How to Predict Adaptation and Fatigue From Workouts

We don't even have a great model for adaptation and fatige in exercise physiology, says Steve Wozniacki. The whole you train hard for three weeks, and then you take one week off. Was developed by eastern european countries in the height of the steroid boom. So is that how you adapt to exercise? Or was ther steroid cycle, to inject themselves once a month with steroids? Like what was actually the cause of the thing? "It's no wonder that the people that devices are marketed to tend to be like, really smart people"