Over the last long time, I’ve written a lot about interval training because it really is good for us. (Quick review: in interval training for cardio, we work really hard for about a minute and then work less hard for as long as it takes us to get our heart rates down a bit. Then lather, rinse, repeat until we are done with our workout. It burns more calories in less time and produces quicker results in terms of cardio fitness than steady-state cardio.)
There is an underlying principle, though, that I’m thinking about today. We can’t always go to 11 (no matter what Spinal Tap says). This is a built-in condition in interval training. Our bodies simply can’t go at maximum intensity for more than about a minute because we run out of ATP and have to use slower energy pathways. (Sorry about the biology flashbacks. I promise there won’t be a quiz.)
When we are doing other kinds of workouts, we have the same limitations on our energy, which is one reason why we rest between sets when we lift weights. But it is not just our energy systems that max out.
A few examples. Let’s say we’re lifting heavy. We are unlikely to set new personal records for more than one lift in any workout. Our bodies use up our energy and strength and general oomph as we go along and toward the end we are not making as much progress. This is also a good reason to mix up our workouts so that we don’t always do the same thing first.
Or let’s say we’re doing Pilates. While we need to concentrate on what we’re doing throughout our Pilates work, some exercises are more complex than others. We want to ensure that we have the attention and energy to concentrate on those, so we want some exercises in our series that have a lower cognitive and/or physical load.
The short version is that we need to allocate our mental and physical resources wisely as we work out.

