But what exactly is the right intensity to develop your so-called aerobic base? The challenge for many is not that they train too slow during these workouts, but too fast. If you don’t finish a workout fully exhausted, you may not think it was an effective workout.
In a previous article I discussed the importance of enhancing peripheral cardiovascular adaptations…this is where the aerobic threshold comes in.
Aerobic threshold is the intensity at which you are most efficient at using fat for energy. As you work above this intensity you begin to use more and more carbohydrate for energy, relying increasingly on anaerobic metabolism. When it comes to building the peripheral aerobic adaptations critical to maximizing your fitness for team sports, aerobic threshold is an intensity you don’t want to ignore.
There are a couple different ways to gauge intensity to ensure you’re working at this threshold. In terms of heart rate, you want to be between 65-70% of your maximum (you’ll need to do an incremental test to exhaustion to determine your max heart rate).
A simple way to do this would be to strap on a heart rate monitor and begin running on a treadmill at 5.0mph, increasing the speed by 0.5mph every minute until you can no longer complete a full 1-minute stage.
You can also do a field-based test such as the “Beep Test.” If you don’t have a heart rate monitor, at the completion of the test just take your pulse from the carotid artery (on the side of the neck), by counting the number of beats for 6-seconds, and multiplying that number by 10 to determine beats per minute.
The problem with determining the aerobic threshold (or any given training intensity) from a heart rate range alone is that it can vary from person to person. Even though you might monitor heart rates for every training session, you can also use Rating of Perceived Exertion (RPE) as an indicator for gauging intensity.
RPE may be the most effective (and ironically, the simplest) way to accurately prescribe workout intensities. The great thing about RPE is that it factors in everything: heart rate, lactate levels, muscle soreness, energy level, desire to train, mental state, etc.
All of these things impact physiology and how difficult a given training session will be. In other words, although your heart rate might be low (indicating a low intensity), the fact that your legs are tired from a hard workout in the weight room the day before means that your perceived exertion could be extremely high.
In this case, muscle soreness is the limiting factor keeping you from pushing harder. Therefore, heart rate, in this workout, is not the best method of gauging intensity. RPE inherently factors in muscle soreness because it’s part of your body’s overall feeling.
There are two common RPE Charts: a 1-10 scale and a 6-20 scale. Here’s what they look like and the subjective feeling of effort and breathing reference for each level:In this case, aerobic threshold falls at an 11 (on the 6-20 scale) or a 3 (on the 1-10 scale). This intensity feels light, could theoretically be sustained for a few hours, and allows you to comfortably carry on a conversation.
By using these markers of intensity, you can accurately work at the intensity appropriate for maximizing peripheral aerobic adaptations, without the need for a heart rate monitor.
The other benefit of using RPE is that it automatically adjusts for improvements in fitness. As you get fitter, you’ll naturally be able to sustain a faster pace at the same “perceived” level of effort. As long as you feel like you’re working at the same intensity, you can have a high degree of confidence that you are in the appropriate intensity range.
NEXT TIME: Other important training levels and their correlation with RPE.
Jason Dierking, MSCC, is Assistant Director of Olympic Sports Performance at the University of Louisville. See other articles in the Home Field Advantage series.
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