Intervals: Size Does Matter
Intervals : The Right way and the Wrong Way as Illustrated by an SRM powermeter – Frank Overton
At this time of year just about everybody in the US is chomping at the bit to start racing. After reading about Danielson in Langkawi, the Tour of the Med, and in the US –the Valley of the Sun, I know I am. Depending on where you live, racing may be starting up, but the big one -– Redlands is six small weeks away. So you’ve put in your winter training, laid down a good base, and now it’s time to “release the hounds” (insert Mr. Burn’s voice from the TV show The Simpsons).
Yes, that’s right, if there is one single thing you can do to become faster, it’s intervals. And with an SRM or a PowerTap it is possible to illustrate how to perform intervals properly. Don’t despair if you haven’t ponied up for a powermeter. Even conceptual understanding of the graphical analysis below will help you conduct your intervals by “feel”.
Traditionally, intervals are performed in Zone 5. But with powermeters there is a lot more to an interval than your heart rate. Consistent power output is crucial to maximizing the amount of work an athlete can perform during each workout. How can you achieve this without a powermeter? Rating of Perceived Exertion (RPE) is one way to gauge your effort during an interval. On a scale of 1 to 10, your RPE should start off easy (1-3) and shift into a moderate RPE by the middle of the interval (4-6) and finish off hard (7-9) due to the onset of fatigue. The graph below illustrates five intervals performed properly.
If you are using a powermeter, adjust your effort based on your power readout. A steady effort produces a nice consistent power output over the course of the interval as shown below – see RIGHT WAY. The bottom line, no matter what device you are using, is to go as hard as you can but gauge your effort so that you can finish the interval with as much effort or power as you started the interval. If you can do this your power output will look like the graph and you are well on your way to winning races.
Starting off too hard at the beginning of an interval is a common mistake especially for cyclists going off of heart rate alone. Notice how the intervals start in the graph – WRONG WAY – with a huge surge followed by a drop in power for the remainder of the interval. In other words the athlete “blew up”. Don’t make the mistake of going as hard as you can in order to get your HR up as soon as possible. Heart rate lags behind your power output and in the case of these intervals is not a true indicator of what’s going on.
There are two reasons why you want a consistent power output for your intervals: First, the total amount of work accomplished is greater and second, you will recover better for your next workout. If you were to look at the total work done (kilojoules) in each graph, the consistent power intervals average 53KJ’s x 5 intervals for a total of 265 KJ’s of work done. Now if you look at the total work done for the intervals with the power surge, you will see that the first interval starts out with a whopping 69KJ’s ! But wait, the athlete isn’t recovered for the second interval and can only manage 52 KJ’s followed by 48, 44, and finally only 40KJ’s. That’s only 253KJ’s , but this was only the first set! The athlete is blown and will underperform his or her intervals during the next set.
No one wants underperformance! Here’s the motto of interval training: Go as hard as you can BUT only as hard as you can maintain for the duration of your entire interval workout. You’ll do more work, recover faster, and start to see a big difference in your training.
Frank is a USA cycling certified coach and category 1 road racer. He can be reached at his website FasCatCoaching.com or may be found riding around Boulder, Colorado in zone 2 on the bike paths or flat roads – – at least until late February when his intensity training begins.