Glossary
Plain-English definitions of the training terms used across the knowledge base — RIR, ROM, TUT, volume, frequency and more.
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Written & reviewed by Ricardo Tapia·Last updated
| Term | Meaning |
|---|---|
| RIR | Reps in reserve — reps left before failure |
| Failure | No more reps possible with good form |
| ROM | Range of motion |
| TUT | Time under tension (~20–40 s/set) |
| Volume | Total weekly sets per muscle (10–20) |
| Frequency | Times you train a muscle per week (2× optimal) |
| Mechanical tension | The main driver of muscle growth |
| Eccentric | The lowering phase (~3 s) |
Educational content only. Not medical advice — consult a professional for your situation.