Just because CrossFit and weightlifters jumped about the same height doesn’t mean they’re equally powerful — the test might not have been sensitive enough to spot a real difference.
Scientific Claim
The lack of significant difference in jump height between functional fitness and strength training groups (p=0.058) does not demonstrate equivalence, and may reflect insufficient statistical power rather than true similarity in explosive performance.
Original Statement
“Jump height was higher (p = 0.003) for the FFT group (53.5 ± 2.4 cm) compared to the control group (45.7 ± 3.6 cm), and did not differ in relation to the ST group (50.8 ± 5.7 cm; p = 0.058).”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The original conclusion incorrectly stated 'the practice of these training methods does not seem to differ in relation to muscular power' — this implies equivalence, which cannot be concluded from a non-significant p-value. The claim corrects this by framing it as a limitation of statistical power.
Gold Standard Evidence Needed
According to GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this specific claim, ordered from strongest to weakest evidence.
Randomized Controlled TrialLevel 1bWhether FFT and ST produce truly equivalent jump height gains when tested under sufficient power.
Whether FFT and ST produce truly equivalent jump height gains when tested under sufficient power.
What This Would Prove
Whether FFT and ST produce truly equivalent jump height gains when tested under sufficient power.
Ideal Study Design
A 12-week RCT with 120 participants per group (FFT vs ST), powered at 90% to detect a 5% difference in jump height, using force plate measurements, standardized protocols, and equivalence testing (TOST) to formally assess similarity.
Limitation: Still cannot prove equivalence in all populations or over longer timeframes.
Systematic Review & Meta-AnalysisLevel 1aWhether FFT and ST are statistically equivalent in improving jump height across multiple studies.
Whether FFT and ST are statistically equivalent in improving jump height across multiple studies.
What This Would Prove
Whether FFT and ST are statistically equivalent in improving jump height across multiple studies.
Ideal Study Design
A meta-analysis using equivalence testing (TOST) on 10+ RCTs comparing jump height changes in FFT vs ST, with pre-specified equivalence margin (e.g., ±5 cm), controlling for training volume and baseline fitness.
Limitation: Dependent on quality and homogeneity of included studies.
Prospective Cohort StudyLevel 2bWhether long-term FFT and ST practitioners show consistent jump height equivalence in real-world settings.
Whether long-term FFT and ST practitioners show consistent jump height equivalence in real-world settings.
What This Would Prove
Whether long-term FFT and ST practitioners show consistent jump height equivalence in real-world settings.
Ideal Study Design
A 5-year cohort study with 200+ men (20–40) in FFT or ST groups, measuring jump height annually with force plates, using equivalence testing to assess whether differences remain within a clinically irrelevant margin over time.
Limitation: Cannot control for confounding lifestyle factors.
Evidence from Studies
Supporting (1)
The study found that people who did functional fitness and those who did strength training jumped about the same height, but the difference wasn’t big enough to say for sure they’re truly equal — it might just be because too few people were tested. This matches the claim’s point.