I’m a big fan of the double run day and would advise including one a week into your schedule. The benefits depend on your race distance, but can include stimulating run adaptations at gene-level, learning to run with fatigue and feeling smoother when running. Try these:
Sprint/standard distance AM and PM 30-40mins. These small chunks of time are easier to crow-bar into routines. Both are relaxed in the off-season, but with skills drills in the PM session. In-season: AM is real easy, PM is 4 x 4mins around threshold or just above.
Middle distance AM steady, 40-60mins; PM during off-season is either time on your feet with slightly tired legs or skills/above race-pace accelerations for 16-30 strides. In-season, include 3 x 1-mile at Olympic race pace.
Long distance AM 60-90mins steady; PM 50-70mins using a treadmill, running at target Ironman pace.
In the off-season, add in some deep-water running (DWR) and swimming, e.g. AM 1hr swim + DWR; PM 40mins steady run outdoors with relaxed 16-stride acceleration every 6mins.
This article appeared in the December 2017 (345) issue of 220 Triathlon. You can subscribe to the magazine here