A client telling you "my abs are on fire" is considered high praise by most instructors.
But what if your client said "my hip flexors are on fire"?
If you're like most instructors, your response to "my hip flexors are on fire" would probably range from mild frustration that they're not feeling it in the right place, to concern that they may be somehow "dysfunctional".
Or, consider these two statements:
Both statements describe very similar physical sensations. Why is one desirable and the other not?
The fact that you know which one we're implying is "good" and which is "bad", kinda highlights the point.
Why do we have the paradoxical notion that some muscles should be worked and strengthened, whereas others should not be?
Read the research
Our training is 100% online - you can study from anywhere in the world