Strength · CREA-STR-01 · v2
Borderline: within 4 points of the Established/Likely boundary, so a re-grade could land either side.
Across the studies here, people who took creatine while doing a resistance-training programme gained more strength than people on a dummy supplement, and this held in young adults, older adults and athletes [1], [2], [4], [5], [6], [7], [11]. The strength measure was usually the heaviest weight a person could lift once. The pattern pointed the same way in group after group, run by more than one independent lab. One study that gave creatine for only five days found it let people do more repetitions but did not raise their single heaviest lift [3], which speaks to a short loading dose rather than a training programme. The panel treated that as a boundary on where the effect applies, not a contradiction of it. The main things holding the finding back are that several studies were small and some of them came from the same research group.
Seven placebo-controlled trials measured strength during a resistance-training programme and all found larger gains with creatine than placebo, mostly measured as a one-repetition maximum [1], [2], [4], [5], [6], [7], [11]. The result recurs in young adults [2], [6], older adults [4], [7], [11] and athletes [1], [5]. [6] showed the gain can appear in as little as two weeks, reaching four of six exercises by eight weeks. [3] is the one study pointing the other way, but it tested five days of loading and found no change in maximal strength, only in strength endurance. [8] showed strength rising during training but gave both sides creatine, so it cannot isolate the creatine effect. The contested point: The division is between chronic training and acute loading: the training trials show a maximal-strength gain [1], [2], [4], [5], [6], [7], while the five-day loading study [3] raised only strength endurance and left maximal strength unchanged. A secondary tension is how independent the evidence really is, since [2], [6], [7] and [8] share one research group.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
[3] explicitly found short-term 5-day loading 'failed to change the maximum strength', only improving strength endurance — the claim holds for chronic training but not acute loading.
Evidential independence is partly inflated: [2], [6], [7] and [8] share the Candow/Forbes/Chilibeck research group, so apparent replication reflects one lab in part.
Where it remains uncertain. A five-day loading study raised strength endurance but not maximal strength [3], and part of the training evidence comes from one shared research group [2], [6], [7], [8].
Aleatory
Several trials run N=10 to 30 ([6] N=18, [8] N=10, [2] N=22), so individual effect estimates carry wide sampling variation.
Epistemic
[2], [6], [7] and [8] share the Candow/Forbes/Chilibeck group, so the degree of truly independent replication is uncertain.
Inferential
[3] tested five-day loading and found no maximal-strength change, so extending training-programme results to short loading is not supported.
The load-bearing papers from a corpus of 11, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Independent group; 1-RM strength superiority with creatine during training
“After the training, the 1-RM strength in the creatine group was significantly greater than in the placebo group ( p < 0.05).”
Panel auditInternal validity: medium · scope of inference: Explosive athletes undergoing 4 weeks of complex (resistance plus plyometric) training; 1-RM half-squat strength.Key limitations: complex training not pure resistance · small sample · blinding not stated · athlete-only population
Direct placebo-controlled 1-RM strength increase during 6-week resistance training
“The creatine group experienced a significant increase ( p < 0.05) in leg press, chest press and total body strength and leg press endurance with no significant changes in the PLA group.”
Panel auditInternal validity: medium · scope of inference: Physically active young adults over six weeks of resistance training; leg press and chest press 1-RM.Key limitations: small unequal groups · within-group inference · short duration · young-adult only
Boundary/counter-evidence: acute loading does not raise maximal strength
“Creatine loading for five days allowed the subjects to perform more repetitions, resulting in greater total work, but failed to change the maximum strength.”
Panel auditInternal validity: medium · scope of inference: Strength-trained men after five days of creatine loading; bench press maximal strength and strength endurance, no training program.Key limitations: no resistance-training program · very short loading period · tiny sample · outcome is maximal strength, not training-induced gain
Strength increased over time on both sides but every limb received creatine, so the abstract cannot isolate whether creatine versus none drove the gain.
Panel auditInternal validity: medium · scope of inference: Recreationally active young adults over 8 weeks of unilateral resistance training; timing of creatine, not its presence.Key limitations: no non-creatine comparator · tiny sample · timing study not efficacy study
4 of 11 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Consistent, direct, placebo-controlled RCT evidence across diverse populations and independent groups supports the claim, with partial author overlap and small samples the main tempering factors.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Independent large multi-site RCT. Much of the direct training evidence shares one research group ([2], [6], [7], [8]), so apparent replication is partly a single lab. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: A pre-registered, adequately powered placebo-controlled resistance-training RCT run by an unaffiliated group reporting 1-RM as a primary endpoint.
Open question: Does the creatine strength benefit during resistance training replicate in adequately powered trials run by groups independent of the Candow/Forbes/Chilibeck lab? Why it is still open: [2], [6], [7] and [8] share authorship, so independence of the training evidence is only partial within this corpus.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 21 Oct 2026 · protocol v0.19