A time-under-load tracker that respects the protocol.

What time under load actually is

TUL is the stopwatch running from the moment the weight leaves the stack until the moment the muscle can no longer move it. In a slow-cadence set — typically 10 seconds concentric, 10 seconds eccentric — TUL replaces reps as the training unit. A 90-second set on a chest press is 90 seconds of continuous force production, not "eight reps."

Why reps lie and TUL doesn't

• Momentum is invisible in a rep count. A 10-rep bench with a bounce and a 10-rep bench with a controlled cadence produce completely different stimuli.
• Range of motion drifts. Reps 8–10 usually get shorter. TUL doesn't reward that.
• Cadence is enforceable. If the app is calling out "up 2… 3… 4…" through your headphones, you can't drift.

What Intensiq tracks per set

• TUL — total seconds under load, to the second.
• Target window — the recommended TUL range per exercise (e.g. 60–90 s for leg press).
• Cadence adherence — how close each rep held the 10/10 tempo.
• Load — auto-progressed only when the previous set finished inside the window, to honest failure.

The evidence for TUL as the training unit

Schoenfeld et al. (Journal of Strength & Conditioning Research, 2015) found matched-effort protocols produced comparable hypertrophy across rep ranges — the constant was total work at sufficient intensity. Burd et al. (PLoS ONE, 2010) showed slow-cadence sets to failure elevated muscle-protein synthesis more than faster tempos at equivalent loads. TUL is how you turn "sufficient intensity" into a number.

Who this is for

HIT practitioners, Body by Science / Heavy Duty trainees, physical therapy patients recovering strength on machines, and anyone who has ever finished a set and honestly not known whether it was hard enough.