Hi Mark, also worth a read, and introduces some of Marcora’s work is — https://www.amazon.co.uk/Endure-Curiously-Elastic-Limits-Performance/dp/0008285098/ref=sr_1_4?crid=1QFCP6MQQ5MNH&keywords=endurance&qid=1555601192&s=books&sprefix=endurance%2Caps%2C143&sr=1-4

Its a good read — enjoy