SSMT Claim Register
SSMT-2026-0005v12026-07-26 Type P · Practice Injury Science blocked
Grade withheld — not published.

A correction to the source editorial exists (BJSM 2019;53(18):e6) but its text was not retrievable. "A correction to the sweet-spot paper" is materially different from "a correction to that paper", and this card contradicts a widely-taught metric. The grade is withheld until that is settled.

The verdict below is shown because withholding it silently would be worse than showing it with its caveat. It must not be cited until resolved.

Claim, as marketed
“Stay in the sweet spot. Avoid the danger zone.”
Canonical claim
The acute:chronic workload ratio predicts injury risk, and keeping athletes within a target ACWR range reduces injuries.
Scope
The ACWR metric and threshold-based management rules built on it, as implemented in athlete-management software. Not a claim about load management generally.
Verdict
Contradicted Fails on both limbs — prediction and intervention.
Independent evidence found against the claim.
Claim drift — 7 of 7
▲Population▲Setting▲Comparator▲Outcome▲Magnitude▲Reproducibility▲Independence
Seven of seven. Reproducibility fires on analytic irreproducibility rather than measurement instability.
Evidence located
0.574
c-statistic (chance = 0.5)
21%
of 108 analyses significant
1.01
RR, the one RCT (n=482)
1
intervention trial — null
Findings

The random-denominator test. Researchers re-analysed published injury data replacing the chronic-load denominator with fixed and randomly generated numbers. Original ACWR: OR 2.45 (1.28–4.71). Divided by a constant: OR 1.95. Random denominators: OR 1.16–2.07. Discrimination was 0.574 for ACWR versus 0.544 for acute load alone — against 0.5 for chance. Independently replicated in a Bayesian analysis of 35 first-division footballers.

Mathematical coupling. The acute week sits inside the four-week chronic denominator in roughly 95% of studies. Correlating a quantity with a function of itself generates correlation from the algebra alone.

Analytic irreproducibility. One dataset (86 players, 6,250 athlete-days, 196 health problems) was analysed 108 different ways. Only 21% of those analyses were statistically significant. The finding is a function of the analyst's choices.

Provenance of the 'sweet spot'. The 0.8–1.3 band comes from a 2016 editorial that fitted a polynomial to binned points (R²=0.53) — not a validated model. It was subsequently reproduced in a consensus statement, which is how it acquired institutional authority.

The intervention test. A cluster RCT of 34 teams and 482 elite youth footballers of both sexes, over a full 10-month season, had coaches plan all training using published ACWR principles delivered through a commercial athlete-management system. Result: RR 1.01 (95% CI 0.91–1.12, p=0.84). No effect. The authors flag high dropout and imperfect adherence.

Two cohorts found injuries concentrated inside the sweet spot. 27.5% of soccer and 83.3% of pentathlon injuries occurred within 0.8–1.3, and the most severe soccer injuries occurred there. In 1,660 children, injury risk was essentially flat at ~3% from a 60% decrease to a 30% increase in activity.

What is NOT contradicted
That large, rapid increases in load relative to habitual load are associated with injury. That signal survives — pooled RR 2.45 (95% CI 1.48–4.06) in fast bowlers. But it is carried by the size of the spike, not by the ratio, and it does not license a threshold-based management rule. "The metric is flawed" is the finding. "Load management doesn't matter" is not.
What would change this verdict
A second adequately-powered, adherence-verified RCT (or a well-executed target-trial emulation) showing that constraining ACWR to a target band reduces injury incidence versus usual practice. Alternatively, demonstration of incremental predictive value over the numerator alone — external validation beating both acute load and a random-denominator control, with a c-statistic clearly above 0.70.
Practitioner read
Big sudden jumps in training load do track with injuries, and ramping athletes up gradually is sound practice. But the ACWR number itself adds essentially nothing: when researchers swapped the chronic-load denominator for a random number, the risk signal barely changed, and its ability to flag which athlete gets hurt is close to a coin flip. The one season-long randomised trial where coaches planned training to keep 482 youth footballers in the sweet spot found zero reduction in injuries and illnesses. Treat the dashboard's red zone as a conversation-starter about whether you spiked someone's week — never as a clearance or a stop sign.
Could not be verified
Listed rather than dropped. Counts are floors, not censuses.
Sources
  1. Impellizzeri FM, et al. (2021). Sports Med 51(3):581–592 — random-denominator test ↗
  2. Dalen-Lorentsen T, et al. (2021). Br J Sports Med 55(2):108–114 — cluster RCT, n=482 ↗
  3. Dalen-Lorentsen T, et al. (2021). JOSPT 51(4):162–173 — 108 analyses ↗
  4. Lolli L, et al. (2019). Br J Sports Med 53(15):921–922 — mathematical coupling ↗
  5. Carbone L, et al. (2022). J Clin Med 11(19):5945 — Bayesian replication ↗
  6. Sedeaud A, et al. (2020). Front Physiol 11:1034 — injuries inside the sweet spot ↗
  7. Wang C, et al. (2022). Am J Epidemiol 191(4):665–673 — n=1,660 children ↗
  8. Blanch P, Gabbett TJ (2016). Br J Sports Med 50(8):471–475 — source of the sweet spot ↗
Every source must resolve at a DOI or PubMed ID.
Changelog
Cite this card
SSMT. "The acute:chronic workload ratio predicts injury risk, and keeping athletes within a target ACWR range reduces injuries." Claim SSMT-2026-0005 v1, graded 2026-07-26. https://sportssciencetech.com/c/SSMT-2026-0005
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