Browse by topic
Movement and health: the fundamentals
The core thesis area — the relationship between movement and the systems of the body that matter for health, including the musculoskeletal, metabolic, cardiovascular, and nervous systems. The strongest and most consistent area of the site's evidence base.
Read the thesisSedentary behavior and sitting
The research on prolonged sitting and uninterrupted sedentary time — its associations with metabolic and cardiovascular risk, and the evidence on breaking up sitting time. One of the areas where the distinction between movement and exercise matters most.
Read the thesis sectionCardiorespiratory fitness and longevity
The evidence on cardiorespiratory fitness — VO₂ max and fitness-test performance — as a predictor of longevity and disease risk. One of the strongest and most consistent findings in the epidemiology of physical activity.
Read the thesis sectionMuscle, strength, and aging
The role of muscle mass and strength in function, independence, and health across the lifespan — including the evidence for resistance training in older adults and the nutritional support for muscle. A central area for the recovery and older-adult sections.
Recovery: older adultsFueling movement
The energy systems that support movement, the role of carbohydrate and fat, the basics of fueling for different kinds of work, and the principle that fuel should match the work. Foundation material for the nutrition section.
Nutrition: the three rolesProtein and tissue repair
The role of protein and amino acids in muscle protein synthesis, tissue repair, and the adaptive response to movement — including the evidence on amounts, distribution, and the contexts in which timing matters.
Nutrition: the three rolesRecovery, sleep, and the body
The role of sleep and recovery in adaptation, performance, and health — including the evidence on sleep and performance, and the place of recovery relative to the foundations of energy and nutrients.
Athletes: recoveryCaffeine and the ergogenic aids
The evidence on caffeine as an ergogenic aid, and on the narrower field of credible supplements for performance — with the cautions and the honest accounting of what the evidence does and does not support.
Nutrition: caffeineOur evidence standard
Every claim on this site is held to one of three levels. We say which is which, and we try to point to the underlying sources. Where a source is behind a paywall, we cite it as fully as we can and describe the finding in plain language.
Established
Multiple lines of evidence, consistent across populations and study designs, reflected in major public-health or clinical guidance. The claims we label established are the ones where the weight of the evidence is strong and the direction is clear.
Suggestive
Evidence pointing in a clear direction, but not yet at the level of established. May be supported by multiple studies with some inconsistency, or by strong mechanistic reasoning with a still-developing human evidence base. The claim is on a direction, not a certainty.
Working it out
An active area of research where the picture is still forming. We include these when they are relevant and interesting, with a clear statement that the evidence is still being developed and that the current picture may change.
How we handle uncertainty
The honest account of the evidence means saying what we know and what we don't. A few principles govern this:
- We separate the strong from the suggestive. Where the evidence is strong, we say so. Where it is suggestive, we say so. We do not represent the suggestive as the established.
- We name the direction, not just the existence, of evidence. "Research suggests X may help with Y" is more honest than "research shows X helps with Y" when the evidence is suggestive. We use the language that matches the state of the evidence.
- We are clear about correlation and causation. Much of the research on movement and health is observational. We say so when it is, and we are careful not to imply causation that the study design does not support.
- We are clear about population and individual. Evidence in populations is real, but it does not always transfer cleanly to the individual. We say when a finding is a population-level association and when it is something that can reasonably be expected to apply to an individual.
- We are clear about what we don't know. Where the evidence is thin or conflicting, or where a question is open, we say so. The honest gaps are part of the honest account.
Our commitments
movelixir commits to stating the level of evidence for each claim, to using language that matches that level, to citing sources where available, and to being clear about the limits of the evidence and of the site's authority. When we get something wrong, the commitment is to correct it — and to mark the correction.
Sources and further reading
The research behind the site draws on the exercise sciences, the sports sciences, the metabolic and cardiovascular literatures, the musculoskeletal literature, the aging and sarcopenia literatures, the nutrition sciences, and the public-health guidance that synthesizes much of this work. The sources are a mixture of primary research, systematic reviews and meta-analyses, consensus statements, and major public-health guidance.
Where a specific source is cited on a page, it appears in a research note on that page. The library is intended to grow over time, as a living record of the research the site is built on — with the same honest accounting applied to each addition.
Want the research behind a specific claim on the site?
Each page has research notes attached to its claims. If a claim you read somewhere on the site is not accompanied by a research note, that is a gap we want to close — and if you write to tell us which claim, we will add the note or the source.