The Impact of High-Intensity Interval Training on Cardiovascular Health and Muscle Quality

In this episode, I’m joined by Dr. Abbie Smith-Ryan—one of the leading researchers in exercise physiology and women’s metabolism—to unpack the science of how women should be training through perimenopause, postmenopause, and beyond. We dive into the physiological changes that impact body composition, performance, and recovery—and how to adjust training and nutrition to match.

We discuss:

• How high-intensity interval training (HIIT) improves VO₂ max, fat oxidation, and muscle quality in women
• Whether fasted training helps or hurts, and why so many women are under-fueled
• What the science really says about lifting heavy and building muscle over 40
• Nutrient timing, rest intervals, and why sex-based differences in physiology matter
• What we still don’t know about hormone therapy, protein needs, and female-specific adaptations

If you’re navigating training, muscle loss, or metabolic changes through midlife, this conversation will give you clarity, confidence, and evidence-based strategies you can actually use.

Who is Dr. Abbie Smith-Ryan?

Dr. Abbie Smith-Ryan is a leading expert in exercise physiology and sports nutrition, currently serving as Associate Chair for Research and Director of the Applied Physiology Lab at the University of North Carolina at Chapel Hill. Her research focuses on evidence-based exercise and nutrition strategies to improve body composition, cardiovascular health, and metabolic function—particularly in women, perimenopausal and postmenopausal populations, and those with obesity. She has authored over 200 peer-reviewed publications and led numerous NIH- and industry-funded clinical trials. Recognized as a top scientist in her field, Dr. Smith-Ryan is also a dedicated educator and mentor, passionate about translating science into actionable strategies that enhance health and performance.

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Find Dr. Abbie Smith-Ryan at:

• Website - https://asmithryan.com/
• Instagram - https://www.instagram.com/asmithryan/
• LinkedIn - https://www.linkedin.com/in/abbiesmithphd/

Find me at:

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Timestamps:

00:00 – Introduction to the episode and what it covers: female physiology, training myths, and metabolism.

02:58 – Why Dr. Smith-Ryan shifted her research focus to perimenopause and midlife women.

05:07 – Does the menstrual cycle really impact performance and outcomes? What science shows so far.

08:20 – High-Intensity Interval Training (HIIT): What it is, why it’s effective, and how her lab uses it.

11:56 – How beginners, including older adults and clinical populations, can start HIIT safely and effectively.

19:20 – VO₂ max improvements and how quickly HIIT produces changes vs. zone 2 or endurance training.

23:45 – How often to do HIIT, how long it should last, and what benefits you can expect.

29:03 – The importance of exercise intensity, and why doing HIIT “every day” means you’re doing it wrong.

32:00 – Nutrition around training: Why women are often under-fueled and how pre- and post-exercise fueling affects outcomes.

36:28 – What really causes weight gain at menopause: metabolic decline vs. muscle loss and lifestyle changes.

41:43 – High-intensity resistance training: How it's different from regular resistance training and why it matters.

51:03 – Sex-based differences in protein metabolism, nutrient timing, and the need for more women-specific studies.

Disclaimer: The Dr. Gabrielle Lyon Podcast and YouTube are for general information purposes only and do not constitute the practice of medicine, nursing, or other professional health care services, including the giving of medical advice, and no doctor/patient relationship is formed. The use of information on this podcast, YouTube, or materials linked from this podcast or YouTube is at the user's own risk. The content of this podcast is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Users should not disregard or delay in obtaining medical advice for any medical condition they may have and should seek the assistance of their health care professional for any such conditions.