By Julian Bermingham PT, DPT, CSCS
If you are a hard-charging weekend warrior, the answer to this question might surprise you! On the other hand, if you have just recently joined the gym and are unsure how to appropriately execute a fitness plan, then read on, as the information below will be tremendously valuable to you.
But first, a quick vocab lesson. Quantitative data refers to the hard, measurable numbers in a workout: the number of sets, repetitions, and the amount of weight being lifted. Most people have a good grasp of this portion of their workout plan. Qualitative data, on the other hand, refers to data that can’t be measured, but must be observed/experienced.
In 1982 the Swedish researcher Dr. Gunnar Borg published his Rating of Perceived Exertion (RPE) scale, which was effectively the first widely used qualitative rating system that was applied to physical activity. The Borg Scale ranges from 6 (no exertion at all) to 20 (very, very hard). Why these seemingly arbitrary numbers? If the researchers added an additional zero to the chosen exertion number, they would get an accurate estimation of heart rate for a given activity (for instance 6 on the BORG = 60 heart beats per minute).
In recent years, members of the strength and conditioning community have come to adopt a modified and more user-friendly version of Dr. Borg’s RPE scale. Following a given exercise or task, the participant can use a 0-10 scale of difficulty, with 0 being no exertion at all, and 10 being “I could not have continued”, or “I could not have performed 1 more repetition.” In this way, trainees are assigning a qualitative measure to their training. Why is this important? Well let’s take this hypothetical example:
On week 1, a trainee performs 1 repetition of a 100 pound bench press and labels it as a 10/10 difficulty.
On week 2 that same individual performs 1 repetition of a 100 pound bench press and labels it as a 7/10 difficulty.
Although the number of sets, reps, and weight lifted are the exact same, we can conclude that from week 1 to week 2, the trainee has become stronger, as the same task is now performed at a lower relative exertion rating.
So why is any of this important to the average gym goer? For every training session there exists some relative risk to performing the exercise, as well as some potential reward for performing the exercise. As intelligent trainees, we want to minimize risk as well as maximize reward. One could easily imagine that if an entire workout was performed at a 10/10 intensity, the risk of injury would be much higher than if all exercises were performed at a 1/10. But if the intensity of the exercise was only a 1/10, very little benefit would be attained by that session.
So here are my recommendations based off of clinical and personal experience. If performance is the goal: most training sessions should be performed between a 7-9 relative intensity on a 0-10 scale. True 10/10 efforts should be reserved for when they matter the most: a competition, a meet, or the big game. In this way we can maximize our benefits of training and minimize the risk of injury.
One final note: in the rehabilitation setting all the above recommendations still apply, but as we attempt to retrain movement patterns, and decrease the perception of threat/harm, exercise intensity can be decreased to a 5-7 RPE, at least until the patient has been successfully rehabilitated.