People who do CrossFit, lift weights, or just stay active all generate about the same peak power when jumping — no one group is clearly stronger or more powerful than the others.
Scientific Claim
Peak power output normalized by body mass does not differ significantly between men experienced in functional fitness training, strength training, or physically active controls, indicating that neither training method confers a clear advantage in maximal lower limb power output relative to general activity.
Original Statement
“PPO showed no statistical difference (p = 0.39) between groups (control, 50.5 ± 6 W kg−1; FFT, 54.1 ± 5.8 W kg−1; ST, 50.6 ± 5.6 W kg−1).”
Evidence Quality Assessment
Claim Status
appropriately stated
Study Design Support
Design supports claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The claim correctly reflects the non-significant result (p=0.39) and avoids implying equivalence or superiority. No causal language is used.
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.
Systematic Review & Meta-AnalysisLevel 1aWhether FFT or ST leads to greater gains in normalized peak power output than untrained controls across populations.
Whether FFT or ST leads to greater gains in normalized peak power output than untrained controls across populations.
What This Would Prove
Whether FFT or ST leads to greater gains in normalized peak power output than untrained controls across populations.
Ideal Study Design
A meta-analysis of 20+ studies comparing PPO (via cycle ergometer or force plate) changes in adults after 8+ weeks of FFT, ST, or control, with standardized normalization (W/kg), training volume, and baseline fitness matching.
Limitation: Cannot isolate whether power gains are due to muscle size, neural adaptation, or technique.
Randomized Controlled TrialLevel 1bWhether 12 weeks of FFT or ST causes greater increases in normalized peak power output than no training.
Whether 12 weeks of FFT or ST causes greater increases in normalized peak power output than no training.
What This Would Prove
Whether 12 weeks of FFT or ST causes greater increases in normalized peak power output than no training.
Ideal Study Design
A 12-week RCT with 75 healthy men aged 20–35 randomized to FFT, ST, or control, measuring PPO via Wingate test or force plate before and after, with standardized warm-up, recovery, and diet control.
Limitation: Short duration may miss long-term adaptations in power development.
Prospective Cohort StudyLevel 2bWhether long-term FFT or ST practitioners maintain higher PPO than controls over time.
Whether long-term FFT or ST practitioners maintain higher PPO than controls over time.
What This Would Prove
Whether long-term FFT or ST practitioners maintain higher PPO than controls over time.
Ideal Study Design
A 5-year cohort tracking 120 adult men (20–40) in FFT, ST, or control groups, measuring PPO annually via standardized ergometry, adjusting for age, body composition, and training consistency.
Limitation: Subject to dropout and self-selection bias.
Evidence from Studies
Supporting (1)
The study found that people who do functional fitness, strength training, or just stay active all have about the same leg power when you account for their body weight — so no one type of training gives a clear edge.