The question of when a interval effort really starts has been posed a number of times. Short intervals of less than a minute leave little room for question. However, the confusion often surrounds the longer 3- to 10-minute threshold intervals. With a threshold interval, the goal is to sustain a heart rate between 97% and 103% of threshold (VT2, LT2, LTHR) or FTP (functional threshold power) for the entire duration. The question lies in the amount of time it takes to arrive at threshold, or what I like to call “cruising altitude.” Depending on a rider’s fitness, fatigue, and a whole host of factors, arriving at threshold will vary from one person to another. Does the amount of time it takes for a rider to get to threshold affect when the interval effectively starts?
It Starts at Go