Power Meters: Nice to have or necessary?

The CompuTrainer comes with a PIG (performance improvement guarantee) plan that suggests effort levels based on the results of the FT test, which I took last week. With results in hand, I set to the task of recalibrating my cycling efforts.

I had a tempo ride scheduled for Wednesday, and to gauge my effort, I followed the PIG guidelines for a tempo ride, which recommend holding 85% of FT power for 45 minutes. For me, this translated into 187 watts for the main set of the workout.

Okay, let’s do this, I thought. I did my warm-up and got into the tempo portion of the session.

I realized about 20 minutes into the workout that maintaining this level of power was almost as hard as the power test itself.

Then, about 35 minutes into the main set, I realized that until now, I have not been cycling hard enough. The watts don’t lie.

Seeing the watts, and feeling the effort required to sustain them was an important learning experience. You may be wondering, how could I not have known that I haven’t been working hard enough? After all, I’ve been using perceived effort and heart rate to gauge my exertion in both cycling and running.

Shouldn’t I have been able to “feel” that I wasn’t working hard enough?

A pause for clarity

In the event that some of you are not familiar with heart rate based training, let me take a brief moment to explain the details of the approach I use. There are several ways to use heart rate to gauge intensity; my approach follows that offered by Friel & Bryn, described in their book Going Long. I assess my effort based on five heart rate zones.

  • Zone 1: active recovery, up to 75% of max heart rate (or 85% of lactate threshold)
  • Zone 2: aerobic endurance, up to 80% of max heart rate (or 90% of lactate threshold)
  • Zone 3: tempo/muscular endurance, 80-85% of max heart rate (or up to 95% of lactate threshold)
  • Zone 4: anerobic threshold/muscular endurnace, 85-90% of max heart rate (or 100% threshold HR)
  • Zone 5: anerobic 90%+ max heart rate (or 100%-110% of threshold)
An overview of my HR zones for running

Each of these zones gets progressively more challenging, brought on by increases in intensity, speed, force and/or power. Throughout the week, training sessions should vary across these zones to ensure performance improvements. In this manner, heart rate becomes a mechanism for ensuring that the effort level of a workout is in keeping with your goals for the individual session, as well as across training cycles.

For example, the goal of a long run is aerobic endurance, as such the average heart rate should be within the zone 2 range. Intervals that are designed to increase speed (and the way the body processes oxygen) will push the heart rate into zones 4 and 5. Tempo runs are designed to help the body improve its response to the lactate threshold, and so, the run should be completed in high zone 3 or zone 4. And so on.

Why I need power for cycling

This approach has worked very well for my running. Apparently, however, the perceived effort + heart rate method has not served me quite as well for cycling. So, what gives? In my case, there are two issues: lag time in heart rate, and accurate heart rate zones. (Shout out to @felog and @alexgonzalezmi for their insights about power, and how it differs from heart rate.)

First, heart rate is not immediately responsive to effort. For example, when climbing a hill, your effort will increase immediately; however, your heart won’t give you an indicator of that increased effort until you’ve been climbing a while. Half way up a hill you might realize: Uh-oh! I pushed that too hard! Overexert yourself too much and you may pay for it dearly–especially in a long distance race.

So, there is always some lag between effort and heart rate response.

I’ve been running since the age of 13, and this lifetime of experience allows me to use both my perception of pace and effort along with heart rate. In this manner, I am fairly sildenafil accurate about my effort. I’ve only been cycling for 2 years, so my perception of pace and effort is not–ah, shall we say–fine tuned. That’s problem number 1.

Problem number 2: the principles of heart rate training–regardless of the sport–work best when you have your zones dialed in. As it turns out, I’ve been all wrong about my zones for cycling. I guess that would be because I never actually tested them. That’s right. My first test of cycling fitness was last week.

Until now, I’ve just been fudging around with my numbers from running, and if my heart rate was low during a ride, I would chalk it up to an unquestioned assumption that my cycling heart rate zones were “naturally” lower than my running zones. In some cases, I would just ignore my numbers. (Hmmm. Wonder why I sucked last year?)

While this assumption may be accurate, I had never done a test to confirm or disprove this hypothesis. After taking the test on the CompuTrainer, it turns out that my threshold heart rate for cycling is only 10 beats slower than that for running. It’s safe to say my “vague” calculations for the past year have not been in line with the results of this test.

For example, during my ride at Ironman Lake Placid last July, my heart rate should have been somewhere in zone 2. Using my newly adjusted numbers, this means my heart rate should have averaged in the high 130s to the mid 140s.

Guess what my average heart rate was?

125 beats per minute.

No wonder I was happy - I was barely working to my potential!

That’s right, folks, I was practically resting during the bike portion of IMLP, which I suppose explains why I had so much fun. I was on a sight seeing tour in the middle of an Ironman. Okay, let’s be charitable and chalk this up to being a rookie, and trying to make sure I had enough gas in the tank to go the distance. (Sure, sure, whatever rationale works…)

So, how about my rides since I began my  “operation become a better cyclist” in November 2010? Surely, I worked harder?

Yes, I might have worked harder, but I didn’t work smarter or to my potential. I’ve been doing intervals with my heart rate at about 150 bpm. Um, yeah, that should be 160 bpm. Or, how about my “tempo” rides, which I should rename my “slow-go” rides with my 140 bpm average heart rate (should be in the 150s).

At the time,  I thought I was working hard enough, based on my perception of the effort. But, the watts tell a different story. Play time is over. It’s time to suffer.

So, what’s the takeaway here?

First, make sure your efforts are consistent with your goals for a given workout. Otherwise, improvement won’t happen. Use all available means in combination to assess your effort: perceived exertion, heart rate, and power (when applicable and available).

Second, power meters are more than a “nice to have” device. Before using my CompuTrainer, I really didn’t get the “big deal” about power meters. Now I do.

A caveat: Triathlon is an incredibly expensive sport. The race fees, the gear, the food bills, the energy and water bills from all the laundry. Lots of costs. Like many of you, John and I are not able to buy everything we want. We must make smart decisions about what gear we should and shouldn’t get, compromise  between top-of-the-line and works-just-fine. So, power meters may seem like just one more unnecessary expense.

At least, that’s what I used to think.  There’s lots of gear we don’t really need to race well. But, a power meter isn’t just a gimmick–especially for long, challenging courses.

After three weeks of using the CompuTrainer, I realize that gauging power makes a difference. In about 4 weeks, I’ll be able to measure how much of a difference watching my watts makes when I take my second FT test.

In the meantime, I’ll be shopping around for power meters I can use while on the road. Suggestions welcome!

What do you think about power meters – necessary or just nice to have?

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