There are many ways to assess if you are progressing within your fitness Journey. Both Objectives (scales, pictures, weight on the bar, quantitative data like RHR, HRV, Blood Glucose) & Subjective (Mood, energy, Digestion, sleep, stress management, relationship with food, clothes fitting).
One of which you can’t really rely on but which a lot of Trainees AND more importantly, trainers fall into the trap of, Is How Sore you are from your sessions.
And Iv been there myself!. Rewind 5 years ago. 19-year-old PT, just qualified, working full time on the gym floor trying to implement everything I know and eager to know more.
You’ve Brian in for PT, he’s new, not much experience… so you put him through his paces.
GVT squats, drop sets, short rest, high intensity… the works, by the time he’s done he’s the same color as a bottle of Milk and doesn't know what day it is. Job done, on to the next Victim.
You get a text from Brian days later saying he's in Agony and nearly has to be Airlifted from the Toilet Bowl. Screenshotted & thrown straight up on the gram almost as a badge of honor as a trainer. And I am not trying to be authoritative here or place myself on a pedestal, I have done this 😂.
If you are new to the gym, have rotated some exercises, increased volume, are in deeper stages of dieting, or returned back training after a bit of time off, you will be sore. Your nervous system must adapt to the stressor through repeated bout effect to create adaption (a good thing).
Its cumulative soreness or chasing soreness as a marker of progression is where the issue lies. Prolonged Muscle soreness can lead to higher levels of local & systemic inflammation which can have a negative downstream effect (possibly decreased IGF-1, GLUT-4 Translocation, androgen receptor density/affinity, chronic fatigue, compromised joint integrity, making daily tasks harder). Basically... all things we dont really want.
In some contexts, soreness is okay, in fact, necessary. But as a Pt/Coach or even trainee, boasting about how you are breaking your self or your clients, is similar to boasting about how hungry you/they are, it's counterproductive in excess & not a direct indication of progress.