Gym basics: sets, reps, equipment and what to write down

A rep (repetition) is one lift of the weight. A set is a group of reps done back to back, then a rest. Machines or free weights (barbells and dumbbells)? In head-to-head studies, neither came out clearly ahead for strength.^[1] What to write down: the exercise, the weight and the reps for every set.

The answer isn't obvious because gyms are loud about it. Free weights are "real" training, machines are for beginners, and logging is for people with spreadsheets. The studies are quieter than the gym floor.

Each finding below carries a confidence label, so you know how sure to be. How to read a fitness claim explains the scale.

Why it matters

Programs are written in this language. "3 × 8–12" means 3 sets of 8 to 12 reps each. If you can't read it, you can't follow it, and you end up guessing on day one.

The written record matters at least as much as the equipment. Making progress in lifting is a loop: plan the session, train, check how it went, then adjust the next one.^[2] You can't check how it went if you don't know what you did. Memory works until you're standing at the rack, trying to recall whether last Tuesday was 40 kg or 45.

The first article in this path covered what actually matters when you start lifting. Showing up and doing a little more over time sat near the top. Both depend on the basics here.

What the research says

Four terms first. Resistance training means making your muscles work against a load, such as weights, machines, bands or your own body weight. A position stand is an official summary of the evidence written by a panel of experts. Here, that's the American College of Sports Medicine (ACSM). A systematic review collects every study it can find on one question, using set rules. A meta-analysis pools the results of many studies on the same question into one estimate.

Lifting works, in many forms

The ACSM's 2026 position stand brought together 137 systematic reviews with more than 30,000 people. Compared with not exercising, resistance training improved strength, muscle size, power and endurance.^[3] Strong evidence. The stand also found that many kinds of training work, including training at home and training with elastic bands.^[3]

Much of that evidence comes from people who were new to training.^[3] If you're just starting, that's you. The studies were in healthy adults and lasted 6 to 52 weeks.^[3]

The stand's main advice for healthy adults: lift with real effort at least twice a week, and work all the major muscle groups.^[3] Expert consensus: this is the panel's advice, drawn from the reviews. How to fit that into a week is the topic of choosing your first program.

How sets, reps and weight fit together

A workout comes down to a few choices. Which exercises, in what order, how many sets and reps, how heavy, and how long to rest between sets.^[2] Progress means changing those choices over time and checking how it's going.^[2] This comes from a 2004 expert review, not from a trial. Expert consensus.

Weight and reps trade off. The heavier the weight, the fewer reps you can do with it.^[3] So coaches describe a weight in two ways. A rep max is the most reps you can do with a weight. If you can lift it 10 times and not 11, it's your 10-rep max. Your one-rep max (1RM) is the heaviest weight you can lift once. A weight can also be written as a share of that, such as 70% of your 1RM.^[3]

How many sets? One set beat no sets, and two sets beat one, so the ACSM advises at least two sets per exercise.^[3] More sets may add a bit more. The authors expect each extra set to add less than the one before, but that part is their hypothesis.^[3] Expert consensus.

How hard? A set doesn't have to end at failure, the point where you can't complete another rep. Taking sets to failure didn't add strength or muscle, so it isn't needed.^[3] Moderate evidence. The ACSM says stopping near failure is enough, for example with 2–3 reps in reserve (RIR): reps you could still have done.^[3] It also says the evidence can't yet pin down an exact target.^[3] This is coaching practice, not a tested finding. There's more in how hard a set should be.

Free weights or machines: no clear difference

Free weights are weights you hold and move freely: barbells, dumbbells and kettlebells. Machines guide the weight along a fixed path. Think of a leg press or a chest press.

For strength, that's moderate evidence. For muscle size it's limited evidence. Only 5 of the studies measured size, and mostly in indirect ways such as tape measurements and skinfolds.^[1]

The authors concluded that the choice comes down to what you prefer and what you want to get better at.^[1] The ACSM's 2026 stand also found that equipment type didn't change strength gains, and said there wasn't enough data to judge muscle size.^[3] But it based that on this same meta-analysis, so it isn't a second, separate line of support.

Why writing it down helps

Getting stronger over months means asking a bit more of your muscles over time: for example more weight or more reps. This is called progressive overload.^[3] The 2026 stand adds a twist. You can still gain without deliberately making training harder.^[3] Overload matters most if you want to keep improving over the long term.^[3] Expert consensus. Either way, you can only beat last time if you know what last time was. That follows from the definition. It isn't a tested finding. Progressive overload has its own article later in the path.

We found no study that tested a training log against no log in people who lift. The evidence for writing things down comes from other goals.

A meta-analysis of 138 experiments, with nearly 20,000 people, tested what happens when people track their progress toward a goal. Tracking helped them reach their goals, by a small-to-moderate amount. The effect was bigger when progress was physically recorded.^[4] The goals were about health and other behaviours, not lifting.

A second meta-analysis looked at 122 evaluations of programs designed to help adults move more and eat better. Of all the techniques those programs used, keeping a record of what you do was the one most linked to which programs worked best.^[5] That's a pattern across programs, not a direct test.

Moderate evidence for goals in general. Applying it to the gym is our step, not the studies'.

How to apply it

The words you'll hear on day one

• Working weight: the weight you use for the sets that count, after you've warmed up.
• Warm-up set: a lighter set before your working sets, to practise the movement.
• Working set: a set at your working weight. These are the sets you count.
• Rest: the break between sets. A program may set it for you.
• Barbell: the long bar you load with weight plates. Collars are the clips that stop plates sliding off.
• Dumbbell: a short weight you hold in one hand.
• Rack: the steel frame that holds a barbell at shoulder height, so you can step under it.
• Cable: a machine where you pull a handle attached to a weight stack by a cable.

Your first sessions

1. Pick a weight you could lift a few more times than your target. If the plan says 10 reps, choose a weight where 12 or 13 would be your limit. That leaves about 2–3 reps in reserve. This is coaching practice built on the ACSM's effort guidance.
2. Do a warm-up set or two first. Use a lighter weight, then move up to your working weight. The warm-up article covers what the research says about this.
3. Do at least two working sets of each exercise. That's the ACSM's minimum.^[3]
4. Use the equipment your gym has and you like. If you want a stronger barbell squat, train the barbell squat. Strength gains are specific to the kind of equipment you train with.^[1]
5. Write down every set. Weight and reps, set by set. Nothing else is required.

What to write down

A log line looks like this:

• Dumbbell bench press: 14 kg × 10, 10, 8.
• Leg press: 70 kg × 12, 12, 11.

Each number is one set. Next session, the goal is to beat one of them by a rep: 14 kg × 10, 10, 9. Want more detail? Add how many reps you had left on the last set (your RIR). You can also mark which sets were warm-ups. Those are extras. Weight and reps are the core.

Common mistakes

Thinking machines don't count. Gym culture treats free weights as the real thing. In the studies that compared them, the researchers found no clear strength difference.^[1] Use whichever you'll show up for. Add free weights if you want to get better at free-weight lifts.

Taking every set to failure. It feels like the hard way must be the right way. But failure isn't needed for gains.^[3] Stop with two or three reps left, and keep the reps clean.

Only writing down the best set. "Bench 50 kg" hides whether that was one set of 8 or three sets of 10. Write every set. Small changes from week to week are the whole point, and you can only see them set by set.

Handling weights carelessly. US emergency rooms logged weight-room injuries from 1990 to 2007. The most common cause was a weight dropping on the person (about 2 in 3 cases).^[6] Limited evidence. The records covered people of all ages, mostly men. Those records count injuries, not how many people lifted, so they can't say which equipment is riskier.^[6] Use collars, put plates back on the rack, and set dumbbells down away from your feet.

How Gymbers fits

The step from this article is writing every set down. The Gymbers app logs the weight and reps for every set, and last session's numbers sit beside each set. You can log warm-up sets too, and log RIR next to each set. A rest timer runs between sets. Programs in the app set a target rep range for each set, and exercises come with a video.