Greater Gastrocnemius Muscle Hypertrophy After Partial Range of Motion Training Performed at Long Muscle Lengths
Kassiano W, Costa B, Nunes JP, Ribeiro AS, Schoenfeld BJ, Cyrino ES · 2023 · Journal of Strength and Conditioning Research
Supports: Entrenar con rango de movimiento completo (sobre todo enfatizando la posición estirada del músculo) produce más hipertrofia que el rango parcial
Effect: En este ensayo, entrenar el gemelo en el TRAMO estirado del recorrido produjo más hipertrofia que el recorrido completo o el tramo acortado, reforzando que la posición estirada (longitud muscular larga) es especialmente estimulante. La línea de evidencia (Pedrosa 2022, Wolf/Schoenfeld 2023) apunta en la misma dirección para otros músculos, aunque el tamaño del efecto es moderado y depende del ejercicio.
Limitations: Es un estudio sobre el gemelo con ~2 meses de duración y medida ecográfica; la generalización a otros músculos se apoya en estudios adicionales, no en este solo. El ROM "óptimo" depende de la articulación y la técnica. Fitorex lo usa como un sesgo de selección orientativo (marca ciertos accesorios como de mayor estímulo en estiramiento), nunca como regla rígida.
Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-Analysis
Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ · 2023 · Sports Medicine
Supports: Para hipertrofia, entrenar cerca del fallo importa más que llegar al fallo absoluto: dejar 0-3 repeticiones en reserva produce un crecimiento muscular similar, y llevar cada serie al fallo total añade fatiga sin ventaja clara
Effect: La hipertrofia fue similar entrenando al fallo o dejando repeticiones en reserva; la relación proximidad-al-fallo/hipertrofia fue débil. Para fuerza pura, entrenar algo más lejos del fallo tendió a ser ligeramente mejor. La conclusión práctica: acumular series efectivas cerca del fallo (RIR 0-3) basta, sin necesidad de fallar en todas.
Limitations: Estudios heterogéneos en cómo definen y verifican el 'fallo'; pocos participantes muy avanzados. Respalda la autorregulación por RIR que ya usa Fitorex (rir-autoregulation): el objetivo es la proximidad al fallo, no el fallo obligatorio.
Muscle-strengthening activities are associated with lower risk of all-cause, cardiovascular disease, and cancer mortality: a systematic review and meta-analysis of cohort studies
Momma H, Kawakami R, Honda T, Sawada SS · 2022 · British Journal of Sports Medicine
Supports: Hacer entrenamiento de fuerza ~30-60 minutos por semana se asocia a menor mortalidad por cualquier causa y menor riesgo de enfermedad cardiovascular, cáncer y diabetes, de forma independiente al ejercicio aeróbico
Effect: Las actividades de fortalecimiento muscular se asociaron a un 10-17% menos de mortalidad por todas las causas, ECV y cáncer; la asociación con la mortalidad total describía una curva en J con un mínimo alrededor de 30-60 min/semana (más volumen no añadía beneficio adicional para la longevidad).
Limitations: Estudios observacionales (asociación, no causalidad); la actividad se midió por autorreporte. No cambia la prescripción de entrenamiento, pero contextualiza que el mínimo eficaz para salud es modesto.
Methodological Considerations for Studies in Sport and Exercise Science With Women as Participants: A Working Guide for Standards of Practice for Research on Women
Elliott-Sale KJ, Minahan CL, de Jonge XAKJ, et al. · 2021 · Sports Medicine
Supports: La duración del ciclo, el momento real de la ovulación y la respuesta individual a cada fase varían mucho de una mujer a otra y de un ciclo a otro en la misma mujer — un método de calendario (fecha + duración media) es una estimación, no una medición hormonal directa
Effect: No es un hallazgo cuantitativo: es una guía metodológica que recomienda confirmar la fase del ciclo con métodos objetivos (LH, temperatura basal) siempre que sea posible, precisamente porque el método de calendario (contar días desde el último inicio de regla) tiene un margen de error real frente al momento hormonal exacto — el que usa Fitorex, por ser el único posible sin pruebas de laboratorio.
Limitations: Es una guía de buenas prácticas para investigación, no un estudio con un tamaño de efecto propio; se cita aquí para ser honestos sobre el límite real del método de calendario que usa la app — por eso los ajustes de Fitorex son deliberadamente suaves y siempre desactivables.
Modelos prácticos de ritmo de ganancia (síntesis de coaching): tablas de Lyle McDonald y Alan Aragon
McDonald L; Aragon AA · 2020 · Literatura práctica de coaching (no un estudio primario revisado por pares)
Supports: El ritmo máximo realista de ganancia de masa muscular DEPENDE de la edad de entrenamiento: un principiante puede ganar un porcentaje del peso corporal por mes varias veces mayor que un avanzado, que se acerca a su techo
Effect: Como orden de magnitud ampliamente usado: 1er año ≈ 1.0–1.5 % del peso/mes, 2º año ≈ 0.5–1.0 %, 3º–4º año ≈ 0.25–0.5 %, avanzado ≈ 0.1–0.25 %; las mujeres, en términos ABSOLUTOS (kg), alrededor de la mitad por su menor masa y testosterona. Fitorex usa estas bandas como RANGO ORIENTATIVO, modulado por edad, adecuación calórica y adherencia — no como una predicción calibrada a la persona.
Limitations: No procede de un ensayo controlado único ni de un metaanálisis: es una síntesis de la experiencia de entrenadores y de datos indirectos (estudios de hipertrofia miden cambios de masa magra a semanas/meses, no 'músculo máximo por año'). La variabilidad individual (genética, respuesta al entrenamiento, sueño, estrés) es enorme; trátalo como escenario típico, no como límite personal. Por eso en la app se etiqueta explícitamente como 'banda poblacional', distinta de los intervalos de confianza que sí se ajustan a tus propios datos.
The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis
McNulty KL, Elliott-Sale KJ, Dolan E, et al. · 2020 · Sports Medicine
Supports: El rendimiento físico (fuerza, resistencia, potencia) cambia muy poco entre fases del ciclo menstrual de media — la fase menstrual/folicular temprana muestra, como mucho, una reducción pequeña frente al resto del ciclo
Effect: Efecto general pequeño (~a favor de un rendimiento algo menor en la fase folicular temprana/menstrual frente a la folicular tardía y la fase lútea), con MUCHA heterogeneidad entre estudios y entre personas — varios estudios individuales no encontraron ninguna diferencia. Fitorex usa este hallazgo para ajustes MODESTOS (±5–10% de volumen, no de peso), nunca para justificar saltarse una sesión.
Limitations: Gran variabilidad metodológica entre los estudios incluidos (formas distintas de confirmar la fase del ciclo, algunos solo por conteo de días de calendario como hace Fitorex); la respuesta individual varía mucho más que la media del grupo, así que el hallazgo describe una tendencia poblacional, no una predicción para una persona concreta.
How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency
Schoenfeld BJ, Grgic J, Krieger J · 2019 · Journal of Sports Sciences
Supports: Training each muscle ≥2 times/week, at equal total volume, is equal to or better than once a week
Effect: A small but consistent advantage of ≥2×/week over 1×/week per muscle, when total weekly volume is held equal between conditions.
Limitations: Many studies do not equate total volume well between the conditions compared; full-body workouts and splits are mixed together in the analysis; participants are mostly young recreationally trained men.
Wake up and smell the coffee: caffeine supplementation and exercise performance — an umbrella review of 21 published meta-analyses
Grgic J, Grgic I, Pickering C, et al. · 2019 · British Journal of Sports Medicine
Supports: Caffeine improves strength, power and endurance performance
Effect: A small-to-moderate effect on muscular strength/power and also on aerobic endurance, consistent across the 21 meta-analyses reviewed.
Limitations: Response varies with genetics (caffeine metabolism) and tolerance from habitual intake; most studies use a single laboratory dose, not real daily consumption patterns.
Effect of resistance training rest interval duration on muscular strength and hypertrophy: related systematic reviews
Grgic J, Lazinica B, Mikulic P, et al. · 2018 · European Journal of Sport Science / Sports Medicine
Supports: Longer rests (≥2–3 min) between sets produce more strength, and probably somewhat more hypertrophy, than short rests (<1 min)
Effect: A small-to-moderate advantage of long rests over short ones, clearer and more consistent for strength than for hypertrophy.
Limitations: Great heterogeneity in protocols and participants' training levels; few studies control for equal total volume between groups with different rest periods.
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults
Morton RW, Murphy KT, McKellar SR, et al. · 2018 · British Journal of Sports Medicine
Supports: More daily protein, up to approximately 1.6 g/kg, is associated with greater muscle mass gains with strength training
Effect: The meta-regression found no clear additional benefit above ~1.6 g/kg/day for most people, although the confidence interval does not rule out some benefit up to ~2.2 g/kg/day in some cases — hence the range Fitorex uses.
Limitations: The population is mostly healthy young adults doing strength training; women and older people are poorly represented; total energy intake is not always controlled between studies.
The development of skeletal muscle hypertrophy through resistance training: the role of muscle damage and muscle protein synthesis
Damas F, Libardi CA, Ugrinowitsch C · 2018 · European Journal of Applied Physiology
Supports: Muscle soreness (DOMS) is not a good indicator of a session's quality and does not predict greater hypertrophy
Effect: It is not a quantitative meta-analysis: the review argues, synthesising several studies, that muscle damage is neither necessary nor sufficient for hypertrophy, and that DOMS attenuates with repeated exposure without hypertrophy ceasing to progress.
Limitations: It is a narrative review, not a statistical synthesis; the exact mechanism that best explains hypertrophy is still debated in the literature.
Can drop set training enhance muscle growth?
Schoenfeld BJ, Grgic J · 2018 · Strength and Conditioning Journal
Supports: Las técnicas de intensidad (dropsets, myo-reps, rest-pause) permiten acumular estímulo efectivo cerca del fallo en menos tiempo, con hipertrofia similar a series tradicionales pero más fatiga por serie
Effect: Los estudios disponibles muestran una hipertrofia comparable entre técnicas de intensidad y volumen tradicional igualado, con la ventaja de un ahorro de tiempo notable; su valor está en llevar las series al fallo real de forma eficiente, no en superar al volumen bien programado.
Limitations: Muestras pequeñas y a corto plazo; aumentan mucho la fatiga local y sistémica, por lo que conviene reservarlas para las últimas series de ejercicios de aislamiento y para quien ya tiene base. Fitorex solo las SUGIERE (nunca las impone) y por defecto solo en nivel avanzado.
How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution
Schoenfeld BJ, Aragon AA · 2018 · Journal of the International Society of Sports Nutrition
Supports: Repartir la proteína en 3-5 tomas de ~0.4 g/kg a lo largo del día es una estrategia razonable para maximizar la síntesis proteica, aunque el total diario sigue siendo lo que más pesa
Effect: La revisión sugiere ~0.4 g/kg por toma repartidos en 4 comidas (~1.6 g/kg/día) como objetivo práctico para cubrir la respuesta anabólica; por encima de cierta dosis por comida el estímulo extra es marginal.
Limitations: Basado en estudios agudos de síntesis proteica, no en ganancias de músculo a largo plazo; el efecto de la distribución es pequeño frente al del total diario y el entrenamiento. Fitorex lo usa como sugerencia de reparto, nunca como regla estricta.
Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis
Williams TD, Tolusso DV, Fedewa MV, Esco MR · 2017 · Sports Medicine
Supports: Planning training in blocks with structured variation of volume and intensity (periodisation) produces better strength gains than keeping the same volume/intensity week after week
Effect: Periodised training showed a small-to-moderate advantage over non-periodised training in 1RM gains (an effect size favouring periodisation, significant across the body of studies); within periodised models, the variants with more variation (undulating/block) tended to match or beat classic linear periodisation.
Limitations: High heterogeneity between studies (different populations, durations and definitions of 'periodised'); the advantage is modest in absolute terms, not a radical leap. Fitorex uses a simple block model (accumulation → intensification → deload, with a volume ramp of 85%→100% within accumulation and a step back to ~92% in intensification) as a practical coaching convention, not a prescription calibrated to the individual.
Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis
Schoenfeld BJ, Ogborn D, Krieger JW · 2017 · Journal of Sports Sciences
Supports: More weekly sets per muscle, within a range, produce more hypertrophy
Effect: A positive dose-response relationship: groups with ≥10 sets/week per muscle showed clearly greater muscle mass gains than groups with <5 sets/week.
Limitations: Most of the included studies last only 6–12 weeks; the definition of an "effective set" varies between studies; few highly trained participants; it does not identify an exact individual ceiling (MRV) — which is why Fitorex treats the range as indicative rather than a fixed limit.
International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine
Kreider RB, Kalman DS, Antonio J, et al. · 2017 · Journal of the International Society of Sports Nutrition
Supports: Creatine monohydrate improves strength and muscle mass alongside strength training
Effect: Described as the most effective legal ergogenic supplement available for strength training, with consistent strength/power improvements over placebo in the vast majority of the studies synthesised.
Limitations: It is a consensus position covering hundreds of studies, not a single meta-analysis with an aggregate effect size; individual response varies ("responders" versus "non-responders").
The Effect of Menstrual Cycle and Contraceptives on ACL Injuries and Laxity: A Systematic Review and Meta-analysis
Herzberg SD, Motu'apuaka ML, Lambert W, Fu R, Brady J, Guise JM · 2017 · Orthopaedic Journal of Sports Medicine
Supports: La laxitud ligamentosa de la rodilla (y posiblemente el riesgo de lesión del ligamento cruzado anterior) varía a lo largo del ciclo menstrual, con cierta tendencia a ser mayor alrededor de la ovulación cuando el estrógeno está más alto
Effect: Asociación entre la fase periovulatoria/folicular y mayor laxitud/riesgo de lesión de LCA en varios de los estudios incluidos, pero el metaanálisis general encontró evidencia de calidad baja-moderada y resultados inconsistentes entre estudios. Fitorex lo trata como un recordatorio prudente de calentar bien y cuidar la técnica en estos días, no como una alarma.
Limitations: Calidad de la evidencia baja-moderada según los propios autores; los métodos para determinar la fase del ciclo varían mucho entre los estudios originales; no establece causalidad directa ni un tamaño de efecto preciso y generalizable.
Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training
Helms ER, Cronin J, Storey A, Zourdos MC · 2016 · Strength and Conditioning Journal
Supports: Adjusting your proximity-to-failure target (RIR) according to how you feel that day is a valid way of autoregulating training
Effect: This is not a meta-analysis with an aggregate effect size: it is a methodological paper validating the RIR/RPE scale as an autoregulation tool — it describes how training further from failure on worse days and closer on better days lets you match the actual load to each session's actual performance.
Limitations: RIR perception varies with experience (beginners estimate it worse than advanced lifters); it is a practical autoregulation tool, not a quantitative finding about exactly how much it improves results compared with a fixed RIR.
The training-injury prevention paradox: should athletes be training smarter and harder?
Gabbett TJ · 2016 · British Journal of Sports Medicine
Supports: Increasing your training load too fast relative to your recent habitual load (an 'acute load' far above your 'chronic load') is associated with more injury risk than raising the load progressively
Effect: It synthesises studies across several team sports where an acute:chronic workload ratio (ACWR) between ~0.8 and 1.3 (the 'sweet spot') was associated with fewer injuries than ratios above ~1.5, even at the SAME accumulated chronic load — the pattern of progression matters, not just the total.
Limitations: Most of the source studies are in team sports (rugby, football) with load measured by GPS/distance covered, not strength training with sRPE; the exact bands (0.8/1.3/1.5) are indicative and debated in the subsequent literature, not an exact and universal physiological limit.
Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise
Fullagar HHK, Skorski S, Duffield R, et al. · 2015 · Sports Medicine
Supports: Sleeping too little harms physical performance and recovery
Effect: Sleep deprivation more consistently harms prolonged submaximal performance and mood/perception of effort than one-off maximal strength, although the effect varies a lot between studies.
Limitations: Great heterogeneity in how "sleep deprivation" is defined and measured across studies; many involve acute laboratory deprivation rather than mild chronic restriction (the more common real-life scenario).
Metabolic adaptation to weight loss: implications for the athlete; y literatura de termogénesis adaptativa
Trexler ET, Smith-Ryan AE, Norton LE · 2014 · Journal of the International Society of Sports Nutrition
Supports: Durante una pérdida de peso sostenida el gasto energético baja más de lo esperado por el solo cambio de peso (termogénesis adaptativa), así que el ritmo de pérdida tiende a DESACELERARSE con el tiempo
Effect: El gasto energético en reposo y por actividad cae por debajo de lo que predice la pérdida de masa; el efecto es mayor con déficits agresivos y periodos largos. Consecuencia práctica: extrapolar linealmente el ritmo actual de pérdida SUBESTIMA el tiempo real para alcanzar un % de grasa bajo. Fitorex avisa de esto en cada estimación de tiempo a % graso.
Limitations: La magnitud de la adaptación varía mucho entre personas y es difícil de medir con precisión fuera del laboratorio; Fitorex no la modela cuantitativamente (no tiene ingesta registrada), solo la usa como advertencia cualitativa de que el tiempo real suele ser mayor que la proyección lineal.
Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring
Plews DJ, Laursen PB, Stanley J, et al. · 2013 · Sports Medicine
Supports: Heart rate variability (HRV) reflects the recovery state of the autonomic nervous system
Effect: HRV tends to rise with good recovery/adaptation and fall with fatigue or overload, but the relationship is neither linear nor universal — it depends heavily on each person's baseline (which is why Fitorex compares it against your own rolling average, never against an absolute value).
Limitations: Great individual variability and influence from factors unrelated to training (stress, alcohol, illness, breathing pattern); most studies were done in elite endurance athletes, not the general gym population.
The behavior change technique taxonomy (v1) of 93 hierarchically clustered techniques
Michie S, Richardson M, Johnston M, et al. · 2013 · Annals of Behavioral Medicine
Supports: There is a standardised vocabulary of behaviour change techniques (self-monitoring, feedback, reinforcement, implementation planning…) that allows you to describe precisely what makes an intervention work
Effect: It does not measure an effect: it is an international consensus process (Delphi method) defining and classifying 93 behaviour change techniques (BCTs) so that interventions can be described, replicated and compared consistently — Fitorex draws on several of these techniques (self-monitoring, feedback on behaviour, if-then planning, reinforcement) without claiming to implement them all.
Limitations: It is a classification framework, not evidence that each technique works on its own; which combination of BCTs works best depends heavily on the context and the person.
The Oslo Sports Trauma Research Center questionnaire on health problems: a new approach to prospective monitoring of illness and injury in elite athletes
Clarsen B, Rønsen O, Myklebust G, Flørenes TW, Bahr R · 2013 · British Journal of Sports Medicine
Supports: Asking periodically about current discomfort/pain (not just about injuries that have already stopped you) detects overuse problems far earlier than waiting for an injury that prevents training altogether
Effect: El cuestionario OSTRC, aplicado semanalmente, capturó muchas más molestias por sobreuso (tendinopatías, dolor articular progresivo) que los registros médicos tradicionales, que solo cuentan lesiones ya lo bastante graves como para consultar — la mayoría de problemas por sobreuso NUNCA llegan a registrarse si solo se cuentan las lesiones que impiden entrenar.
Limitations: Diseñado y validado en deportistas de élite con seguimiento médico regular; Fitorex adapta la idea central (preguntar por dolor actual de forma periódica, no solo reaccionar a lesiones) de forma simplificada y sin supervisión médica — un check-in en la app no sustituye la valoración de un fisioterapeuta o médico deportivo.
Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises
Wilson JM, Marin PJ, Rhea MR, Wilson SMC, Loenneke JP, Anderson JC · 2012 · Journal of Strength and Conditioning Research
Supports: Combining cardio with strength training can blunt strength and hypertrophy gains (the 'interference effect'), but the magnitude depends on how they are combined: cardio volume, its intensity, the modality and the order
Effect: Interference with hypertrophy and strength was greater the more frequent and longer the aerobic work, and greater with running than with cycling (more muscle damage). Strength training alone, compared with concurrent training, showed better power and hypertrophy gains; with moderate aerobic volumes the effect is small.
Limitations: A 2012 meta-analysis with studies that are very heterogeneous in duration, participant level and protocols; it does not isolate nutrition or the real time separation between sessions well. The practical rules Fitorex applies (strength before cardio, ≥6 h apart, prefer Z2 and cycling) are the usual synthesis of this literature, not figures measured by this study.
Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes
Garthe I, Raastad T, Refsnes PE, et al. · 2011 · International Journal of Sport Nutrition and Exercise Metabolism
Supports: A more moderate calorie deficit, alongside more protein, preserves lean mass better than an aggressive deficit
Effect: The slower weight-loss group preserved significantly more lean mass than the rapid-loss group, with similar fat loss between the two groups.
Limitations: A small sample (elite athletes, ~24 people) and a single study, not a meta-analysis — Fitorex's rate ranges rest on this finding alongside the general consensus of the body composition literature, not on this trial alone.
The effect of an upper-body agonist-antagonist resistance training protocol on volume load and efficiency
Robbins DW, Young WB, Behm DG, Payne WR · 2010 · Journal of Strength and Conditioning Research
Supports: Alternating exercises for antagonist groups (a superset) lets you do the same work in considerably less time, without losing volume load
Effect: The agonist-antagonist protocol maintained a volume load similar to the traditional approach in roughly half the time, meaning far greater efficiency per minute of session.
Limitations: An acute study (comparing sessions, not weeks of adaptation) and only in the upper body, with few trained participants. The ~35% saving Fitorex estimates is a conservative programming convention, not this study's exact number; in heavy exercises with complicated setups the real saving may be smaller.
A meta-analysis of motivational interviewing: Twenty-five years of empirical studies
Lundahl BW, Kunz C, Brownell C, Tollefson D, Burke BL · 2010 · Research on Social Work Practice
Supports: Motivational interviewing (exploring and reinforcing the person's own motivation rather than imposing external reasons) improves adherence to health behaviour change
Effect: A small-to-moderate but consistent effect favouring motivational interviewing over no treatment and over other active treatments, replicated across multiple health domains (not just addiction, its origin).
Limitations: High heterogeneity between studies in how it is applied and how fidelity to the technique is measured; Fitorex does NOT offer real motivational interviewing (that requires a trained professional) — it only applies its core logic (the importance/confidence rule, reflecting rather than lecturing) in a simplified, automated way.
Progression Models in Resistance Training for Healthy Adults (ACSM Position Stand)
Ratamess NA, Alvar BA, Evetoch TK, et al. (American College of Sports Medicine) · 2009 · Medicine & Science in Sports & Exercise
Supports: Before your working sets, a few ramp-up sets with increasing load prepare the neuromuscular system without accumulating significant fatigue
Effect: This is not a trial measuring a quantified effect of ramp warm-ups specifically: it is a consensus position reviewing the strength training prescription literature and recommending 1–2+ ramp-up sets with progressive loads before the real work as general good practice.
Limitations: The exact percentages Fitorex uses (40/60/80% of your working weight) are a common practical convention in strength coaching, not a protocol literally prescribed by this consensus position; the real benefit varies with the exercise, the person and how much general warm-up you have already done.
A Behavior Model for Persuasive Design
Fogg BJ · 2009 · Proceedings of the 4th International Conference on Persuasive Technology (ACM)
Supports: Anchoring a tiny behaviour to a routine you already do, and celebrating it immediately, is an effective way of establishing a new habit
Effect: It is not a trial with an effect size: it proposes that behaviour occurs when Motivation, Ability and a Trigger coincide at the same instant (B=MAP) — hence making the behaviour VERY small (low ability demand) and anchoring it to an existing trigger reduces dependence on motivation, the least reliable of the three.
Limitations: It is a conceptual model, not a synthesis of controlled trials; its empirical validation comes mostly from the author's own programmes (Tiny Habits), with fewer independent replications than other techniques on this list.
Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial
Soligard T, Myklebust G, Steffen K, et al. · 2008 · BMJ
Supports: Un calentamiento dinámico estructurado (movilidad, activación, control neuromuscular) antes de entrenar reduce el riesgo de lesión frente a no calentar o calentar de forma pasiva
Effect: El programa de calentamiento (FIFA 11+) redujo aproximadamente un tercio las lesiones totales, y más aún las lesiones graves y por sobreuso, frente al calentamiento habitual del grupo control, en un ensayo grande por clústeres (equipos completos, no individuos sueltos).
Limitations: Estudiado en fútbol juvenil femenino con un programa específico de ese deporte (equilibrio, pliometría, carrera), no en entrenamiento de fuerza en gimnasio; el mecanismo (mejor control neuromuscular) es generalizable, pero la magnitud exacta del efecto en levantamiento de pesas no está probada igual de bien.
Effects of tapering on performance: a meta-analysis
Bosquet L, Montpetit J, Arvisais D, Mujika I · 2007 · Medicine & Science in Sports & Exercise
Supports: Markedly reducing training volume in the 1–3 weeks before an important date (competition, a max test), while maintaining or slightly raising intensity, improves performance compared with continuing to train at the same volume
Effect: Tapering improved performance by around 3% on average compared with maintaining the usual load — a progressive, non-linear volume reduction (cutting volume a lot while maintaining intensity) was the strategy with the best evidence among the variants compared.
Limitations: Most of the original studies are in endurance sports/swimming, not pure strength — the exact magnitude may differ in strength training. Fitorex applies the same principle (drop volume, maintain/raise intensity) in its 2-week 'Peak' model (taper to 70%, peak at 40% of prescribed volume) as a practical convention, not a prescription calibrated to your specific sport.
Implementation intentions and goal achievement: A meta-analysis of effects and processes
Gollwitzer PM, Sheeran P · 2006 · Advances in Experimental Social Psychology
Supports: Planning a specific situation and your exact response to it in advance ('if X happens, then I will do Y') increases the probability of meeting a goal compared with merely intending it
Effect: A medium-to-large and consistent effect on goal achievement (d≈0.65 aggregated in the original meta-analysis) compared with simply setting a general goal — the if-then plan delegates the decision to the moment of the cue, instead of depending on willpower in real time.
Limitations: The effect varies with goal difficulty and with whether the person already genuinely intends to change; it works less well if the chosen 'trigger situation' is vague or infrequent in the person's real life.
Relapse prevention for alcohol and drug problems: That was Zen, this is Tao
Witkiewitz K, Marlatt GA · 2004 · American Psychologist
Supports: A one-off slip (a lapse) is not the same as a full relapse; treating it as a total failure ('I have broken it now, so why bother') is what most predicts giving up altogether
Effect: It is not a meta-analysis with an aggregate figure: it synthesises that anticipating high-risk situations and having a coping plan reduces the probability of a one-off slip escalating into complete abandonment (the model describes this jump as the 'abstinence violation effect').
Limitations: Developed and validated mostly in addiction (alcohol/drugs); extrapolating it to training adherence is a reasonable application but not a proven finding in that specific context.
A comparison of linear and daily undulating periodized programs with equated volume and intensity for strength
Rhea MR, Ball SD, Phillips WT, Burkett LN · 2002 · Journal of Strength and Conditioning Research
Supports: Varying volume and intensity every week (instead of progressing gradually within one long block) also produces good strength gains, and in some studies matched or exceeded them
Effect: The undulating periodisation group (daily/weekly variation of volume and intensity) achieved greater 1RM gains in the squat and bench press than the classic linear periodisation group, with total volume and intensity equated between groups.
Limitations: A single trial with a small sample (not a meta-analysis) and a short duration (~12 weeks) — the advantage of the undulating variant over linear does not replicate consistently across the subsequent literature; Fitorex offers the undulating model as a valid ALTERNATIVE to linear (alternating volume/intensity weeks), not as the objectively superior model.
A new approach to monitoring exercise training
Foster C, Florhaug JA, Franklin J, et al. · 2001 · Journal of Strength and Conditioning Research
Supports: The perceived effort of a session multiplied by its duration is a valid way of quantifying training load without heart rate sensors
Effect: The sRPE method (session RPE × minutes) correlated well with heart-rate-based load methods (TRIMP) in the original study.
Limitations: Session RPE is subjective and varies with each person's experience; in Fitorex it is approximated as the average per-set RPE you logged that day (excluding warm-ups) — if you do not log RPE on your sets, that day contributes no real load to the model, and it is never filled in with an invented value.
Monitoring training in athletes with reference to overtraining syndrome
Foster C · 1998 · Medicine & Science in Sports & Exercise
Supports: Training with the same load every day (little variation) is associated with more risk of overtraining/illness than the same total load spread out more variably
Effect: In the swimming team studied, the periods with the highest monotony (mean daily load ÷ standard deviation) and strain (total load × monotony) coincided with more episodes of illness/overtraining symptoms than periods of similar total load but more day-to-day variation.
Limitations: An observational study in an elite swimming team, not a controlled trial; load was measured with sRPE (session RPE × duration), the same method Fitorex uses — but the sample size is small and the finding is correlational, not causal.
Energy intakes are higher during the luteal phase of ovulatory menstrual cycles
Barr SI, Janelle KC, Prior JC · 1995 · The American Journal of Clinical Nutrition
Supports: El gasto energético en reposo y la ingesta espontánea de energía tienden a ser algo más altos durante la fase lútea (tras la ovulación) que durante la fase folicular, coincidiendo con el aumento de progesterona
Effect: La ingesta energética espontánea fue en promedio un ~2–7% más alta en la fase lútea que en la folicular en el grupo estudiado (del orden de 90–300 kcal/día en mujeres de peso medio) — coherente con la literatura sobre el efecto termogénico de la progesterona sobre el metabolismo basal. Fitorex usa una cifra fija conservadora (+150 a +200 kcal/día) dentro de ese rango, no un valor medido en ti.
Limitations: Estudio observacional en un grupo pequeño de mujeres; la magnitud exacta varía mucho entre personas y ciclos, y depende de si el ciclo fue ovulatorio; Fitorex no mide tu gasto energético real (no hay diario de comidas validado por calorimetría), así que este ajuste es una ESTIMACIÓN poblacional aplicada por fase, no una recalibración individual.
Stages and processes of self-change of smoking: toward an integrative model of change
Prochaska JO, DiClemente CC · 1983 · Journal of Consulting and Clinical Psychology
Supports: Changing a health habit passes through recognisable stages (precontemplation, contemplation, preparation, action, maintenance), and the useful strategy depends on which one you are in
Effect: An original observational study (not a controlled trial): it identified that people quitting smoking on their own passed through the same recognisable stages, and that the change processes they used varied systematically by stage.
Limitations: The original model is about smoking, not exercise; assigning a stage from just 2 questions (importance/confidence), as Fitorex does, is a practical simplified approximation, not the validated staging instrument (e.g. URICA) a clinical study would use.
A systems model of training for athletic performance
Banister EW, Calvert TW, Savage MV, Bach T · 1975 · Australian Journal of Sports Medicine
Supports: Daily training load can be summarised as a 'chronic' load (fitness, decaying slowly) and an 'acute' load (fatigue, decaying quickly) to estimate your relative balance
Effect: The original impulse-response model (two exponentials with time constants of ~42 days for the fitness component and ~7–15 days for the fatigue component) reasonably predicted performance variation in the individual time series of the athletes studied — but to be genuinely precise it needs those constants CALIBRATED with each person's real performance data. Fitorex uses the typical population constants (42/7, the same practical convention used by endurance training-load tools), so the result is an INDICATIVE TREND, not a prediction calibrated to you.
Limitations: It was validated on short time series from a small number of athletes; the relationship between 'training impulse' and real performance is more complex and non-linear in practice; Fitorex has no objective performance data (times, marks) with which to calibrate the constants individually.
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