The guide

Gym words in plain English

What set, rep, RPE, superset, 1RM, deload and other gym words mean, in plain English, for your first weeks of lifting.

4 min read · Updated 20 October 2026

The gym has its own words, used as if everyone knows them. Most are simple once someone says them plainly.

The basics

Rep, short for repetition: one complete movement of an exercise, such as lowering a weight and lifting it back up once.
Set: a group of reps done without resting. "3 sets of 10", often written 3 × 10, means 10 reps, a rest, 10 more, a rest, then 10 more.
Rest: the time between sets. A 2018 review found that for people new to lifting, resting 1 to 2 minutes builds strength about as well as resting longer.
Warm-up: activity before you train, to get ready. A common way, not a rule, is a few minutes of easy movement or a light first set. A review of 32 studies of warm-ups that went beyond stretching found they helped performance in about 4 of every 5 tests, with little sign of harm.
Superset: two exercises done back to back with little or no rest between them. It fits the same work into less time. A 2025 review found long-term results similar to doing the sets the usual way.

How hard a set is

Failure: the point in a set where you can't complete another rep.
RIR, reps in reserve: how many more reps you could have done when you stopped. Stopping at 2 RIR means you had about two left.
RPE, rating of perceived exertion: how hard a set felt. One version used in lifting runs up to 10 and is built to match reps in reserve: RPE 10 means none left, RPE 9 one left, RPE 8 two, and so on.

You don't need to go to failure. In its 2026 guidance, the American College of Sports Medicine (ACSM) found it adds no benefit. It says stopping near failure, about 2 or 3 reps short, is enough effort.

Expect your guesses to be a little off. On average, people think they have about one rep fewer left than they do, however long they've lifted, though guesses get better closer to failure. So you may have a little more left than you think, and stopping a little early is fine.

How heavy

1RM, one-rep max: the heaviest weight you can lift once. Plans often give weights as a percentage of it, such as 80 percent.
RM, repetition maximum: the same idea for more than one rep. If 10 reps is the most you can do with a weight, that weight is your 10RM.
Progressive overload: asking a little more of your muscles over time, with more weight, reps, sets or days a week. U.S. health guidelines and ACSM's 2026 guidance both recommend building up this way.

Kinds of exercise

Compound (multi-joint) exercise: one that moves more than one joint at once, such as a squat (sitting down and standing back up) or a bench press (lying on a bench and pressing a weight up from your chest).
Isolation (single-joint) exercise: one that moves a single joint, such as a leg extension (a seated machine where you straighten your knees) or a curl (bending your elbow to lift a weight).

ACSM's 2009 guidance put compound exercises first in a session, for strength. For muscle growth, its 2026 update found too little data to favor either.

Kinds of equipment

Free weights: weights you hold and control yourself, such as dumbbells (a short handle with a weight at each end) and barbells (a long bar loaded with plates, the flat round weights).
Machines: equipment that guides the weight along a fixed path, so it asks less of your balance and coordination.

Planning your weeks

Health guidelines ask for strength work on all the major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms) at least 2 days a week.

Deload: a planned stretch of lighter training, to let tiredness fade. In a 2022 study, coaches typically ran one for 5 to 7 days every 4 to 6 weeks, with fewer sets or reps and less effort. It's common practice, not a rule.

Around the gym

Working in: sharing a machine or bench by taking turns, doing your set while the other person rests. Wait until they finish a set, then ask, "Mind if I work in?" A towel or bottle on a machine may mean someone is using it, so ask before you take it.

Stay safe

Speak to a doctor first if you have a health condition or haven't exercised for some time, says England's National Health Service (NHS). If you're pregnant, ask your doctor or midwife what's right for you. Otherwise, U.S. guidelines say healthy people who build up gradually generally don't need to see one first. If you haven't been active, they say to start low and go slow. Stop if anything hurts or you feel unwell, and see a doctor about new symptoms such as chest pain or dizziness.

In the app

Train Personal logs a set with one tap, with last time's numbers already filled in, and rest starts by itself. It asks how hard a set was with five effort words, and it tells you when to add weight and says why. Your progress shows as records, your best estimated single lift (an estimated 1RM) and a chart for each exercise. You can choose how much the app explains: full, short or off.