Research
What we cite, and why it matters.
Auriga’s coaching is built on roughly 30 peer-reviewed studies. Here they are. Every claim links to its source.
The cycle and training
The cycle and training
Estrogen and progesterone rise and fall across roughly 28 days. The evidence is clearer than the headlines: cycle phase does not change strength outcomes radically — but it changes how a session feels, how fast you recover, and how willing you are to push. Auriga’s cycling-user defaults sit on these studies.
Phase has a small, real effect on performance
A meta-analysis of 78 studies found cycle phase produces a trivial-to-small effect on exercise performance — large enough to inform programming, too small to justify rigid phase protocols.
Foundation for Auriga’s position: phase informs how a session feels, but day-to-day signals (RPE, sleep, symptoms) drive the prescription.
Estrogen supports muscle protein synthesis in the follicular half
Rising estrogen through follicular and ovulation phases coincides with the body’s clearest build window — better recovery, higher work capacity, and a small edge on top-set strength.
Basis for Auriga flagging follicular and ovulation phases as a build window for cycling users.
Follow-on synthesis used for Auriga’s peri/postmeno bias toward heavier loads and longer rest.
Late luteal — slower recovery, higher RPE at the same load
Progesterone in the second half of the cycle modestly slows recovery and tilts perceived effort up. Auriga trims the last accessory sets in late luteal when symptoms or phase suggest the same load is costing more.
Periodised cycle-aware programming outperformed flat programming on lean mass and power in trained women.
Standard reference for compound 6-10, accessory 8-12 rep ranges and the autoregulation logic Auriga uses on cycling users.
RPE and reps-in-reserve are reliable load gauges
For trained adults, the RIR-based RPE scale tracks proximity to failure accurately enough to drive autoregulated programming. This is the engine under Auriga’s "last set’s RPE" logic.
Core validation of the RIR-based RPE scale Auriga prompts after every working set.
Practical guidance Auriga uses for autoregulated load adjustments and progressive overload triggers.
Confirms RPE precision on compound lifts; basis for Auriga’s confidence in RPE-driven main-lift programming.
Perimenopause
Perimenopause
Estrogen becomes volatile. Cycles get longer, shorter, or skip. Sleep fragments. The body starts losing efficiency at building and repairing muscle (anabolic resistance), and bone density begins to drop about 1% per year. Phase-based programming becomes unreliable; heavier loads, longer rest, and higher protein become the more useful levers.
Anabolic resistance — same dose, smaller MPS response
Older adults need a higher per-meal protein dose to fully stimulate muscle protein synthesis. Auriga lifts the per-meal floor from 0.4 to 0.55 g/kg in perimenopause and beyond on the strength of these studies.
Direct basis for Auriga’s 0.55 g/kg per-meal protein floor in anabolic-resistance stages.
Sets the 1.0-1.2 g/kg floor for older adults; pushes to ~2.0 g/kg for active lifters in clinical practice.
Heavier loads at lower reps preserve type-II fibres
As estrogen declines, the bias shifts toward heavier compounds (4-6 reps at 75-85% 1RM on main lifts) to maintain type-II fibre recruitment and neural drive.
Confirms heavier loads as superior for strength outcomes; informs Auriga’s peri/postmeno main-lift bias.
Practitioner synthesis underpinning Auriga’s heavy-compound, longer-rest perimenopause programming.
HIIT helps, but the lift is non-negotiable
One to two structured high-intensity intervals per week add cardiometabolic and mitochondrial benefit on top of resistance training. Auriga prescribes 1-2 HIIT sessions weekly through perimenopause and postmenopause.
Direct evidence for 2× weekly HIIT in postmenopausal women — basis for Auriga’s peri/post HIIT defaults.
Foundational HIIT review supporting the cardiometabolic case for short, intense intervals.
RED-S — under-fuelling has bigger consequences here
Relative Energy Deficiency in Sport raises bone, endocrine, and immune risk. Auriga’s defaults steer cycling and perimenopausal users away from caloric-deficit-while-training patterns, especially when sleep or symptoms suggest stress is high.
Reference Auriga uses for the energy-availability framing in symptom logs and onboarding.
Postmenopause
Postmenopause
Twelve or more months past the last period. Estrogen sits at a low, stable baseline. Without resistance training, women lose 1-2% of muscle mass and bone density each year. The research on heavy lifting in this stage is unambiguous, and the LIFTMOR trial is the protocol Auriga’s postmenopause defaults are built on.
LIFTMOR — heavy lifting builds bone in postmenopausal women
5×5 at 80-85% 1RM on squat, deadlift, and overhead press improved femoral neck and lumbar bone mineral density over eight months. Auriga’s 3-5 rep main-lift range and bone-density-lift requirement come straight from this trial.
Primary evidence for Auriga’s "at least one bone-density lift in every postmenopausal session" rule.
Replication of the LIFTMOR effect; supports the generalisability of HiRIT in real-world settings.
Sarcopenia — heavy resistance work is the only intervention that holds
Without progressive overload, women in postmenopause lose 1-2% of muscle mass per year. Heavy compound lifting maintains and modestly grows lean mass into the seventies and beyond.
Standard guideline reference Auriga uses for postmenopausal lifting frequency and load progression.
Underpins Auriga’s push to 2.0 g/kg/day protein for active postmenopausal lifters.
Slower progression protects connective tissue
Joints and tendons take longer to adapt. Auriga drops upper-body increments to 0.5 kg and lower-body to 1 kg in postmenopause to preserve form across the long arc.
Practical RPE-driven progression model Auriga uses to keep loads productive without overshooting.
Practitioner synthesis on slower progression in anabolic-resistance stages.
Postpartum
Postpartum
Whether you delivered six weeks ago or eight months ago, your core, pelvic floor, and connective tissue are still healing. Hormones (relaxin, oxytocin, prolactin if you’re nursing) still affect joint stability and recovery. Auriga’s postpartum mode is built around three phases — bodyweight only, then moderate load, then a graded return — gated by the consensus statements below.
Phased return — ACOG and IOC
Auriga’s phase 1 (bodyweight, weeks 0-4 post-clearance), phase 2 (moderate load, 4-12), and phase 3 (graded return, >12) match the ACOG postpartum guidelines and the IOC expert consensus on postpartum exercise.
Foundational guideline for Auriga’s three-phase postpartum gating logic.
IOC consensus on postpartum return-to-training; basis for Auriga’s plyometric and overhead-pressing gates.
Diastasis recti — common, screen before loading
Diastasis is a normal feature of late pregnancy that resolves slowly in some women and not at all in others. Auriga avoids spinal flexion under load (no crunches, sit-ups, leg raises) and unscaled overhead pressing until cleared.
Prevalence and risk-factor data Auriga uses to default postpartum users into diastasis-safe substitutions.
Delphi consensus on common postpartum impairments; informs Auriga’s pelvic floor and core-rebuild prompts.
Lactation — protein needs go up, not down
Nursing adds about 25 g of protein per day for milk synthesis on top of baseline. Auriga’s default postpartum target is 1.7 g/kg + 25 g additive while lactating.
Direct basis for Auriga’s lactation +25 g/day protein additive.
PCOS & endometriosis
PCOS and endometriosis
Both conditions are common, both are systemic, and both interact with training. The literature on resistance training in PCOS is small but consistent: it helps. The literature on exercise in endometriosis is younger but points the same way. Auriga doesn’t modify programming for either condition today, but the science under what we already do supports doing the work.
PCOS — resistance training improves the markers that matter
Resistance training improves insulin sensitivity, body composition, and androgen-related markers in women with polycystic ovary syndrome. Standard hypertrophy and strength templates apply.
Evidence resistance training increases lean mass and lowers free androgen index in PCOS.
Review supporting progressive resistance training as a first-line non-pharmacological lever in PCOS.
Endometriosis — exercise reduces pain and improves quality of life
A 2021 review found regular physical activity is associated with lower pain scores and better quality of life in women with endometriosis. The evidence is preliminary but consistent in direction.
Best available synthesis on exercise and endometriosis pain — used by Auriga to caution against rest-based defaults.
Hormonal birth control
Hormonal birth control
The pill, hormonal IUD, ring, or implant suppresses ovulation and stabilises hormone levels — which means there is no real cycle to predict. Most cycle-aware fitness apps either ignore this and apply phase rules anyway (wrong) or fall back to generic programming (lazy). Auriga turns phase prediction off and leans on sleep, RPE, and symptoms instead.
Hormonal contraceptives flatten the cycle
Combined oral contraceptives, hormonal IUDs, rings, and implants all suppress endogenous estrogen and progesterone fluctuations. The published evidence on training response is mixed, with most well-controlled studies showing no meaningful difference between users and naturally cycling women on strength outcomes.
Same meta-analysis cited under "The cycle and training" — its small-effect finding is what justifies Auriga’s flat-default approach for hormonal BC users.
Practitioner synthesis covering hormonal BC: cycle features off, coach on RPE / sleep / symptoms instead.
Coaching on signals, not predicted phases
For users on hormonal birth control, Auriga’s readiness logic uses sleep quality, last-set RPE, and symptom flags rather than a predicted phase wheel. The cycle UI is hidden; the smart-coach engine still works.
Validates the RPE/RIR engine Auriga uses as the primary readiness signal for hormonal BC users.
Programming principles
Programming principles
Auriga’s coaching is stage-aware on top, but the engine is the same across stages: progressive overload, RPE-based autoregulation, controlled tempo, intentional rest, and sleep treated as a recovery tool — not a nice-to-have.
Progressive overload — the single biggest driver of strength
Hitting all sets at the top of the rep range is the trigger Auriga uses to nudge weight up. The principle is old; the meta-analytic backing is current.
Quantifies the load-response curve Auriga uses for compound rep ranges.
Standard reference for progressive overload prescription across cycling adults.
RPE / RIR autoregulation
Trained adults can rate proximity to failure precisely enough to drive load adjustments. Auriga prompts an RPE after every working set and uses the trend to deload, hold, or push.
Core validation of the RIR-based RPE scale — the engine of Auriga’s autoregulation.
Confirms RPE accuracy on compound lifts under heavy loads.
Tempo and time under tension
Controlled eccentrics and a deliberate concentric beat empty-rep momentum on hypertrophy outcomes. Auriga’s default tempo (controlled down, drive up) is set on this evidence.
Meta-analytic basis for Auriga’s controlled-tempo defaults on accessory work.
Modern review on tempo and adaptations — supports Auriga’s eccentric-emphasis defaults.
Practitioner reference for Auriga’s tempo notation in main-lift programming.
Inter-set rest — long enough to actually rest
90-120 seconds on accessories, 150-240 seconds on compounds. Longer rest measurably increases strength and hypertrophy outcomes versus the 60-second default a lot of apps still ship.
Foundational rest-interval review — basis for Auriga’s 90-180 s default windows.
Direct evidence Auriga uses to default compound rest to ≥150 s on cycling users.
Sleep as a recovery tool
Restricted sleep blunts hormonal recovery and lifts perceived exertion. Auriga’s readiness check trims volume on broken-sleep days rather than holding the prescription steady.
Cited as part of the broader fitness-context case for Auriga’s sleep-aware readiness logic.
Nutrition
Nutrition
Auriga doesn’t yet ship a nutrition coach. The protein targets behind the in-app stage logic — and the targets we publish on this site — come from the sources below. We’ll expand this section when nutrition coaching ships.
Protein for hypertrophy in cycling adults
1.4-2.0 g/kg/day is the evidence-supported range for trained adults pursuing hypertrophy. Auriga’s cycling-user default is 2.0 g/kg/day.
Sets the 1.4 g/kg floor for hypertrophy in regularly cycling adults.
ISSN position stand confirming the 1.4-2.0 g/kg range for trained populations.
Per-meal distribution maximises 24-hour MPS
Roughly 0.4 g/kg per meal across four meals beats front-loaded or back-loaded distributions on 24-hour muscle protein synthesis.
Direct basis for Auriga’s 0.4 g/kg × 4 meals default in cycling stages.
Higher per-meal floor for anabolic-resistance stages
Older adults need a higher per-meal dose to fully stimulate MPS. Auriga lifts the per-meal floor to 0.55 g/kg in perimenopause, postmenopause, and postpartum.
Sets Auriga’s 0.55 g/kg per-meal floor for anabolic-resistance stages.
Backstop for Auriga’s push to ~2.0 g/kg/day in active postmenopausal lifters.
Practitioner synthesis used for Auriga’s peri (1.8 g/kg) and postmeno (2.0 g/kg) defaults.
Postpartum lactation — additive, not multiplicative
Nursing adds about 25 g/day of protein for milk synthesis on top of baseline. Auriga keeps the baseline target at 1.7 g/kg and applies the +25 g/day on top.
Direct source for Auriga’s lactation +25 g/day additive.