Evidence library
What our choices are based on
Every provider in this industry calls itself evidence-based. What rarely happens is that someone shows which sources that actually means and what's in them. This library does. For each study you'll find the conclusion, how strong the evidence is, what REZA does with it, and a link to the original publication.
It also includes studies that show something other than expected. A library where everything confirms its own story isn't a library, it's a sales pitch.
Two ways to use this library
“I mainly want to know what to do.”
Practice-focused summaries: the conclusion, what it means for your training or nutrition, little methodology.
“I want to look at the underlying studies.”
For anyone who wants the methodology, limitations, evidence rating and direct source link — via each study's detail page.
How we appraise research
A study isn't good because it's large, and it isn't wrong because it's small. What counts is whether the design can answer the question.
We look at study design, because a randomised trial says something different from an observation. At the control group, because progress without comparison proves nothing. At the size and spread of the effect, because a statistically significant difference can be negligible in practice. And at the participants, because a finding in trained twenty-somethings doesn't automatically apply to a fifty-year-old just starting out.
Systematic reviews and meta-analyses of randomised trials therefore carry more weight than single studies. Position stands from scientific associations carry substantial weight because they've been appraised by multiple researchers. We don't include animal research where the translation to humans is unclear. Research funded by a party with an interest in the outcome is only included with that noted.
What we don't do is select only the sources that suit us. Where the literature is divided on a point, that's stated.
REZA's practical assessment of the evidence strength
- A
High confidence
Multiple consistent meta-analyses or a position stand. Sufficient basis for a fixed choice in the coaching.
- B
Reasonable confidence
A solid systematic review with caveats, or consistent indications with a limited scope.
- C
Interpret with caution
Limited, mixed or hard-to-translate evidence. Useful as direction, not as a rule.
- D
Not usable as a basis
Insufficient quality or insufficient applicability to our target group. Included for illustration or refutation.
The library
The library is organised by the five pillars and holds 167 selected publications. This collection keeps growing: new research is added once it genuinely adds to or contradicts existing knowledge.
Last updated: September 23, 2026
New2 publications added on September 23, 2026. See what is new
This library isn't an appendix. Its contents determine how programmes are built and where the limits sit on what we're willing to promise. Where the evidence is strong, the approach is definite. Where it's thin, we leave room for the idea that it could be different.
This information is general education about scientific research. It is not personal medical advice and does not replace diagnosis or treatment by a doctor or other healthcare professional. If you have symptoms, a medical condition or take medication, consult your GP or treating professional before changing your training or nutrition.