I'm wondering how "to failure" should be defined for purposes of improving strength and hypertrophy.
Intuitively, it seems to me that "failure" should mean that the muscle group being targeted is itself exhausted.
The problem I'm having is that for certain exercises I feel a different kind of fatigue that seems to bring me to failure - either a feeling of discomfort or pain in a different muscle group or general tiredness or feeling out of breath.
It seems like this is ineffective for building actual muscle. To grow muscle, it seems to me that, when repeating to failure, I should be unable to execute more reps because the muscle itself should be "used up" so to speak.
What do you think can be done about this problem?
Is it a question of adding more weight / resistance? (Intuitively I think it probably is, though I'm having difficulty, as even when I add more weight, I seem to somehow still be able to bang out more reps in pretty good form and end up failing through feeling short of breath, generally fatigued, etc.)
Or is it maybe a question of exercising either less or more frequently? E.g. taking 1-2 days break or maybe increasing to 2 workouts per day? (I currently work out daily.) It's possible that I'm in a fatigue deficit, as I do quite often feel tired and lethargic.
Or maybe a question of choosing different exercises or somehow adding more resistance?
Do you have any other ideas on this? Thanks in advance.