Are you “doing cardio” or “training cardio”? As a trainer and instructor, there’s a huge difference. Sure, doing cardio has it’s place and gets you in the door, but training cardio takes your efficiency to a new level. When I work with clients individually and in classes, training always has a purpose. In most cases, the goal is to make your metabolic system more efficient at doing it’s job, one of which is to burn body fat, sounds good, right? Learning just a bit about heart rate and power can make the distinction between “training and doing” cardio.
Let’s start with Heart Rate!
Below is a helpful chart to use when using a 1-10 scale for rate of perceived exertion, also known as RPE (how hard you feel your are working, 10 being max).
It is important that we train using all of these zones through out the week. Using a Heart rate monitor will give you the most accurate feedback. If you do use a heart rate monitor, each zone represents a % of your max heart rate. For example a 7.5 is equivalent to a 75% of max HR.
Calculating Maximum Heart Rate
Maximum heart rate used to be calculated using the formula 220-age (40 year old would have a max HR of 180). A revised formula of 208-(age x .7) can be used as a more accurate guess of your age predicted maximum heart rate (both formulas are close). Either way these are formulas that do not take into consideration sex and fitness level.
The best way to find your true HR training zones is to work with a heart rate monitor. Using a heart rate monitor will allow you real time monitoring and a more accurate way to view and analyze your results. (workout results pictured using Polar H7 and iCardio app).
….On to Power
Watts are a unit of measurement for power that you’ll commonly see on exercise equipment. We use power specifically in exercise to measure how much work is being done, also known as output. This allows us an alternate method of measuring exercise intensity.
Before power meters were common on exercise equipment heart rate was the best (sometimes only) way to measure workout intensity. People that don’t train with an actual heart rate monitor were left with making their best guess, otherwise known as Rate of Perceived Exertion (RPE). But heart rate and power are not necessarily interchangeable but can be programmed together for a more efficient workout. I have found power to be most useful on exercise bikes and the Cybex Arc Trainer.
How does heart rate compare to power?
Legendary endurance sports coach, Joe Friel considers heart rate the input and power as the output. Heart rate specifically tells you how hard you are working toward a goal, power tells you how close to that goal you are getting. Say for example you are trying to push a boulder uphill, heart rate tells you how hard you are pushing the boulder and power output tells you how far the boulder is moving as you push it.
Why should I care about power?
Using power gives you a more accurate & immediate measurement of intensity. As soon as your feet hit the pedal, power is recorded. Heart rate is quite different and much more variable (age, diet, stress, etc). Heart rate can also take seconds or even minutes to represent the appropriate level of intensity. This is seen in very short interval bursts, the interval is over and your heart rate keeps going up. Working with power allows you to train for a specific goal, in this case it would be to push the boulder up the hill farther (higher output) with less effort (lower heart rate or lower input). Also if you happen to care about calories burned, a higher overall output for class requires more energy, aka calories. So Power up!
How do I know where my power output should be?
There is no right or wrong level of power that you should work to obtain, it’s best to figure out where you are and work to increase that value. The most common way to obtain a baseline measurement of power is by using a test call “Functional Threshold Power” (FTP). FTP is the highest level of sustained power output over a 60 minute period. Thankfully, the test is typically done using a 20 minute sample. FTP can be estimated by working as hard as you can for 20 minutes and multiplying the average power output by .95. This is difficult with bikes that show you a power reading during your workout, but do not give you an average power reading for a lap or phase of your workout. If an average reading is not available on your equipment, you can do this manually by noting a sample every minute manually. Yep, pen & paper style!
Here’s a great read on power and heart rate zones, note that you’ll need a heart rate monitor to maximize the accuracy of these tools. Joe Friel’s Testing Guide
Train hard… Train efficiently! Questions? Post your comments below.