I explain you the circuits that Shami uses. The phylosophy of circuits for strength endurance is always the same, but the stations depend on the situation of the place of training. In the case of Shami, he carries out his circuits in Eldama Ravine, a village 120 km far from Eldoret, with a lot of hills.
His circuits, that he must carry out at max intensity, are the following :
a) 120m bounding (flat)
b) 300m running fast (flat)
c) 20 sagittal splits on the place
d) 60m sprint climbing
e) 40m skipping climbing
f) 60m sprint climbing
g) 40m heels-to-buttocks climbing
h) 60m sprint uphill
i) 40m bounding climbing
l) 100m sprint climbing
m) 10 squat-jumps on the place
The circuits is carried out on a small hill, with 420m of flat rough road before starting 400m of hard hill. So, all is about 820m. After finishing, the athletes of the group WALK for about 300m downhill, going back to the start. One loop is about 1,120m.
Of course, if you have other options, you can change something. For example, with Rita Jeptoo I use something a little bit different : when we are 4-3 months far from the competition, her circuits are uphill only, for about 600m, and there is more attention for technical exercises, done at high intensity, while the run (about 80m climbing between every station) is at 80% of max speed. In this case, the current focus is for increasing strength and specific technical ability when tired. So, we use Aerobic Resistance in order to support STRENGTH ENDURANCE. Instead, during the last 2 months, we go to qualify the intensity of the sprints, and the exercises lose part of their importance. The final focus is to use strength for supporting AEROBIC POWER.
We use this type of preparation ALWAYS, after every Marathon, for recovering the personal level of strength, that during the specific period of preparation for a Marathon the athletes go in part to lose. But, in the case of Rita running Boston, that is a very hilly marathon, we maintain this type of training till last period, because to have strength endurance is one of the most important goals in order to finish with high speed (last year Rita ran 16:15 between 35 and 40k, and was the 4th performer in all the race (better than the top 8 men) from 40 to the finish). Don't forget the "heartbreak hill"....