I'm in the need for Speed

After the Tokyo Marathon which was last Feb.26,2012
I injured the outer side of my left Calf muscle TWICE !!!
The 1st  injury was because I strained the calf muscle when I tried to run faster.
The 2ND time I re injured my calf muscle is because when the leg “ Seemed “ to be getting better I would push the pace which aggravated the injury more.
Another reason why I re injured myself is I was still running 5 – 6 days a week and averaging 80 km a week.
I never really gave my legs the much needed rest.
Anyway, after the Double Whammy.
My leg is 95 % better and no more major pain
but what I notice is my speed really suffered.
I run slower now and admittedly I struggle to maintain a decent pace.
I have been doing some speed work lately.
I incorporate 5 sets of 500 meters sprints in my daily 13 to 15 km run which seems to work 
Hopefully in a few weeks I’m back to my Racing Form.
Hopefully !