After several months of base-building, athletes usually begin to transition into high-intensity training to improve their fitness further and prepare for spring races. This period might occur around three months or so before your first race of the year, possibly even sooner if you plan to peak at the beginning of the season.
Transitioning to High-Intensity Interval Training
What sort of intervals should you do during this transition into high intensity? Should you go straight into threshold or even VO2 max intervals? This is often a big question mark for athletes, and there is no one-size-fits-all approach in terms of exactly what type of intensity you should do.
However, regardless of what types of intervals you find work best, dialing in the length of your intervals and rest periods can make a big difference in how your body adapts to the training. One way to approach this transition into high-intensity is the “Short-to-Long” interval approach. Let’s call it STL for now.
Why Short-to-Long HIIT Makes Sense
The STL approach consists of starting with shorter intervals and longer rest periods at the top end of a power zone. From there, it progresses to longer intervals with shorter rest periods targeting the same power.
Theoretically, by starting out with shorter intervals, you can hold a higher power than what you would with longer intervals while still accumulating plenty of minutes at high intensity. This improves your body’s capacity to handle higher power outputs than it would otherwise. As your body adapts, the intervals are gradually lengthened, and you find yourself at a new level of fitness.
The key with these intervals is that they are only done slightly above a targeted power zone so that the power is still manageable. Starting out, the intervals must be long enough so that you can accumulate a lot of minutes at the target power but not so long to where you can’t sustain it for the whole workout.
STL Intervals in Practice
For example, an athlete might have done an early-season power test to yield an estimated FTP of 300 w. He aims to increase his FTP to 315 w before beginning race-specific training for his peak event.
To build his FTP to this goal, he wants to accustom his body to holding 315 w for an extended period of time. However, he can’t just start doing 2 x 20-minute efforts at 315 w because he likely could not complete this workout. This is where the STL approach comes in.
In this scenario, he might start doing 4 x 8-minute intervals with 8 minutes of rest, targeting 315 w. These intervals are short enough to where he can sustain the desired power, and the long rest periods will give him plenty of time to recover so he can repeat the effort. With this approach, he can accumulate 32 minutes at 315 w.
Once the athlete gets this down, he can slowly increase the workload and decrease the rest. Say he then progresses to doing 3 x 10-minute intervals with 8 minutes of rest at the same power and slowly increases the duration from there.
Eventually, he might be able to progress to 3 x 15-minute intervals with 5 minutes of rest at 315 w. Now his body has become accustomed to holding this power for a long period of time, and he can recover quickly from the effort, thus yielding an increase in FTP.
Rather than jumping right into long intervals at a lower power (2 x 20, for example), the STL approach will first teach your body to hold a higher power in small doses of intensity with plenty of recovery. Over time your body will get more accustomed to this power, and you can then work on sustaining this power by gradually doing longer intervals.
Another significant benefit of this method is that it is mentally easier, too. After the base season, jumping straight into long intervals can be intimidating. By starting with shorter intervals, you can “ease into” the intensity a little more while still improving fitness.
