People who do CrossFit, lift weights, or just stay active all generate about the same peak power when jumping — no one group is significantly stronger or more explosive.
Scientific Claim
Peak power output normalized by body mass does not differ significantly between functional fitness training practitioners, strength training practitioners, or physically active controls, indicating that neither training method confers a clear advantage in maximal lower limb power output under these conditions.
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 causal language, aligning with the observational design’s limitations.
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, ST, or general activity leads to differential gains in normalized peak power output.
Whether FFT, ST, or general activity leads to differential gains in normalized peak power output.
What This Would Prove
Whether FFT, ST, or general activity leads to differential gains in normalized peak power output.
Ideal Study Design
A meta-analysis of 20+ RCTs comparing FFT, ST, and control groups measuring PPO via isokinetic dynamometry or force plates after 8–24 weeks of training in healthy adults aged 18–40.
Limitation: Cannot account for individual variability in power development or training history.
Randomized Controlled TrialLevel 1bWhether FFT or ST causes greater increases in normalized peak power output than no structured training.
Whether FFT or ST causes greater increases in normalized peak power output than no structured training.
What This Would Prove
Whether FFT or ST causes greater increases in normalized peak power output than no structured training.
Ideal Study Design
A 12-week RCT of 90 sedentary men randomized to FFT, ST, or control (no training), with PPO measured via Wingate test and normalized to body mass, controlling for baseline fitness and diet.
Limitation: Short-term design may miss long-term adaptations.
Prospective Cohort StudyLevel 2bWhether experienced FFT or ST practitioners maintain higher PPO than controls over time.
Whether experienced FFT or ST practitioners maintain higher PPO than controls over time.
What This Would Prove
Whether experienced FFT or ST practitioners maintain higher PPO than controls over time.
Ideal Study Design
A 5-year cohort tracking 120 experienced (≥2 years) FFT and ST practitioners and 60 controls with annual PPO testing via force plates, adjusting for age, body composition, and training volume.
Limitation: Cannot determine if higher PPO was caused by training or pre-existing traits.
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 neither training style is clearly better for explosive leg power.