What is "junk volume"
Junk volume is any extra sets/reps/contractions done after a given muscle has stimulated sufficiently to maximise the anabolic pathways and ultimately create growth. we all know somebody - "I spent 4 hours in the gym yesterday"...
What's wrong with that?
Well, In a nutshell - muscle growth / muscle protein synthesis (MPS) occurs when there has been sufficient stimulus to a muscle, followed by enough amino acids in the blood stream to repair the damage done and ultimately grow & get stronger in the hours & days after a gym session -we don't grow in the gym. In Lehman's terms, we go to the gym and work, we breakdown and create muscle damage, we recover (and grow), we repeat - that is the process of muscle growth.
So, surely more work in the gym = more muscle damage = more growth? Actually, not necessarily.
You see when we place stimulus on a muscle, there is a point of diminishing returns. This point varies from individual to individual but studies have shown once you go past this point (relative to you), you're not actually going to see any benefit. Instead due to the extra stress and damage placed on the target muscle, you risk inhibiting recovery, and as we know muscle growth occurs not in the gym, but in the 24-72 hours AFTER your session, so by adding in lots of pointless sets you also run a high likelihood of not being recovered in time for your next session. Do this enough and not only will you begin to feel shit, you'll also start to see your lifts/runs/whatever regress and start going backwards aka regression.
Okay, so how much volume is right then?
This varies from person to person. A brand new trainee will see sufficient stimulus (and probably feel it) after just 3-8 working sets on a given muscle per week. Likewise, someone who's 5 years into their training career would likely need double that.
As a VERY general rule of thumb, for new trainees I'd recommend up to 8 working sets per muscle group tapering up with experience to 16-20 for larger muscle groups per week.
There's nothing wrong with high volume supersets etc but they need to be used strategically to maximise muscle stimulus without causing excessive tissue damage. Remember, we train to stimulate - not annihilate!
Thanks for reading
Luke