The Numbers Worth Logging (and the Ones That Aren't)
Training logs fail in two directions. Most are too sparse to answer any question — a list of exercises with no numbers. A few are so elaborate that filling them in becomes its own task, and they get abandoned inside a month.
The useful middle is narrower than people expect. Three numbers per set, and a couple of things noted weekly.
The three that matter
Weight, sets, reps. That is the irreducible core, and almost every other useful figure is derived from it.
From those three you can compute your tonnage with the Training Volume Calculator, estimate your max from your best set with the 1RM calculator, and check what intensity you were actually working at with the percentage calculator. Three logged numbers, three derived ones, ten seconds a set.
The critical part is honesty about reps. A set recorded as five that was really four and a grind will quietly corrupt every derived figure, and the corruption compounds — a max estimated from an inflated set produces working weights that are too heavy, which produces more inflated sets.
Worth logging weekly
- Bodyweight. Not daily — daily readings swing several hundred grams on water and food alone and invite reacting to noise. A weekly figure taken under consistent conditions is enough to see a trend, and it is what makes a Wilks score meaningful over a bodyweight change.
- Whether it was a deload. One word. Without it, every fourth week reads as a collapse.
- Anything unusual. Illness, a missed session, three hours' sleep, a new gym with different plates. This is the context that explains an anomalous week six months later, when you will not remember.
Worth logging sometimes
Reps in reserve. How many more you could have done. It is the single most informative optional field, because it separates "3 × 5 at 120kg, comfortable" from "3 × 5 at 120kg, barely" — two entries that look identical in a plain log and mean very different things.
Rest between sets. Only when you are deliberately manipulating it. Otherwise it is noise.
Not worth logging
- How the session felt, on a scale. Mood scores drift with everything except training and rarely change a decision.
- Estimated calories burned. Wildly unreliable from any wearable, and irrelevant to whether you are getting stronger.
- Every warm-up set. Log the working sets. Warm-ups are a ladder to them, not data.
- Anything you will not review. The honest test for any field: when did you last make a decision because of it? If the answer is never, delete the field.
Reviewing it
A log you never read is a diary. Monthly is about right — often enough to catch a stall, rare enough that normal week-to-week variation does not look like a trend.
Three questions per review. Is the weight on the main lifts higher than a month ago? Is the weekly tonnage trending up outside deloads? Are the rep counts holding, or have they quietly slipped while the weight went up?
That third one catches the most common self-deception in lifting: adding weight while shedding reps, so the bar looks heavier and the actual work is flat or falling.
The point of any of it
A log is not a record of effort, it is an instrument for making decisions — whether to add weight, whether to deload, whether the last block worked. Every field that does not feed a decision is overhead, and overhead is why logs get abandoned.
Weight, sets, reps, and a weekly bodyweight. Start there. Add a field only when you notice a question you cannot answer.
Paper, spreadsheet, or app
All three work. They fail differently, which is the useful thing to know before choosing.
Paper is fastest to write in and hardest to analyse. A notebook in a gym bag gets filled in reliably because there is no unlocking, loading or tapping between you and the entry. Six months later, computing a weekly tonnage trend from it is tedious enough that nobody does.
A spreadsheet is the opposite: slightly more friction at entry, and it will happily compute anything you want afterwards. If you are going to look at trends across blocks, this is the format that makes it painless.
An app sits in between and adds one real risk: many are built to maximise engagement rather than usefulness, and they encourage logging fields you will never review because more fields look like more value. They also own your data, and export is often worse than promised.
The honest answer is that the format matters far less than whether you actually fill it in. If you have abandoned three apps, use paper. If your notebook has six months of data you have never once reviewed, move to a spreadsheet.
Reviewing across blocks, not just weeks
The monthly review catches stalls. A longer view answers a different and more interesting question: which of the things you tried actually worked?
Once you have a few blocks logged, look back with three comparisons in mind. How much did each main lift move per block, and was one block clearly better than the others? What was different about that block — more frequency, different rep ranges, a different deload rhythm? And was your bodyweight moving during it, because a block run in a surplus and one run in a deficit are not comparable on bar weight alone (the Wilks Calculator is the fairer comparison there).
This is the payoff that makes logging worth the seconds it costs. Nobody can hold four blocks of training in memory accurately, and everyone believes they can — which is why lifters routinely repeat the programme that felt best rather than the one that worked best.
The failure mode at the other end
There is a version of this that goes wrong through excess. Logging bar speed, heart rate variability, sleep stages, subjective readiness, joint-by-joint soreness scores and a session rating out of ten produces a beautiful dataset and, usually, worse training — because the effort goes into measurement rather than into the sets, and because more numbers means more opportunities to find a reason not to train hard today.
A log is instrumentation for a decision. The decisions available to you are: add weight, hold, add reps, deload, or change something structural. If a field has never once changed which of those you chose, it is not instrumentation. It is a hobby attached to your hobby.
Weight, sets, reps. Bodyweight weekly. Deloads marked. Anything genuinely unusual noted. That set answers every question in this article, and it takes less time to maintain than reading it did.