01Overload is not only weight

Progressive overload is exposing the muscle to a mechanical stimulus that progressively exceeds what it already tolerates. Wackerhage et al. (2023) established mechanical tension as the primary stimulus for hypertrophy. There is more than one way to produce it.

Plotkin et al. (2022) split 43 trained subjects into two groups for eight weeks: one progressed load, the other progressed repetitions at the same weight. There were no significant differences in hypertrophy. What mattered was that the total stimulus grew over time, not which variable went up.

Lever	How it moves	When to lean on it
Load	More kilos at the same repetitions	Beginners, where the nervous system still has room
Repetitions	More reps at the same weight	Intermediates: equivalent to load for hypertrophy (Plotkin, 2022)
Proximity to failure	Fewer repetitions left in reserve	When load and reps are stuck: 1–2 RIR is enough (Refalo, 2024)
Volume	More weekly sets per muscle group	Dose-response with diminishing returns past the individual threshold (Pelland, 2026)
Range of motion	More travel, especially in lengthened positions	Advanced: the human evidence is still maturing

If the only metric you record is the weight lifted, four of the five levers stay invisible to you. The client who did 3×8 at 80 kg last week and 3×10 at 80 kg today progressed.

02Effort is prescribed too: RIR

RIR is the repetitions you had left when the set ended. Zero RIR is absolute failure. Helms et al. (2016) formalised its equivalence with RPE, and prescribing proximity to failure turns a vague “go heavy” into something concrete and repeatable.

Refalo et al. (2023), in a systematic review with meta-analysis, found that training closer to failure offers at best a small advantage for hypertrophy. Their eight-week trial (2024) showed it in practice: leaving one or two repetitions in reserve produced the same muscle mass as taking every set to failure, with less accumulated fatigue.

Estimating it is a trainable skill. Steele et al. (2017) analysed 141 people and almost all of them underestimated their failure point: experienced lifters were off by 1 or 2 repetitions, beginners by 4 or 5. Recording weight, repetitions and RIR set by set is what closes that gap.

RPE	RIR	What it feels like
10	0	Not one more repetition would go
9	1	One was left
8	2	Two were left; the bar is already slowing down
7	3	Three were left; speed is still high
6 or less	4 or more	Technique work or a deload week

Failure has a cost: more fatigue, longer rests, and technique that frays on the last repetitions. If growth is nearly identical, paying that on every set is rarely worth it.

03The deload: when and how much

A client's form on any given day is their fitness minus the fatigue they are carrying. After several hard weeks fatigue hides the progress: the weights feel heavier, technique frays, motivation drops. A deload lets the fatigue fall while most of the adaptation stays.

The fear of losing muscle does not hold up. Coleman et al. (2024) followed 39 people for nine weeks: one group slotted a deload week into the middle, the other trained straight through. There were no appreciable differences in muscle growth, power or local endurance. A slight disadvantage did show up in some maximal-strength measures on the way back. The deload is the tool for when fatigue justifies it, not a pause everybody owes the calendar.

Signals to bring it forward

Performance stalls or drops on lifts that had been going up.
Joint niggles that never quite clear between sessions.
Worse sleep, more irritability or no drive for several days in a row.
Technique degrades on sets they used to control well.

How much to cut: volume is the main lever. Half the sets and a couple of repetitions less per set, leaving two to three in reserve. Intensity can stay fairly high. Keeping the frequency preserves technique and habit: same days, shorter sessions, each one ending with the feeling that they could have done a good deal more. One every five or six weeks is the reasonable average, or sooner if the signals arrive first.

04A six-week block, lever by lever

The order worth moving the levers in when you do not know which one to move. One per week, and measurable.

Week	Volume	Target effort	What you record
1	Block baseline	3 RIR	Weight, repetitions and RIR for every set
2	Baseline	2 RIR	Same table: first comparison against week 1
3	+1 set on the main lifts	2 RIR	If the weight does not go up, the repetitions should
4	Same as week 3	1–2 RIR	Proximity to failure as the lever, load untouched
5	Same as week 3	1 RIR	Peak of the block: this is where fatigue signals show up
6	Half the sets	2–3 RIR	Deload: same frequency, short sessions

05The weekly review, in ten minutes

For each client, look at the last session of every main lift: the weight went up, the repetitions went up, or the RIR came down.
Mark who progressed on repetitions. It is real progress and it does not show if you only look at kilos.
Note who has gone two weeks without moving any of the five levers.
Go over the fatigue signals before you program next week.
If you are going to raise something, raise a single lever and keep it measurable.

Where this handbook comes from

It is the distillate of three posts on the Kaizer blog. If you want the long version of any of the three parts, they are here:

The progression handbook for coaches