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The method

Accordion Training™

Heavy days close in to a few big lifts. Light days open up to more variety. Weight goes up only when you've earned it.

  • Heavy, moderate, light
  • Earned Load
  • Sets for every muscle
  • Works with no signal
The bellows, folded tight for a heavy day
Movements
6
Reps, big lifts
5–8
Rest, min
2–3
Sets
18–22

Fewer lifts, more sets of each, heavier weight. The session closes in around the big compound lifts.

Week MonChest WedLegs FriBack
Week 1 Moderate Heavy Light
Week 2 Light Moderate Heavy
Week 3 Heavy Light Moderate
Week 4 Lighter week: same days, less weight, fewer sets

The days shift by one each week, so every muscle gets a heavy, a moderate and a light session in each four-week block. The fourth week is lighter, so you recover before the next block starts.

Earned Load

Hit the top of the rep range on every set and the target moves up next time. Fall short and it waits. Weight goes up when your logs say you're ready, not because it's Monday.

Built on what the research says builds muscle: enough hard sets for every muscle, steady progression and planned recovery. bellos gets all three right for you, every week.

The research behind it

  • Enough hard sets for every muscle. More weekly sets per muscle build more muscle, with diminishing returns.Pelland et al., 2024, meta-regression (SportRxiv preprint)
  • Every rep range builds muscle. Muscle grows across a wide range of reps when sets are taken close to failure. Heavier loads build the most strength.Schoenfeld et al., Sports, 2021
  • Heavy, moderate and light days. Rotating rep ranges builds muscle as well as other plans when the sets are equal, so it's a sound way to cover every range.Grgic et al., PeerJ, 2017; Moesgaard et al., Sports Medicine, 2022
  • Planned variety. Changing exercises on a schedule helps different parts of a muscle grow. Random rotation doesn't.Kassiano et al., J Strength Cond Res, 2022
  • A lighter week. Planned deloads every 4 to 8 weeks are the expert consensus.Bell et al., Sports Medicine – Open, 2023

Every set has a reason

Most people stall for simple reasons: too few hard sets for some muscles, weight added at random, and no rest. bellos takes care of all three, so your time at the gym goes to lifting.

Example week · sets per muscle
Chest
10
Back
10
Quads
9
Glutes, hams
11
Target bandThis week

A plan that pays attention

Your next workouts are rebuilt from what you actually lifted.

  • Every muscle gets its share of sets, every week. No lopsided weeks.
  • Heavy, moderate and light days rotate, so you train every rep range without planning it.
  • Machine taken? Swap it in one tap and keep the plan's intent.
Incline Dumbbell Press

Last time at 8–12: 30 lb × 10, 10, 9

lb eachReps
13010
2309
33012

A quiet companion

Today's workout, last time's numbers and a place to type your reps. One tap logs a set.

  • No feed, no badges, no streaks and no pop-ups mid-set.
  • Works with no signal. Every set is saved the moment you tap.
  • A rest timer that counts down and then gets out of the way.
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