There is a pattern that repeats in a lot of training histories. Someone starts a strength training programme, sticks with it for six or eight weeks, and notices their posture getting worse. The shoulders sit further forward, the upper back feels locked, and standing tall takes effort it did not take before. They stop, spend a few months on yoga or restorative work, feel normal again, and then start over. After that happens two or three times, they conclude that their body does not tolerate strength training.
The evidence behind that conclusion is personal and it repeats, so it is understandable that people arrive at it. It also runs against what the research shows, and the gap between the two is worth closing if you want to train with kettlebells without repeating the cycle.
This article covers what is happening when strength training seems to wreck your posture, why kettlebell training in particular gets blamed for back problems, and what the research says about posture, fascia, and load. The first half is plain language. The second half goes into the studies.
What “strength training is making my posture worse” usually means
Most people who reach this conclusion are working from a sensation rather than a measurement: tightness through the chest and front of the shoulders, a sense of being pulled into a hunch, effort required to stand upright. There is usually no before-and-after photograph, no craniovertebral angle, no kyphosis measurement to go with it.
That matters, because the sensation of being pulled forward and the measured position of your spine are two separate things, and they come apart more often than people expect. Muscle soreness, protective guarding, and unfamiliar tension all produce the feeling of poor posture without changing a single angle. So the useful question is not whether your body is rejecting the training, but what changed in those six weeks and whether the change explains the sensation.
Four ordinary things explain it more often than a faulty body does.
Four things that explain it better than a faulty body
Load and technique got ahead of skill
This is the most common one and the easiest to verify. Someone buys a kettlebell, watches a video, and starts swinging. The hip-hinge swing looks simple from the outside, which is part of why it goes wrong. Rounding under load at the bottom, standing too upright at the wrong moment, using the arms to lift instead of letting the hips drive, holding the breath through every repetition, any of these can produce back and neck complaints within a couple of weeks.
A tweaked lower back after a fortnight of unsupervised swinging tells you a skill was loaded before it was built. It does not tell you your body is unsuited to strength training. Those two explanations point to different fixes, and only one of them involves quitting.
The programme built one side of the body harder than the other
A conventional push, pull, legs split can be run well. It can also be run in a way that piles pressing volume on top of a body that already spends nine hours a day in flexion, while the pulling volume that exists on paper gets performed with less intent and less load. When the chest and front-delt work drives adaptation and the mid-back work does not, eight weeks later the front is tighter and the upper back is no stronger, which produces the sensation people describe. The cause there is how the programme was balanced, and the fix is to rebalance it.
Tension gets switched on and never switched off
This one is under-discussed, and it is worth looking at hardest in anyone who resets themselves with yin yoga or Alexander Technique and finds that it works.
If those practices reliably restore you, that points somewhere specific. Both of them train the nervous system to stop generating unnecessary tension. Some people brace the trunk, jaw, neck, and shoulders for the whole duration of a set, including the portions where nothing is being lifted, and carry a residue of that bracing into the rest of the day. Weeks of that feels like posture deteriorating, and a practice that teaches the body to let go is exactly what would relieve it. The direction to work in, then, is learning where tension belongs during an exercise and where it does not, which is a skill you can build inside the training rather than a reason to stop.
The stop-start cycle prevents adaptation
Six weeks of training followed by three months off gives you a series of first weeks rather than a training history. Every restart is performed by a body that has lost most of what it gained, so every restart carries the soreness, stiffness, and awkwardness of week one. When the whole of someone’s experience is made of week ones, strength training will reliably feel like it does not agree with them, because they have not yet reached the part where it settles. Most of the trial evidence later in this article runs twelve weeks or longer for a reason.
Where kettlebells fit into this
Kettlebell training gets blamed for back problems more than most tools, partly because a kettlebell is easy to buy and start using badly, and partly because the ballistic exercises load a hinge pattern most people have never been taught.
There is another side to that. Ballistic kettlebell work is one of the few things in a gym that explicitly trains the switch between tension and relaxation. In a hip-hinge swing done well there is a sharp contraction at the top and a genuine release on the way down: the bell floats, the arms hang, the shoulders stay down, and then everything fires again at lockout. That contraction and relaxation cycle is one of the distinguishing features McGill and Marshall identified in the swing (McGill and Marshall, 2012). For the detail on which muscles fire and when, that is covered in Muscles Worked With Kettlebell Swings.
For someone whose underlying problem is chronic over-bracing, that is a useful property, because the skill the exercise trains is the skill they are missing. Whether it trains it depends on how it is coached. A swing performed with a clenched jaw, gripped shoulders, and a trunk braced from start to finish rehearses the over-bracing under load instead of relieving it.
What the research actually says
Strength training is used to improve posture, not to degrade it
If strength training reliably made posture worse, trials would tend to show it. They tend to show improvement. A randomised controlled trial run in two Portuguese secondary schools assigned 130 adolescents with forward head and protracted shoulder posture to a 32-week resistance and stretching programme or a control group, and found improvements in cervical and shoulder angles in the training group that the control group did not show (Ruivo et al., 2016; Ruivo et al., 2017).
A 2024 systematic review and meta-analysis of therapeutic exercise for upper crossed syndrome reached a similar place. Strength exercises, stretching, shoulder-focused work, and comprehensive programmes targeting all the involved muscles all appeared effective for reducing forward head posture, rounded shoulders, and thoracic kyphosis (Sepehri et al., 2024).
Resistance training is prescribed as a treatment for the exact postural presentations people worry about developing, which is difficult to square with the idea that it causes them.
Posture and pain are a looser relationship than you were told
There is a second assumption buried in all of this: that a given posture is the source of the discomfort. The evidence for that link is weaker than the fitness industry implies.
A systematic review and meta-analysis of 46 studies on static postural parameters in low back pain found no difference in thoracic kyphosis between people with and without low back pain, and no difference in leg length discrepancy either (Sugavanam et al., 2024). Pelvic tilt was statistically higher in the low back pain group, and lumbar lordosis may be lower, yet the authors held back from firm conclusions on the lumbo-pelvic parameters because of the high heterogeneity between studies, recommending an individualised approach to postural assessment instead.
That has a bearing in both directions. Posture is a shaky thing to organise your training anxieties around, and the postural change you believe you are feeling may not carry the consequence you fear it does.
Does strength training make you tight?
The belief that strength training shortens muscles and reduces range of motion has been tested directly. A systematic review and meta-analysis of eleven randomised controlled trials with 452 participants compared strength training against stretching for range of motion and found no difference between the two (Afonso et al., 2021).
Full-range strength work functions as a flexibility intervention in its own right. Training through range keeps range.
The fascia claim
Care is needed here, because two very different claims travel under the same word.
Claim one: fascia exists, is continuous, and transmits force. This has support. Wilke and colleagues reviewed anatomical dissection studies and found strong evidence for structural continuity in three of the six examined myofascial meridians, with moderate evidence for parts of the spiral and lateral lines (Wilke et al., 2016). Not all of the proposed lines survived scrutiny: the superficial front line had no verified transition across seven studies, and no structural connection between rectus femoris and rectus abdominis was reported. The map is partly confirmed and partly not.
Claim two: your individual fascia type makes strength training unsuitable for you. This is a separate claim, and it does not carry the same support.
The idea usually traces back to an informal categorisation used in fascia and yoga education, splitting people into a stiffer “Viking” type and a more elastic “temple dancer” type, assessed by things like bending your thumb toward your forearm. The source material itself presents it as a rough simplification along a spectrum. There is no validated diagnostic for it, no established threshold, no published trial in which people categorised this way responded differently to a strength programme, and no proposed mechanism by which a connective-tissue phenotype would make progressive loading harmful.
Even the fascia-focused literature does not tell people to avoid strength training. Robert Schleip’s own guidance points the other way, recommending that hypermobile individuals spend time with weights and dynamic stability work rather than more stretching.
If a trainer tells you your fascia means strength training is not for you, the questions to ask are which test they used, what the result was, and what published evidence links that result to a training recommendation. Those questions have answers for load, volume, and technique. For a fascia-type prohibition, they do not.
Why the swing injured your back
The hip-hinge swing produces a loading profile unlike most barbell exercises. McGill and Marshall measured spine loads during kettlebell swings, snatches, and carries in seven subjects, plus a case study on an experienced instructor. Compression during the 16 kg two-hand swing came in at about 3,200 N, which is modest next to heavy barbell work. The distinguishing feature was a posterior shear of L4 on L5, opposite in polarity to a traditional lifting pattern (McGill and Marshall, 2012).
The authors drew a two-sided conclusion from it. The profile offers an explanation for why many people credit kettlebell swings with restoring back health and function while a few find that swings irritate tissues. Their practical note was that the large shear-to-compression ratio suggests the approach may be contraindicated for some individuals with spine shear-load intolerance.
Two points follow. Shear intolerance is a specific clinical presentation, and it is not a general description of anyone who finds swings hard. And the profile is dictated by technique: a hinge performed with a rounding lumbar spine, an early arm pull, or a load beyond current control changes what those tissues experience. For most people the work is to groove the hinge before adding load to it.
The trial evidence on kettlebell training for people already in pain runs in an encouraging direction. In a single-blind randomised controlled trial, 40 adults from occupations with high rates of musculoskeletal pain performed ballistic full-body kettlebell exercise three times a week for eight weeks. Neck and shoulder pain fell by 2.1 points and low back pain by 1.4 points relative to control, with a significant improvement in trunk extensor strength (Jay et al., 2011).
That sits inside a broader picture. A 2025 systematic review and meta-analysis of ten randomised trials in Disability and Rehabilitation found that resistance training produced significant improvements in pain intensity, quality of life, and disability in people with nonspecific chronic low back pain. The authors recommended programmes be structured, progressive, and run for at least twelve weeks (Disability and Rehabilitation, 2025).
Twelve weeks is longer than most of the attempts that ended in “my body does not tolerate this.”
Restarting without repeating the loop
If the four explanations above describe your situation better than a structural problem does, the restart can look different from the previous ones.
Start with a load that feels unreasonably easy and hold it there longer than instinct suggests. The first month is buying skill and tissue tolerance, not stimulus, so an 8 kg or 12 kg bell for a hinge you are still learning earns its place.
Groove the hinge before you load it: deadlift pattern first, then a low swing, then a full-height swing. A large share of swing-related back complaints trace back to a hinge that was never established.
Keep the tension work in the week rather than saving it for the wreckage. If yin yoga and constructive rest reliably restore you, they earn a place in the programme alongside the training, not only after you have quit it.
Audit your own tension during a set: jaw, tongue, brow, neck, grip. A jaw clenched through the backswing is rehearsing the habit that costs you.
Balance the programme toward what your day does not already supply. Most people need more mid-back and rear-shoulder work than their programme contains, and less pressing than their preferences pull them toward.
Give it twelve weeks before you evaluate it. Six weeks is a warm-up.
If it still goes wrong
Nothing here rules out a genuine structural or medical cause, and that cannot be assessed from a distance. Persistent pain that follows a specific pattern, radiating symptoms, numbness, night pain, or a history of spinal pathology all warrant assessment by a clinician rather than a training article. A structural cause is possible. The reason it is worth naming the four ordinary explanations first is that people tend to reach “my body rejects strength training” long before they have ruled those four out, and the four fit most cases better.
Most people who believe they are the exception have not yet trained with appropriate load, appropriate programming, and appropriate tension management for long enough to find out whether they are.
Frequently asked questions
Can strength training cause bad posture?
Not through any established mechanism. Controlled trials of resistance-based programmes show improvements in forward head posture, rounded shoulders, and thoracic kyphosis. Unbalanced programmes and chronic over-bracing can produce the sensation of worsening posture without changing measured spinal position.
Are kettlebell swings bad for your lower back?
The hip-hinge swing produces modest spinal compression but an unusual posterior shear at L4 on L5. That profile appears to help many people and irritate a minority, particularly those with shear load intolerance. Technique and load progression determine which group you end up in far more often than anatomy does.
Why does my back hurt after kettlebell swings?
The common causes are a lumbar spine that rounds at the bottom of the hinge, pulling with the arms instead of driving with the hips, a load beyond current skill, and breath-holding through the set. All four are technique issues, and all four are fixable.
Can your fascia type mean strength training is wrong for you?
There is no validated test for fascia type and no published evidence that any such categorisation predicts response to strength training. Fascial continuity is real and partially verified in dissection studies. The leap from that to an individual training prohibition is not supported.
Is being stiff after training a sign something is wrong?
Stiffness in the days after unfamiliar training is ordinary and diminishes as you adapt to a given exercise. Stiffness that persists across months of consistent training more often reflects excessive volume, insufficient recovery, or tension habits than any unsuitability of training for your body.
How long before I can judge whether a programme is working?
Trials of resistance training for back pain generally recommend at least twelve weeks of structured, progressive work. Programmes abandoned at six weeks have not been tested.
References
- Afonso, J., Ramirez-Campillo, R., Moscão, J., Rocha, T., Zacca, R., Martins, A., Milheiro, A.A., Ferreira, J., Sarmento, H., and Clemente, F.M. (2021). Strength Training versus Stretching for Improving Range of Motion: A Systematic Review and Meta-Analysis. Healthcare, 9(4), 427. https://doi.org/10.3390/healthcare9040427
- Jay, K., Frisch, D., Hansen, K., Zebis, M.K., Andersen, C.H., Mortensen, O.S., and Andersen, L.L. (2011). Kettlebell training for musculoskeletal and cardiovascular health: a randomized controlled trial. Scandinavian Journal of Work, Environment & Health, 37(3), 196-203. https://doi.org/10.5271/sjweh.3136
- McGill, S.M., and Marshall, L.W. (2012). Kettlebell swing, snatch, and bottoms-up carry: back and hip muscle activation, motion, and low back loads. Journal of Strength and Conditioning Research, 26(1), 16-27. https://doi.org/10.1519/JSC.0b013e31823a4063
- Ruivo, R.M., Carita, A.I., and Pezarat-Correia, P. (2016). The effects of training and detraining after an 8 month resistance and stretching training program on forward head and protracted shoulder postures in adolescents: Randomised controlled study. Manual Therapy, 21, 76-82. https://doi.org/10.1016/j.math.2015.05.001 | PubMed
- Ruivo, R.M., Pezarat-Correia, P., and Carita, A.I. (2017). Effects of a Resistance and Stretching Training Program on Forward Head and Protracted Shoulder Posture in Adolescents. Journal of Manipulative and Physiological Therapeutics, 40(1), 1-10. https://doi.org/10.1016/j.jmpt.2016.10.005 | PubMed
- Sepehri, S., Sheikhhoseini, R., Piri, H., and Sayyadi, P. (2024). The effect of various therapeutic exercises on forward head posture, rounded shoulder, and hyperkyphosis among people with upper crossed syndrome: a systematic review and meta-analysis. BMC Musculoskeletal Disorders, 25(1), 105. https://doi.org/10.1186/s12891-024-07224-4 | PubMed
- Sugavanam, T., Sannasi, R., Anand, P.A., and Javia, P.A. (2024). Postural asymmetry in low back pain: a systematic review and meta-analysis of observational studies. Disability and Rehabilitation, 47(7), 1659-1676. https://doi.org/10.1080/09638288.2024.2385070
- Does resistance training improve pain intensity, quality of life, and disability in people with chronic nonspecific low back pain? A systematic review and meta-analysis (2025). Disability and Rehabilitation, 48(6), 1532-1545. https://doi.org/10.1080/09638288.2025.2566275 | PubMed
- Wilke, J., Krause, F., Vogt, L., and Banzer, W. (2016). What Is Evidence-Based About Myofascial Chains: A Systematic Review. Archives of Physical Medicine and Rehabilitation, 97(3), 454-461. https://doi.org/10.1016/j.apmr.2015.07.023 | PubMed
