Intensity & proximity to failure

Why leaving too many reps in reserve wastes work, how to track RIR, and why mechanical tension drives growth.

1 min read

Written & reviewed by Ricardo Tapia·Last updated June 16, 2026

Leaving 3–5 reps in reserve is mostly wasted work. Beginners think they're closer to failure than they are.

Push every set — give it a reason to count.
Mechanical tension is the #1 driver of muscle growth: train heavy with good form.
Track RIR (reps in reserve): RIR 2 means you could do ~2 more.

New terms? The glossary defines RIR, failure and mechanical tension.

Sources & references

Schoenfeld BJ, et al. Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. J Strength Cond Res. 2017;31(12):3508-3523.

Educational content only. Not medical advice — consult a professional for your situation.