We created two versions of Block 3. The only difference between the two versions is the interval volume within each workout. The first version uses time for the interval volume. Time is a great option for “newer” runners looking for a lower volume options as well as for running indoors on a treadmill. Groups really like the “time” option because all runners advance through the workout together. The second version uses distance for the interval volume. Distance must be included because the goal is a 10k distance.