Wednesday Tempo Run

1 mile easy
20-40 mins of 6 mins at 1/2 marathon effort, 4 mins at marathon effort
1 mile easy

Fluctuating between 1/2 and marathon pace will introduce a bit of lactic, but this should be
cleared during the slower 5 min reps. You should never be near needing to walk or really
slow down. This is a progression from the 5 min efforts in the past few weeks try see if you
can do more total time than you have before.