The operational principles for building strength and hypertrophy via resistance training, independent of life-stage: progressive overload as the universal mechanism, exercise selection/sequencing, training frequency, and how to gauge fatigue/recovery. See Training to Failure & Stimulus-to-Fatigue Ratio for the specific question of how close to failure to train.
"The principle underlying resistance training regardless of whether we're talking about hypertrophy or strength is one of progressive overload." Beyond simply adding weight, overload can come from: lower RIR, more volume/sets, less rest, supersets, time under tension, or slower eccentrics — useful for joints where adding weight isn't advisable. Track a total-load metric (load × reps × sets, adjusted for rest); beginners can raise it 5-10%/week, advanced lifters closer to 1%/week.
Compound lifts (squat, deadlift, press, row) are the foundation of strength/mass and should be prioritized before isolation work, but require neuromuscular control/technical skill to translate strength safely. Supersets work best pairing opposing/unrelated muscles (one rests while the other works) rather than closely related ones (chest/triceps, back/biceps); pre-fatigue supersetting (fatiguing a smaller muscle first, e.g. curls before pull-ups) is a targeted plateau-breaker, not default programming.
Training frequency is flexible — once-weekly per-body-part splits (with correct exercise selection, intensity, and volume) can work as well as 2-3x/week full-body rotations; beginners should favor full-body sessions, more advanced trainees can shift to focused per-body-part sessions. Deload roughly every 8 weeks, plus an annual ~2-week break, though ordinary life interruptions (e.g. vacations) often substitute for a formal deload for recreational lifters.
Willingness to train — specifically reluctance after warming up, not reluctance before arriving — is described as a highly predictive overtraining signal, but only once experienced (low motivation in beginners shouldn't excuse skipping). HRV monitoring (chest/arm strap preferred over wrist) combined with elevated resting heart rate signals fatigue/high sympathetic drive, though it's a weaker predictor for weight-room vs. cardio performance. Motor-unit synchronization is a separate limiting factor from muscle fatigue — full strength gains require recovery time for neurologic adaptation, not just adequate load/volume.
Training to Failure & Stimulus-to-Fatigue Ratio, Strength, Grip Strength & VO2 Max as Mortality Predictors, Training Strategy for Healthspan & Aging, Creatine Supplementation
Simply doing more hard sets is presented (RP Strength's Dr. Mike) as the single most dependable way to cause more growth, and doing fewer sets the most dependable way to grow less — provided sets are taken reasonably hard. Notably, sets of 5 reps produce equivalent long-term hypertrophy to sets of 10–30 reps despite producing a much smaller pump, showing that pump magnitude and volume-driven growth outcome can diverge sharply. Switching to a novel exercise or rep range also produces both a bigger pump and more short-term growth, relevant to exercise rotation/periodization choices.