How Orion Coach coaches

The principles

Recovery comes first, effort is measured in reps in reserve, progress happens one small step at a time, and the program sets the ceiling on volume. Day to day, Orion makes a session lighter than the program, not bigger, with one narrow exception for beginners who clearly had reps to spare (plus a set-count reset when you graduate to a new exercise).

Recovery beats intensity. Training creates fatigue, and you adapt while you recover, not while you lift. Before each session Orion reads your recovery data and how sore each muscle got, and eases the session off when those say you have not recovered.

There is a productive range of weekly volume for each muscle. Too few hard sets and the muscle does not grow. Too many and you cannot recover by the next session. Programs are written to sit inside that range and build across a block. See weekly volume.

The program sets the ceiling. How many sets each exercise gets each week is decided when your program is built, from a coach-reviewed library, not invented on the fly. During the block Orion trims volume when you are under-recovered or short on time, but it does not add sets because you feel great or barely got sore. On a good day you progress the normal way, with more reps or more weight. The one narrow exception is for beginners who clearly had reps to spare.

Leave reps in the tank. Most working sets stop about 2 reps short of failure. Grinding every set to failure costs recovery for little extra growth, and it makes the data noisy. See reps in reserve.

Small steps, every session. Orion looks at what you actually did on each set (the weight, the reps, the RIR you reported) and changes one thing by one step. Many small, correct adjustments beat occasional big jumps. See progression.

Numbers come from rules, not from a chatbot. In your program sessions, a deterministic engine decides your sets, reps, weights, RIR targets, warm-ups and trims. An AI model writes only the short explanation you read, and the session still loads if that call fails. (Off-program Quick Sessions and swap suggestions are picked by AI.)

Weekly volume: MEV, MAV and MRV

Each muscle has a range of weekly hard sets that grows it without outrunning recovery. Orion's programs start each muscle near the bottom of that range and build toward the top across a block, and the session engine trims below what the program prescribes rather than adding to it.

Volume here means hard working sets per muscle per week. Research on weekly volume finds that, within limits, more weekly sets tend to produce more growth (Schoenfeld, Ogborn and Krieger, 2017). Coaches describe the useful range with three landmarks:

• MEV, minimum effective volume: the fewest weekly sets that still grow the muscle.
• MAV, maximum adaptive volume: the range where most people grow best.
• MRV, maximum recoverable volume: the most you can do and still recover. Past it, fatigue outruns adaptation. It varies a lot from person to person.

These are the reference bands, in working sets per week, that Orion's programs are written against. They are population estimates, not personal prescriptions.

How a program uses them

• Hypertrophy programs start each muscle near the low end in week 1 and build toward the high end across the block, without going past it. Strength programs start the main lifts at 2 or 3 sets, and many build to 4 or 5 by the peak week.
• Every exercise stores its own set count for each week, so the plan for week 4 is fixed before week 1 starts. In longer blocks, weeks past the written ramp repeat the peak week.
• Guard rails apply to every session: at most 5 sets of any compound lift and 8 of any isolation exercise.

Runtime only reduces

When Orion builds the session on the day, it can make it lighter than the program, not bigger. Recovery, soreness and fatigue signals can take sets away or add reps in reserve. A time budget (30, 45 or 60 minutes) trims isolation and accessory work first, keeps most of your main lift, and never touches weights or reps. The one narrow exception: a beginner whose last session on a lift was far too easy (averaging more than 1.5 reps more in reserve than asked) gets one extra set on it. The other edge case is the first session after graduating to a new exercise (see the dumbbell ceiling), where the set count resets to that exercise's base prescription.

Effort: reps in reserve (RIR)

Orion prescribes how hard each set should be as reps in reserve: mostly RIR 2, some RIR 3, a few RIR 1. It never prescribes RIR 0 (training to failure) as a target.

Reps in reserve (RIR) is how many more clean reps you could have done when you ended the set. RIR 2 means you stopped with about two left. RIR 0 means you could not have done another rep, which is training to failure. The scale was validated for resistance training by Zourdos and colleagues (2016), and Helms and colleagues (2016) describe how to use it to set and adjust loads. RPE, the 1 to 10 exertion scale, maps onto it roughly as RPE = 10 minus RIR. Orion asks for RIR.

• Most working sets in the program library target RIR 2. Some target RIR 3, and a few RIR 1.
• Orion never prescribes RIR 0 as a target. Going to failure is something a lifter can choose, not something Orion programs. A meta-analysis of 15 studies found no evidence that training to momentary failure builds more muscle than stopping short of it (Refalo and colleagues, 2023).
• You log RIR on each set (0, 1, 2, 3, or 4 and up). That number drives the next set. It is the main feedback signal in the whole system.
• Warm-up sets, on the first loaded lift only, sit at RIR 5.

Progression: double progression, one step at a time

Orion adds reps at the same weight until you reach the top of your rep range at the target effort, then adds one weight step and resets to the bottom of the range. Every change is one step, however easy the set felt.

Each set has a target weight and a target rep count inside a rep range. This is double progression: reps go up first, then weight. A training study found that adding reps and adding load both produced similar muscle growth over 8 weeks (Plotkin and colleagues, 2022), which is why the rep climb counts as real progress even when the weight does not move.

What happens after each set

One weight step is 5 lb per hand on dumbbells, 5 lb on a barbell (2.5 lb if you own microplates, and only weights your plates can actually make), and 10 lb on a pulley. Orion never progresses by a percentage.

Beginners get one rep target instead of a range, and the weight goes up only when they finish within a rep of the target with at least 2 more reps in reserve than asked.

If you choose to go heavier than prescribed and still hit your target RIR, Orion keeps your heavier weight instead of cutting you back.

The dumbbell ceiling: graduating to a harder exercise

When the next weight step would pass your heaviest dumbbell, Orion keeps the weight and adds reps, up to 3 past the top of the range. Then it moves you to a harder dumbbell exercise for the same muscle, so the weight you own is heavy again.

Home gyms have a load ceiling, usually your heaviest pair of dumbbells (50 lb per hand by default). Once the next weight step would take you past it, Orion keeps the weight and pushes reps higher instead, up to 3 past the top of your rep range. Lighter loads taken close to failure still build muscle about as well as heavy ones (Schoenfeld, Grgic, Ogborn and Krieger, 2017), though heavier loads build more maximal strength. That is why the rep climb is useful work, and why Orion then moves you to a harder exercise.

When you graduate

• Fast: one session at your ceiling averaging 3 or more reps past the top of the range, with RIR logged on every set, averaging at least 1.5 more reps in reserve than asked.
• Slow: three sessions in a row at your ceiling averaging 3 or more reps past the top of the range.

Then you move to the next harder dumbbell exercise for the same muscle, for example goblet squat to reverse lunge or split squat, and later to Bulgarian split squat. The new exercise usually starts lighter, back at the bottom of its rep range. For that first session its set count resets to the exercise's base prescription, which can sit a set above or below that week's program number.

Barbell main lifts work differently. When you have run out of plates to add, late in a block, and you have hit the top of the range at the target effort for 2 straight sessions, the lift steps up to a harder version: pin squat, deficit deadlift, pin press, seated overhead press or Pendlay row. That step is not used for beginners.

Autoregulation: adjusting to the day

Orion adjusts training to how you are actually doing, using four inputs: the reps and RIR you log on each set, per-muscle soreness check-ins, whole-body recovery data, and multi-week fatigue signals. Any of them can make training lighter. None of them adds sets beyond the program, apart from one narrow exception for beginners who clearly had reps to spare.

Autoregulation means adjusting training to how you are actually performing and recovering instead of following fixed numbers no matter what. Orion has four layers of it, each covered below:

1. Set by set: the RIR you log moves the next set by one step. Progression.
2. Muscle by muscle: soreness check-ins can ease a sore muscle off. Soreness.
3. Day by day: recovery data adjusts the whole session. Recovery.
4. Week by week: fatigue signals trigger an early deload. Deloads.

Soreness check-ins

Soreness never adds sets. Minimal and moderate soreness hold your program as written; high soreness eases that muscle off, and high soreness on two or more muscles in a week counts toward a deload.

After a session, Orion asks how each trained muscle feels, with three answers that run from barely sore, through pretty sore (sore for a day or so, fine by next time), to super sore. The reminder arrives 24 to 36 hours after you train, during daytime hours, and you can also answer in the app.

• Soreness never adds sets. Soreness is a poor gauge of how well a session worked (Schoenfeld and Contreras, 2013), so feeling fresh is not treated as a sign you need more.
• Super sore on 2 or more different muscles in a week counts as one of the deload signals.
• Soreness is per muscle and uses your most recent check-in for that muscle. Check-ins from the first time you do a given workout day are ignored, because brand-new movements make almost anyone sore.
• If you turn check-ins off, nothing is adjusted on a signal Orion does not have.

Recovery data: HRV, resting heart rate, sleep and Body Battery

Before each session Orion reads HRV, resting heart rate and sleep from Apple Health automatically (or the Garmin Body Battery and HRV you type in) and sorts the day into recovered, a little off, or clearly off. Off days get more reps in reserve and fewer sets for the whole session; the recovery check never changes the weights.

Recovery data comes from Apple Health, automatically (HRV, resting heart rate and sleep, with your permission), or from Garmin numbers you type in (Body Battery and HRV) before a workout. There is no automatic Garmin sync. Every comparison is against your own averages, not population norms, which is the approach HRV researchers recommend (Plews and colleagues, 2013, in endurance athletes). This is a whole-body call, not targeted at particular muscles.

Warning signs

• Resting heart rate 5 or more beats above your 7-day average
• HRV more than 10% below your 7-day average
• Under 6 hours of sleep, or deep sleep under 70% of your average (as your watch estimates it)
• Body Battery under 30
• An energy check-in of Low

• The recovery check never changes your weights. Nothing is cut, and a planned weight increase still goes ahead. It adds room before failure, takes sets off and pauses the rep climb, and a good day does not add anything. If a set then comes in 2 or more reps harder than the raised target, the normal set-by-set rule still applies.
• Average-based signs need at least 5 days of your data before they can fire (the 30-day trend check below needs 14).
• If you trained in the last 36 hours, the HRV thresholds widen to 15% and 25%, because a dip the day after lifting is normal. After 5 pm, the Body Battery thresholds drop to 20 and 10, because it drains through the day.
• If your 7-day HRV average sits under 92% of your 30-day average, every set gets one more rep in reserve on top. Extra reserve is capped at 3 reps.

Blocks (mesocycles)

Programs run in blocks of 4, 6, 8 or 12 weeks (6 by default). Volume builds across the block, and blocks longer than 4 weeks end with a planned deload week by default.

A mesocycle, or block, is a run of weeks with a planned build. In Orion your program sets how sets build week to week, usually adding sets over the first weeks and, when the block has one, pulling them back for the deload week at the end. Programs come in 3 to 6 days a week, for strength, hypertrophy or both, at beginner, intermediate or advanced level, fitted to the equipment you own.

When the next block starts, your starting weights anchor on your last real working weights from the prior block, not on the deload week.

Deloads

A deload is a lighter recovery week: fewer sets, the same weights, every working set at RIR 3. Besides the planned one at the end of each block, Orion applies one automatically when 2 of 3 fatigue signals show up, cutting sets by about 40% from the program's base count; you can skip it.

A deload clears accumulated fatigue. Weights stay at your current working weights, reps stay at the program's targets, and every working set targets RIR 3. Evidence on deloads is still thin. In one trial, trained lifters who took a full week off in the middle of a 9-week program grew about the same in the lower body as those who kept training, but gained less lower-body strength (Coleman and colleagues, 2024). An Orion deload keeps you training at lower volume rather than stopping, and it is there to manage fatigue, not as a promise of extra gains.

Planned deloads

Blocks longer than 4 weeks end with a deload week by default (you can switch it off when you set up the program, and a 4-week block has none unless you add it). Its set counts are written into the program, usually a third to a half fewer sets than your heaviest week, and never under 2 sets per exercise.

Early deloads, applied automatically

Orion applies an early deload when at least 2 of these 3 are true:

1. Sets are harder than asked. Over the past 7 days you averaged at least 1 rep less in reserve than the target, across at least 5 logged sets.
2. Strength has stalled. On at least 2 of your 3 most recent main lifts, this week's average estimated one-rep max is no higher than the past two weeks' average.
3. Soreness is stacking. Super sore on 2 or more different muscles in the past 7 days.

• It sets every exercise to about 60% of its base programmed set count (never under 2), which is usually 40% or more below your current week, for a full week, at RIR 3 with weights held. The program calendar pauses for that week, so you do not lose a week of the block.
• With soreness check-ins off, only the first two signals exist, so both must be true.
• It is applied, not suggested. You can skip it from the banner on its first day, and then no other early deload is called for 28 days.
• It is never called in the first 14 days of a program or before you have completed 2 sessions, in or the week before a planned deload, within 14 days of finishing a deload, or within 28 days of the last one Orion called. That keeps early deloads to at most one every 4 weeks.

Coming back after a break

Up to 14 days off, your weights carry over. From 15 to 59 days off, you restart at 85% of your last working weights. After 60 days or more, you restart from your program's starting weights.

Strength fades when you stop training, and the loss grows the longer you are away (Bosquet and colleagues, 2013). Orion's three tiers are a coaching rule built on that, not numbers taken from a single study.

The gap is measured from your last training session anywhere in the app, not per exercise, and the rule applies both when a new block starts and after a gap in the middle of one. Starting a little under the line is deliberate. The normal progression rules bring you back up quickly.

Starting weights and calibration

Starting weights come from your program's experience level, or from your own records on a lift if you logged it in the last 90 days, capped at what your equipment allows. After that, what you log decides.

Your program's starting weights are written for your experience level, so a beginner program starts lighter than an advanced one on the same lift. If you logged an exercise in the last 90 days, Orion anchors to an estimate from that record instead. Everything is capped at what your gear allows: if your heaviest dumbbell is lighter than a lift calls for, the reps go up instead (and if the gap is large, the set may move a rep closer to failure or switch to a single-leg version). With a barbell but no history on a lift, the starting load is estimated from what you lift with dumbbells.

At signup Orion asks for your goal, experience, body weight, the equipment you own (including your heaviest dumbbell), how many pull-ups and dips you can do, and any injuries. Log RIR on every set from the first session, because from then on your real sets decide.

What Orion does not do

Orion does not program training to failure, add sets because you feel great, cut your weights on a rough recovery day, sync with Garmin automatically, or give medical advice.

• It does not program training to failure.
• It does not add sets on a good day or when you barely got sore.
• It does not cut your weights because of a rough recovery day.
• It does not tell you to skip a session or take a rest day.
• It does not change your training because of body weight or body-fat trends. Those are for you and the Coach chat to discuss.
• It does not sync with Garmin automatically, read live heart rate from a watch, or show a readiness score.
• It does not program kettlebells, cable machines or tempo protocols.
• It does not give medical or rehab advice. If something hurts in a way that worries you, see a doctor.

Glossary

RIR (reps in reserve)

How many more clean reps you could have done when you ended a set. RIR 2 means you stopped with about two reps left; RIR 0 means you could not do another. How Orion uses it

RPE (rating of perceived exertion)

A 1 to 10 effort scale. On the reps-in-reserve version, RPE 8 is roughly RIR 2. Orion asks for RIR, not RPE. How Orion uses it

Training to failure

Ending a set because you cannot complete another rep with good form (RIR 0). Orion never prescribes it. How Orion uses it

MEV (minimum effective volume)

The fewest weekly hard sets for a muscle that still make it grow. How Orion uses it

MAV (maximum adaptive volume)

The range of weekly hard sets where a muscle grows best for most people. Orion's programs build toward it and stay at or under its upper end. How Orion uses it

MRV (maximum recoverable volume)

The most weekly hard sets you can do and still recover from week to week. Past it, fatigue outruns adaptation. It varies a lot between people. How Orion uses it

Double progression

Progressing first by reps at a fixed weight, then by weight once you reach the top of the rep range, with reps reset to the bottom. How Orion uses it

Progressive overload

Gradually asking more of a muscle over time: more reps, more weight, or a harder exercise. How Orion uses it

Autoregulation

Adjusting the training you do to how you are performing and recovering, rather than following fixed numbers no matter what. How Orion uses it

DOMS (delayed onset muscle soreness)

Muscle soreness that peaks a day or two after training, especially after new or unaccustomed exercises. How Orion uses it

HRV (heart rate variability)

The variation in time between heartbeats. Compared with your own recent average, a clear drop can be a sign you have not recovered. How Orion uses it

Body Battery

Garmin's 0 to 100 estimate of your energy reserves. Orion uses it only if you type it in before a workout. How Orion uses it

Mesocycle (block)

A training block of several weeks with a planned build in volume, usually ending with a deload. How Orion uses it

Deload

A lighter week, planned or triggered by fatigue signals, that lets accumulated fatigue clear. How Orion uses it

Estimated one-rep max (e1RM)

The most you could likely lift once, estimated from a set of several reps. Orion uses the Epley formula up to 10 reps and Brzycki above 10. How Orion uses it

Sources

The research behind the principles. The specific thresholds on this page (the RIR targets, recovery cutoffs, deload signals and break tiers) are Orion's coaching rules, informed by this work, not numbers copied from any one study.

1. Zourdos MC, Klemp A, Dolan C, Quiles JM, et al. (2016). Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research, 30(1), 267 to 275. Used for: The reps-in-reserve effort scale.
2. Helms ER, Cronin J, Storey A, Zourdos MC (2016). Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal, 38(4), 42 to 49. Used for: Using RIR to set and adjust training loads.
3. Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ (2023). Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: a systematic review with meta-analysis. Sports Medicine, 53(3), 649 to 665. Used for: No evidence that training to momentary failure builds more muscle than stopping short.
4. Schoenfeld BJ, Ogborn D, Krieger JW (2017). Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis. Journal of Sports Sciences, 35(11), 1073 to 1082. Used for: More weekly sets per muscle tend to produce more growth.
5. Plotkin D, Coleman M, Van Every D, Maldonado J, et al. (2022). Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. PeerJ, 10, e14142. Used for: Adding reps and adding load both work as progression.
6. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis. Journal of Strength and Conditioning Research, 31(12), 3508 to 3523. Used for: Higher-rep, lighter-load sets still build muscle (the dumbbell ceiling).
7. Schoenfeld BJ, Contreras B (2013). Is postexercise muscle soreness a valid indicator of muscular adaptations?. Strength and Conditioning Journal, 35(5), 16 to 21. Used for: Soreness is a poor measure of how well a session worked.
8. Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M (2013). Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring. Sports Medicine, 43(9), 773 to 781. Used for: Reading HRV against your own rolling baseline.
9. Coleman M, Burke R, Augustin F, Piñero A, et al. (2024). Gaining more from doing less? The effects of a one-week deload period during supervised resistance training on muscular adaptations. PeerJ, 12, e16777. Used for: What a full week off training does and does not cost.
10. Bosquet L, Berryman N, Dupuy O, Mekary S, et al. (2013). Effect of training cessation on muscular performance: a meta-analysis. Scandinavian Journal of Medicine and Science in Sports, 23(3), e140 to e149. Used for: Strength loss after a break grows with the length of the break.

About Coach Orion

Coach Orion is the coach inside the Orion Coach iPhone app, the set of rules described on this page. It is not a person. Articles bylined “Coach Orion” explain what the app actually does in a situation and why, and every rule they state is checked against the app's code before it is published. Articles bylined “Orion Coach team” are written by the people who build the app.

Orion Coach is made by Empire Grove LLC. When a rule changes in the app, this page changes with it; the date at the top is the last update. This is general fitness information, not medical advice.