Alan Couzens, MS (Sports Science), CSCS, PES.
I recently had an interesting email exchange with a couple of buddies on the merits (& limits) of field testing. There are a number of training approaches that place a lot of faith in determining training zones and training prescriptions based on short duration field tests (CP30 on the bike, 1000m time trial in the pool etc.). As a coach, I think it is important that you are aware of the limits of using this approach to make training recommendations.
Let me throw in a quick case study of 2 athletes with similar CP60 values to illustrate my point.
CP60 = 275 watts (Heart Rate = 174)
CP60 = 262 watts (Heart Rate = 154)
One is me, the other is an athlete that I coach.
Even if we were to use these more moderate 60 minute values in place of the 30 minute test suggested in ‘Going Long’, following the %FT approach, these are the heart rate zones that we would come up with for each of our athletes:
Z1: <140 bpm <123
Z2: 140-153 bpm 123-136 bpm
Z3: 154-165 bpm 137-143 bpm
Z4: 165-174bpm 143-154 bpm
So, how do these numbers stack up in the real world?
First of all, from a training perspective. If we adhere to the general prescription from a number of training authorities out there that the bulk of the athlete’s training should take place in Zone 2, one of our athletes, (i.e. me) is in a world of trouble. Over the course of the past year, the most Zone 2 (as defined by this method) that I have been able to tolerate has been 3:40 of a 20:00 week (~18%). If I were to go out there and try and follow some well known coaches recommendations that suggest that 70% or more of the athlete’s week should be made up of Zone 2 training, my training week would be done by Tuesday and you’d find me flat out, staring at the ceiling by the middle of the week. On the other hand, my buddy regularly does 10hrs+ in what this method would define as his Zone 3!!
Now, from a race perspective, the typical pacing prescription for an intermediate Ironman is Zone 2 – 3. In, the real world, however, the longest that I have personally been able to hold the very bottom number in my 'Zone 2' is 7:14 (a long way from my IM finish time!!). On the flip side, my athlete is able to go 11hrs+ at the top of his Zone 2.
As to the ‘why’ we see this wide range in our athletes ability to tolerate a given % of their functional threshold heart rate or power, we have witnessed a good correlation between an athletes ability to hold long durations at a given % of their FT and a high ability to oxidize fat as a substrate at each respective %. In the example given, at the bottom of our Zone 2, I am burning about 120kcal/hr more carbohydrate than my athlete. Is it any wonder that I run out of it sooner??
However, from a practical perspective, the take home message is that the best way to set up your athlete’s ‘Ironman training zone’ is to use their actual average heart rate or power for an Ironman. Likewise, the best way to set their base (day in, day out) training heart rate is to use their actual average heart rate over the course of a standard training week.
The point is that the further your training prescriptions get from the actual intensity measured during a test, the more they are based on assumptions of what ‘should’ happen in the real world, and like most assumptions that we make, they are generally based on a ‘best possible’ scenario.
Before you use these assumptions to guide the future direction of your training plan, be sure to ask yourself whether they are valid for the athlete you are or if you are, instead, designing a program for the athlete that you should be.