Dose-Response Study of High-Intensity Training and Menstrual Dysfunction in Women

Based on the Journal of Applied Physiology, Medicine & Science in Sports & Exercise, Sports Medicine, British Journal of Sports Medicine, and other international peer-reviewed journals, this article provides an in-depth analysis of the scientific evidence on the “dose-response relationship between training load and menstrual dysfunction” in the field of female exercise physiology. It also incorporates Taiwan’s local climate, events, and sports culture context to offer evidence-based training and health strategies.

In the realm of female exercise physiology, the “dose-response relationship between training load and menstrual dysfunction” is a topic that carries both academic depth and practical value, yet it has long been misunderstood or overlooked. The knowledge accumulated in exercise science over the past decades has largely focused on healthy adult males, meaning that many of the unique physiological characteristics and needs of female exercise physiology have only received systematic attention and research in recent years. In fact, adolescents, women, and special populations (such as the elderly, pregnant and postpartum women, and those with chronic diseases) differ fundamentally in physiological structure, hormonal environment, developmental stage, and health context from the ‘standard young male athlete.’ Directly applying adult male training principles and physiological data to them can, at best, reduce effectiveness and, at worst, cause health damage. This is precisely why understanding the “dose-response relationship between training load and menstrual dysfunction” is so important—it allows us to move beyond the myth of a ‘one-size-fits-all’ approach and provide scientific guidance that truly aligns with the physiology and needs of different populations. Taiwan is moving toward an aged society, gender equality awareness is rising, and youth sports participation is increasingly common. These trends make the local application of female exercise physiology particularly valuable. This article will guide you from the physiological mechanisms at the cellular and systemic levels, through empirical research in top international journals, the quantitative relationship between dose and effect, and the differing responses across populations, to directly actionable training applications and Taiwan’s local context. Finally, it will debunk long-standing myths, ensuring your understanding of the “dose-response relationship between training load and menstrual dysfunction” is truly built on science, rather than hearsay or outdated stereotypes.

Academic Research Review

Regarding the scientific exploration of the “dose-response relationship between training load and menstrual dysfunction,” the field of female exercise physiology has accumulated rigorous and rich evidence in recent years. Below are several representative studies selected for their value in methodological design, study populations, and strength of conclusions, which together construct our current understanding:

1. De Souza et al. (2010). Human Reproduction confirmed that the core of menstrual dysfunction is low energy availability rather than exercise itself, and described its continuum of presentation.

2. Williams et al. (2015). Journal of Clinical Endocrinology & Metabolism experimentally manipulated energy availability to quantify its suppression of luteinizing hormone pulsatility.

3. Loucks & Thuma (2003). Journal of Clinical Endocrinology & Metabolism established the threshold of 30 kcal/kg FFM for energy availability.

4. Redman & Loucks (2005). Sports Medicine reviewed the mechanisms of exercise and menstrual dysfunction, clarifying the ‘exercise stress hypothesis’ versus the ‘energy deficiency hypothesis.’

Looking at these studies, it is clear that the scientific picture of the “dose-response relationship between training load and menstrual dysfunction” has deepened with advancements in research methods and a growing awareness of ‘population specificity.’ Early research often interpreted data from adolescents, women, or special populations directly through the framework of adult males, ignoring the fundamental differences brought by developmental stage, hormonal cycles, aging processes, or disease context. In recent years, high-quality research has increasingly emphasized research methods ‘tailored to specific populations’—analyzing adolescents by biological maturity rather than chronological age, incorporating menstrual cycle and energy availability as control variables in female studies, and conducting stratified assessments of anabolic resistance and cardiovascular risk in the elderly. This methodological evolution has allowed us to progress from ‘treating differences as noise’ to ‘treating differences as the core of research.’ It is worth noting that research in this field still faces several challenges: the number of studies on women and special populations remains relatively low compared to men, sample sizes are often limited; longitudinal tracking (especially long-term development in adolescents) is costly; and ethical considerations prevent certain interventions in vulnerable populations. Therefore, when interpreting conclusions, we must both value the population-specific insights these studies reveal and pay attention to the level of evidence and scope of applicability—a conclusion drawn from a specific age, sex, or health status group may not be generalizable to other populations. It is this dual prudence regarding population differences and evidence quality that forms the foundation for the scientific application of female exercise physiology, and it is also the consistent stance of this article.

Core Mechanisms

Regarding the causes of menstrual dysfunction in female athletes (oligomenorrhea, amenorrhea), there have been two hypotheses: one posits that the ‘physiological stress’ of exercise itself suppresses menstruation, while the other argues the root cause is ‘energy deficiency.’ Through key experimental studies, the evidence clearly supports the latter: it is low energy availability, not the stress of exercise or the training load itself, that truly suppresses the hypothalamic-pituitary-gonadal axis. Loucks’ classic experiments manipulated food intake and exercise to maintain energy availability at different levels, finding that when energy availability dropped below approximately 30 kcal per kilogram of fat-free mass, the pulse frequency of luteinizing hormone (LH) was suppressed—even with identical exercise loads, LH pulsatility returned to normal once energy was replenished. This established the ‘energy deficiency hypothesis’: when the body perceives an energy deficit, it downregulates GnRH pulsatility via the hypothalamus, shutting down the energy-costly reproductive function to preserve survival. Therefore, the dose-response relationship of menstrual dysfunction is essentially a dose-response of ‘energy availability,’ not a direct dose-response of ‘training intensity or training volume.’ This distinction is crucial: it means women can engage in high volumes of intense training while maintaining normal menstrual cycles—as long as they consume sufficient energy to match expenditure. Conversely, even if training volume is not extreme, menstrual disruption can still occur if dietary restriction creates an energy deficit. Clinically, menstrual dysfunction is a sensitive ‘gauge’ of energy deficiency and a core indicator of RED-S. The key to restoring menstruation is not reducing training (although temporary adjustments may sometimes be necessary), but increasing energy intake and restoring positive energy balance. This scientific consensus has fundamentally changed the approach to managing menstrual issues in female athletes.

To truly understand the “dose-response relationship between training load and menstrual dysfunction,” one must return to the unique physiological context of female exercise physiology: how the developing body, fluctuating hormones, aging systems, or disease effects alter exercise responses at the cellular, tissue, and systemic levels. The table below summarizes the key points of this topic across different physiological levels, helping you build a complete mechanistic picture:

| Physiological Level | Key Mechanisms | Implications for Training and Health |

|—|—|—|

| Endocrine/Hormonal | Population differences in sex hormones, growth and metabolic hormones | Affects adaptation direction, energy regulation, and reproductive/skeletal health |

| Bone and Muscle | Bone mass accumulation/loss, muscle fiber composition and protein synthesis | Determines bone density, strength development, and injury risk |

| Cardiovascular and Metabolic | Population-specific characteristics of cardiac remodeling, VO2max, and substrate utilization | Affects endurance performance, recovery, and long-term health |

| Neural and Psychological | Neuromuscular control, motivation, and psychosocial needs | Determines skill development, injury prevention, and continued participation |

Special emphasis should be placed on the two dimensions of ‘developmental stage’ and ‘individual variability.’ The same intervention can produce vastly different or even opposite effects under different maturity levels, ages, sexes, hormonal states, or health conditions—this is precisely where female exercise physiology is most susceptible to being misled by oversimplified advice. For adolescents, for example, the effects, risks, and optimal timing of a training stimulus differ before and after PHV; for women, energy availability and menstrual function are key regulators behind many physiological responses; for the elderly, anabolic resistance and the rate of decline make the meaning of ‘stimulus intensity’ different from that in younger individuals. The “dose-response relationship between training load and menstrual dysfunction” deserves in-depth exploration precisely because it can specifically influence key aspects of female exercise physiology. The more thoroughly you understand the mechanisms, the better you can judge ‘for whom, at what stage, what to do, and how much,’ rather than blindly applying unsuitable general rules. This ability to adjust according to population and individual context is the dividing line between those who understand female exercise physiology and those who train blindly.

Dose-Response Relationship

In female exercise physiology, ‘dose determines effect’ is a core principle, but this dose often needs to be recalibrated according to population characteristics. Too low a stimulus fails to reach the adaptation threshold and produces no benefit; too high a load may exceed the compensatory capacity of vulnerable populations, causing injury, developmental disruption, or health damage. The table below organizes the dose-effect correspondence of the “dose-response relationship between training load and menstrual dysfunction,” serving as the most important quantitative reference when developing training and health plans for specific populations:

| Dose / Condition | Physiological State | Effects and Key Points |

|—|—|—|

| Energy availability ≥45 | Normal menstrual cycle | Normal LH pulsatility, reproductive function maintained |

| 30–45 | Suboptimal | LH pulsatility begins to be affected in some individuals |

| <30 | Suppression threshold | LH pulsatility suppressed, high risk of menstrual dysfunction |

| Recovery strategy | Increase energy intake | Replenishing energy is more fundamental than reducing training |

From the table above, it is clear that dose-response relationships in female exercise physiology often exhibit threshold-type or inverted U-shaped curves: before reaching the effective dose, benefits increase with dose; but beyond a certain critical point, not only is there no additional benefit, but risks and costs rise sharply—this is especially critical for vulnerable populations (developing adolescents, women prone to energy imbalance, and elderly with reduced compensatory capacity). This means that ‘finding the optimal dose for that population and individual’ is far more important than ‘pursuing more and stronger at all costs.’ It is recommended that in practical application, responses be continuously monitored using objective indicators (such as performance, recovery, health markers, and subjective feelings), and calibrated according to population characteristics and individual data. Remember: the group average reported in research is a starting point, not an endpoint; each person’s maturity, hormonal status, health background, and genetics will cause the optimal dose to shift individually. Only by calibrating with your own data and professional assessment can you safely translate group science into a personal prescription.

Differences Across Populations

The impact of the “dose-response relationship between training load and menstrual dysfunction” is not equal for everyone. Age and maturity, sex, training status, hormonal state, health conditions, and genetic background all significantly modulate individual response magnitude. Ignoring these differences and applying a single recommendation is one of the most common and dangerous errors in the application of female exercise physiology.

| Population Aspect | Response Characteristics | Practical Recommendations |

|—|—|—|

| Beginners vs. Advanced | Advanced individuals have mature adaptations, better tolerance but smaller marginal gains | Beginners should progress conservatively, build a foundation before increasing load |

| Men vs. Women | Differences in hormones, body composition, bone, and metabolic characteristics | Women need individualized assessment of energy, iron, and bone health |

| Young vs. Old | Older individuals recover more slowly, have anabolic resistance, and accelerated decline | Elderly need sufficient stimulus intensity but longer recovery and screening |

| Developmental Stage | Maturity influences adaptation direction, risk, and timing | Arrange training by biological maturity rather than age |

Regarding specific population considerations for this topic: adolescent girls often have irregular cycles for several years after menarche, but persistent amenorrhea is not normal; energy deficiency has the highest prevalence in sports that emphasize leanness.

When interpreting individual differences, one must also be wary of a statistical trap: research reports mostly ‘group average responses,’ but beneath the average often lies enormous individual variability. In the same intervention, some may be strong responders while others barely respond. This is why even if a study shows ‘average effectiveness,’ you still need to combine professional assessment and your own response to confirm applicability. Taking common athletic populations in Taiwan as an example—whether it’s adolescents burdened with heavy schoolwork, women balancing family and training, or middle-aged and older adults pursuing healthy aging—correctly understanding the physiological characteristics of your own population group is the only way to avoid the ineffective or even harmful consequences of ‘copying someone else’s training plan.’ After understanding population differences, you will realize: truly professional female exercise physiology advice is always an individualized prescription that ‘varies by person and stage,’ not a one-size-fits-all slogan.

Practical Training Applications

Theory must ultimately translate into practical training and health operations. Below is a practical framework for converting the “dose-response relationship between training load and menstrual dysfunction” into concrete applications:

• Population Matching: All training and health recommendations must first ask, ‘Is this suitable for this population?’—adolescents prioritize development and protection, women prioritize energy and bone health, and the elderly prioritize safety and functional maintenance. The starting points are all different.

• Progression and Monitoring: Progress gradually from an appropriate starting point, continuously monitor responses using objective indicators (performance, recovery, health markers) and subjective feelings, and dynamically adjust according to individual conditions.

• Health Over Performance: For vulnerable populations, long-term health (development, bone, endocrine, cardiovascular) always takes precedence over short-term performance. Never sacrifice health for temporary numbers.

• Holistic Context: Training is just one piece of the puzzle; sleep, nutrition (especially energy availability), recovery, psychological and social support are equally critical. A single intervention cannot compensate for overall imbalance.

• Professional Collaboration: When dealing with growing adolescents, women’s specific health issues, or elderly and chronic disease populations, seeking collaborative assessment from coaches, medical professionals, nutritionists, and psychologists in a timely manner is a guarantee of safety and effectiveness.

Using practical planning as an example, when developing a plan, one should first clarify the population characteristics and health context of the individual, then set reasonable goals, doses, and monitoring indicators accordingly. The most common mistake many people make is directly applying practices seen on social media or in adult elites to adolescents, women, or the elderly, ignoring the underlying physiological differences—this is precisely what female exercise physiology strives to avoid. Daily training and life are the best laboratories for observing population and individual responses and building personalized data.

It is recommended to integrate training logs with health monitoring, recording key indicators (such as growth and injuries for adolescents, menstrual and iron status for women, strength and recovery for the elderly) along with training content and physical responses. After weeks to months of accumulation, the value of this personalized database will far exceed any general guide. Additionally, do not overlook the often-underestimated aspect of ‘recovery and long-term development’—for vulnerable populations, excessively pursuing short-term progress at the expense of recovery and health often leads to injury, burnout, or health problems, thereby interrupting the engine of long-term progress. Treating population matching and health priority as core training principles will make a noticeable difference in both your results and safety.

Local Applications in Taiwan

Taiwan’s unique climate, terrain, social structure, and sports culture add a distinct local flavor to the application of the “dose-response relationship between training load and menstrual dysfunction.” Climatically, the hot and humid summers and cold and damp winters pose additional challenges for different populations (especially adolescents and the elderly, who have different thermoregulatory capacities); topographically, the extreme elevation gain from sea level to Wuling at 3,275 meters provides a rich training environment; socially, Taiwan is moving toward an aged society, faces heavy academic pressure, and has rising gender equality awareness—all of which profoundly affect the exercise circumstances of various populations.

Using local contexts as examples: adolescent athletes often face the dual pressure of academics and training, lacking systematic recovery and long-term development planning; female sports enthusiasts face insufficient attention to energy availability, iron, bone health, and women’s specific health issues; and the elderly need friendly, safe exercise environments and communities that accommodate different abilities. Leveraging Taiwan’s dense network of convenience stores for refueling, diverse cycling and running routes, and the growing sports community, while designing activities tailored to different populations (such as diverse development for adolescents, women-friendly equipment and environments, and group rides for the elderly), is how the science of female exercise physiology can truly be implemented for every sports enthusiast in Taiwan, promoting health and sports participation for all.

Debunking Common Myths

Myth: “Amenorrhea is proof of hard training.” Amenorrhea is a warning sign of energy deficiency, not a badge of honor. Long-term low estrogen can damage bone and health; the solution is to replenish energy, not to reduce training or ignore the symptoms.

Such myths are widespread often because they ‘sound reasonable,’ are easily passed by word of mouth, or stem from inappropriately applying adult male concepts to other populations. However, the value of science lies in testing intuition with rigorous evidence: many seemingly obvious notions do not hold up under rigorous research on specific populations. The field of female exercise physiology is especially rife with outdated stereotypes and oversimplified claims that compress complex population differences, developmental stages, and individual variability into a single slogan. The next time you hear a definitive exercise recommendation for adolescents, women, or special populations, it’s worth asking: ‘What is the level of evidence for this claim? Is it based on research on this population? Or is it directly extrapolated from conclusions on another population?’ Cultivating this evidence-based, population-specific critical thinking is more valuable than memorizing any single conclusion, and it is a key step for female exercise physiology to move toward scientific rigor and avoid harm.

Conclusion

The “dose-response relationship between training load and menstrual dysfunction” is a topic in female exercise physiology that combines theoretical depth with practical value. From the international journal evidence reviewed in this article, it is clear that adolescents, women, and special populations have unique characteristics and needs in exercise physiology—they are by no means ‘scaled-down’ or ‘special-case’ versions of adult males. Understanding and respecting these differences is precisely the starting point for scientific, individualized training. The key lies in mastering the mechanisms, calibrating the dose, adjusting according to population and individual, and always placing long-term health above short-term performance. For sports enthusiasts in Taiwan, while mastering scientific principles, it is even more important to integrate local climate, environment, and social context, transforming general rules into prescriptions suitable for one’s own population and self. May every adolescent, woman, and senior who sweats through exercise at various stages of life and growth safely, healthily, and sustainably enjoy the joy and benefits of sport through the wisdom of female exercise physiology. The value of exercise has never been limited by age, sex, or condition—let science become a force that benefits everyone.

Related Reading

• The Impact of the Menstrual Cycle on Athletic Performance: A Quantitative Study of Hormonal Fluctuations
• Eating Disorders and Exercise in Adolescent Females: A Prevalence Survey of Taiwanese High School Students
• Iron Needs of Female Endurance Athletes: A Study on Supplementation for Menstrual Blood Loss and Training
• Benefits of Resistance Training in Women: A Comparative and Mechanistic Study with Men