Determinants of functional-fitness (CrossFit) performance: no single predictor
Body composition, strength, and competition experience dominate
Key Findings
No single parameter predicts across all workout types — findings are conflicting and WOD-dependent.
Most consistent influences: body composition and high-level competitive experience — more consistent than any specific performance variable.
In one-third of the studies, high total-body strength (CrossFit Total) and trunk strength (back-squat) correlated with higher workout scores.
Not from this paper's abstract; from one of the 21 included studies (Dexheimer et al. 2019, DOI 10.3390/sports7040093, numbers checked against its abstract): back-squat explained 42% of "Fran" variance, VO2max 68% of "Nancy", anaerobic peak power 57% of the CrossFit Total — the limiter is task-specific.
Practical Application
Across 21 studies no single test predicted CrossFit performance regardless of workout; body composition and competition experience were the most consistent influences, with total-body and back-squat strength correlating with scores in a third of studies — so for HYROX/hybrid, treat determinants as task-specific: aerobic segments reward VO2max/economy; strength stations reward whole-body/trunk strength; the overall race rewards body composition.
Don't over-index on one lab number — build the broad base (aerobic + strength + body composition) + log race/simulation experience.
Use race simulations to expose YOUR limiter, then bias training.
Limitations
Primary studies small, cross-sectional, mostly recreational CrossFitters; CrossFit ≠ HYROX (varied vs standardized); "competition experience" is a proxy for skill/training age.
Systematic review without meta-analysis; no pooled effect sizes.
How this entry was checked and changed
Why this level
regraded 2026-09-27 from B: systematic review without meta-analysis of small cross-sectional studies
Content correction 2026-09-27
Dexheimer 2019 variance figures (42/68/57%) relabelled as "not from this paper's abstract" (from an included study, checked against its own abstract).
Level B -> B+ (SR without meta-analysis of cross-sectional studies, consistent with rubric use for REF-591/593); Tier "mixed" -> Tier 1-3; lead line now states the review's finding before the HYROX application; "lower body-fat%" -> "body composition" (the abstract does not specify fat%).