Issue 01: What You’re Running On
After more than 28 years working in human health and performance, I’ve come to believe that one of the most important things a woman can understand about her health is something no one has ever taught her to measure. It’s not her cholesterol, sleep score, VO₂ max, or the number on the scale, although each offers valuable information. It’s the reserve beneath those measurements that shapes how much she can give, adapt, and recover. I call it capacity, one of the most overlooked dimensions of women’s health, because being able to accomplish extraordinary things doesn’t necessarily mean you have the reserves to sustain them.
You’ve Probably Felt Your Capacity Change Without Knowing Why
If you’re a high-performing woman who’s spent years building a career, leading others, maybe raising a family, or being the person everyone counts on, you’ve probably felt your capacity change without knowing why. Somewhere in your 30s, 40s, or 50s, what you could once demand of your body and what it could comfortably deliver may have shifted. Perhaps stressful events require more recovery, travel takes a greater toll, or your mental clarity feels less dependable. You’re still accomplishing everything, and from the outside, no one would suspect that maintaining your usual level of performance is taking more out of you than it once did. And because you’re resourceful, you adapt. You improve your nutrition, invest in supplements, explore peptides or biohacking tools, seek healthcare guidance, or become more disciplined about exercise. Yet despite doing more for your health, you may feel further from the vitality you’re trying to reclaim. I understand that frustration, professionally and personally.
My early career focused on sports performance and recovery, working with professional and Olympic track athletes. We paid close attention to the physical, mental, and emotional demands placed on athletes, how well they adapted, and what they needed to sustain performance. We understood that performing well didn’t necessarily mean recovering adequately. Over time, I recognized a striking parallel with the high-performing women I saw in clinical practice. These women were making consequential decisions, managing competing responsibilities, and navigating significant physiological changes, often with little consideration for what it took to recover from the demands of their lives. That observation stopped me in my tracks because I was one of those women. We understand that athletes need personalized support and recovery to sustain their performance, yet we rarely give high-performing women the same consideration, even as they push beyond their limits to meet life’s demands.
Reassuring Test Results, and Still Struggling to Feel Well
About seven years ago, that observation became deeply personal when I experienced a serious health crisis that I kept largely private. It brought me closer to losing my life than I care to admit. Despite decades of clinical training and experience, I found myself searching for answers within the very healthcare system I’d spent my professional life working in. What opened my eyes wasn’t solely my experience, but what I discovered in the research. And here’s the elephant in the room that many people overlook: for generations, medical research was conducted predominantly on men, with women frequently excluded or underrepresented in clinical studies. It wasn’t until 1993 that federal law required women’s inclusion in NIH-funded clinical research. Think about that for a moment. We’ve only had a few decades of more systematic efforts to understand how women’s bodies respond differently to disease, medications, and treatment. A 2025 National Academies report found that only 7.9% of NIH research grant funding in 2023 was specifically dedicated to women’s health. Yes, progress has been made, but we still have a long way to go.
The deeper I went into research available to anyone willing to look, the more I understood why women could follow conventional medical advice, receive reassuring test results, and still struggle to feel well. Their experiences weren’t always understood through the lens of female physiology, particularly as hormones, metabolism, stress responses, and recovery changed throughout life. That realization became a seismic pivot in my work. I began connecting the dots between biological systems, examining how physical, mental, and emotional health influence one another, with greater attention to female biology rather than relying solely on health models historically centered on men.
Eventually, I stepped away from clinical practice and founded HealthStyle by Dr. Kenna, bringing nearly three decades of experience in human performance, functional and holistic health into my role as a Strategic Health Advisor. My focus became helping women understand their unique physiology, recognize connections influencing their health, and make informed decisions about protecting and rebuilding their capacity while supporting their long-term health and longevity. Because women deserve more than being told their test results look fine when they know something doesn’t feel right. They deserve to understand what supports the energy, clarity, resilience, and vitality they need to thrive.
Changes in capacity don’t always announce themselves through illness or abnormal lab results. Often, they appear in how a woman sleeps, thinks, recovers, or responds to demands she once handled effortlessly. Conventional and alternative testing remain valuable, but understanding why someone no longer feels like herself often requires looking at how biological systems work together. We encourage women to optimize individual aspects of their health but spend far less time helping them understand whether those strategies support their changing physiology. More exercise, greater restriction, or another supplement isn’t necessarily the answer. Sometimes we need to understand what the body is telling us before deciding what it needs.
Are You Measuring What You Accomplish, or What It Costs You?
That’s why I created The Capacity Code. We’ll explore the science behind women’s capacity, how our physical, mental, and emotional health are connected, and what influences our ability to sustain the lives we want to live. I’ll connect emerging research with everyday experiences and help you recognize relationships often missed when we examine health one piece at a time. Before the next issue, I’d encourage you to consider something: Are you measuring how much you can accomplish, or are you paying attention to what it costs you? Think about the energy you expend, the mental and emotional demands you carry, and whether you’re truly recovering or simply finding new ways to push through.
You’ve spent years building a life that asks a great deal of you, and I believe you deserve to feel as good as the life you’ve worked so hard to create. Your health is about more than how your body functions. It’s also about your energy, clarity, emotional well-being, and that spark that makes you feel fully alive. That’s your true vitality sweet spot!
There’s more available to you than you’ve been led to believe. And I hope The Capacity Code helps you discover just how much is possible.
In it with you,
Dr. Kenna
Founder & CEO HealthStyle by Dr. KennaDisclaimer
The Capacity Code is written for educational and informational purposes only. It reflects the experience, observation, and perspective of Dr. Kenna Ducey-Clark, DC, and is not intended to diagnose, treat, cure, or prevent any condition, or to replace care from your own licensed healthcare provider. Reading this newsletter, subscribing, or participating in the comments does not create a doctor–patient or advisor–client relationship. Always consult your physician before starting, stopping, or changing any medication, nutritional supplementation, testing, or health practice. The comment section is an open forum; views shared by readers are their own, and are not reviewed, endorsed, or verified by me or by Healthstyle by Dr. Kenna.
