Female Training, Hormones & Nutrition: Fact vs. Fiction | Dr. Lauren Colenso-Semple
In a Nutshell
Training must be consistently challenging with progressive overload; sex, menstrual cycle phase, and menopause do not meaningfully alter strength gains, muscle growth rates, or optimal programming. Men and women adapt at equivalent relative rates, with no evidence supporting cycle-syncing, sex-specific volume allowances, or hormone-based training adjustments. Core requirements remain identical across populations: adequate stimulus, consistency, sufficient protein and calories, and autoregulation for individual symptoms rather than demographic categories.
These notes were generated by AI and may contain inaccuracies.
The most important element is that training must be challenging enough. When finishing the last rep—whether the sixth, twelfth, or fifteenth—you should feel like you could only do one, maybe two more. If that threshold is not reached, the weight is not heavy enough and load must be increased. There is no must-do exercise, no must-do rep range, no must-do workout length, and no must-do days per week. The requirements are that the training is challenging, performed consistently, and progressed over time. As strength increases, load must also increase.
Dr. Lauren Colenso-Semple holds a PhD in integrative physiology. Her research focuses on female physiology, exercise, and nutrition. She is both a scientific communicator and practitioner who has coached hundreds of people to their fitness goals. Approximately ten years prior to this conversation, she and Andy Galpin considered writing a literature review examining potential sex differences in training responses. The review aimed to identify areas where mechanisms suggested hypotheses worth testing in women, such as whether women can train more frequently or whether estrogen provides protective effects allowing faster recovery or reduced muscle damage.
At the time, studies were commonly first conducted in young college-aged men, with limited female data. The goal was to replicate those studies in women. Questions included whether fluctuating estrogen and progesterone across the menstrual cycle produce meaningful differences, given that men and women gain muscle size and strength at similar relative rates despite large differences in testosterone.
Dr. Colenso-Semple's interest originated from a desire to optimize her own results and those of her clients. She did not assume men and women should train differently but believed the possibility should be investigated rather than assuming male findings automatically apply to women. In her coaching experience, she never applied different protocols based on sex. Evidence-based coaching communities did not push for sex-specific recommendations; differences were typically limited to exercise selection for targeted hypertrophy goals.
Women have historically received ineffective training prescriptions due to long-standing cultural beliefs. Physical activity was discouraged out of unfounded fears it would destroy fertility. Women were barred from events such as marathon running on the grounds that they could not physiologically complete them. Once exercise was recognized as beneficial and safe, the fitness industry capitalized on novelty by promoting new classes and equipment rather than emphasizing consistency and progression. Persistent messaging warned that lifting weights would make women bulky, steering them toward ineffective modalities and frequent program changes instead of foundational practices.
When developing training or nutrition recommendations, the first question is the individual's goal. Subsequent questions address experience level, available time commitment, need for flexible versus regimented programming, equipment access, tolerance for repeating the same exercises, and psychological preference for variety. These factors determine whether a program is goal-oriented and sustainable long enough to produce results.
Sex ranks very low in the hierarchy of variables. No adjustment to program type or conversational approach is made solely because a client is female. Individual background, history, preferences, and goals drive decisions. The flexibility inherent in resistance training allows substitutions for disliked exercises, unavailable equipment, or injuries.
Marketing that targets extremely narrow demographic buckets can make people feel seen, yet lumping all women into one category discards individualization and goal-oriented programming. Telling a woman over 40 that she must follow a specific protocol without first learning her goals—whether longevity, powerlifting, marathon running, or bodybuilding—constitutes poor coaching. Different goals require drastically different programs. For the general population seeking health and consistency, advanced nuances are irrelevant. For elite athletes optimizing every variable, tracking menstrual symptoms alongside performance data or evaluating hormonal contraceptive effects over months may be appropriate.
No strong data set currently supports broad female-specific training or recovery recommendations. Many studies initially performed in men have since been replicated in women. Scientific papers deliberately minimize inter-individual variability to isolate variables and therefore cannot prescribe exact training programs. While individual differences in volume tolerance exist—some people, both men and women, handle substantially more volume than others—there is no evidence that all women can handle more volume or train more frequently due to estrogen or fiber-type differences.
The hypothesis that estrogen may enhance recovery originates from rodent studies in which ovaries were removed, eliminating hormone production. In this extreme model, the satellite cell pool became depleted; injecting estradiol appeared to reverse the effect. Satellite cells participate in recovery and repair, leading to speculation that absence of estrogen impairs recovery. However, translating this to normally cycling human women requires a substantial leap. The same ovariectomy model suggested estrogen might be anabolic because muscle mass maintenance was impaired after ovary removal. These findings provided a plausible mechanistic starting point but remain far removed from typical human physiology.
Additional considerations include whether lower absolute loads typically lifted by women produce less systemic fatigue independent of hormonal factors. Absolute load is known to influence fatigue; powerlifters and weightlifters recognize that lifting triple body weight at 175 kg creates greater fatigue than the same relative percentage at 75 kg.
Presence of a hormone does not automatically mean muscle growth occurs. Research on muscle loss and hormone therapy aligns more closely with menopause models than with cycle syncing or acute hormone fluctuations. Studies often begin with rodent models, but rodents lack menstrual cycles entirely. When ovaries are removed, all hormone production shuts down, making it impossible to isolate estrogen effects since multiple hormones function together physiologically.
Researchers examined protein synthesis differences between men and women to test theories that estrogen affects protein synthesis, myosin function, or the satellite cell pool. These targeted pathways must be extrapolated from simple rodent models to complex human physiology. Changing one variable often triggers downstream changes in many other systems, so direct cause-and-effect relationships rarely occur. Acute findings frequently fail to translate to long-term human adaptations.
Acute fat oxidation during exercise provides an example of this disconnect. Fasted cardio increases fat oxidation acutely, but this does not translate to greater long-term fat loss. Protein synthesis serves as another clear example. An intervention that elevates muscle protein synthesis by 40% does not produce 40% larger muscles in 8-10 weeks. The expected outcome would be closer to 2-3% growth if any occurs. These measures are highly related but not one-to-one exchanges.
Removing an ovary to reach zero estrogen differs significantly from menopause or natural cycle phase variations. The conversation returns to documented sex differences and their practical implications.
Testosterone primarily drives reproductive function but acts on any tissues possessing receptors. During male puberty, rising testosterone produces secondary sex characteristics and increases muscle mass. Untrained adult men average more muscle and greater strength than untrained adult women on acute strength tests. This baseline difference stems from pubertal testosterone effects.
Women experience small daily testosterone fluctuations at extremely low concentrations. The minimum difference between male and female testosterone levels reaches 15-fold. These tiny fluctuations occur at concentrations so low that most assays lack sensitivity to detect them reliably.
Day one of the menstrual cycle is defined as the first day of bleeding. The full cycle spans from day one of one period to day one of the next period. A textbook 28-day cycle divides into follicular and luteal phases with ovulation occurring mid-cycle.
At cycle onset, all hormones remain low. Estradiol begins rising and peaks just before ovulation. Ovulation features a short luteinizing hormone spike lasting hours to two days, ending the follicular phase. The luteal phase includes a moderate secondary estradiol peak paired with progesterone that rises and peaks mid-luteal phase before both hormones decline.
All hormone fluctuations prepare for egg release and potential implantation. The ovarian cycle supports pregnancy preparation. Progesterone promotes gestation. Testosterone supports egg release and post-ovulation fertility functions, sometimes showing slightly higher levels in the luteal phase.
Testosterone levels in women decline gradually across the adult lifespan from already low baseline values. Peak testosterone occurs between ages 18-25. This age-related decline has greater symptomatic impact in men than women outside of libido considerations. Normal-range testosterone in women shows no established connection to exercise performance. Testosterone does not decrease during menopause transition.
Textbook estrogen peaks in women reach 700-800 pg/mL or higher. Male testosterone levels show no comparable magnitude of increase. Men produce estrogen, though individual peak extent varies.
The standard 28-day cycle with ovulation on day 14 rarely occurs exactly as depicted. Significant variability exists both between women and within the same woman across cycles. Normal cycle lengths range from 21 to 35 days. Ovulation timing also varies, creating unequal phase lengths. One study participant with a consistent 30-day cycle ovulated regularly on day 9, while another ovulated consistently on day 19.
Peak magnitudes also differ substantially. Some women show small estradiol peaks while others show large peaks, with no predictable relationship between estradiol and progesterone peak sizes. These patterns prove unpredictable and make research standardization extremely difficult.
Urinary luteinizing hormone test strips predict impending ovulation since the LH spike precedes egg release. A positive LH test does not guarantee complete ovulation occurred. The gold standard confirmation uses vaginal ultrasound. Secondary confirmation measures mid-luteal progesterone; absence of the expected peak indicates an anovulatory cycle.
Commercial ovulation predictor kits are widely available. For shorter average cycles, testing should begin around day 10 and continue daily. Apps assuming fixed relationships between cycle length and ovulation timing are unreliable since short cycles do not always mean early ovulation.
Cycle length consistency within a 3-4 day range is typical. Women may show consistent cycle length with varying ovulation day, consistent ovulation timing with varying cycle length, or any combination of these patterns.
Journals frequently require menstrual cycle standardization for publication. This demands recruiting only women with regular natural cycles, excluding hormonal contraceptive users (roughly half the premenopausal population), tracking multiple cycles, measuring hormones repeatedly, and scheduling all testing and training at identical cycle phases for each participant individually. These requirements multiply study length and cost by factors of 5-10x compared to male-only studies.
The assumption that cycle phase must matter created barriers to including women in research. Studies accepting variability in age, training status, and dietary reporting simultaneously rejected menstrual cycle variability as unacceptable. Investigating whether cycle phase actually affects outcomes could reduce unnecessary barriers if no meaningful differences emerge.
The study compared each woman to herself across two distinct hormone profiles. Testing occurred in the late follicular phase with peak estrogen and repeated in the mid-luteal phase featuring both peak progesterone and the secondary estrogen peak. The hypothesis predicted measurable differences in protein synthesis if estrogen acts anabolically and progesterone acts catabolically.
Traditional methods for measuring muscle protein synthesis involve infusing a labeled tracer through an IV, followed by muscle biopsies to track incorporation rates. These studies are typically conducted over a few hours in a fasted state. Modern approaches use orally ingested tracers that can be consumed daily, providing a more comprehensive view of muscle protein synthesis across an entire week. This integrated method accounts for meals, sleep, exercise, and daily activities, offering greater ecological validity while still directly measuring incorporation through biopsies.
Screening for menstrual cycle research requires excluding approximately 75% or more of potential participants. Requirements include: no birth control use for at least one year, no children, no history of pregnancy, no perimenopausal status, regular menstrual cycles between 27-32 days consistent across six months, no menstrual cycle dysfunction, no PCOS, no endometriosis, no amenorrhea, no obesity, no other health conditions or diseases, and age range of 18-30 years.
Participants track ovulation using urinary test strips over multiple months. Researchers require participants to photograph and text results, enabling accurate prediction of ovulation timing. Testing phases begin a week before predicted ovulation to capture the estrogen peak, and during the mid-luteal phase to capture the progesterone peak. The study used a randomized order for phase testing across participants.
Each testing phase includes blood hormone measurements, resting muscle biopsies, tracer ingestion, unilateral exercise to compare exercised versus resting legs, multiple exercise bouts, and additional tracers to measure protein breakdown. Hourly blood draws over five hours assess whole-body protein breakdown decay curves. The second phase requires two baseline biopsies due to prior tracer ingestion. Total biopsies across both phases reach seven per participant.
The extensive screening requirements, need for cycle tracking over multiple months, multiple biopsy procedures, and repeated testing across phases explain why rigorous women's health research is resource-intensive. Historical menstrual cycle studies often assumed 28-day cycles with mid-cycle ovulation, included women on oral contraceptives, and made claims about hormones without actually measuring them.
The research found no differences in muscle protein synthesis response across menstrual cycle phases. There is no physiological rationale for standardizing, manipulating, or altering training based on cycle phase. Claims suggesting women should lift weights during certain phases or avoid training during others lack supporting evidence. Incorporating cycle-based training modifications is potentially harmful as it may unnecessarily reduce training volume or overcomplicate programming.
Individual responses vary widely, with some women reporting inability to train on day one of their period while others report PRs on the same day. Every effective training program should include autoregulation for symptoms. Menstrual cycle phase is one of many factors coaches should monitor, but it does not justify broad prescriptive changes to training protocols.
On average, speed and power performance do not change across the menstrual cycle in women. Strength performance data is robust enough to conclude that cycle phase does not affect strength on average. While individual women may feel stronger or weaker at different times, average physiological performance remains consistent. The data on speed and power is less robust than for strength, but current evidence suggests no meaningful effect.
Men tend to be faster and more powerful on average due to greater muscle mass and strength. However, relative adaptations to training are comparable regardless of sex. Men and women increase strength at the same relative rate when training properly, eating adequately, and managing sleep and stress. Men and women also gain muscle at the same relative rate, particularly when accounting for lean body mass. Absolute loads will be higher for men on average, but percentage gains remain equivalent.
Testosterone, estrogen, and progesterone fluctuations during the menstrual cycle do not meaningfully affect anabolic capacity or strength gains. If these hormones exerted profound effects, acute performance differences and correlations between hormone peaks and muscle mass would be observable, but neither appears in the data. Normal-range testosterone levels are not predictive of propensity to gain size or strength. Puberty represents the primary period where testosterone drives meaningful developmental differences.
Women maintain the ability to gain muscle strength and size at comparable relative rates through perimenopause and postmenopause. Cross-sectional studies show age-related muscle loss trajectories, but these do not account for physical activity or nutrition status. People who begin resistance training at age 75 can still gain muscle. Strength and muscle size do not change through menopause independent of lifestyle factors. If exercise stops or nutrition declines, muscle and strength are lost regardless of menopausal status.
Sixty to seventy percent of women gain weight during the menopause transition. Increased body fat without proportional muscle gain alters body composition, which may create the appearance of muscle loss when the primary change is fat gain. The SWAN study followed women through the transition and found muscle mass remained fairly stable despite trends toward increased body fat, indicating estrogen absence is not the primary driver of body composition changes.
Studies comparing women on hormone replacement therapy versus those not using it show no differences in lean mass, suggesting estrogen replacement does not provide the protective muscle-maintaining effect once hypothesized based on rodent models.
Testosterone during puberty provides the most significant developmental boost to muscle. Within normal physiological ranges, higher or lower normal values do not necessarily predict who will grow muscle faster. Subclinical low testosterone (below approximately 200 ng/dL in men) corrected to normal range may improve outcomes. Exogenous testosterone at pharmacological levels above physiological ranges does enhance muscle growth in both men and women. Postmenopausal women given testosterone at low-normal doses for libido do not experience meaningful muscle growth effects.
Narrative reviews summarize existing literature and generate research questions but do not provide new data. Cross-sectional studies identify associations and patterns but cannot establish causation. Media often overinterprets associations as causal relationships. A historical example involved coffee consumption being linked to lung cancer in cross-sectional data, when smoking was the actual confounding variable driving the association. Transparency about study design, data quality, and what conclusions are appropriate for each type of research is essential for accurate interpretation.
Observational studies from medical records have limitations because healthcare professionals enter codes associated with a diagnosis or drug, and researchers do not have someone's full health history. Rodent models are used in research because researchers can perform invasive procedures that would never be possible or ethical in humans, including removing organs, deleting genes, and breeding lines of mutant mice. These models allow researchers to answer mechanistic questions and generate hypotheses that can then be tested in humans.
All forms of research are important to reach clinical trials. New drugs are initially tested in animals, then progress through phase one, two, and three clinical trials before FDA approval. Translating potential mechanisms or rodent data directly into practical recommendations is problematic because human metabolisms, physiology, and lifespans differ from rodents. The same caution applies to training and nutrition recommendations derived from animal models.
Animal studies should not be dismissed entirely if the purpose is scientific interest rather than deriving practical recommendations. Rodent studies can generate interesting mechanistic discussions, but they should not be translated into public guidance. The distinction lies between scientifically interesting conversations and practical recommendations.
When evaluating whether a study applies to a specific individual, such as a 65-year-old female powerlifter, consider that differences between men and women or between older and younger adults are fewer than differences between rodents and humans. For exercise-induced adaptations, training status is often more important than sex or age in determining the magnitude of adaptations. Untrained individuals show substantial initial adaptations, while those who have trained for a long time experience fewer adaptations due to limited capacity.
No study is designed to tell someone exactly how to train. However, multiple studies conducted in young men, older men, younger women, and older women show consistent patterns regarding training volume and frequency. Volume is important, while frequency matters primarily as a function of volume. When data is limited for a specific population, researchers can reasonably lean on findings from other populations when patterns are consistent.
There are no known sex-specific differences in strength training adaptations. Research on age shows no substantial differences outside of pre-puberty. Claims that training programs for 65-year-old female powerlifters need to be drastically different lack supporting evidence. The burden of proof has sometimes been flipped, requiring evidence that standard approaches work rather than demonstrating that sex-specific modifications are necessary.
The current state of research indicates that training philosophies and approaches have no sex-specific bearing. The status quo has been challenged through research and continues to hold. There is no real rationale for age-specific, menopause-specific, or sex-specific strength training programs. If large substantial differences existed, researchers would have detected signals in the data.
The strength-endurance continuum and concurrent training represent areas where initial assumptions evolved through multiple studies across different populations. Some resistance to accepting the current evidence stems from a desire for sex-based differences to exist.
The most important element is that training must be challenging enough. Whether performing sets of 6, 12, 15, or any rep range in between, the final rep should leave the lifter feeling they could only complete one or two more repetitions. If this threshold is not reached, the weight is insufficient and load should be increased. Challenging loads vary by exercise, and trial and error is required when starting a program.
There are no must-do exercises, must-do rep ranges, must-do workout lengths, or required training days per week. The essential requirements are that training is challenging, performed consistently, and includes progression over time as strength increases.
Sex differences in training preferences exist at the behavioral level rather than the physiological level. Women often prefer training lower body and glutes, while men tend to prioritize arms and chest. These preferences influence programming frequency based on client goals rather than physiological necessity. Individualized, goal-oriented training addresses these secondary considerations.
Nutrition drives fat loss, and a calorie deficit works for men and women of all ages. Leaning too heavily on exercise for fat loss often leads to disappointment. Endurance training recommendations, whether sprint training or longer duration work, should be goal-oriented and appropriate for men or women of any age. Large-scale systematic reviews and meta-analyses show that adaptations to endurance exercise vary based on training status rather than sex.
For general fitness and health, individuals should engage in activities they enjoy or will perform consistently. Practicality often outweighs potential moderate physiological differences. Time efficiency may favor higher intensity work, but recommendations should account for sustainability. Some combination of training modalities is generally advisable, though most people will not maintain multiple approaches.
Body fat redistribution during menopause represents an area with proposed estrogen-related mechanisms that remain poorly understood. Not all individuals experience these changes despite universal hormone level decreases, indicating the process is more complex than hormone absence alone. The solution for losing body fat from any area remains a calorie deficit regardless of underlying mechanisms.
Middle-aged populations between 35 and 53 years old have been historically understudied in aging research, which typically focuses on college-aged participants. This gap is particularly relevant for understanding the menopause transition. Capturing data 5 to 10 years before menopause may help identify predictors of symptoms and physiological changes.
Low energy availability is a genuine concern for female athlete populations but is frequently misunderstood as a risk for women engaging in normal fitness activities. The vast majority of people worldwide do not suffer from insufficient energy intake. Low energy availability is defined as a mismatch between energy consumed and energy expended through exercise, distinct from a general caloric deficit. It typically involves high exercise volumes, sometimes multiple daily sessions, combined with underfueling or intentional maintenance of low body fat for performance or aesthetic reasons.
Current equations for calculating energy availability do not account for non-exercise energy expenditure throughout the day. A more holistic approach would benefit the scientific understanding. Identification methods vary, with some focusing on menstrual cycle dysfunction, others on blood work and physiological parameters, and still others on subjective measures of energy levels and wellbeing. A combination approach may be most appropriate without relying on strict numerical cutoffs that fail to capture the complete picture.
If low energy availability is required for a sport, the goal is to minimize the duration and exit the state as quickly as possible. Recovery timelines are not fully understood and may be lengthy in some cases. Repeated cycles, such as a high-level bikini competitor performing multiple shows annually, are likely problematic. The consequences of prolonged caloric deficit combined with high exercise output differ from caloric deficit alone.
Caloric deficit combined with extremely high exercise output creates unique problems that differ from moderate training scenarios. When training occurs multiple times per day over extended periods, the consequences become more severe than simple caloric restriction with three or four weekly workouts.
Menstrual cycle dysfunction or loss of menstrual period represents one of the earlier visible signs. Looking deeper reveals broader endocrine system disruption, cardiovascular issues, gastrointestinal issues, downregulation of muscle protein synthesis leading to inability to build new tissue and potential muscle loss, and loss of bone mineral density. These effects compound across multiple body systems.
Recovery timelines extend far beyond initial expectations. Simply lowering training load or increasing food intake does not produce immediate resolution. Menstrual cycle recovery alone can require months. Other disrupted systems need extended recalibration periods. Muscle and bone tissue repair represent time-consuming processes that may not be fully reversible.
Young athletes face particular risk. A teenage gymnast who has not yet reached peak bone mass can experience permanent long-term consequences from extended low energy availability.
Relying too heavily on any single creator represents a problematic approach. Multiple perspectives should be considered, and each message's context should be evaluated for personal applicability. Content about low energy availability may not apply to every individual situation.
Focus should remain on the most basic, important elements without distraction from peripheral advice that disrupts foundational practices. The core foundation consists of a consistent challenging training program. The next layer involves a consistent diet. If fat loss represents a goal, a calorie deficit enters at this stage.
Disrupting the consistent, challenging, progressive training program through group fitness classes, altered exercise timing, or unwanted high-intensity training creates sprawl in the foundation. Stopping effective diets based on creator messaging about specific foods being bad, or shifting attention to supplements at the expense of fruits and vegetables, similarly undermines progress.
Progress toward personal goals serves as the primary indicator of effectiveness. What works for an individual may not receive endorsement from preferred creators, but results validate continuation.
When something is already being done consistently with progress occurring, maintain that approach without change. Experimentation requires isolation of variables. Testing fasted versus fed training means keeping all other training elements identical while alternating conditions for several weeks or sessions to develop a genuine sense of personal response.
The critical requirement involves asking the right question while keeping surrounding variables constant. Changing multiple elements simultaneously prevents identification of what actually creates differences. This principle applies equally to experimenting with rep ranges or training intensities.
Most people do not allow sufficient time for proper evaluation. A training program requires a minimum of two months, with three to four months preferred. Early training results represent the largest gains an individual will ever experience regardless of program selection. This creates a common error where people attribute initial rapid progress to specific variables and make unnecessary changes.
Progression cannot occur without sustained adherence. Anything done in the beginning produces effective results, making premature changes particularly problematic.
Substantial research exists on women and women's health, though more remains needed. Current evidence does not support fundamentally different training approaches based solely on being male or female. Strength progression and muscle growth occur at comparable rates across age groups, including during and after the menopause transition.
Individual coaching remains essential. Symptoms, lack of progress, or physiological factors such as menstrual cycle phase may warrant training adjustments, provided these modifications stay within evidence-based practice categories. This represents standard individualized application rather than deviation from established principles.
Additional research specifically addressing the perimenopause and menopause window represents a needed area of focus.
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