The chain of custody
This page lists every source the research draws on. For each citation, the chain is the same path: from the claim in the body, to the citation marker attached to it, to the source itself. You can walk that path for any single claim without accepting the conclusion on trust.
The path, in one diagram
Claim in the research → citation marker (e.g. [18]) → entry on this page → live source URL
Open the source URL in any citation entry below and read for yourself. If the cited passage doesn't say what we said it does, the method has failed and we want to know.
Evidence tiers
Each source is tagged by the strength of evidence it represents, so you can weigh it appropriately. A claim grounded in a meta-analysis is on firmer footing than one resting on a small, single study — and the research treats them that way.
| Tier | Evidence type | Examples in this research |
|---|
| T1 | Systematic review, meta-analysis, or expert consensus statement | Step-rate meta-analysis; machines-vs-free-weights review; injury-prevention meta-analysis; supplement consensus |
| T2 | Primary study directly on point (trial, cohort, biomechanical study) | Breaststroker's-knee analysis; deficit-and-protein study; run-load cohort; sleep trial |
| T3 | Smaller-sample or analogous-population study (directional) | Handstand wrist-pain survey |
A note on retrieval: most sources were captured in full; several were grounded against the published abstract where the full text was access-blocked — the finding is present, but not the full-text method detail. Those are honest limits, carried into the research writeup itself.
Citations
Twenty sources covering the load-bearing claims of the program — the nineteen findings from the program's research brief, plus the step-rate meta-analysis that grounds the cadence recommendation. Sources retrieved June 2026.
[1] Running step-rate systematic review & meta-analysis T1
"Increasing running step rate will broadly reduce kinematic and kinetic variables at the ankle, knee and hip. There is insufficient evidence to determine the effects of changing running step rate on injury or performance."
Retrieved 2026-06-10 · systematic review & meta-analysis (Sports Medicine - Open) · grounds the cadence recommendation; note the explicit limit on direct injury/performance evidence
[2] Pose "lean and pull" running retraining trial T2
"A 4-week switch to a midfoot strike produced no significant change in impact loading rates or trunk flexion; authors advise other methods for reducing impact loading."
Retrieved 2026-06-09 · controlled retraining trial · evidence against the "lean and push behind" cue
[3] Forefoot / minimalist footwear and Achilles load T2
"Forefoot striking in minimal shoes raised Achilles loading magnitude; minimal/barefoot raised loading rate regardless of strike, with possible tendinopathy risk."
Retrieved 2026-06-09 · biomechanical study
[4] Forward trunk lean and joint-load redistribution T2
"A ~25-degree trunk lean lowered peak knee/patellofemoral load but raised the hip-extension moment — a redistribution, not a total-load reduction."
Retrieved 2026-06-09 · biomechanical study
[5] Single-run load spike and injury risk T2
"Injury rate rose when a single run exceeded ~10% of the longest run in the prior 30 days (large spikes hazard ratio 2.28; 5,205 runners)."
Retrieved 2026-06-09 · cohort study
[6] Polarized vs. threshold training in recreational runners T2
"80/20 polarized training was not superior to focused/threshold training (8-week RCT, n=38); consistent easy-dominant volume matters most."
Retrieved 2026-06-09 · randomized controlled trial · small sample; the 80/20 question is genuinely equivocal for recreationals
[7] Canine heat-related illness risk T2
"Heat-related illness in dogs is potentially fatal (14.2% case-fatality), worse for heavier, older, and brachycephalic dogs (VetCompass, 905,543 dogs)."
Retrieved 2026-06-09 · large veterinary-records study
[8] Deficit rate and protein for trained athletes T2
"For resistance-trained athletes, target 0.5-1.0% body weight per week with protein 2.2-3.0 g/kg/day; creatine 3-5 g/day and caffeine 3-6 mg/kg/day are ergogenic."
Retrieved 2026-06-09 · review of physique-athlete nutrition
[9] Resistance training spares lean mass in a deficit T1
"At >=10 weekly sets/muscle, resistance training showed low-to-no lean-mass loss during a deficit; mediated by experience, pre-diet volume, and deficit size."
Retrieved 2026-06-09 · systematic review
[10] Sleep restriction and body-composition loss T2
"At equal calories, 5.5 h vs 8.5 h of sleep cut the fat share of weight loss by 55% and raised lean-mass loss by 60%."
Retrieved 2026-06-09 · controlled trial · small sample (n=10); treat magnitude as directional
[11] Relative Energy Deficiency in Sport (REDs) T1
"Low energy availability harms health and performance in male and female athletes (2023 IOC consensus statement)."
Retrieved 2026-06-09 · expert consensus statement
[12] Supplements with good evidence T1
"Only caffeine, creatine, buffers, and nitrate have good evidence as performance supplements (IOC consensus)."
Retrieved 2026-06-09 · expert consensus statement
[13] Creatine safety and effectiveness T1
"Creatine is safe and effective up to 30 g/day for 5 years in healthy people; ~3-5 g/day maintenance (ISSN position)."
Retrieved 2026-06-09 · position stand · safety data is for healthy people
[14] Machines vs. free weights for hypertrophy T1
"Machines and free weights produced no difference in hypertrophy (13 studies, n=1,016)."
Retrieved 2026-06-09 · systematic review
[15] Training to failure vs. reps in reserve T1
"No significant hypertrophy advantage to training to failure versus leaving reps in reserve."
Retrieved 2026-06-09 · systematic review / meta-analysis
[16] Strength training for injury prevention T1
"Across 25 RCTs (26,610 participants), strength training reduced sports injuries to less than a third and overuse injuries by almost half; stretching showed no protective effect."
Retrieved 2026-06-09 · meta-analysis
[17] Aquatic offloading and load with speed T2
"Water cut hip/knee joint force by 36-55%, but speed and resistance raised it by up to 59% (in-vivo instrumented implants)."
Retrieved 2026-06-09 · in-vivo measurement study · small sample (n=12); treat magnitude as directional
[18] Breaststroker's knee: epidemiology & biomechanics T2
"An extremely high incidence of knee pain was documented both among breaststroke specialists (73%) and nonbreaststrokers (48%)... dramatic differences in the injury rate were noted when hip abduction angles at kick initiation were less than 37 degrees or greater than 42 degrees."
Retrieved 2026-06-09 · epidemiological + biomechanical analysis (Am J Sports Med) · hip-led kick is the protective lever
[19] Extreme hip range and impingement T2
"Dancers' and gymnasts' extreme hip range of motion can produce impingement and impingement-induced instability, even with normal bony anatomy."
Retrieved 2026-06-09 · clinical review · analogous population (dancers/gymnasts), not identical
[20] Handstand-related wrist pain T3
"Wrist pain affected 56.7% of handstand practitioners; risk tracked with intensity and biomechanics, not just volume."
Retrieved 2026-06-09 · practitioner survey · directional