The Short Answer
Training to failure means reaching the point where you cannot complete another repetition with acceptable technique.
You do not need to reach failure on every set.
Reps in Reserve
If you finish a set and believe you could have performed two more good repetitions, you had approximately two reps in reserve.
Failure Can be Useful
Training close to failure can provide a strong stimulus.
But constantly pushing every set to absolute failure can create unnecessary fatigue.
For Beginners
Focus first on:
- Technique
- Consistency
- Controlled repetitions
- Appropriate resistance
- Gradual progression