Fitbod sets your reps, sets and weight from your logged training history, using its proprietary mStrength™ technology to vary intensity and volume between sessions rather than repeating the same prescription. Complete an exercise comfortably and Fitbod gradually increases load or reps; struggle with it and future recommendations ease back. Your Reps in Reserve ratings and Max Effort Day results refine this further.
Table of Contents
Your workout history is the foundation
mStrength™ and why your workouts vary
Estimated Strength and Max Effort Days
Reps in Reserve: telling Fitbod how hard it was
Adjusting a recommendation yourself
Frequently Asked Questions (FAQ)
Key takeaways
- Recommendations come from your logged performance: weight lifted, reps completed and sets performed.
- mStrength™ deliberately varies intensity across workouts, so some sessions favor higher reps at lower weight and others fewer reps at heavier loads.
- Your fitness goal sets the rep ranges: higher reps with lower weight targets hypertrophy, lower reps with heavier weight targets strength.
- Logging Reps in Reserve after a set tells Fitbod how hard it actually was, on a scale from 0 (failure) to 4+ (very easy).
- Max Effort Days appear periodically to reassess your true strength and recalibrate future recommendations.
- New exercises start with deliberately conservative weights.
Your workout history is the foundation
Fitbod tracks the weight, reps and sets you complete for every exercise. That history drives everything else:
- Consistently completing an exercise with ease leads Fitbod to gradually increase weight or reps, applying progressive overload.
- Struggling to complete sets leads Fitbod to adjust future recommendations downward to avoid overtraining.
- If you haven't logged workouts in a while, Fitbod automatically reduces weight suggestions to ease you back in safely.
- Exercises you're doing for the first time start with more conservative weights, since there's no history to draw on.
mStrength™ and why your workouts vary
mStrength™ is Fitbod's proprietary technology for varying intensity and volume across workouts. You won't be given the same reps and sets every day. The prescription changes deliberately from session to session.
In practice, some workouts emphasize higher reps at lower weight, while others push heavier loads for fewer reps. This isn't inconsistency. Varying the stimulus is what prevents plateaus, reduces burnout and injury risk, and supports strength gains over the long term.
This means a lighter-feeling session isn't a sign something's wrong. It's part of the pattern.
Estimated Strength and Max Effort Days
Fitbod calculates an Estimated Strength figure for each exercise, effectively a projected one-rep max, based on your sets, reps and weight over time. It accounts for recent activity, so it can drop if you haven't logged an exercise in a while. For bodyweight exercises, only reps are used; added weight isn't factored in.
To keep that estimate accurate, Fitbod periodically schedules a Max Effort Day for an exercise. These are labeled "MAX EFFORT DAY" in the app, and consist of a few lighter ramp-up sets followed by two AMRAP sets ("as many reps as possible") at your full working weight, marked with "+ reps."
Max Effort Days are generated automatically based on your training history and can't be manually triggered. They also won't appear when you've recently done the same exercise, when an exercise is too new to have enough history, when a similar-muscle exercise already has one in that workout, or for band, superset and circuit exercises. Only one per muscle appears per workout, and Focus Exercises pause them.
You can't disable them entirely, but you can hide them on an exercise-by-exercise basis.
Attempting Max Effort Days when you can is the most effective way to keep Fitbod's picture of your strength accurate.
Reps in Reserve: telling Fitbod how hard it was
Reps in Reserve (RiR) is the number of additional reps you could have completed before reaching failure. Logging it after a set gives Fitbod a direct read on your effort that the numbers alone don't capture:
| RiR | What it means |
| 4+ | Very easy, far from failure: typical of warm-up sets |
| 3 | Moderate effort: endurance and volume training |
| 2 | Challenging but controlled: the usual target for hypertrophy |
| 1 | Near failure: strength-focused training |
| 0 | Complete failure: max effort, not sustainable every set |
Fitbod adjusts weight and reps based on what you log. Consistently reporting a high RiR signals the work is too easy, and Fitbod may increase weight or reps in response. The algorithm gives more weight to your strongest and most recent performances.
You're prompted for RiR after a set. For supersets and circuits, the prompt appears once all sets are complete. You can also log it manually for an individual exercise through the More menu.
RiR applies to strength-based exercises only, not distance or timed movements. One current limitation: Fitbod doesn't yet account for fatigue carried over from preceding movements in a superset when interpreting your rating.
Adjusting a recommendation yourself
You're never locked into what Fitbod suggests:
- If a set feels too easy, increase the weight or reps directly.
- If it's too difficult, reduce them.
Either way, Fitbod learns from the adjustment and refines future recommendations.
Frequently Asked Questions (FAQ)
Should I be training to failure on every set?
No. On the RiR scale, 0 means complete failure, and that level of effort isn't sustainable set after set. Most training sits higher: 2 RiR, challenging but controlled, is the usual target for hypertrophy, and 1 RiR is typical for strength-focused work. Max Effort Days are the exception, where the AMRAP sets are meant to be taken to your limit safely.
Why do I get a Max Effort Day for some exercises and not others?
Several conditions have to line up. Max Effort Days won't appear for an exercise you've done very recently, for one that's too new to have enough history behind it, or for band, superset and circuit exercises. Only one appears per muscle group per workout, so a similar exercise may already have taken the slot, and Focus Exercises pause them entirely.
What happens if I don't log Reps in Reserve?
Fitbod still works from your completed sets, reps and weight, so recommendations continue to adjust without it. RiR simply adds information those numbers can't carry, which is how hard the work actually felt. Two people completing the same set can be at very different levels of effort, and that's the gap RiR closes.
Why the numbers move around
If there's one thing worth taking from this, it's that a recommendation isn't a verdict on what you should be able to lift. It's Fitbod's best reading of your recent training, and it's designed to shift. A lighter day is often deliberate, a heavier one means the history supports it, and a recommendation that feels wrong is worth correcting rather than working around. Adjusting it is how the next one gets better.