Health & fitness articles
Plain-language summaries of published research, each with the study it's based on.
Meta-analysis of trials
How many weekly sets build muscle?
More weekly sets per muscle group produce more muscle growth, up to a point. Each extra set per week was linked to roughly 0.37% more muscle-size gain, and higher-volume programs beat lower-volume ones by about 3.9% in the pooled data.
Meta-analysis of trials
Protein: how much do you need to gain muscle?
Protein supplementation on top of resistance training modestly increases muscle size and strength, with benefits levelling off around 1.6 g of protein per kg of body weight per day (95% CI 1.03 to 2.20). The review pooled 49 trials and 1,863 participants.
Meta-analysis of trials
HIIT or steady cardio: which improves fitness more?
Both raise VO2max (aerobic fitness). In a meta-analysis of women, moderate-to-vigorous continuous training and HIIT improved VO2max by almost the same amount (about 3.2 ml/kg/min each; difference between them -0.42, 95% CI -1.43 to 0.60). HIIT's main advantage is time: similar gains in shorter sessions.
Systematic review
Why sleep matters for your workouts
Losing sleep lowers exercise performance by an average of 7.56% (95% CI -11.9 to -3.13) across 69 publications and every exercise type studied. The effect was consistent after full sleep deprivation and after waking early (late restriction), but not after going to bed late. Most participants in these studies (89%) were men.
Meta-analysis of trials
Creatine: does it help older lifters too?
Creatine plus resistance training beat placebo plus training in adults averaging 57 to 70 years old: lean tissue mass rose 1.37 kg more (95% CI 0.97 to 1.76), with better chest-press and leg-press strength. The pooled data came from 22 trials and 721 participants.
Observational cohorts
Daily steps: how many are enough?
More steps a day is linked to lower risk of death, but the benefit levels off and the plateau depends on age. A 2025 review of prospective studies found that 7,000 steps a day was linked to meaningful health improvements, though 10,000 remains a fine target for people who are already active. These are observational studies, so they show association, not proof of cause.
Observational cohorts
Strength training and a longer life
Adults who did muscle-strengthening activities had a 10 to 17% lower risk of all-cause mortality, cardiovascular disease, total cancer, diabetes and lung cancer, across 16 prospective cohort studies. The largest reduction (about 10 to 20%) came at roughly 30 to 60 minutes a week, and combining it with aerobic exercise looked better still. These are observational cohorts, so treat the numbers as association.
Network meta-analysis
Exercise as a treatment for depression
In a network meta-analysis of randomised trials, walking or jogging, yoga and strength training showed the largest reductions in depressive symptoms, and yoga and strength training were the best tolerated (fewest drop-outs). The review rated confidence in the evidence as low for walking and jogging and very low for the other types, so the ranking between them is not certain.
Meta-analysis of trials
Intermittent fasting vs. eating less every day
Across 11 randomised trials (8 to 24 weeks), intermittent energy restriction and continuous calorie restriction produced comparable weight loss (difference -0.61 kg, 95% CI -1.70 to 0.47). Fasting insulin fell slightly more with intermittent fasting, but the clinical relevance is uncertain. The best plan is the one a person can sustain. Note that this review searched studies up to May 2018, so newer trials are not included.
Cochrane review
Exercise prevents falls in older adults
Balance and functional exercises cut the rate of falls by 24% (rate ratio 0.76, 95% CI 0.70 to 0.81; 39 studies, 7,920 participants, high-certainty evidence) in older people living in the community. This is the strongest evidence in this list, from a Cochrane review.