Tonight's session is a hill repeat session.
Whilst our tempo runs (as we did on Tuesday) trigger adaptions and increase the number of mitochondria in your muscle fibres.
Mitochondria play a vital role in converting energy from food, the more mitochondria you have the more energy you can create during exercise.
Hill repeats significantly turbocharge those mitochondria significantly increasing their output of aerobic energy.
Also when running hill repeats it means you will naturally shorten the distance your foot has to travel downward and will require you to produce extra force to fight the gravity of the hill.
This means that you will improve your muscular force on the ground which should result in a quicker cadence and increased stride length when running on level ground.