If you're unfamiliar with the term, "training to failure" refers to performing as many reps during a set as you possibly can. Only once your body "fails" and you can no longer squeeze out another rep is the set complete.
It's also often referred to as "AMRAP," short for "As Many Reps as Possible."
Leaving a few reps in the tank rather than consistently training to failure is easier, yet leads to better results. While training to failure every now and then can have benefit, it should be used only on occasion as opposed to being your default approach.
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