Study archive · page 10

A systematic review of 14 randomised trials found that physical activity programmes improved at least one cardiorespiratory fitness or cardiovascular risk measure in women, yet only one trial actually compared premenopausal with postmenopausal women, and all but two trials were rated low methodological quality.

⚠What it shows: Treat this as a signal rather than settled science: a sweep of all the studies found 14 trials, all showing some benefit, but all except two were rated low quality and only one compared women before and after menopause, so menopause-specific effects remain largely untested.Systematic review · Menopause

Pooling 6 controlled trials in 585 healthy women, adding exercise to hormone therapy produced no significant extra gain in bone mineral density at the spine or hip compared with hormone therapy alone, despite a small trend in favour of the combination.

⚠What it shows: Treat this as an open question rather than a closed case: results pooled from 6 trials covering 585 women showed a small trend favouring the combination that never reached significance. The trials used very different hormone doses and enrolled women in different hormonal states, which may have blurred any real effect.Meta-analysis · J Clin Endocrinol Metab

Pooled results from randomised trials in 998 pregnant and postpartum women found exercise improved sleep quality, sleep efficiency, sleep duration, time to fall asleep, insomnia and daytime tiredness, with medium to very large effects.

⚠What it shows: A consistent and sizeable benefit, but from a small evidence base: results pooled from trials in 998 pregnant and postpartum women across eight countries, and only seven of the ten included trials had data that could be combined.Meta-analysis · Behav Sleep Med

Pooled results from 13 randomised trials in 694 postmenopausal women found structured exercise programmes reduced BMI by 0.87 kg/m2, lowered body fat percentage and trimmed waist-to-hip ratio by 0.03. Evidence on body image was too limited to draw any conclusion.

⚠What it shows: Strong for the fat and waistline results: pooled from 13 trials in 694 postmenopausal women, mostly at low risk of bias, and the findings agreed closely across trials for BMI and waist-to-hip ratio. The body image question is wide open, since only one study measured it before and after.Study · Menopause

Adults with insomnia showed markedly elevated circulating cortisol and raised inflammatory markers including IL-6, TNF-α, CRP, IL-1β, IL-2 and IFN-γ compared with healthy sleepers, in a meta-analysis pooling 32 studies of 4578 people with insomnia and 28382 controls. Neuropeptide Y was reduced, while several other markers including BDNF showed no difference.

⚠What it shows: A consistent pattern but not proof of cause: results pooled from 32 studies that compared people with insomnia against healthy sleepers rather than testing anything, so it cannot say whether poor sleep drives these blood changes or something else drives both.Meta-analysis · Front Immunol

Pooled results from 13 randomised trials in 782 perinatal women suggest mind-body therapies such as mindfulness, Pilates and yoga improve sleep quality compared with controls, though the certainty of the evidence was rated low.

⚠What it shows: Encouraging but shaky: results pooled from 13 trials in 782 women during and after pregnancy showed better sleep scores, yet the studies disagreed strongly with each other. The reviewers themselves rated the overall evidence as low certainty.Meta-analysis · Front Public Health

Pooled trial data found non-drug interventions significantly improved sleep quality in nurses working rotating shifts. Mindfulness programmes were beneficial, while aromatherapy showed no significant improvement.

⚠What it shows: A believable overall benefit but an untidy evidence base: results pooled from 11 trials of shift-working nurses, and the trials disagreed with each other a great deal, so the true size of the effect is uncertain. The clearest single message is that aromatherapy, one of the most popular options, did not show a significant benefit.Study · Occup Med (Lond)

Pooled results from ten randomised trials in 1463 midlife and older women found that programmed exercise lasting 12 weeks to 4 months reduced mild-to-moderate anxiety symptoms, while longer programmes running 6 to 14 months showed no reduction at all.

⚠What it shows: Decent evidence with one wobble: results pooled from ten trials in 1463 midlife and older women, and the benefit for the shorter programmes only just cleared statistical significance. Why year-long programmes showed nothing is still unexplained.Meta-analysis · Climacteric

Across 39 trials with 2,059 participants, mindfulness-based stress reduction programmes lowered cortisol, and beat control conditions in head-to-head comparisons. The effect was modest and varied considerably between studies.

⚠What it shows: A solid overall signal: results pooled from 39 trials in 2,059 people show a real but modest drop in cortisol, clearest in properly controlled trials and smaller when mindfulness was compared against other active programmes. The studies disagreed with each other for reasons the analysis could not explain.Study · Health Psychol

Across 30 low risk of bias trials of physical activity programmes, most participants failed to achieve their activity goals at every timepoint, with failure rates between 57.9% and 77.0%, and achievement declined further over time. Goals people set themselves, or set collaboratively, were achieved more often than goals prescribed to them.

⚠What it shows: A thorough sweep of all the studies on this, pooling 89 trials of 10,219 people, with the main analysis limited to the 30 most trustworthy studies. It measures goal achievement inside structured programmes, so it may not describe targets you set entirely on your own.Review · Health Psychol Rev

A systematic review of 15 randomised controlled trials found mixed evidence on whether low-load lifting with blood flow restriction damages muscle: some trials suggest damage may occur within 1 week, longer-term studies found none, and the technique still delivered gains in muscle strength and size.

⚠What it shows: Treat this as an open question rather than a verdict: a sweep of all the trials found only 15 in healthy adults, and nearly half of them could not say either way whether the cuffs cause muscle damage. The reviewers themselves call for bigger trials before anyone can be confident.Systematic review · Clin Physiol Funct Imaging

An umbrella review of meta-analyses in people with sarcopenic obesity found resistance training improved gait speed by 0.14 to 0.17 m/s and lower leg strength by 9.97 kg, while aerobic exercise, mixed exercise and calorie-restricted diets with protein supplementation showed no significant benefit; certainty of evidence was moderate to very low.

⚠What it shows: Treat this as a pointer rather than a verdict: it pulls together four earlier reviews whose trials covered between 30 and 225 people, and the authors rate the certainty of the evidence as moderate to very low. Resistance training's edge may partly reflect it being the most studied option.Systematic review · Curr Obes Rep

In pooled results from 9 trials in 1420 older adults with sarcopenia, combining vitamin D with protein supplementation and exercise clearly improved hand grip strength, while vitamin D on its own shortened chair-stand time but did not improve gait speed or muscle mass.

⚠What it shows: Reasonably solid as far as it goes: results pooled from 9 trials in 1420 older adults with age-related muscle loss. Many of the comparisons are indirect, drawn across trials rather than within them, so the winning combination has not been tested head to head in one large trial.Meta-analysis · Nutrients

A systematic review of 18 randomised controlled trials covering 819 healthy adults concluded that probiotic supplements have only a limited effect on circulating immune and inflammatory markers; 8 trials reported some changes, but the evidence was too inconsistent to size any effect.

⚠What it shows: A solid basis for scepticism: this sweep of all the trials in healthy adults, 819 people across 18 studies, found the results so inconsistent that they could not even be combined into a single estimate. It says nothing about people with illness, where probiotics may behave differently.Systematic review · J Acad Nutr Diet

Pooled results from seven randomised trials suggest synbiotic supplements improve fasting glucose, insulin levels, insulin resistance, triglycerides and total cholesterol in people with diabetes, but have no effect on LDL or HDL cholesterol.

⚠What it shows: Promising but thin: results pooled from just seven trials in people with diabetes, and several of the improvements only just cleared the bar for statistical significance. Different products and doses across the trials mean a couple of new studies could shift the picture.Meta-analysis · Probiotics Antimicrob Proteins

Pooled results from 41 randomised trials in 2991 people with diabetes found probiotics and synbiotics modestly improved long-term blood sugar (HbA1c), fasting glucose and insulin levels. Supplements containing multiple species were particularly effective for HbA1c.

⚠What it shows: Solid enough to take seriously, but the benefit is modest rather than dramatic: results pooled from 41 trials in 2991 people with diabetes. The trials disagreed with each other a fair amount, and which strains work best is still unsettled.Meta-analysis · Clin Nutr

A pooled review of fifteen studies found that depression, distress and fear of movement predicted whether non-specific low back pain became persistent, while physical factors such as trunk movement showed limited and inconclusive evidence. The certainty of the evidence was rated low across the board.

⚠What it shows: Treat this as a strong lead rather than a verdict: a sweep of fifteen studies, one covering 15,778 people, found the psychological links, but the authors rate the certainty of evidence as low to very low throughout. It shows prediction, not proof that treating mood or fear prevents lasting pain.Meta-analysis · Eur J Pain

Pooled across eight randomised trials, neuromuscular electrical stimulation did not reliably improve pain, disability, quadriceps strength or walking distance in knee osteoarthritis. Added to structured exercise, though, it reduced pain more than exercise alone.

⚠What it shows: Take the headline null seriously and the bright spots gently: only eight trials fed this pooled analysis, and the one clear functional gain came largely from a single study. The pain benefit alongside exercise looks the most credible use, not the device on its own.Study · Orthop Rev (Pavia)

A meta-analysis of 19 randomised controlled trials found that wearable activity trackers used as physical activity interventions produced moderate, significant reductions in body weight and waist circumference and large reductions in BMI, with stronger effects in people with obesity or chronic disease and when used for 12 weeks or more. Each additional week of use was linked to a further body weight reduction of more than 0.37%.

⚠What it shows: One of the stronger findings in this space: results pooled from 19 trials where people were assigned trackers at random, though the biggest gains appeared in people with obesity or chronic disease, so leaner users may see smaller returns.Meta-analysis · Obes Rev

A pooled analysis of 20 randomised trials in 1608 adults found sleep interventions delivered through wearables significantly reduced sleep disturbance and sleep-related impairment, and improved overnight breathing measures.

⚠What it shows: Promising but not yet decisive: results pooled from 20 trials in 1608 adults across nine countries, and the authors themselves say longer, more rigorous trials in a wider range of people are still needed before firm conclusions.Meta-analysis · Nurs Health Sci

In apparently healthy adults, the risk of sudden cardiac death or a serious heart event during or immediately after exercise is extremely low, well below 0.01 per 10,000 participant hours, and the long-term health benefits of regular vigorous exercise outweigh that brief rise in risk.

⚠What it shows: Solid ground: a sweep of all the studies on this in apparently healthy adults, so the reassurance rests on a broad evidence base. The unresolved problem is that most exercise deaths involve hidden heart disease that had shown no sign of itself beforehand.Meta-analysis · Can J Cardiol

In a Cochrane review of 25 randomised trials, combined oral contraceptive pills reduced facial acne lesion counts, severity grades and self-assessed acne compared with placebo, with few clear differences in effectiveness between pill types.

⚠What it shows: Strong evidence for the basic effect: results pooled from 25 trials where women were assigned treatments at random showed the pill beat placebo for acne, but comparisons between pill formulations rested on limited and sometimes conflicting data, and how the pill stacks up against other acne treatments is unknown.Meta-analysis · Cochrane Database Syst Rev

In a network meta-analysis of 58 trials covering 24 214 adults with overweight or obesity but without diabetes, next generation incretin drugs outperformed conventional GLP-1 agonists for weight loss: retatrutide cut body weight by 22.10% versus placebo, tirzepatide by 19.28% and CagriSema by 17.32%.

⚠What it shows: Strong evidence overall, pooling 58 trials of 24 214 adults, but few of these drugs have been tested against each other directly, so the rankings rest partly on indirect comparisons. The tolerability findings, including more people stopping retatrutide and danuglipron, were rated low certainty.Study · BMJ Med

Pooled results from 23 studies link outdoor particulate air pollution with lower lung function in healthy adults: each 10 µg/m3 rise in short-term PM2.5 exposure was associated with a 7.02 mL drop in FEV1, and a 10 µg/m3 difference in long-term PM10 exposure with a 71.36 mL lower FEV1 overall.

⚠What it shows: Solid enough to take seriously: results pooled from 23 studies of healthy adults all point the same way. The studies followed people rather than testing on them, though, and for long-term exposure smoking and other habits could explain part of the effect.Meta-analysis · Occup Environ Med