Circuit training: what it is, what it does, and how to build a circuit

What it is

Exercise stations done one after another with little rest, then repeated. The classic circuit used 9 to 12 stations at light to moderate weights, and many now put cardio stations between the strength ones.

Sources 1, 2

It builds strength and muscle

The American College of Sports Medicine's (ACSM) 2026 overview counts circuit training among the methods that build strength and muscle. How much is less certain: the largest meta-analysis found strength gains of about a fifth, but most of its studies were at high risk of bias.

Sources 3, 4

A moderate boost to fitness

VO2 max (the most oxygen your body can use, a measure of aerobic fitness) rose by about 6% on average. Bodyweight circuits raised it a little less than running or cycling training.

Sources 4, 5

A little fat loss

About 1 kg of fat lost and 1 kg of muscle gained on average, with body weight unchanged. In people with overweight or obesity, about 4 kg of weight came off in 9 trials.

Sources 4, 6

Against straight sets

Heavy or near-failure circuits matched traditional sets for strength and lean mass in less time in three small trials. Light, easy circuits build less maximal strength.

Sources 7, 8, 9, 3

Where it came from

Circuit training was developed at the University of Leeds in the 1950s by R.E. Morgan and a colleague. The classic design used 9 to 12 stations of 15 to 45 seconds, or 8 to 20 reps, at about 40 to 60% of the most you can lift once (your one-rep maximum), with 15 to 30 seconds, or no rest, between stations. Machines, free weights, bands or bodyweight all work.

Sources 2, 1, 10

Formats you'll meet

Circuits are arranged in a few common ways:

• Timed circuit: each station for a set time, then a short changeover. Our circuit training workout is 40 seconds on, 20 to move.
• Rep circuit: a set number of reps at each station, then straight on to the next.
• Straight sets (a station format): all the sets of one exercise, resting between them, before moving on. This is traditional strength training, not a circuit.
• Supersets: two exercises back to back, then a rest, which is a two-station circuit.
• Interval circuit: short, hard stations with short rests, like the 7-minute workout.
• Aerobic circuit: cardio stations of 30 seconds to 3 minutes between the strength stations. Kravitz notes that its extra benefit for heart and lung fitness "has not been conclusively supported in experimental research".

Sources 1, 2, 10

Design rules from a national coaching body

Coaching Ireland's fact sheet suggests working the upper, middle and lower body in turn, balancing the front and back of the body, varying direction (forwards and back, up and down, side to side) and alternating high and low-impact moves. Its muscular endurance circuit uses 30 seconds of work and 15 of rest. Its beginners' cardio circuit uses 30 seconds on and 10 off, for 2 circuits with 90 seconds between, and its combined circuit alternates cardio and strength stations on the same timing.

Source 2

Circuits and HIIT

Circuit training is a way of arranging exercises; HIIT (high-intensity interval training) is a pattern of effort, hard bursts with easier recovery. A circuit becomes interval training when its stations are short and hard, like the 7-minute workout. The NHS lists circuit training among its very vigorous activities.

Sources 11, 10

Strength and muscleStrong evidence

The ACSM's 2026 overview of reviews counts circuit resistance training among the methods that improve strength (3 reviews, 843 people) and muscle size (1 review, 236 people) against no training.

Source 3

How much strength and muscleMixed evidence

A meta-analysis of 45 studies (897 people trained in circuits, aged 18 to 42, for 4 to 28 weeks) found bench and leg press strength up by about 20% and 23%, muscle up by about 1.2 kg and fat down by about 1 kg, with body weight unchanged. But most of the studies were at high risk of bias and their results varied widely, so treat the sizes as rough.

Another analysis found the biggest bench press gains at 30 to 60% of one-rep maximum, in sessions of at least 22.5 minutes, though its authors note that less fit volunteers in those studies may explain why lighter loads looked best.

Sources 4, 12

Aerobic fitnessEmerging evidence

VO2 max rose by about 2.9 mL/kg/min (millilitres of oxygen per kilogram of body weight per minute), about 6%, across 45 studies. The largest gains came with about 14 to 30 sessions over 6 to 12 weeks, in sessions of at least 20 to 30 minutes. Bodyweight interval circuits raised aerobic fitness a little less than running or cycling training (19 trials), though in one 5-week trial in sedentary young women, a circuit raised VO2 max by 11%, more than separate strength and cardio sessions.

Sources 4, 12, 5, 13

Body fat and weightEmerging evidence

Across 45 studies, fat fell by about 1 kg on average, with muscle gained and body weight unchanged. In 9 randomised trials (837 people), circuits took off about 3.8 kg in people with overweight or obesity and nothing in people of a healthy weight. In adults with overweight or obesity, combined aerobic and strength training ranked first, and circuit-style hybrid training second, of five exercise types for heart and metabolic health (81 trials).

European guidance puts the weight loss to expect from exercise alone at no more than 2 to 3 kg, so circuits help most alongside eating less.

Sources 4, 6, 14, 15

Older adultsEmerging evidence

In 15 trials of 576 people aged 60 to 75, circuits improved strength and lean mass (about 1.4 kg), lengthened the 6-minute walk by about 94 metres and lowered blood pressure by about 10/4 mmHg, though most trials raised some concerns about bias. In 10 studies of adults averaging 64.5 years, circuits increased upper and lower-body strength, and middle-aged and older women gained fitness and strength and lost fat in 16 studies.

In a review of interval or circuit strength training in older adults, 74 to 96% of sessions were attended and no serious adverse events were reported, on low-certainty evidence.

Sources 16, 17, 18, 19

Heavy circuits matched traditional setsEmerging evidence

In 33 trained men, 8 weeks of heavy circuits (a weight they could lift about 6 times, with about 35 seconds between stations) matched training with 3-minute rests for squat and bench press strength and lean mass, in shorter sessions; only the circuit group lost body fat, but bike sprint power rose only with traditional sets. In 37 adults aged about 62, heavy circuits twice a week for 12 weeks matched traditional training for strength, lean mass and bone density. In 14 trained women, near-failure circuits matched straight sets for strength and lean mass in sessions of about 50 to 60 minutes instead of 75 to 85. All small trials.

Sources 7, 8, 9

Light circuits build less maximal strengthEmerging evidence

The 7-minute workout's authors noted that light circuits may be less effective for maximal strength and power, and in sedentary young women, separate strength training built more chest, back and thigh strength than a bodyweight circuit.

Sources 10, 13

SupersetsStrong evidence

Across 19 studies (313 people), supersets kept the same reps and volume in less time and gave similar long-term gains in strength, endurance and muscle, at the cost of higher effort. Pooled markers of muscle damage weren't higher, though one study found more. Pairing opposing muscles kept the volume best.

Source 20

Set structureStrong evidence

The ACSM's 2026 overview found set structure (traditional, cluster or rest redistribution) made no consistent difference to strength or power, and found too little data to judge its effect on muscle size.

Source 3

Which to choose

Circuits are a time-efficient way to strength-train if the strength stations are genuinely hard and opposing muscles take turns. For your heaviest lifts, or if maximal strength or power is your goal, straight sets with longer rests remain the standard (our rest between sets guide).

Sources 7, 9, 20

Stations and timings

Classic circuits: 9 to 12 stations of 15 to 45 seconds or 8 to 20 reps, with 15 to 30 seconds to move. Our editorial starting point: 8 stations of 40 seconds, with 20 seconds to move.

Sources 1, 2, 10

How heavy

In trials, circuits matched straight sets when the sets were heavy (a 6-rep maximum) or close to failure. Our plans use 2 to 3 reps in reserve (RIR: how many more reps you could have done). For timed stations, pick a weight you could lift about 15 to 20 times (our suggestion).

Sources 3, 7, 9

How often

Two or three days a week, with a day between. The World Health Organization (WHO) recommends muscle strengthening on 2 or more days a week, and subgroup analyses found larger strength gains with 3 sessions a week and with 21 to 30 sessions in all.

Sources 21, 4

Rounds and rests

Two or three rounds: the coaching fact sheet's beginner circuits use 2, with 90 seconds between. Our editorial range is 1 to 2 minutes between rounds, moving gently.

Sources 2, 10

Check with your GP first if

• You haven't exercised for some time, or have a medical condition or concerns (the NHS advice before any new exercise).
• You're inactive and have heart, metabolic or kidney disease, such as diabetes, or get chest discomfort, unusual breathlessness, dizziness or fainting when active.
• Your blood pressure is high and not yet controlled: keep breathing through every rep rather than holding your breath under load, and keep to moderate effort until it's controlled.
• You have a current disc-related back problem: get it assessed before you load a hinge such as the Romanian deadlift.
• You live with obesity and plan short, hard interval circuits: European guidance advises a heart-risk check and supervision before high-intensity intervals.
• You're pregnant: don't start a new vigorous activity, and avoid lying flat on your back for more than a few minutes in later pregnancy.
• You have ME/CFS: NICE (the National Institute for Health and Care Excellence) advises against exercise outside a specialist programme; see our ME/CFS guide instead.

Sources 11, 22, 15, 23, 24

Call 999 now (911 in the US)

Stop and call 999 (don't drive yourself to A&E) for:

• Sudden chest pain or discomfort that doesn't go away: it can feel tight, heavy, like squeezing or pressure, or like burning. Or pain that spreads to your arms, neck, jaw, stomach or back.
• Chest pain with sweating, feeling sick, light-headedness or breathlessness.
• Severe difficulty breathing: gasping, choking or not able to get words out, lips or skin turning very pale, blue or grey, or sudden confusion.
• Someone who faints while exercising, or who has fainted and can't be woken within a minute, has chest pain or a pounding, fluttering or irregular heartbeat, or hasn't fully recovered.
• Palpitations that don't go away, or come with chest pain, breathlessness, or feeling faint or fainting.

Sources 25, 26, 27, 28, 29

Call NHS 111 (in the US, your doctor or urgent care)

Get advice the same day for:

• Being suddenly more short of breath than usual.
• Palpitations with chest pain, breathlessness or fainting that have now stopped: ask your GP surgery for an urgent appointment, or contact 111.
• In the days after an unusually hard session, especially your first: dark, red or cola-coloured urine, passing less urine than usual, or muscle pain, tenderness or weakness far worse than normal soreness. These can be signs of rhabdomyolysis, a breakdown of muscle that can harm the kidneys; in reported cases after spin classes, symptoms appeared about 3 days later.

Sources 25, 27, 29, 30, 31

See a GP

• Chest pain that comes and goes, or went away quickly but you're still worried.
• Palpitations that keep coming back, are happening more often or last more than a few minutes, or any palpitations if you have a heart condition or a family history of heart problems.
• Breathlessness that gets worse during normal activities or when you lie down, or comes with swollen ankles.
• A faint at any time other than during exercise (fainting during exercise needs 999).

Sources 26, 29, 27, 28

During the circuit

Drop to a lighter weight rather than let your back round on the hinge, and stop a move for sharp or increasing joint pain; see a GP or physiotherapist if it keeps happening (our suggestion, as in our plans). Some muscle soreness for a day or two after a new routine is normal.

"Circuits only build endurance, not strength or muscle"Strong evidence

Circuit training builds strength and muscle against no training, by the ACSM's overview, and heavy or near-failure circuits matched traditional sets in small trials. Light, easy circuits build less maximal strength.

Sources 3, 7, 8, 9

"Circuits burn fat for hours afterwards"Strong evidence

The extra energy you use after any session (the afterburn) is about 6 to 15% of the session's own cost. In trials, circuits took off about 1 kg of fat over about 10 weeks.

Sources 32, 33, 4

"A circuit gives you all the cardio you need"Mixed evidence

Circuits raise VO2 max by about 6% on average, but bodyweight interval circuits raised aerobic fitness less than running or cycling training in pooled trials, though one short trial found the opposite. Walking or other cardio still helps (our zone 2 guide).

Sources 4, 5, 13

"Light weights and high reps tone, heavy weights bulk"Strong evidence

Muscle grows across a wide range of loads when sets are hard, and heavier loads build more maximal strength (as in our plans' shared notes). There's no special toning effect of circuits.

Source 3

"Shorter rest is always better"Mixed evidence

Short changeovers save time and went with larger gains in some subgroup analyses, but back-to-back moves for the same muscles cut the work you can do, and for your heaviest lifts longer rests build more strength (our rest between sets guide).

Sources 4, 20