and/or tempo runs? My legs are starting to feel like heavy bricks on all of these super slow easy runs.
Thanks for any advice!