Cyclists do it, swimmers do it, and, strange to say, even great Finnish runners of the past did it. It is the doubling or even trebling of the training load in quantity and quality for a period of not less than two days and not more than seven days, followed by an equal number of recovery days. Well, one very good example was the spate of shattering world records achieved by the Chinese women runners under the direction of the autocratic coach, Ma Junren.
Most athletes train severely one day and have one or two days of easy training to recover.
By exercising strenuously for consecutive days, recovery never lasts for more than 22-23 hours, ie, the time between workouts. These raised responses are often called super-compensation. It will be noted that this routine is mathematically precise. Eventually, work done in Week 1 will be doubled. This will take five months to achieve.