With 2020 well underway…a flood of new, returning fitness-seekers are HIITing gyms, fitness studios and CYCLE STUDIOS everywhere. Many unaware of or uneducated about how to effectively manage the intensity of their fitness activity. I’ll review a few common tools and techniques for keeping it safe.
RPE: Rating of Perceived Exertion
The most basic technique available to all participants is the 10-point Borg RPE scale. Simply put, this is a non-scientific, self-assessment of how intensely someone is exerting themselves. This has been used as long as I can remember and breaks down as follows:
0 – Nothing at all
1 – Very light
2 – Light
3 – Moderate
4 – Somewhat heavy
5 – Heavy
6 – Heavier
7 – Very heavy
8 – Very, very heavy
9 – Approaching max effort
10 – Most intense & max effort
I like this more illustrative breakdown from BRITISH CYCLING, https://www.britishcycling.org.uk/knowledge
1 – Sitting on a sofa doing nothing.
2 – Getting up to make a cup of tea. (Very British!)
3 – Easy paced recreational riding, slight feeling of exertion.
4 – All-day paced riding, not easy but definitely sustainable. Able to maintain a full uninterrupted conversation.
5 – Riding consciously quicker but still able to talk easily.
6 – Upping the effort, only able to talk in short sentences.
7 – Building on Level 6, you could probably just about respond “I’m fine!” if someone asked you how you felt.
8 – Riding hard, you can only sustain this for a couple of minutes and only communicate with single word answers.
9 – Almost as hard as you can possibly push your pedals.
10 – 100% sprint for the line.
While this is certainly a workable means of assessing exertion and intensity…with adequate tools, there are better ways that help remove the margin of error in self-assessed RPE.
Heart Rate (HR) Monitoring assessment of Exertion
After an individual base line for a person’s MAXIMUM Heart Rate is established, then workout intensity can be measured as a percentage of current actual HR vs. their MAX HR.
The % of MAX HR is only as accurate as the baseline measurement of MAX HR.
These are common ways to determine that important baseline / MAX HR:
A common rule of thumb estimate of a person’s MAX HR is based on the formula: 220 less current age. So if I’m currently 56, then 164 hbpm (heart beats per minute) would be my MAX safe HR. The calculations are not done yet! Since MAX HR may not be your TARGET HR, you need to apply a percentage to calculate an appropriate TARGET. The American Heart Association generally recommends a target heart rate of:
– Moderate exercise intensity: 50% to about 70% of your maximum heart rate (Approx. RPE = 6-8)
– Vigorous exercise intensity: 70% to about 85% of your maximum heart rate (Approx. RPE = 9-10)
Other sources indicate that moderate intensity will rise as high as 75-80% of max HR and highest intensity could land at 90-100% for a short duration.
There are more involved calculations based on resting heart rate too, but I’ll leave the Heart Rate discussion here.
Measurement of Power relative to Functional Threshold Power (FTP) to assess Exertion
FTP, Functional Threshold Power is basically the maximum sustained power, expressed in Watts (like a light bulb), that is generated in an hour. Because a one-hour test may not be the most suitable method, there are several other ways to calculate FTP: ramp test (based on degree to which rider can maintain output within an increasing range, increased every fixed interval (i.e. 4 minutes), a 5-minute test (all out effort), a popular 20-minute test, or others.
As with the HR measurements, FTP is similar to Max HR, in terms of being the reference point or benchmark for measuring performance. A major difference is that when a person is performing at very high intensity, the % of FTP can be as much as 150% of FTP. Also, generally speaking…Aerobic exercise becomes Anaerobic as you go beyond 100% of your FTP.
Power and FTP measures require well-calibrated tools, like a power meter. Without it, you’ll have to consider either RPE or HR measurements.
There may be other more sophisticated tools and techniques, but I’m not getting into them here.
The following table may be a helpful way to bring each of these 3 methods of measurement together and group levels into sets of 4 or 5 intensity ZONE…finally, add some color and you should have a helpful resource to understand, assess and manage the intensity of your workout.
ZONE # (1-4) – COLOR – RPE (1-10) – % MAX HR – % FTP
1 – Green (Blue) – 1-6.5 – <65% – <60%
2 – Yellow (Green) – 6-7.5 – 60-80% – 60-85%
3 – Orange (Yellow) – 7.5-9 – 80-90% – 85-110%
4 – Red – 9-10 – 90-95% – 110-140%
This is only to be used as a guideline for correlating the three methods discussed above. Ultimately, always come back to how you feel…if it doesn’t feel right or makes you VERY UNCOMFORTABLE, then stop doing it!
Enjoy the Ride!