Explore the evidence behind HALE.
This is the library the whole app is built on — real studies, summarised in plain English and graded A–D. With an account, the same library is filtered to your goals, your training history and your week.
This week
Reads doing the rounds
Training
Full-range lifting beats stretching for flexibility
The same lifts that build muscle also build the mobility gains most people chase in stretching class.
6 min read
Physiology
How two people can eat the same food and one gets fat
The 700 kcal-a-day difference hiding in plain sight.
7 min read
Recovery
Both too little and too much sleep raise mortality
The U-shaped curve you've probably heard about — with the actual numbers.
5 min read
Myth-buster
One thing most people get wrong
“High reps 'tone' muscle; low reps just build size.”
Tone is visible muscle at low body fat — a body-composition outcome, not a rep-range one. Any rep range 5–30 grows muscle when taken close to failure, and body fat is set by diet.
Read the full breakdown
How we grade
Every claim carries its evidence
Strong — multiple high-quality meta-analyses or large trials agree.
Moderate — consistent trial evidence with some caveats or variation.
Mixed — limited or conflicting evidence; the effect is likely small.
Weak — expert opinion or low-quality studies. A reasonable bet, not a fact.
The library
4 study spotlights from 92 in the library
Schoenfeld BJ, Ogborn D, Krieger JW · 2017 · Journal of Sports Sciences
Dose-response relationship between weekly resistance training volume and increases in muscle mass
Meta-analysis showing a clear dose-response between weekly sets per muscle and hypertrophy, with meaningful gains across roughly 10–20 sets per week.
Hall KD et al. · 2011 · The Lancet
Quantification of the effect of energy imbalance on bodyweight
Mathematical and clinical confirmation that long-term bodyweight change is driven almost entirely by sustained calorie balance, with basal metabolism accounting for the majority of daily energy use.
Cappuccio FP et al. · 2010 · Sleep
Sleep duration and all-cause mortality: a systematic review and meta-analysis
Meta-analysis of 16 prospective studies (>1.3M participants): both short (<7h) and long (>9h) sleep durations were associated with significantly increased mortality risk.
Paluch AE et al. · 2022 · The Lancet Public Health
Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts
Pooled cohort of 47,471 adults: higher daily step counts were associated with progressively lower mortality risk, with benefits plateauing around 6,000–10,000 steps/day depending on age.
Search above to explore the full library.
Evidence is general. Advice should be personal.
A study on trained men in their twenties doesn't automatically apply to a post-menopausal beginner. With an account, this library gets filtered to you: weekly reads chosen for your goals, a saved shelf, and a training and nutrition plan built from the same studies.