Determining the intensity of a workout can help make it more effective and easier to scale. For example, asking someone to run for five minutes is physically different than asking them to run hard for five minutes. The same concept applies to strength training.
But while there are some straightforward ways to measure intensity of cardiovascular or aerobic training, strength training is a bit more challenging. Yet knowing how hard you’re lifting can help you structure your workout programs more effectively. For example, you can vary workout intensity to prevent overtraining while still getting sufficient volume and working hard enough to get results.
It can also help you adapt your workout to how you feel that day. Let's face it: some days we just don't have the mojo and some days we feel superhuman. Using RPE can help you adjust your workout intensity accordingly.
One well-known way to measure exercise intensity is with a heart monitor, where a faster heart rate correlates to a harder workout. There are even target heart rate “zones” to help people determine how hard they’re working based on a percentage of their maximum heart rate (which is almost certainly NOT 220 minus your age ). This is an easy and effective way to measure exercise intensity but it doesn’t help with strength training where your heart rate tends to spike briefly near the end of sets (but can beat more strongly due to increased blood pressure during heavy lifts...which is perfectly fine for healthy folks).
A very simple method of determining intensity is with the “talk test.” This attempts to measure how hard you're working based on your ability to speak, ranging from carrying on a conversation to struggling to utter two consecutive syllables.
This can work well enough for aerobic exercise (like running) but again doesn’t translate well to strength training where shortness of breath usually only occurs with very high intensity (heavy loads), high rep counts (ever do a set of 20 loaded squats?), and/or short rests between sets.
Another method is known as Rate of Perceived Exertion (RPE). This relies on exercisers to determine their own intensity level based on how hard they think they’re working. It originated with the Borg scale where the original version tried to roughly correlate with an estimated heart rate for a healthy young person (multiply by 10):
- 7 – Extremely light
- 9 – Very light
- 11 – Light
- 13 – Somewhat hard
- 15 – Hard
- 17 – Very hard
- 19 – Extremely hard
- 20 – Maximal exertion
This was later simplified to be on a scale of 0 to 10 (or so):
- Nothing at all
- 0.5 Extremely weak (Just noticeabl
- 0. 7
- 1 Very weak
- 2 Weak Light
- 2. 5
- 3 Moderate
- 5 Strong Heavy
- 7 Very strong
- 10 Extremely strong “Maximal”
- 11 Absolute maximum (Highest Possible)
That's right, this scale goes to 11.
These categories don’t translate well to strength training either. So what does work?
Michael Tuchscherer came up with his own RPE scale for lifting weights. I've seen a few variations of this but like this one best:
- 10: Maximal, no reps left in the tank
- 9: Last rep is tough but still one rep left in the tank
- 8: Weight is too heavy to maintain fast bar speed but isn’t a struggle; 2–4 reps left
- 7: Weight moves quickly when maximal force is applied to the weight; “speed weight”
- 6: Light speed work; moves quickly with moderate force
- 5: Most warm-up weights
- 4: Recovery; usually 20 plus rep sets; not hard but intended to flush the muscle
Anything below a 4 is irrelevant.
At StrongFast, we use a modified version of this as follows:
- 10 - Max effort
- 9 - Could you have MAYBE done 1 more rep?
- 8 - Could you have DEFINITELY done 1 more rep?
- 7 - Weight is too heavy to maintain fast bar speed but isn’t a struggle
- 6 - Bar speed slows down only on the last rep
- 5 - Weight moves quickly when maximal force is applied to the weight; "speed weight"
- 4 - Bar speed on the last rep is the same as the first
- 3 - Light speed work; moves quickly with moderate force
- 2 - Most warm-up weights
It takes some experience to make this work: most beginners tend to underestimate how much they can lift, and some overestimate. Experienced lifters generally know their limits and reach (and exceed) them regularly, making this a useful measure of intensity. Of course, there are always some who will overestimate how much more they had left; for them, this is useless. But that's not us, right?
For the high-tech folks, there are now a variety of devices available that measure bar speed. When reps start to slow down, you know you’re reaching your limit.
But for most of us, RPE is a sufficient way to measure intensity for strength training.
How are hard are you working out?
Be seeing you.