Above workout was similar to "Potassium Pump Workout." Brilliant coach Bobby McGee describes it here.
6:15PM - F500 - cross-training
30min incline walk (15%, 3.1-3.3mph) - at 5, 10, 15 and 20min marks did the following circuit:
1 (each side) Turkish get-up (35lbs)
10 GHD back extensions (see example of back extensions within this excellent post entitled "Strength Training for Hilly Marathon Success).