If you want a stronger barbell squat, make the barbell squat your main lift. The Smith machine squat works well as a second squat, or as your main squat when the barbell number is not the goal. In the trials available, the two built muscle about equally. Strength mostly improved on whichever version people trained.
This guide compares the two using seven published studies, then gives a table for choosing, a way to program both, and a method for logging them.
Is the Smith machine squat as good as a barbell squat?
For building leg muscle, the Smith machine squat appears to be about as good as the barbell squat. For building a stronger barbell squat, it is not. The trials show similar growth from both, but strength gains lean toward the version you practise. Your goal decides which one should come first.
A Smith machine squat is a squat performed with a barbell fixed to vertical (or slightly angled) rails, so the bar can only travel along one path. A barbell squat is a squat with a free bar on your back, where you control the bar path and your balance.
Our guide to free weights versus machines covers the same trade-off across all exercises. Here is how it plays out for the squat:
| Factor | Barbell squat | Smith machine squat |
|---|---|---|
| Bar path | Set by you | Set by the rails |
| Balance demand | You balance the bar front to back and side to side | The rails control balance along the bar's path |
| Trunk and calf muscle activity | Higher (Anderson and Behm, 2005) | Lowest of the squats tested (Anderson and Behm, 2005) |
| Foot position | Under the bar, so you stay balanced | Can sit under or in front of the bar, which changes hip and knee loading (Abelbeck, 2002) |
| Muscle growth in trials | Similar to machines (Haugen et al., 2023) | Similar to free weights (Saeterbakken et al., 2019) |
| Strength transfer to the barbell squat | Direct | Partial; gains favour the trained version |
| Load comparability | Standard 20 kg bar | Bar weight varies by machine, and 1RMs differ (Cotterman et al., 2005) |
| Racking | Needs safety arms or a spotter for failed reps | You can usually hook the bar onto the frame at many heights |
The last row is practical reasoning, not a study result. Check your gym's hooks and safety stops before relying on them.
Does the Smith machine squat build as much muscle?
Yes, as far as the current evidence shows. A 2023 meta-analysis found no difference in muscle growth between free-weight and machine training. A 2019 squat trial found similar gains in muscle thickness whether men trained on a Smith machine, with a free bar, or with a free bar on a wobble board.
Haugen and colleagues (2023) pooled 13 studies with 1,016 participants who trained for at least six weeks. For hypertrophy, the difference between free weights and machines was close to zero (SMD -0.055, p = 0.751). Two of the included trials used the Smith machine squat in their machine groups.
One of those was Saeterbakken and colleagues (2019). After a three-week familiarisation period, 59 physically active men were randomised to squat on a Smith machine, with a free bar, with a free bar on a wobble board, or not at all. All three training groups showed similar improvement in muscle thickness over the following seven weeks.
The other was Schwanbeck and colleagues (2020), which randomised 46 people, 26 of them women, to free weights or machines for 8 weeks. Quadriceps and biceps thickness rose with no difference between groups.
These trials are short, with about 11 to 13 men per group in the Saeterbakken study, so they support a direction rather than a guarantee.
Does Smith machine strength carry over to the barbell squat?
Only partly. Strength gains lean toward the version you train. In a 2019 trial, free-weight squat training raised strength similarly on the barbell and the Smith machine. Smith machine training improved the Smith squat more than the free squats. If the barbell squat is your test, you need to practise it.
The Saeterbakken trial is the clearest direct comparison. Between weeks 3 and 10, the free-weight and wobble board groups improved their 10-rep maximum (10RM) similarly in every squat condition, including the Smith machine. The Smith machine group improved more on the Smith squat than on the free squats. Free-bar training carried over to the machine, but machine training carried over less to the free bar.
The meta-analysis points the same way. Free-weight training produced larger gains on free-weight strength tests (SMD -0.210, p = 0.023). Machine training showed a non-significant trend toward larger gains on machine tests (SMD 0.291, p = 0.064). The authors summarised it plainly:
"strength changes are specific to the training modality" (Haugen et al., 2023)
That does not make the Smith machine useless for barbell strength. In the Schwanbeck (2020) trial, free-weight squat and Smith machine squat strength rose by 11 to 19% in both the free-weight and machine groups, with no difference between them. Over 8 weeks, both kinds of training built squat strength in general. The specificity findings above suggest the gap matters most when one particular squat is the number you care about.
Your numbers will also differ between the two. Cotterman, Darby and Skelly (2005) tested 16 men and 16 women on a parallel back squat with each setup. Squat 1RM was greater on the Smith machine than with free weights. Split by sex, the difference was significant for women only. A 1RM on one setup was the best predictor of 1RM on the other, but the two numbers were not the same.
The same specificity logic applies within the barbell squat. Our comparisons of high-bar and low-bar squats and front and back squats cover how much each variation carries over.
Which muscles work less on the Smith machine?
In the available studies, the Smith machine squat produced lower activity in the calves, hamstrings, part of the quads and the trunk muscles that hold you upright. One six-person study found 43% higher average activity in the free squat. A second study found trunk and calf activity lowest on the Smith machine.
Schwanbeck, Chilibeck and Binsted (2009) had six trained people do one set of 8 reps at their own 8-rep maximum on each squat while measuring electromyography (EMG), the electrical activity of a muscle. Free-weight squat activity was higher by:
| Muscle | Higher activity in the free-weight squat |
|---|---|
| Gastrocnemius (calf) | 34% |
| Biceps femoris (hamstring) | 26% |
| Vastus medialis (inner quad) | 49% |
| Average across all muscles measured | 43% |
The other muscles measured showed no significant difference. Note that the vastus medialis is a working quad muscle, not just a stabiliser. The caveats are large: six people did one set each, and EMG measures activity in a moment, not growth over months.
Anderson and Behm (2005) compared a Smith machine squat, a free squat and a squat on balance discs in 14 men. Activity in the soleus (a deep calf muscle), the abdominal stabilisers and the upper and lower erector spinae was highest on the balance discs and lowest on the Smith machine. If you squat only on the Smith machine, holding your trunk and balance under load gets less practice.
Where should your feet go on a Smith machine squat?
Put your feet roughly under the bar if you want the Smith squat to resemble a barbell squat. Moving the feet forward shifts the work from the knees toward the hips. A biomechanical model found that knee moments fell and hip moments rose as the feet moved forward. Choose one stance and keep it.
Abelbeck (2002) built a biomechanical model of a squat on a bar that moves in a straight line, the setup a Smith machine uses. As the feet moved farther in front of the bar, the turning force (moment) about the knee decreased and the moment about the hip increased. The paper's conclusion was direct:
"foot position is a critical factor in hip and knee moments" (Abelbeck, 2002)
This was a model, not a training trial, so it tells you how the load shifts, not what grows. A free bar forces your feet under it or you fall over; the rails remove that constraint. Because a feet-forward and a feet-under-bar Smith squat load your joints differently, write your stance in a note and keep it the same across a block.
The bar is a second variable. Some Smith machine bars are counterbalanced and feel close to weightless, while others weigh 15 kg or more. Our guide to how much a barbell weighs covers how to find and record the starting weight on your machine.
When should you choose each one?
Choose the barbell squat when the barbell number matters to you. Choose the Smith machine squat when you want leg volume with less balance demand. Use both if you can recover from them. The table below combines the trials above with practical reasoning, and it is not a validated protocol.
| Your situation | Better pick | Why |
|---|---|---|
| You test or compete in the barbell squat | Barbell squat | Strength gains favour the trained version (Haugen et al., 2023; Saeterbakken et al., 2019). |
| You want leg muscle and balance is limiting your sets | Either; Smith works | Muscle thickness gains were similar across setups (Saeterbakken et al., 2019). |
| You train alone and the rack has no safety arms | Smith machine | The bar can be hooked onto the frame if a rep fails (practical reasoning). |
| You are learning to squat | Barbell with light loads, Smith as extra volume | The barbell trains balance and trunk control that the rails provide for you (Anderson and Behm, 2005). |
| Your lower back or balance ends barbell sets before your legs do | Smith machine as a second squat | The fixed path lets the legs keep working (practical reasoning). |
| You have knee or back pain that persists | See a physiotherapist or doctor first | A comparison of trials cannot tell you which lift is safe for an injury. |
For another stable option, see the leg press versus squat comparison.
How do you program Smith machine squats alongside barbell squats?
Do the barbell squat first with heavier sets that stop one to three reps short of failure. Follow it with Smith machine squats for 8 to 15 reps taken closer to failure. This is practical reasoning, not a tested protocol. It puts the skill lift first and the stable lift last.
A simple lower-body day looks like this:
- Barbell squat: 3 to 4 sets of 4 to 8 reps, stopping with 1 to 3 repetitions in reserve (RIR).
- Smith machine squat: 2 to 3 sets of 8 to 15 reps, finishing close to failure.
- Hamstrings and calves: a hinge or leg curl and a calf raise, since squats of either kind leave these muscles some work to do.
Give the Smith squat one or two lighter sets even after heavy barbell work, because the groove feels different. Our guide to how many warm-up sets gives a structure that scales with load.
Progress each lift on its own. Double progression suits the Smith machine squat well: pick a rep range such as 10 to 15, add reps until you reach the top, then add load and start again. If you rate effort with RIR, a barbell set at 2 RIR and a Smith set at 0 to 1 RIR are both honest hard sets, just on different tools.
If you train for muscle rather than a barbell number, the order can flip. Keep whichever order you choose for the whole block so your numbers stay comparable.
How do you log Smith machine and barbell squats in IronLedger?
Log them as two separate lifts, and record the stance and the bar's starting weight in a note. Then compare each lift with its own history, not with the other. IronLedger keeps a separate history for each exercise, so you can see whether either squat is actually moving over a block.
IronLedger is a free strength training app for iOS, with Android in testing. On the product page you can see how it handles each of these:
- Separate exercises. The exercise library lists Smith Machine Squat as its own exercise, separate from barbell squat variants, so the two never share a history.
- Per-set logging. Each set records load, reps, RPE in half steps or RIR, and a free-text note. Use the note for stance and the machine's bar weight.
- Estimated 1RM per lift. IronLedger uses the Epley formula and shows the trend on the progress page. Our guide to estimated one-rep max explains the limits of the estimate.
- Personal records per lift. Records are tracked per exercise, so a Smith machine PR never inflates your barbell squat record.
- Mid-session changes. If the rack is taken, you can replace the exercise while the workout is running.
- Load recommendations that show their reason. On IronLedger's five built-in programs that recommend loads, hit every prescribed rep at an easy effort (RPE 7 or below, or RIR 3 or more) and the next session adds 2.5 kg or lb. Miss reps or log RPE 9 or higher, or RIR 0, and it holds. Edits become manual overrides, and custom and imported programs do not get recommendations.
What mistakes should you avoid?
Most mistakes come from treating the Smith machine squat as the same lift as the barbell squat. It is a related lift with its own numbers, stance options and bar weight. Judge it by its own trend, and keep the barbell squat in your program if the barbell number matters to you.
- Counting Smith numbers as barbell numbers. Squat 1RMs differed between the setups in Cotterman et al. (2005). A Smith PR is not a barbell PR.
- Replacing the barbell squat when the barbell is the goal. Smith training improved the Smith squat most in Saeterbakken et al. (2019).
- Changing your stance between sessions. Foot position changes hip and knee loading (Abelbeck, 2002). Record it and keep it.
- Forgetting the bar weight. Some Smith bars are counterbalanced and others weigh 15 kg or more. Log the same way every session.
- Ignoring pain. Persistent knee or back pain needs assessment, and no exercise comparison can replace it.
Frequently asked questions
It appears to be. A 2023 meta-analysis of 13 studies found no difference in muscle growth between free-weight and machine training. A 2019 squat trial found similar muscle thickness gains on the Smith machine and with a free bar.
Sources and references
- Haugen et al., Effect of free-weight vs. machine-based strength training on maximal strength, hypertrophy and jump performance: a systematic review and meta-analysis: no hypertrophy difference; free-weight training favoured free-weight strength tests (BMC Sports Sci Med Rehabil, 2023).
- Saeterbakken et al., The short- and long-term effects of resistance training with different stability requirements: similar muscle thickness gains; Smith training improved the Smith squat most (PLoS ONE, 2019).
- Schwanbeck et al., Effects of training with free weights versus machines on muscle mass, strength, free testosterone, and free cortisol levels: free-weight and Smith squat strength rose 11 to 19% in both groups (J Strength Cond Res, 2020).
- Cotterman, Darby and Skelly, Comparison of muscle force production using the Smith machine and free weights for bench press and squat exercises: squat 1RM greater on the Smith machine (J Strength Cond Res, 2005).
- Schwanbeck, Chilibeck and Binsted, A comparison of free weight squat to Smith machine squat using electromyography: free-weight squat EMG 43% higher on average (J Strength Cond Res, 2009).
- Anderson and Behm, Trunk muscle activity increases with unstable squat movements: trunk and soleus activity lowest on the Smith machine (Can J Appl Physiol, 2005).
- Abelbeck, Biomechanical model and evaluation of a linear motion squat type exercise: feet forward lowered knee moments and raised hip moments (J Strength Cond Res, 2002).
- IronLedger product page: per-set RPE and RIR, notes, estimated 1RM and personal records.
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