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.