A time-under-load tracker for slow strength sets.
Time under load (TUL), also called time under tension (TUT), is how many seconds a muscle works against resistance in a set. Intense Fit times each set, calls out a steady cadence, and logs the seconds next to your load and reps.
What time under load is
TUL runs from the moment the weight leaves the stack until the set ends. At a slow cadence — for example about ten seconds up and ten down — a set of a few reps can last a minute or more. That makes seconds a useful number to log alongside reps.
TUL is one number, not the whole story
Seconds alone do not tell you whether a set built strength or muscle. Read them together with the load, the cadence and range of motion you kept, and how close to your limit you trained. A long set with a light weight and a short set with a heavy weight are different stimuli. That is why Intense Fit logs all of them together. For more, read our honest guide to time under tension.
What Intense Fit tracks per set
- Time under load — a set timer, to the second.
- Cadence cues — spoken counts and beeps to help you hold a slow, steady tempo.
- Load and reps — compared with your last session of the same exercise. Reps can be entered by hand.
- Optional camera estimates — with the camera on, the app tries to estimate reps and cadence. They are estimates; without the camera, reps are marked "not captured".
- Next-load suggestion — based on your logged load and time under load. You decide the weight.
The app does not detect muscular failure and does not guarantee strength or muscle gain. It is not medical or rehabilitation advice.
Common questions
How is this different from a HIIT timer or a general gym log?
A HIIT timer counts work and rest intervals for conditioning. A general log records sets and reps. A TUL tracker times each strength set and keeps those seconds with the load and reps, which matters most when you train with a slow cadence and few sets.
Which training styles is it for?
Slow-cadence, one-set-per-exercise training, such as Body by Science-style sessions or Heavy Duty-style training. Intense Fit is independent and not affiliated with either.
Where can I use it?
In your phone's browser at intensefit.co/app. A native Android app is in closed beta: request Android beta access.
Learn more
The tracker is free. A typical session in this protocol takes around twelve minutes.
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