Choosing exercises and using full range of motion

Use the full range of motion you can control on every rep. In the studies, full reps built more strength than half reps, and about as much muscle or a little more.^[1][2][3] Half reps still count if you do them in the stretched part of the lift, like the bottom of a squat. Those grew muscle about as well as full reps.^[3][4]

For choosing exercises, use both kinds: big lifts that move several joints, and smaller ones that move one. They built about the same total muscle, but they grew different parts of it.^[5][6] Then keep the same exercises for weeks. Changing them every session hasn't been shown to help.^[7]

The answer isn't obvious because gym advice splits into camps. One camp says half reps are useless. Another says stretched half reps beat full reps. The studies don't clearly back either.^[3][8]

In How long should you rest between sets? you set the minutes between sets. This article is about the sets themselves: which exercises go in them, and how far each rep should move.

Why exercise choice and range matter

Two things tend to go wrong for beginners. The first is cutting reps short. Load a leg press heavier than you can handle, and each rep shrinks to a few centimetres near the top. The number on the machine goes up. But short reps at the top of a lift grew the least muscle in the studies.^[4][3]

The second is the exercise menu. A gym has dozens of machines, and the internet has hundreds of variations. Some people do only the big barbell lifts and skip the rest. Others change every session so their muscles stay "confused". The studies below support neither habit.

Free weights versus machines has its own section in gym basics, so it isn't repeated here.

What the research says

A few terms first. Range of motion is how far a joint moves during a rep. A full rep moves through the joint's whole range. A partial rep (a half rep) covers only part of it.^[1] Hypertrophy means muscle growth: the muscle fibres get bigger. A meta-analysis pools the results of many studies on the same question into one estimate. A position stand is an official summary of the evidence written by a panel of experts.

Full range built more strength

Moderate evidence. Only two reviews sat behind the strength finding, and the panel rated their quality at 50%.^[1]

Two meta-analyses show why the panel was cautious. A 2021 meta-analysis of 16 studies found that full-range training built more strength than partial training, a moderate difference.^[2] It also found more muscle growth in the legs with full range.^[2] But that leg result rested on only 4 studies.^[3]

A larger 2023 meta-analysis pooled 23 studies.^[3] Full range came out ahead again on every outcome, but the gaps were trivial to small.^[3] For muscle size, full and partial reps came out about the same.^[3] The authors wrote that full range "may prove to be an effective 'default' strategy".^[3]

So there is moderate evidence that full range builds a bit more strength. On muscle size the evidence is mixed: the studies agree on the direction, but not on how big the gap is.

Where the half rep happens matters

Most of the partial reps in these studies were done at the short end of the movement.^[3] That's the top of a squat or curl, where the muscle is shortest and the weight feels easiest. A lengthened partial is the opposite: a half rep in the stretched part of the lift. Think of the bottom half of a squat, or the arms-straight half of a curl.

• Short top-end partials grew the least. A 2023 review of 11 studies looked at range of motion and muscle growth.^[4] It found that full reps, and partials in the stretched first part of the movement, grew several muscles more than partials in the final part.^[4] Moderate evidence.
• Stretched partials grew about as well as full reps. In the 2023 meta-analysis, they came out slightly ahead of full reps for muscle size. But only 6 studies tested them, and the studies can't tell that edge apart from no effect.^[3] The authors called this part of the analysis exploratory.^[3] Limited evidence.

The biggest test so far found only small differences. A 2025 randomised trial (people were put into groups by chance) ran across 15 personal-training studios for 12 weeks.^[8] About 300 people who already trained did either full reps or lengthened partials. Arm and thigh muscle size changed about the same in both groups.^[8] The authors called the differences "small and practically equivalent", though their strict pre-set test could not formally confirm it.^[8] Limited evidence: one trial, though a large one. Muscle size was estimated from tape and skinfold measurements rather than scanned, and the lengthened partials were used only on one-joint arm and leg exercises.^[8]

A 2025 meta-analysis of 12 studies in young adults asked a related question. Does training a muscle at longer lengths grow its top, middle or bottom more? The differences were trivial at every site.^[9] Moderate evidence. The authors added a caution: on average, the muscle lengths being compared differed by only about 22%.^[9]

Stretched half reps are a fair option, then. They aren't a shortcut to more muscle.

Compound and isolation exercises: same total, different parts

Two more terms. A compound (multi-joint) exercise moves several joints at once, like a squat, a row or a press. An isolation (single-joint) exercise moves one joint, like a biceps curl or a leg extension.

A meta-analysis of 7 studies compared the two. Whole-muscle growth came out about the same.^[5] In one 10-week trial, 29 untrained young men did either lat pulldowns or biceps curls. The muscles that bend the elbow grew about the same in both groups: 6.1% versus 5.8% thicker.^[10] Moderate evidence. The ACSM couldn't separate the two either.^[1]

But the two kinds grew different parts of a muscle. In a 12-week trial, 17 untrained adults trained one leg on a leg extension and the other on a leg press.^[6] The leg extension grew the rectus femoris (one of the four front-thigh muscles) by 13.2%. The leg press grew it by 1.1%.^[6] The front thigh as a whole grew by a similar amount either way (7.1% versus 4.9%).^[6] Only the leg press grew the glutes (+15.4%) and a large inner-thigh muscle (+6.2%).^[6]

A 2026 trial in 63 untrained young women found a matching pattern.^[11] Leg extensions grew the rectus femoris more than squats on a Smith machine: +12.3% versus +5.7% at the middle of the muscle. (A Smith machine is a barbell fixed on rails.) The squats grew the lower part of the outer thigh more: +18.2% versus +11.2%.^[11] Limited evidence: two small trials, both on the legs.

Some single trials also found more growth when a muscle was trained in a stretched position. Seated leg curls grew the hamstrings more than lying leg curls: +14% versus +9% in 12 weeks.^[12] Overhead triceps extensions grew the triceps more than the arms-down version: +19.9% versus +13.9%.^[13] Limited evidence: each trial had about 20 adults, who trained one limb each way. Treat them as examples of how exercise choice can shift growth, not as rules. Across studies, the long-length effect was small.^[9]

You get better at what you practise

People tested best on the range of motion they had trained.^[3] In the 2026 squat trial, squat strength rose 46.7% with squat training and 21.3% with leg extensions.^[11] The ACSM adds that for people who aren't advanced, strength carries over a lot from one kind of exercise to others.^[1] Moderate evidence. If you want a bigger squat, squat.

Should you keep changing exercises?

A 2022 review of 8 studies, all in young men, looked at changing exercises.^[14] It said some planned variety "seems to" help growth in more parts of a muscle. It also warned that changing exercises too often, at random, "may actually hinder" gains.^[14] Limited evidence: the review didn't pool the numbers.

The newest trial found no difference. In it, 70 young women trained their legs 3 times a week for 10 weeks.^[7] One group did the leg press and stiff-leg deadlift every session. The other rotated between three pairs of leg exercises across the week. Muscle and strength grew about the same in both groups.^[7] Limited evidence: one trial. The ACSM couldn't decide whether varying exercises matters either.^[1]

How to apply it

The steps below come from the studies above. The exact numbers (how many exercises, how many weeks) go further than any trial. This is coaching practice, not a tested finding.

1. Use the full range you can control. Lower each rep as far as the joint moves under control, then come all the way back. Full range means the joint's normal range, not as deep as you can force it.
2. If you shorten a rep, keep the stretched half. Half reps at the bottom of a squat or curl count. Short reps near the top are the ones to drop.^[4][3]
3. Give each muscle a compound and an isolation exercise. For the front thigh, a leg press and a leg extension. For the back of the thigh, a Romanian deadlift and a seated leg curl.^[6][12]
4. Count the hard sets for each muscle across the week. See how many sets per week build muscle.
5. Put the lift you most want to get stronger at first. Strength gains favoured exercises done at the start of a session. Muscle growth wasn't affected by the order.^[1]
6. Keep your exercises for 6 to 12 weeks. Then swap one or two if you want. Keeping them lets you see whether the weight is going up.
7. Learn new lifts light. Learning the lifts covers how.

A worked example

Say a 70 kg lifter has a lower-body day. (These numbers are illustrative, not from a study.)

• Leg press: 3 sets of 10
• Romanian deadlift: 3 sets of 8
• Leg extension: 2 sets of 12
• Seated leg curl: 2 sets of 12

In week 1 she loads the leg press to 120 kg. Her reps come down only a hand's width. So she drops to 80 kg and lowers until her knees bend as far as they comfortably go: 80 kg × 10, 10, 9. The number looks smaller. Each rep now covers the full range.

She keeps the same four exercises for 8 weeks. By week 8 the leg press reads 95 kg × 10, 10, 10, through the same full range. Then she swaps the leg press for squats on a Smith machine, and keeps the other three.

What's practical versus optimal. Stretched half reps might add a little growth for some muscles, but the evidence is thin. Full reps are easier to judge from set to set, and they build strength too. So full range is the default. Coaching practice.

Common mistakes

Loading more than you can move through a full range. A bigger number feels like progress. But short reps near the top grew the least muscle.^[4] Drop the weight until you reach full range, and build back up from there.

Thinking every half rep is wasted. Half reps in the stretched part of a lift grew muscle about as well as full reps.^[3][8] Where you cut a rep short matters more than whether you do.

Doing only big lifts, or only machines for single muscles. The leg press barely grew the rectus femoris, and the leg extension didn't grow the glutes.^[6] Use both kinds of exercise.

Changing exercises every session. The idea is that muscles need "confusing". In the newest trial, rotating exercises built no more muscle than keeping them fixed.^[7] Changing too often, at random, may hold you back.^[14]

Hunting for the one best exercise. In these trials, each exercise grew some muscles, or parts of a muscle, more than the other did.^[6][11] Pick a few good ones and keep them.

How Gymbers fits

Coach programs in the Gymbers app settle the exercise question before you start. Programs are written by coaches who train, with every session laid out in order. Exercises in the app come with a video, which helps when a lift is new. Each exercise has its own history and charts, so you can see whether it's still moving after a few weeks.