VO2 Intervals and Heart Rate
 

Hey,

So I just completed today's prescribed VO2 / L5 intervals. 5X5 at 113-115% of FTP. Promisingly, perceived exertion was down in relation to the level of power, though there still was that odd "I want to puke" feeling near the end of the last two.

My question is this: Should my heart rate max out as the interval gets longer? I remember reading other descriptions of these intervals, and people talk about a slow but steady rise in heart rate to about near max. What I usually see is a slow rise during the first 3 minutes, then in the last two minutes, things will settle in at 179-181. My max heart rate is 190.

So do other people generally see a steady heart rate near the end of L5 intervals, or is closer to max generally expected?

Since I'm playing with power, the question might be moot. But, I still have an interest with how the body responds to exercise in terms of heart rate.

If you know your LT HR, you could check your numbers, but it sounds like you were in roughly the right HR zone.

One thing you may notice is HR drift, where the HR for each interval goes up slightly even when the power is the same. As far as the response to an interval, it does take a couple minutes for the HR to settle in for a steady effort. That's why Friel et al recommend using the average HR for the last 20 minutes of a 30-minute TT effort to determine LT HR.

LT heart rate is 172ish. Not really established through thorough testing, but observed heart rate during threshold intervals and longer hill climbs, etc.