A coach prescribes a tempo block. “1010” — one second concentric, no hold at the top, one second eccentric, no pause at the bottom. Four weeks in, the lifter still feels strong, the weights are creeping up, and the tempo is… whatever feels normal that day.
You can’t hold yourself accountable to a tempo if you can’t see it.
What tempo actually is
Tempo is the duration profile of a rep, broken into four numbers:
- Concentric duration — the seconds spent lifting the load.
- Eccentric duration — the seconds spent lowering it.
- Hold duration — the seconds at the top of the rep where force stays near peak.
- Tempo ratio (C:E) — concentric duration divided by eccentric duration. Often written as “1:1” or “1:3.”
Together these form the tempo signature of a rep. The signature stays consistent across a clean set; it drifts when fatigue arrives or form breaks down. A movement done at a 1:3 tempo has a fundamentally different signature from the same movement at a 1:1, even when load and rep count are identical.
Why it matters
The eccentric is where most of the tension lives. A 1:1-tempo set of 10 reps takes about 20 seconds and accumulates a known dose. The same 10 reps at a 1:3 tempo take about 40 — twice the time-under-tension, on the same load. This is not the same workout twice. It is two different doses.
Lifters have been freestyling this dimension for decades because nothing measured it. You’d write “3×10 RPE 8” in a log and run the set at the tempo your nervous system felt like producing that day. On any single session that’s defensible. Across a four-week block it isn’t — the tempo discipline you assumed you were applying was almost certainly drifting toward “whatever feels heavy enough.”
Once tempo is on a screen, two things change. First, the prescription closes: a “2:4 tempo” block becomes a number you either hit or miss, set by set. Second, the lifter starts to notice which part of the rep is dropping. Concentric usually goes first under fatigue; eccentric collapses last. The order tells you something about the limit you’re up against.
What to track together
Don’t watch one tempo number in isolation. Track the four as a single signature.
| Metric | What it tells you |
|---|---|
| Concentric duration | Whether you rushed the lift. Often the first to drop under fatigue. |
| Eccentric duration | Where most tension lives. The most adjustable lever for hypertrophy. |
| Hold duration | Whether you actually paused at the top. Brief but stimulus-shifting. |
| Tempo ratio (C:E) | The compact prescription target. “1:3” describes a stimulus quality. |
The interesting moments are when one number drifts and the others don’t. Eccentric crashing while concentric stays flat usually means form is breaking before strength is. Concentric ballooning while eccentric stays at target usually means you’re grinding through a sticking point that wasn’t there earlier in the set.
What gear it needs
Tempo metrics want 80 Hz. On a Tindeq Progressor or a C100 with the high-rate firmware retrofit, they’re honest to within tens of milliseconds — fine resolution for a 2-second eccentric.
On an 8 Hz crane scale (the WH-C06), tempo is computable but the resolution is 125 ms per sample. For a 1:1 lifter that’s enough; for someone trying to hold a 5-second slow eccentric within 200 ms of target, it isn’t. tensr surfaces the metric on low-rate sensors with a warning flag rather than hiding it — the number is still useful for set-level averages, just not for live per-rep coaching.
If tempo discipline is the reason you bought the sensor, this is one of the metrics worth paying for the higher sample rate.
What to do tomorrow
Pick one movement you do at least twice a week. Prescribe a 2:4 tempo for the next session — two seconds concentric, four seconds eccentric. Run a working set without watching the screen. Then look at the on-tempo rep percentage.
It will be lower than you think. It always is. That gap — between the tempo you assumed you were running and the tempo you actually ran — is the work the prescription was supposed to do.
Don’t try to fix it in one session. The next post (effective reps) is about the part of the set that actually matters; the post after that (decay) is about where the set should end. Tempo is the dial that connects them.
The eccentric is the lever. Pull it deliberately and the number moves.