Exercise Safety Guidelines During Pregnancy: Clinical Research on Intensity, Type, and Duration

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 behind “Exercise Guidelines During Pregnancy” within the field of special-population exercise science. It also incorporates Taiwan’s local climate, racing, and sports culture contexts to offer evidence-based training and health strategies.

Within the realm of special-population exercise science, “Exercise Guidelines During Pregnancy” is a topic that holds both academic depth and practical value, yet has long been misunderstood or overlooked. Over the past few decades, knowledge accumulated in exercise science has largely focused on healthy adult males, meaning that many unique physiological characteristics and needs of special populations were only systematically recognized and studied in recent years. In fact, adolescents, women, and special populations (such as older adults, pregnant and postpartum women, and those with chronic diseases) differ fundamentally from the “standard young male athlete” in terms of physiological structure, hormonal environment, developmental stage, and health context. Directly applying adult male training principles and physiological data to these groups can lead to diminished results at best, and health harm at worst. This is precisely why understanding “Exercise Guidelines During Pregnancy” is so important—it allows us to move beyond the “one-size-fits-all” myth 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 special-population exercise science particularly valuable. This article will take you from the cellular and systemic physiological mechanisms, through empirical studies in top international journals, the quantitative dose-response relationships, and differences in responses across populations, to directly applicable training strategies and Taiwan’s local context. Finally, we will debunk long-standing myths, ensuring your understanding of “Exercise Guidelines During Pregnancy” is truly built on science, not hearsay or outdated stereotypes.

Academic Research Review

Regarding the scientific exploration of “Exercise Guidelines During Pregnancy,” the field of special-population exercise science 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 form our current understanding:

1. ACOG (2020). Obstetrics & Gynecology. The American College of Obstetricians and Gynecologists’ exercise guidelines during pregnancy recommend that most pregnant women engage in at least 150 minutes of moderate-intensity exercise per week.

2. Mottola et al. (2018). British Journal of Sports Medicine. The Canadian clinical practice guidelines for exercise during pregnancy provide evidence-based recommendations on intensity and contraindications.

3. Davenport et al. (2018). British Journal of Sports Medicine. A systematic review and meta-analysis confirming that exercise during pregnancy reduces the risk of gestational diabetes, preeclampsia, and excessive weight gain.

4. Barakat et al. (2016). American Journal of Obstetrics & Gynecology. A randomized controlled trial confirming the safety and benefits of regular exercise during pregnancy for both mother and baby.

Taken together, these studies show that the scientific picture of “Exercise Guidelines During Pregnancy” has been continuously refined alongside advances in research methods and a growing awareness of “population specificity.” Early studies 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 contexts. In contrast, recent high-quality research increasingly emphasizes 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 older adults. This methodological evolution has allowed us to progress from “treating differences as noise” to “placing differences at the core of research.” It is worth noting that this field still faces several challenges: research on women and special populations remains relatively scarce compared to men, with sample sizes 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 remain mindful of 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. This dual caution regarding population differences and evidence quality forms the foundation of the scientific application of special-population exercise science and is the consistent stance of this article.

Core Mechanisms

The concept of exercise during pregnancy has shifted from the past notion of “rest more, move less” to “encouraging regular exercise within safe limits.” Modern evidence clearly shows that for pregnant women without contraindications, regular moderate-intensity exercise is not only safe but also significantly reduces the risk of gestational diabetes, preeclampsia, gestational hypertension, and excessive weight gain, improves mood and sleep, and may shorten labor. Physiologically, exercise during pregnancy requires consideration of several changes: increased blood volume and cardiac output, and elevated resting heart rate, making heart rate-based intensity assessment less reliable. Instead, the Rating of Perceived Exertion (RPE, maintained at a level of “somewhat hard but still able to converse”) is more practical. Regarding thermoregulation, overheating should be avoided in the early stages (especially the first trimester), with attention to staying cool and hydrated. As the abdomen grows, the center of gravity shifts, and increased relaxin levels loosen ligaments, raising the risk of balance issues and falls. Therefore, activities with a risk of falling or collision (such as road racing, mountain biking, or contact sports) should be avoided. Supine exercise in the second and third trimesters may compress the inferior vena cava and should be avoided. Suitable activities include brisk walking, swimming, stationary cycling, prenatal yoga, and moderate strength training. Contraindications (such as certain cardiopulmonary diseases, cervical insufficiency, placenta previa, or risk of preterm labor) require medical evaluation. Warning signs such as vaginal bleeding, regular contractions, amniotic fluid leakage, dizziness, or chest pain warrant immediate cessation and medical attention. Individualization and communication with the obstetric care team are central to safe exercise during pregnancy.

To truly understand “Exercise Guidelines During Pregnancy,” one must return to the unique physiological context of special-population exercise science: 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 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 sustained 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 depending on maturity, age, sex, hormonal status, or health conditions—this is precisely where special-population exercise science is most susceptible to being misled by oversimplified recommendations. 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 older adults, anabolic resistance and the rate of decline make the meaning of “stimulus intensity” different from that in younger individuals. “Exercise Guidelines During Pregnancy” deserves in-depth exploration precisely because it can specifically influence key aspects of special-population exercise science. 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 truly understand special-population exercise science and those who train blindly.

Dose-Response Relationships

In special-population exercise science, “the dose determines the effect” is a core principle, but this dose often needs to be recalibrated according to population characteristics. Too little stimulus fails to reach the adaptation threshold and produces no benefit; excessive load may exceed the compensatory capacity of vulnerable populations, causing injury, developmental disruption, or health damage. The table below outlines the dose-response relationships for “Exercise Guidelines During Pregnancy,” serving as the most important quantitative reference when developing training and health plans for specific populations:

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

|—|—|—|

| 150 minutes per week of moderate intensity | Baseline recommended dose | Reduces pregnancy complications, improves mood |

| Intensity assessed by RPE | “Able to converse” level | Heart rate unreliable during pregnancy; use perceived exertion instead |

| Avoid | Fall/collision risk, supine position, overheating | Use stationary cycling, swimming, brisk walking instead |

| Stop and seek care | Bleeding, contractions, dizziness, chest pain | Stop immediately and seek medical evaluation |

As shown in the table above, dose-response relationships in special-population exercise science often exhibit threshold-type or inverted U-shaped curves: before reaching an effective dose, benefits increase with dose; but beyond a certain critical point, not only are there no additional benefits, but risks and costs rise sharply—this is especially critical for vulnerable populations (developing adolescents, women prone to energy imbalance, and older adults with reduced compensatory capacity). This means that “finding the optimal dose for the specific population and individual” is far more important than “pursuing more and harder at all costs.” In practical application, it is recommended to continuously monitor responses using objective indicators (such as performance, recovery, health markers, and subjective feelings) and calibrate 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 “Exercise Guidelines During Pregnancy” is not uniform across individuals. 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 mistakes in the application of special-population exercise science.

| Population Dimension | Response Characteristics | Practical Recommendations |

|—|—|—|

| Beginner vs. Advanced | Advanced individuals have mature adaptations and better tolerance but less marginal room | Beginners should progress conservatively, building a foundation before increasing load |

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

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

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

Regarding the specific population considerations for this topic: those with an existing exercise habit can maintain higher intensity but still need adjustments; sedentary individuals should progress gradually from low intensity. High-risk pregnancies require individualized medical assessment.

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 exercise 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 essential to avoid the ineffective or even harmful consequences of “copying someone else’s training plan.” After understanding population differences, you will realize: truly professional special-population exercise science advice is always an individualized prescription that “varies by person and by 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 “Exercise Guidelines During Pregnancy” 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, older adults prioritize safety and functional maintenance; the starting points differ.

• Progression and Monitoring: Progress gradually from an appropriate starting point, continuously monitor responses with objective indicators (performance, recovery, health markers) and subjective feelings, and adjust dynamically based on 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 older and chronically ill populations, seeking collaborative assessment from coaches, medical professionals, nutritionists, and psychologists is a safeguard for safety and effectiveness.

Using practical planning as an example: when developing a plan, 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 elite adults to adolescents, women, or older adults, ignoring the underlying physiological differences—this is precisely what special-population exercise science strives to avoid. Daily training and life serve as the best laboratory 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 in adolescents, menstrual and iron status in women, strength and recovery in older adults) alongside training content and physical responses. After weeks to months of accumulation, the value of this personalized database will far exceed any general guideline. Additionally, don’t 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, ultimately interrupting the engine of long-term progress. Treating population matching and health-first 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 “Exercise Guidelines During Pregnancy.” Climatically, the hot and humid summers and cold and damp winters pose additional challenges for different populations (especially adolescents and older adults with differing thermoregulatory capacities); topographically, the extreme elevation gain from sea level to Wuling at 3,275 meters provides a rich training environment; socially, Taiwan is entering an aged society, academic pressure is heavy, and gender equality awareness is rising—all of which profoundly affect the exercise circumstances of various populations.

Taking local contexts as examples: adolescent athletes often face dual pressures from academics and training, lacking systematic recovery and long-term development planning; female sports enthusiasts face insufficient attention to energy availability, iron status, bone health, and women’s specific health issues; older adults 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 older adults), will allow the science of special-population exercise to truly reach every sports enthusiast in Taiwan, promoting health and sports participation for all.

Debunking Common Myths

Myth: “Pregnant women should rest more; exercise will harm the baby.” For pregnant women without contraindications, regular moderate-intensity exercise is safe and reduces complications; what should truly be avoided are specific high-risk activities and overheating, not all physical activity.

These 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. Yet 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 special-population exercise science 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 categorical exercise recommendation for adolescents, women, or special populations, consider asking: “What is the level of evidence for this claim? Was it studied in this population? Or is it a conclusion from another group being directly applied here?” Cultivating this evidence-based, population-specific critical thinking is more valuable than memorizing any single conclusion, and it is a key step toward making special-population exercise science more scientific and preventing harm.

Conclusion

“Exercise Guidelines During Pregnancy” is a topic within special-population exercise science that combines theoretical depth with practical value. As the international journal evidence reviewed in this article shows, 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 the starting point for scientific, individualized training. The key lies in mastering mechanisms, calibrating doses, adjusting according to population and individual, and always prioritizing long-term health over short-term performance. For sports enthusiasts in Taiwan, while grasping scientific principles, it is equally important to integrate local climate, environmental, and social contexts, transforming general rules into prescriptions suitable for one’s own population and individual. May every adolescent, woman, and older adult who sweats through exercise at various stages of life safely, healthily, and sustainably enjoy the joy and benefits of sport through the wisdom of special-population exercise science. The value of exercise has never been limited by age, sex, or circumstance—let science become a force that benefits everyone.

Related Reading

• Safety of High-Intensity Interval Training in Older Adults: A Study on Cardiac Risk Assessment
• Mental Health and Sports Participation in Adolescents: A Longitudinal Study on Depression Prevention
• Growth Plate Protection in Adolescent Cyclists: A Safety Study on Resistance Training
• Psychological Development and Sports Participation in Adolescents: A Longitudinal Study on Motivational Evolution