Het gangbare advies in de sportschool stelt vrije gewichten boven machines. Een meta-analyse uit 2023 van 13 directe vergelijkende studies vond geen verschil in kracht of spiergrootte wanneer de inspanning en het volume gelijk waren. Wat de keuze tussen beide bepaalt, is uw doel, de techniek die u wilt beheersen en hoe veilig u alleen traint.
De laatste factor is welke methode u daadwerkelijk zult volhouden. Voor de meeste mensen is het beste antwoord een combinatie van beide.
Findings & Outcomes
When you match effort and the number of hard sets, the two tools produce roughly equal strength and roughly equal muscle. A 2023 meta-analysis pooled 13 trials that compared free weights and machines head-to-head. It found no difference in maximal strength, muscle size, or jump height.
A separate pooling of 12 strength trials put the gap near zero for both dynamic and isometric strength. Across the five trials that measured muscle size, the answer was the same.
An eight-week randomized trial in 46 adults tracked this directly. Biceps and quadriceps thickness rose equally in both groups. The shared strength tests climbed 11 to 19 percent whether people trained on free weights or machines.
Where Each One Has An Edge
Each tool gives a small extra edge on the exact movement you practiced. In the 2023 meta-analysis, free-weight training raised free-weight test scores more, while machine training raised machine-test scores more.
Free weights also load the stabilizers harder, the muscles that keep a weight balanced and control its path. In EMG recordings, the free-weight squat drew more from the calf, hamstring, and inner-thigh muscles than the guided Smith-machine version. The free-weight bench press recruited the shoulder stabilizers more than the machine press.
Safety And Skill
The leading weight-room injury is a weight dropping on the person; free weights were involved in 90% of emergency-department weight-training injuries in a national US count.
Machines set the path of the movement, so there is less to learn and less that can go wrong while you learn it. That suits beginners, older adults, and anyone training hard alone: you can push close to failure and then stop, with no weight to drop on yourself. A free weight moves freely, so you control its path yourself, a skill that takes weeks of practice. For a heavy squat or bench press, set the rack's safety pins or use a spotter, so a failed rep gets caught instead of landing on you.
What Each Equipment Level Adds
A trial in previously sedentary women found simple elastic bands and weight machines producing comparable early gains in muscle and function once effort was matched. Bands and a loaded backpack build real strength on their own. Machines add safe heavy loading. Free weights add the coordination demand and the widest range of movements.
The Research & Studies
Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.
Muscle And Strength
Maximal strength gains came out equal, free weights against machines
When effort and volume are matched, machines and free weights build about the same amount of strength. Neither one came out ahead.
The 2023 meta-analysis included 13 studies that directly compared free-weight and machine-based training for at least six weeks in adults aged 18 to 60, with 1,016 participants in total (789 men, 219 women); 12 studies carried maximal-strength outcomes. In the head-to-head pooling neither modality gained more: dynamic strength SMD 0.084 (95% CI -0.106 to 0.273, p=0.387) and isometric strength SMD -0.079 (95% CI -0.432 to 0.273, p=0.660). A separate part of the same analysis found each tool has a small edge on tests that resemble how you trained, which is the specificity finding.
The study · 1
Haugen et al., free-weight vs machine-based strength training on maximal strength, hypertrophy and jump performance · BMC Sports Sci Med Rehabil 2023;15(1):103
Counts once: this finding and 3 others here come from the same source, so they are one body of evidence, not separate confirmations.
Muscle size gains came out equal (SMD -0.055)
For building muscle size, machines and free weights came out even.
Five of the 13 studies in the 2023 meta-analysis measured muscle hypertrophy. In the direct comparison the two modalities were equivalent (SMD -0.055, 95% CI -0.397 to 0.287, p=0.751). The muscle-size pool is smaller than the strength pool, so the estimate is less precise, but it points the same way: growth follows the hard work done, not the tool it is done on.
The study · 1
Haugen et al., free-weight vs machine-based strength training on maximal strength, hypertrophy and jump performance · BMC Sports Sci Med Rehabil 2023;15(1):103
Counts once: this finding and 3 others here come from the same source, so they are one body of evidence, not separate confirmations.
An 8-week trial found equal muscle, both arms up 11 to 19 percent
In a head-to-head trial, both groups gained the same muscle thickness and the same strength on the shared tests over two months.
In this 8-week randomized trial, 46 adults (26 women, mean age about 22) trained each muscle group two to three times a week with three to four sets of four to ten reps. Biceps and quadriceps thickness increased in both arms (p<0.01) with no group difference, and free-weight bench press, free-weight squat and Smith-machine squat strength rose 11 to 19 percent in both arms (p<0.01) with no group difference. One machine-specific test was the exception: machine bench press strength increased more in the machine-trained group (13.9 versus 8.6 percent), an example of training specificity.
The study · 1
Schwanbeck et al., training with free weights versus machines on muscle mass, strength, free testosterone and free cortisol · J Strength Cond Res 2020;34(7):1851-1859
Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.
Your strength shows up most on the tool you trained (free-weight tests p=0.023)
You get a little extra on the exact kind of lift you practiced: free weights help free-weight tests, machines help machine tests.
In the 2023 meta-analysis, the modality that matched the test had the edge. Free-weight training improved free-weight strength tests more than machine training did (SMD -0.210, 95% CI -0.391 to -0.029, p=0.023). Machine training tended to improve machine-based tests more than free weights did (SMD 0.291, 95% CI -0.017 to 0.600, p=0.064), a difference that fell just short of the usual significance cut. This is task specificity: the edge appears only when the test mirrors the training tool, while the overall head-to-head strength comparison was equal.
Train on what you want to be strong at. For barbell lifts or carrying real objects, spend more time with free weights; for a specific machine movement or a rehab target, the machine transfers best to that.
The study · 1
Haugen et al., free-weight vs machine-based strength training on maximal strength, hypertrophy and jump performance · BMC Sports Sci Med Rehabil 2023;15(1):103
Counts once: this finding and 3 others here come from the same source, so they are one body of evidence, not separate confirmations.
Jump and explosive power improved about equally (p=0.290)
Jumping power improved about the same with either free weights or machines.
Five of the thirteen studies in the 2023 meta-analysis measured jump performance. The direct comparison of countermovement jump found no difference between free weights and machines (SMD -0.209, 95% CI -0.597 to 0.179, p=0.290). Peak power is trained best by movements that mimic the target action, so athletes usually add dedicated jump and sprint work on top of either resistance tool.
The study · 1
Haugen et al., free-weight vs machine-based strength training on maximal strength, hypertrophy and jump performance · BMC Sports Sci Med Rehabil 2023;15(1):103
Counts once: this finding and 3 others here come from the same source, so they are one body of evidence, not separate confirmations.
Squat and leg press both improved function, each more on what it resembled
Both the barbell squat and the leg-press machine improved real-world measures like jumping and balance, each a bit more on the thing it resembled.
Participants were pair-matched on strength and randomized to squat only, leg press only, or both, for ten weeks of two lower-body sessions a week at 8 to 12 RM. The squat showed greater transfer to maximal squat strength; effect sizes for countermovement jump favored the squat and the combined group, while effect sizes for dynamic balance favored the leg press and the combined group. No statistical differences reached significance between conditions, so the pattern is a direction, not a settled number.
Who this may not transfer to:The published summary does not state the sex mix, and the small sample has not been repeated across balanced groups, so read the carryover pattern cautiously for any specific reader.
Pick the movement that matches your goal: the squat for athletic power and free-weight strength, the leg press when balance demand or joint comfort is the priority, or both together.
The study · 1
Rossi et al., strength, body composition and functional outcomes in the squat versus leg press · J Sports Med Phys Fitness 2018;58(3):263-270
Bands and machines gave beginners similar early gains
For beginners, guided machines and simple bands produced similar early gains, and both are easy to start with.
Forty-five previously sedentary middle-aged women were randomized to elastic bands, weight machines, or a control group, training twice a week for ten weeks with intensity equalized by target number of repetitions and rate of perceived exertion. Both training groups reduced fat mass and increased fat-free mass and functional test scores (knee push-up and 60-second squat) while the control group did not change. The two guided, low-skill tools produced comparable adaptations in this early phase of training.
Who this may not transfer to:All participants were sedentary middle-aged women; the comparison has not been repeated in men or in trained lifters.
The study · 1
Colado and Triplett, elastic bands versus weight machines for sedentary middle-aged women · J Strength Cond Res 2008;22(5):1441-1448
How it works
The free-weight squat recruited stabilizers 43 percent more than the Smith machine
The free-weight squat switched on the calf, hamstring and stabilizing muscles more than the guided machine version.
Six healthy participants each performed one set of eight reps at their eight-rep max for the free-weight squat and the Smith-machine squat in randomized order, with EMG recorded from the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae and rectus abdominis. Activation was significantly higher in the free-weight squat for gastrocnemius (+34 percent), biceps femoris (+26 percent) and vastus medialis (+49 percent), with a 43 percent higher average across all muscles (p<0.05). This is a single acute session, so it shows demand on the day, not a training outcome.
Who this may not transfer to:Six healthy adults; the sex mix was not reported and the finding has not been checked in a larger or balanced sample.
The study · 1
Schwanbeck et al., free weight squat versus Smith machine squat using electromyography · J Strength Cond Res 2009;23(9):2588-2591
The free-weight bench press recruited the shoulder stabilizer more
Pressing free weights called on the shoulder stabilizers more than the guided machine press did.
This EMG study compared the Smith-machine and free-weight bench press at 70 and 90 percent of one-rep max in experienced and inexperienced pressers, with two testing sessions each. Normalized activation of the medial deltoid was greater on the free-weight press, while the pectoralis major and anterior deltoid were comparable between tools; activation was higher at 90 than 70 percent for both. It is an acute session, not a training study, so it shows a stabilizer demand, not more growth over time.
Who this may not transfer to:The published summary does not state the sex mix, and the acute finding has not been checked in a larger balanced sample.
The study · 1
Schick et al., muscle activation between a Smith machine and free weight bench press · J Strength Cond Res 2010;24(3):779-784
Free weights gave men a bigger acute testosterone rise, with no extra muscle
Free-weight sessions gave men a bigger short-term testosterone bump, but it did not add up to more muscle.
In the same 8-week randomized trial of 46 adults, salivary hormones were sampled around sessions at the start, midpoint and end. Men in the free-weight group had a greater increase in free testosterone from before to after acute sessions than men on machines and than all women (p<0.01), while free cortisol responses did not differ between groups. Muscle thickness and strength gains were equal between the free-weight and machine arms, so the transient hormone difference did not become a physique difference.
Who this may not transfer to:The testosterone difference was specific to the men in the trial; women did not show the same rise.
The study · 1
Schwanbeck et al., training with free weights versus machines on muscle mass, strength, free testosterone and free cortisol · J Strength Cond Res 2020;34(7):1851-1859
Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.
When To Choose Which
The best default is both. Use machines for the lifts you want to push heavy, because the guided path lets you go hard safely. Use free weights for the movements where balance and everyday carryover matter.
Older adults gain strength as readily as anyone, and a machine makes it easier to start safely. Adherence decides the outcome, the tool you will train with twice a week for years beats the one you abandon.
Go Deeper
- Resistance training: the dose that drives gains, and how to progress it over weeks.
- The minimum effective dose: how far a minimal-equipment program can take you.
- Protein and muscle: what to eat around training so the work turns into muscle.
- The sit-to-stand test: a quick check of everyday leg strength.
Cautions For This Practice
Everything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.
Free weights were involved in 90.4 percent of ER weight-training injuries
This descriptive epidemiology study drew on the US National Electronic Injury Surveillance System, a 100-hospital sample weighted to national estimates. From 1990 to 2007 it counted 25,335 sampled injuries, an estimated 970,801 nationwide; mean age 27.6 years, 82.3 percent male. Free weights were involved in 90.4 percent, the commonest mechanism was a weight dropping on the person (65.5 percent), and free-weight users had a greater share of fractures and dislocations than machine users (23.6 versus 9.7 percent). Adults 55 and older were injured relatively more on machines (18.2 versus 9.3 percent), a reminder that the safer tool depends on who is lifting.Kerr et al., epidemiology of weight training-related injuries presenting to US emergency departments 1990 to 2007
Learn the movement before you load it
Good form matters on both. A machine fixes the path, which shortens the learning curve. A free weight leaves the path to you. Spend the first sessions light, grooving the pattern before you add load.
Add load in small steps
Adding weight too fast is the most common way to get hurt: the load climbs faster than the muscle and tendon can adapt to it. Add weight in small steps on either tool. Get the form right first, then increase the load.
Spot or set the safeties for heavy free-weight lifts
For a heavy barbell bench or squat, train with a spotter or set the rack's safety pins. A missed rep is then caught, not dropped on you. Machines tend to fail more safely on their own, which is part of why they suit training alone.
Clear it first if a condition or injury applies
An existing injury, recent surgery, uncontrolled blood pressure, or a joint or connective-tissue condition can change what movements and what tool suit you. Ask a doctor or a qualified coach. They will often point you to a machine while a free-weight pattern is rebuilt.
Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.
Common Questions
Does higher muscle activation with free weights mean more growth?
No. The EMG differences come from single sessions. Over a full training block the two tools even out, and the extra activation on the day has not been shown to become extra muscle over the months.
Which is better for building leg strength?
About the same. A small trial comparing the barbell squat with the leg-press machine found both improving functional measures.
Explore Related
Other pages this one connects to, by the evidence they share, the outcomes they touch, and the ground they cover.
All 11 sources on this page independently checked and cross-referenced.
Thomas Dehli, Founder & Editor, Sacred Lotus
Sacred Lotus has published Chinese medicine reference material since 2001. Integrative pages are held to the same standard as the herb and formula library: cite the source, grade the claim at its real strength, and say where the research has not looked. This page is educational and it is not medical advice. Last reviewed and updated August 10, 2026.
Evidence strength
How confidently the research supports a claim. Strength describes the evidence, not our endorsement.