Someone on the EN Forums asked this question:
“There has been a lot of discussion of “5-hour power” lately. Most of this has been in the context of the importance of maximizing 5-hour power rather than FTP.
Is this a well-known concept that I seem to have missed? Can someone please articulate crisply:
• what “5-hour power” means (definition and measurement)
•importantly, how “5-hour power” relates to ironman race execution, quantitatively”
My reply, edited for the blog: Going back in time, Endurance Nation created charts in 2007/8 to help us plan our bike legs in half and full Ironman racing. The coaches and a few of their then team members collected a bunch of race data correlating TSS (Training Stress Score, a measurement of how “hard” a given activity is, how much it will fatigue the athlete) to IF (Intensity Factor, the percent of effort relative to an all out one hour effort), to time of bike leg. They produced a nice little color coded chart we use to plan our bike on race day. Among them was Chris W., who always had a lot of thoughtful things to say on race execution and riding with power.
When I first joined EN in 2009, and began to learn about race-day bike execution, I glommed on to a post Chris made when he said that instead of the chart (which he had helped create), he used the Training Peaks (WKO+) Mean Maximal Power curve to establish his target for bike power in an IM. Specifically, looking at his power at the five hour point on that graph. The MMP curve is created by the software from all the rides one has done during a given time frame. Crudely, it will take the highest Normalized Power (think a fancy term for average power), over a 5 second perido, over a one minure period, over a five minute period, over 20 minutes, 30, 60, 90, 120, etc. etc. all the way out to the longest ride taken. It then draws a curve which will show that power at any given point in time.
Since Ironman bike legs for Age Groupers are most often between 5 and 6.5 hours, that made tons of sense to me. I started to evangelize the concept whenever the topic of race execution came up. Since that number is the highest NP over a five hour period one has demonstrated on rides recorded in TP, that would usually happen during the race rehearsals. So in simple terms, it’s just a quick way of using the RR to lock in a race day target for NP.
Now, should one be specifically training to five hour power? Of course! That’s what IM training is all about. We do 20-30 minute intervals at “race pace plus”, e.g.
“WU: 20-30′ @ 65-70% (IF) /Zone1 to 2/Easy.
MS1: 8 x 25′ (5′) @ 75-80%/High Zone 2 – Low Zone 3/Upper Steady.
MS2: Remainder of ride time is @70-75%/Zone2/Steady. In aerobars, no surges, constant power, etc.
WD: 10′ Easy spin. ”
That’s 200-250 minutes in intervals just above race day effort – in line with the 2/3rds recommendation for a 5.5-6.5 hour time trial.
My conclusions here:
- Five hour power is a good way to predict or target race day effort for an IM bike leg, in conjunction with the EN charts.
- EN plans are specifically designed to increase one’s ability to ride to that target.
Just want to make sure I am giving a crisp answer to the original questions:
1. I propose that “5-hr power” as a metric be defined as the watts which appear at the five hour point on the TP/WKO+ Mean Maximal Power Curve.
2. I believe that 5 HP number, read two weeks before an Ironman, can be used for “most” AG athletes as their target NP for their bike leg. “Most” means those who are riding in the range of 310-400 minutes for the bike leg. Those who are faster could use a shorter time on the MMP curve; those who are longer, might consider the 6HP.
TP/WKO+ doesn’t care what kind of ride you are doing to generate that 5HP number. It could be a 5+ hour ride at a steady power level (VI in the range of 1.02-1.04), like a race rehearsal, or it could be an EN “Saturday Ride” which includes race pace plus intervals and recovery periods, as long as the ride takes longer than 5 hours. I don;t know this for a fact, but I bet both types of rides generate 5 HP #s very close to each other.
If it helps you to think you are doing something special in training to improve that 5 HP, go for it. But I’d bet that whatever you end up doing will be an awful lot like what our coaches have us doing in the last two months before an IM.