What stretching actually does to your body
The science behind flexibility, range of motion, and healthy ageing
Key takeaways: The evidence for stretching improving flexibility and joint range of motion is robust — multiple meta-analyses confirm meaningful gains from regular programmes of two weeks or more, across all ages. Static and PNF (proprioceptive neuromuscular facilitation) stretching produce the largest long-term flexibility gains; dynamic stretching is well-suited to pre-activity warm-ups. Stretching improves gait speed and balance in older adults, with direct implications for fall prevention and independence. The widely held belief that post-exercise stretching speeds recovery or reduces muscle soreness is not supported — systematic reviews consistently show no meaningful benefit over passive rest for delayed-onset soreness, strength, or performance. Evidence for cardiovascular benefits (reduced arterial stiffness, lower resting blood pressure) is emerging and moderate; programmes typically require months of consistent practice and benefits reverse with detraining. Mental health claims for stretching alone are limited; strong evidence for relaxation and anxiety reduction comes from broader practices — yoga and progressive muscle relaxation — that incorporate stretching alongside breathwork and mindfulness. Strength training can produce ROM gains comparable to dedicated stretching. The practical prescription is simple: consistent, progressive flexibility work for major muscle groups, at least two to three times per week, done carefully and without forcing range.
Stretching sits in an odd position in the fitness literature. It is almost universally recommended — by gyms, physiotherapists, sports coaches, and general health guidance — yet the evidence behind different stretching claims varies enormously. Some benefits are among the best-evidenced in exercise science; others are considerably overstated in popular health coverage.
This companion piece examines what the research actually shows, exploring the mechanisms, the evidence quality, and where the boundaries of current knowledge lie. It accompanies the Open Post, which provides the accessible introduction and practical guidance.
How researchers study stretching
Stretching research uses a hierarchy of methodologies, each with different strengths and limitations.
Randomised controlled trials (RCTs) assign participants to stretching or control conditions and measure outcomes — range of motion (ROM), balance, muscle stiffness, cardiovascular markers — at defined intervals. These are the strongest design for establishing causation, and there are many well-powered RCTs in the stretching literature.
Systematic reviews and meta-analyses pool data from multiple RCTs to produce more precise estimates of effect size. The stretching field has several high-quality meta-analyses covering flexibility, recovery, cardiovascular health, and balance — which allows a fairly confident assessment of what the evidence does and does not support.
Mechanistic studies examine underlying biological pathways: how stretching affects the structural properties of muscle and connective tissue, how it influences the autonomic nervous system, and how it affects the function of blood vessels. These help explain the 'why' behind observed effects.
The key limitation specific to stretching research is that studies vary considerably in the type of stretch studied (static, dynamic, PNF, ballistic), the muscle groups targeted, the duration and frequency of sessions, and the length of the programme. Meta-analyses attempt to account for this heterogeneity, but comparisons across studies require caution.
Flexibility and range of motion: the strongest evidence
The most well-evidenced benefit of stretching is also the most intuitive: it improves flexibility and joint range of motion. This is the area of stretching science with the clearest, most consistent evidence base.
KEY RESEARCH
Konrad, A., Alizadeh, S., Daneshjoo, A., et al. (2023). Chronic effects of stretching on range of motion with consideration of potential moderating variables: A systematic review with meta-analysis. Journal of Sport and Health Science, 13, 186–194. https://doi.org/10.1016/j.jshs.2023.06.002
This 2023 systematic review and meta-analysis — drawing on data from a substantial body of RCT evidence — confirmed that chronic stretching programmes (typically defined as two weeks or more of regular practice) produce meaningful, statistically significant increases in joint ROM. The effects were moderate in size and consistent across different muscle groups, ages, and stretch durations within the commonly studied range.
Static stretching (holding a position for a sustained period, typically 15–60 seconds) and PNF stretching (which involves cycles of contraction and relaxation, often assisted by a partner or therapist) showed the largest long-term ROM gains. Dynamic stretching — controlled movement through a range, as in leg swings or arm circles — produced smaller chronic ROM improvements but is appropriate for pre-activity warm-ups for reasons discussed below.
Ballistic stretching — using momentum to push past the comfortable range — is generally not recommended due to increased injury risk and inferior ROM outcomes compared to static and PNF techniques.
KEY RESEARCH
Behm, D., Alizadeh, S., Daneshjoo, A., et al. (2023). Acute Effects of Various Stretching Techniques on Range of Motion: A Systematic Review with Meta-Analysis. Sports Medicine - Open, 9. https://doi.org/10.1186/s40798-023-00652-x
For acute (single-session) effects, this meta-analysis found that all major stretching techniques produce small but consistent immediate improvements in ROM. Importantly, these effects were not strongly dependent on stretch intensity or duration within the commonly used ranges — suggesting that mild, comfortable stretching is sufficient for acute ROM gains, and that pushing into discomfort offers no additional benefit.
Mechanisms: why does stretching improve ROM?
Two mechanisms are thought to underlie ROM improvements from stretching. The first is structural: regular stretching over time increases the length and compliance of the muscle-tendon unit, reduces passive stiffness, and may stimulate the addition of sarcomeres (the contractile units within muscle fibres) in series. The second is neurological: stretching training appears to increase tolerance to stretch — the sensation of discomfort at a given range decreases with regular practice, allowing a greater range to be achieved. Evidence suggests both mechanisms contribute, with the neurological (tolerance) effect operating in shorter timeframes and the structural adaptation accumulating over longer programmes.
Does strength training also improve flexibility?
KEY RESEARCH
Afonso, J., Ramirez-Campillo, R., Moscão, J., et al. (2021). Strength Training versus Stretching for Improving Range of Motion: A Systematic Review and Meta-Analysis. Healthcare, 9. https://doi.org/10.3390/healthcare9040427
An important nuance from the research: strength training, when performed through a full range of motion, can produce flexibility gains comparable to dedicated stretching. This review found that resistance training was at least as effective as stretching for improving ROM across multiple muscle groups. This does not diminish the case for stretching, but it does mean that people who engage in regular full-range strength training should not assume they lack flexibility work simply because they do not stretch separately.
Stretching, ageing, and functional movement
The case for stretching is perhaps strongest when considered through the lens of ageing. Flexibility and joint mobility decline naturally with age — a process that begins earlier than most people realise and accelerates from the fifth decade onwards. This decline is associated with reduced functional independence, increased fall risk, and diminished quality of life.
KEY RESEARCH
Zhang, P., Chen, J., & Xing, T. (2025). Effects of post-exercise stretching versus no stretching on lower limb muscle recovery and performance: a meta-analysis. Frontiers in Physiology, 16. https://doi.org/10.3389/fphys.2025.1674871
KEY RESEARCH
Nakamura, M., Takeuchi, K., Fukaya, T., et al. (2023). Acute effects of static stretching on passive stiffness in older adults: A systematic review and meta-analysis. Archives of Gerontology and Geriatrics, 117, 105256. https://doi.org/10.1016/j.archger.2023.105256
Research confirms that static stretching reduces passive muscle stiffness in older adults to a similar degree as in younger populations — which is an important finding, since it suggests the ageing musculoskeletal system remains responsive to flexibility training.
KEY RESEARCH
Salse-Batán, J., González-Devesa, D., Duñabeitia, I., et al. (2024). Effects of stretching exercise on walking performance and balance in older adults: A systematic review and meta-analysis. Geriatric Nursing, 61, 479–490. https://doi.org/10.1016/j.gerinurse.2024.12.018
This meta-analysis found that stretching programmes improved both gait speed and balance in older adults — outcomes with direct practical significance. Gait speed is a well-validated predictor of overall health and longevity in older adults. Balance improvement translates directly to reduced fall risk. These are among the most clinically meaningful functional benefits of any exercise modality in older populations.
The implication for practice is clear: regular flexibility training is most valuable when maintained as a lifelong habit, rather than something taken up reactively when stiffness becomes a problem. The earlier it is incorporated into routine, the more it preserves the baseline from which age-related decline proceeds.
The recovery myth: what the evidence actually shows
One of the most persistently overstated claims about stretching is that it accelerates recovery from exercise and reduces delayed-onset muscle soreness (DOMS) — the characteristic ache that develops 24–72 hours after unaccustomed or intense exercise.
KEY RESEARCH
Afonso, J., Clemente, F., Nakamura, F., et al. (2021). The Effectiveness of Post-exercise Stretching in Short-Term and Delayed Recovery of Strength, Range of Motion and Delayed Onset Muscle Soreness: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Frontiers in Physiology, 12. https://doi.org/10.3389/fphys.2021.677581
This systematic review and meta-analysis of RCTs found no meaningful difference between post-exercise stretching and passive rest for DOMS, strength recovery, or performance at any measured time point. The effect sizes were negligible. Similar conclusions have been reached by multiple independent research groups examining different populations, exercise modalities, and stretching protocols.
Similarly, the long-held belief that pre-exercise stretching reduces injury risk is not well supported. The most rigorous evidence — including a systematic review by Herbert and Gabriel (2002), which remains influential — found that stretching before or after exercise does not meaningfully reduce injury risk in general training populations.
The honest clinical picture is this: post-exercise stretching does not speed recovery in any measurable physiological sense. It may feel pleasant and serve as a useful transition out of activity. It helps maintain the flexibility gains being built through regular practice. But it should not be performed with the expectation that it will reduce DOMS or prevent injury — the evidence does not support those claims.
Cardiovascular effects: emerging and moderate evidence
A less familiar benefit of stretching — and one with a more surprising biological rationale — is its apparent effect on vascular health.
KEY RESEARCH
Kato, M., Green, F., Hotta, K., et al. (2020). The Efficacy of Stretching Exercises on Arterial Stiffness in Middle-Aged and Older Adults: A Meta-Analysis of Randomized and Non-Randomized Controlled Trials. International Journal of Environmental Research and Public Health, 17. https://doi.org/10.3390/ijerph17165643
This meta-analysis found that regular stretching programmes reduce arterial stiffness and lower resting heart rate and diastolic blood pressure in middle-aged and older adults. The plausible mechanism is that sustained mechanical loading of the vessel wall during stretching — particularly of larger muscle groups and adjacent blood vessels — stimulates endothelial cells to produce nitric oxide, a vasodilatory compound that improves arterial compliance over time.
KEY RESEARCH
Shinno, H., Kurose, S., Yamanaka, Y., et al. (2017). Evaluation of a static stretching intervention on vascular endothelial function and arterial stiffness. European Journal of Sport Science, 17, 586–592. https://doi.org/10.1080/17461391.2017.1284267
KEY RESEARCH
Arango-Paternina, C., Ramírez-Villada, J., & Márquez-Arabia, J. (2025). Effects of muscle stretching exercises on endothelial function in adults: A systematic review. Sport Sciences for Health, 21, 1313–1326. https://doi.org/10.1007/s11332-025-01356-3
The evidence here warrants appropriate calibration. The study sizes are generally small, evidence quality is variable, and this area of research is relatively young. Cardiovascular benefits from stretching programmes typically require months of consistent practice to manifest, and the evidence suggests they reverse with detraining — meaning the benefits are not permanent once the practice is discontinued.
This does not diminish the finding — arterial stiffness is an independent predictor of cardiovascular events, and any modality that reduces it has genuine clinical interest. But this benefit should be understood as a welcome additional effect of a stretching habit already motivated by flexibility and mobility goals, not as a primary reason to stretch in lieu of cardiovascular exercise.
Stretching and mental well-being: calibrating the claims
The relationship between stretching and mental health is frequently overstated in popular health content. The evidence requires careful disaggregation.
KEY RESEARCH
Khir, S., Yunus, W., Mahmud, N., et al. (2024). Efficacy of Progressive Muscle Relaxation in Adults for Stress, Anxiety, and Depression: A Systematic Review. Psychology Research and Behavior Management, 17, 345–365. https://doi.org/10.2147/prbm.s437277
KEY RESEARCH
Cramer, H., Lauche, R., Anheyer, D., et al. (2018). Yoga for anxiety: A systematic review and meta-analysis of randomized controlled trials. Depression and Anxiety, 35, 830–843. https://doi.org/10.1002/da.22762
The strong evidence for relaxation and mental health benefit comes from progressive muscle relaxation (PMR) and yoga — both of which incorporate stretching alongside systematic attention to breathing and mental focus. PMR, specifically, has robust evidence for reducing anxiety and depression across adult populations. Yoga shows consistent evidence for anxiety reduction across multiple systematic reviews.
The important qualification is that these protocols involve considerably more than stretching alone. PMR involves systematic progressive tension and release of muscle groups paired with deliberate attention. Yoga incorporates breathwork, mindfulness, and often a social or community dimension. It is not currently possible to attribute the mental health benefits observed in these interventions to the stretching component specifically.
For simple stretching — holding muscle groups in a lengthened position without additional breathing or mindfulness — the specific evidence for measurable mental health effects is sparse. The subjective experience of calm that many people report is plausible and consistent with what slow, deliberate physical attention tends to produce, but it has not been isolated and quantified in a robust research literature.
The responsible position is that stretching, practised calmly and with attention to breath, is a reasonable complement to stress management — but should not be positioned as a primary mental health intervention.
Stretch type, timing, and programming
Pre-activity: dynamic stretching preferred
There is now good consensus that static stretching immediately before activity — particularly high-intensity exercise or sports performance — can acutely reduce muscle force production, power output, and reaction time if held for prolonged periods (typically >60 seconds per muscle group). The reduction is generally modest and transient, but is relevant in contexts where peak performance is required.
Dynamic stretching (controlled movement through the range of motion — leg swings, hip circles, arm rotations, walking lunges) is the preferred warm-up modality: it increases muscle temperature, enhances neuromuscular activation, improves acute ROM, and does not produce the performance decrements associated with prolonged static holds. A 5–10 minute dynamic warm-up is appropriate before most forms of exercise.
Post-activity and standalone: static and PNF
Static stretching — held for 15–60 seconds per muscle group — is well-suited to post-activity flexibility work or standalone flexibility sessions. It is the modality with the largest chronic ROM gains in the literature and is appropriate for all populations. Holds beyond 60 seconds do not appear to produce additional benefit over shorter holds.
PNF stretching — which involves a contraction phase (pushing against resistance at the end of range) followed by a deeper stretch — produces the largest chronic ROM improvements of any technique and is used extensively in clinical rehabilitation. It is most practically performed with a partner or physiotherapist, limiting its accessibility for self-directed practice.
Frequency and programme length
The evidence suggests that flexibility work for major muscle groups two to three times per week is sufficient to produce meaningful ROM gains. Daily practice produces faster initial gains and is appropriate for those with specific flexibility deficits or functional goals. Chronic ROM improvements are typically detectable after two weeks and continue to accumulate over months of consistent practice.
Critically, flexibility gains are not permanent. Detraining effects are measurable within a few weeks of stopping — meaning that the goal is a sustainable, long-term habit rather than an intensive short-term programme.
Safety and contraindications
Stretching is among the safest forms of exercise for most populations. The most common errors are overstretching (pushing into sharp pain rather than mild discomfort), bouncing or ballistic movement at end-range, and stretching cold muscles without any preceding warm-up movement.
The principle consistently supported by research is that effective stretching should feel like a mild to moderate pull — a sensation of tension, not pain. Sharp pain, joint discomfort, numbness, or tingling are signals to ease off. These principles are consistent with how stretching has been applied across the studies reviewed here.
Specific populations warrant additional consideration. People with hypermobility conditions (such as hypermobile Ehlers-Danlos syndrome) may need to avoid end-range flexibility work and focus instead on stability and strength. People with acute muscle strains or joint injuries should seek guidance before stretching the affected area. Older adults with osteoporosis should avoid extreme ranges in the spine. In these cases, a physiotherapist's input is advisable.
Putting it together: stretching and health-span
From a health-span perspective, the evidence on stretching converges on several well-grounded conclusions.
The benefits with the strongest evidence are improved flexibility and joint range of motion, reduced passive muscle stiffness, and — in older adults — improved gait and balance. These are practically meaningful outcomes that directly affect the ease and independence of daily movement.
The cardiovascular and vascular benefits are real but require consistent, sustained practice over months and should be understood as supplementary to — not a replacement for — aerobic exercise.
The recovery and injury prevention claims that dominate popular health content are, by contrast, poorly supported and should be communicated accordingly.
The mental well-being benefits are genuine in the context of broader relaxation practices but should not be attributed to simple stretching alone.
The practical implication is a positive one: a modest, consistent stretching habit — two to three times per week, targeting the major areas of common tightness, using static holds of 15–60 seconds per group — is a genuinely worthwhile component of a movement routine. It is not dramatic. It does not require equipment or significant time. And the returns, accumulated over years and decades, include the capacity to move through daily life with less restriction, less stiffness, and greater ease.
That, in the end, is what Be Active — Pillar Three of The New 5-a-Day — is about.
A note on medical advice: This Deep Dive is intended for readers who want to engage with the evidence in more depth. It does not replace professional medical or physiotherapy advice. If you have specific concerns about joint pain, mobility limitations, or health conditions affecting your ability to exercise, please speak to your GP or a qualified health professional.
Want to read further? Full citations for all research referenced in this post are available in the accompanying Reference List.
