The Science
VidarFit is evidence-informed. Every system below lists the research behind it — mostly primary, peer-reviewed studies, plus a few credible secondary sources, labeled as such. Some magnitudes are practitioner-derived, and those carry a label too. Not every number is peer-reviewed; saying which is the point.
Recovery & freshness
CalibratingEvidence Medium — The curve shape and per-muscle recovery windows are well studied; several dose magnitudes are practitioner estimates.
Tracks recovery muscle by muscle on a non-linear (exponential) curve, so each session trains what's fresh and spares what's still repairing — heavier, higher-RIR, and eccentric work all extend the window.
Honest note. The curve shape and per-muscle recovery windows come from this literature; a few secondary-mover credits and the running→set-equivalent doses are practitioner estimates, labeled low-confidence in the calibration notes. A separate low-confidence assumption sets how much of a run's dose lands immediately — its freshness-at-t=0 amplitude: no source calibrates that against our freshness scale, so it stays a monotonic heuristic pending your own recovery data.
Key sources11
- Chalchat et al. (2022) — Time course of recovery from exercise-induced muscle damage (141-study meta-analysis) · PMC
- Pareja-Blanco et al. (2017) — Recovery following resistance training to failure vs. not-to-failure · Scand J Med Sci Sports
- Pareja-Blanco et al. (2016) — Velocity loss as a resistance-training stimulus indicator · Scand J Med Sci Sports
- Refalo et al. (2023) — Proximity to failure & acute neuromuscular fatigue · J Strength Cond Res
- Bartolomei et al. (2017) — Recovery after high-intensity vs. high-volume resistance protocols · J Strength Cond Res
- Chen et al. (2019) — Muscle damage & the repeated-bout effect across muscle groups · Eur J Appl Physiol
- Nosaka et al. (2001) — Duration of the protective repeated-bout effect · Med Sci Sports Exerc
- Bontemps et al. (2020) — Downhill (eccentric) running: a narrative review — backs a reserved downhill-damage path, not yet active in-app · PMC
- Doma et al. (2019) — Concurrent-training interference & recovery asymmetry · Sports Med 2019;49:669
- Wilson et al. (2012) — Concurrent training interference: a meta-analysis · J Strength Cond Res
- Markov et al. (2022) — Acute effects of aerobic exercise on subsequent strength/power · PMC
Readiness & autoregulation
AppliedEvidence Low — The check-in instrument is validated; how much a low score should trim volume and load is mostly practitioner heuristic.
A 30-second daily check-in — sleep, energy, soreness, time — sets a readiness score that adjusts the day's volume, load and RIR out loud, rather than silently under- or over-reaching.
Honest note. The instrument itself — subjective wellness over objective monitoring, and the choice to autoregulate out loud — is directly evidence-based and validated. The deload dose-response on top of it (how much a lower score trims volume, load and RIR) is a practitioner heuristic, not a calibrated dose-response: our own backing review rates those magnitudes Medium down to Low, and the load-factor mapping is its single largest evidence gap. The per-user baselining that would keep a chronically harsh or lenient self-scorer honest — the report's main anti-gaming safeguard — is not yet built.
Key sources8
- Hooper & Mackinnon (1995) — Monitoring overtraining: recovery & wellness markers · Sports Med
- Saw, Main & Gastin (2016) — Subjective vs. objective monitoring of athlete response (systematic review) · Br J Sports Med
- Laurent et al. (2011) — Perceived Recovery Status (PRS) scale · J Strength Cond Res
- Pareja-Blanco et al. (2017) — Velocity loss during resistance training & adaptation · Scand J Med Sci Sports
- Pelland et al. (2025) — Resistance-training dose-response meta-regression · meta-regression
- Helms et al. (2018) — RPE / RIR autoregulation of training volume · J Strength Cond Res
- Buchheit (2014) — Heart-rate measures for monitoring training status (review) · Front Physiol
- Bell et al. (2025) — A practical approach to deloading (evidence review) · Sheffield Hallam (review, secondary)secondary
Strength-gain feasibility
CalibratingEvidence Medium — Gain rates trace to real longitudinal datasets; the calibration wrapped around them is lower-confidence.
When you set a target lift and a date, it charts an honest trajectory from evidence-based weekly gain rates by training age and lift — easing off when you're ahead, adding work when you're behind, and refusing to promise a number that isn't reachable in the time.
Honest note. The expected rates of gain come from these datasets. The limits that keep a projection realistic, and the adjustments for lifts the datasets do not measure directly, are VidarFit calibration assembled from that evidence and flagged lower-confidence — considered judgements, not physiological thresholds.
Key sources10
- Latella et al. (2020) — 15-year longitudinal powerlifting progression · PMC
- Latella et al. (2022) — Per-lift rates of strength adaptation · Med Sci Sports Exerc
- Steele & Latella et al. (2024) — Modeling the growth of strength adaptation · Sports Med
- Steele et al. (2022) — Minimal-dose resistance training: long-term strength · Res Q Exerc Sport
- Aarskog et al. (2012) — 6RM vs. 12RM to increase 1RM in healthy young adults (bench +8.4–9.2% / 8 wk) · Physiother Res Int
- Ahtiainen et al. (2016) — Heterogeneity of strength response (n=287, +21.1 ± 11.5%) · PMC
- Hubal et al. (2005) — Inter-individual variability in strength/size gains · Med Sci Sports Exerc
- Jung et al. (2023) — Lower- vs. upper-body weekly strength gains · PMC
- Brown et al. (2017) — Weekly time-course of neuromuscular adaptation · PMC
- ACSM (2009) — Position Stand: progression models in resistance training · Med Sci Sports Exerc (secondary)secondary
Strength-to-weight ratio
AppliedEvidence Medium — Deterministic arithmetic on your own logs; the one primary source here mainly backs the caveat, not population comparisons.
For eligible barbell lifts, divides an estimated one-rep max (from a set of 10 reps or fewer) by your most recent logged bodyweight — shown alongside, never instead of, the underlying lift estimate.
Honest note. The ×BW value is deterministic arithmetic, not a body-composition or health score. Simple ratio scaling can still favor lighter athletes and does not make different exercises, sexes, ages, or techniques directly comparable — so no Beginner/Advanced/Elite population tier cutoffs are applied. Your own trend over time is the honest comparison.
Load & effort (RIR)
CalibratingEvidence Medium — The %1RM–reps relationship is peer-reviewed; the base reps×RIR chart is practitioner-validated, not peer-reviewed.
Uses a rep-range and reps-left rule for eligible weighted muscle-building progression. Load estimates still help choose starting weights and serve other workout types; estimated one-rep max remains a separate progress measure.
Honest note. The max-reps-at-%1RM relationship and the 1RM-prediction equations are peer-reviewed. The base reps×RIR→%1RM lookup derives from the RTS/Tuchscherer coaching chart, which is practitioner-validated, not peer-reviewed — we disclose that openly and the primary literature calibrates its shape. The overhead-press (vertical-press) load table carries no OHP-specific reps-to-failure data: it is extrapolated as a flat offset from the bench table — a LOW-MED-confidence magnitude — and for high-stakes vertical-press prescriptions we fall back to the bench table. The displayed deadlift one-rep max also carries a small upward correction: a practitioner-applied, display-only adjustment (LOW confidence, never fed into your prescribed loads) tied to LeSuer's finding that the standard equations underestimate deadlift 1RM by roughly ten percent — so that one figure is not itself a peer-reviewed prediction.
Key sources5
- Nuzzo, Pinto, Nosaka & Steele (2024) — Maximal reps at a given %1RM: meta-regression · PMC
- Shimano et al. (Kraemer) (2006) — Reps to failure at %1RM in free-weight lifts · J Strength Cond Res 2006;20:819
- Arazi & Asadi (2011) — %1RM–reps relationship: trained vs. untrained · J Hum Kinet
- LeSuer et al. (1997) — Accuracy of 1RM-prediction equations (bench, squat, deadlift) — deadlift underestimated ~10%, the basis for the displayed-deadlift correction · J Strength Cond Res
- NSCA (2016) — Essentials of Strength Training & Conditioning, 4th ed. (reps↔%1RM) · Human Kinetics (textbook, secondary)secondary
Running
BetaEvidence Medium — Intensity distribution and injury-aware progression are strongly evidenced; pace and heart-rate zones start from textbook and age-estimate priors.
Prescribes easy / threshold / interval paces and personalized heart-rate zones, and builds a run plan labeled by your goal race distance and date, using a mostly-easy intensity distribution and injury-aware progression limits.
Honest note. The intensity-distribution and injury-progression evidence is strong. The pace-zone boundaries follow Daniels' system (a textbook, cited directly) as coaching-consensus starting zones — per-athlete pace calibration is planned, not yet built. Heart-rate zones start from an age-estimated HRmax (Tanaka) as a low-confidence prior that sharpens as you log real runs; the zone seams sit at the LT1 ≈ 70% and LT2 ≈ 88% HRmax thresholds and scale by heart-rate reserve, following the endurance-training literature below, while talk-test / RPE stays the primary signal because heart rate lags and drifts. The goal race distance labels the plan today; distance-specific periodization is still to come.
Key sources12
- Seiler & Kjerland (2006) — Training-intensity distribution in endurance athletes · Scand J Med Sci Sports
- Stöggl & Sperlich (2015) — Polarized training yields greater endurance gains · PMC
- Muñoz et al. (2014) — Polarized vs. threshold training in runners · Int J Sports Physiol Perform
- Rosenblat et al. (2019) — Polarized vs. threshold: a meta-analysis · J Strength Cond Res
- Buist et al. (2008) — GRONORUN: graded running program & injury (RCT) · Am J Sports Med
- Tanaka, Monahan & Seals (2001) — Age-predicted maximal heart rate (HRmax = 208 − 0.7·age); backs the HR-zone cold-start prior · J Am Coll Cardiol
- Seiler (2010) — Best-practice training-intensity & duration distribution in endurance athletes (3-domain model; LT1 ≈ 70% / LT2 ≈ 88% HRmax seams) · Int J Sports Physiol Perform 2010;5(3):276
- Swain & Leutholtz (1997) — Heart-rate reserve is equivalent to %VO₂ reserve — basis for %HRR (Karvonen) zone scaling · Med Sci Sports Exerc 1997;29(3):410
- Garber et al. (ACSM) (2011) — ACSM Position Stand: quantity & quality of exercise — %HRR / %HRmax intensity anchors · Med Sci Sports Exerc 2011;43(7):1334 (position stand)secondary
- Coyle & González-Alonso (2001) — Cardiovascular drift during prolonged exercise — why HR lags/drifts and stays a guide, not a real-time target · Exerc Sport Sci Rev 2001;29(2):88
- Riegel (1981) — Athletic records & endurance-time prediction · Am Sci
- Daniels (2013) — Daniels' Running Formula (VDOT, E/M/T/I/R zones) · Human Kinetics (textbook, secondary)secondary
Nutrition
CalibratingEvidence Low — Mixed, graded at its weaker half: the protein anchor is well-evidenced, but the calorie and rate-of-change magnitudes rest on narrative recommendations rather than dose-finding trials.
Sets protein, calorie and macro targets from your bodyweight, goal and a safe rate of change — enough protein to build or protect muscle, an energy target sized to the trajectory, not a fixed guess.
Honest note. Protein plateaus and deficit protein needs are directly evidence-based. The rate-of-gain targets are a deliberately conservative baseline (about 0.25–0.5% bodyweight/week for novice/intermediate, slower for advanced — Iraki 2019; gaining faster mainly adds fat, Helms 2023 / Garthe 2013), labeled lower-confidence because they trace to narrative recommendations, not dose-finding trials; the compliance→expected-progress multiplier is a modeled layer on top. A goal weight and date, when set, nudge that pace within the same safe range — never past it — and the calorie number stays an initial estimate that recalibrates from your logged weigh-ins. When you're cutting and have a body-fat figure, protein is set from your estimated lean mass (a composition-adjusted target aimed at protecting muscle — depending on your body fat it can land above or below the bodyweight-based number); note the underlying protein range was studied in already-lean athletes (Helms 2014), and a tape/scale body-fat figure carries a few points of error (RFM/Navy ~3.5 points, Woolcott & Bergman 2018), so an entered or estimated value is treated the same — as an estimate.
Key sources10
- Morton et al. (2018) — Protein supplementation & resistance training (49-RCT meta-analysis; ~1.6 g/kg plateau) · Br J Sports Med
- Tagawa et al. (2020) — Dose-response of protein on lean mass (105 RCTs) · Nutr Rev
- Helms et al. (2014) — Protein for lean athletes in a deficit (2.3–3.1 g/kg FFM) · Int J Sport Nutr Exerc Metab
- Iraki et al. (2019) — Nutrition recommendations for bodybuilders in the off-season: gain ~0.25–0.5% BW/week (novice/intermediate) · Sports (Basel)
- Helms et al. (2023) — Moderate vs high surplus in trained lifters — faster gain mainly increased fat, no lean/strength advantage · Sports Med Open
- Longland et al. (2016) — High-protein deficit: simultaneous fat loss & lean gain (RCT) · Am J Clin Nutr
- Garthe et al. (2011) — Two weight-LOSS rates & body composition/performance in elite athletes (slower change protects lean mass) · Int J Sport Nutr Exerc Metab
- Murphy & Koehler (2021) — Energy deficiency impairs lean-mass gains (meta-analysis) · Scand J Med Sci Sports
- Woolcott & Bergman (2018) — Relative Fat Mass (RFM) as a body-fat estimate — validated vs DXA (~3.5 pt error); the deficit-protein lean-mass basis when a body-fat figure is available · Sci Rep
- Jäger et al. (ISSN) (2017) — ISSN Position Stand: protein & exercise (1.4–2.0 g/kg) · J Int Soc Sports Nutr (secondary)secondary
The large majority of citations above — the ones with no label — are primary, peer-reviewed studies. A few are marked secondary: a credible textbook, position stand, or established training system that is not itself peer-reviewed, used deliberately and disclosed rather than hidden. Weak or anecdotal sources are excluded entirely. The full provenance grading lives in the repository's evidence audit. Links open PubMed, PMC, or the publisher via DOI.