A recent report from the National Academy of Science documents (not for the first time!) that we humans have a unique ability to develop our heart’s capacity for stress. The investigators compare us with our relatives, the apes and chimpanzees, and say that these animals, unlike us, don’t have this resource: they are only equipped for very short periods of intense activity like fighting or climbing,
Some of this we have always been aware of. In fact, my own research on the developing heart showed that in the uterus, when the baby’s circulation operates at a low blood pressure, the heart wall is relatively thin. After birth, when the baby is delivered, the blood pressure rises normally and the heart structure changes appropriately, producing more contracting units in the heart wall and generating more energy producing units called mitochondria.
We have evolved with an ability to reshape our heart muscles not only at birth, but throughout life, so that they are optimally structured to meet the demand for the kind of stress we require of our bodies. For example, when our hearts work to pump blood against high pressure and need to generate more force, the wall of the pumping chamber thickens. Patients with chronically high blood pressure have what we call myocardial hypertrophy, which we can see on an echocardiogram. Unfortunately, the heart remodeled in this way is less well equipped for exercise. On the other hand, when we need a larger amount of blood for physical activity, the heart accommodates by increasing the beat-to-beat volume of blood to meet the muscles’ demand for an increase in oxygen. The pumping chamber needs to be thinner walled and more distensible to achieve this. Individuals who consistently engage in regular, moderately intensive exercise have a heart with less muscle, leaving a pumping chamber with an increased capacity to distend and to hold more blood per beat. (Incidentally, there are subtle but significant differences in the pattern of response to a demand for increased heart work in men and women although the basic results are similar.)
I have to confess that I am skeptical that apes and chimps don’t have the same ability as we do to modify the heart’s architecture and strength. These animals don’t do sustained moderate physical activity; only when they are fighting or climbing does their otherwise sedentary life change. In other words, stress for them is episodic and short-lived. To be sure about whether or not the hearts in other mammals have the same basic response to the type and duration of work they are asked to perform, we would have to expose them to a constant level of higher than normal blood pressure or force them to do a low level of controlled physical activity at least daily for significant periods of time to make sure they, like us, also own intelligent hearts!
Marianne J. Legato, MD, Ph. D. (hon. c.), FACP is an internationally renowned academic, physician, author, lecturer, and pioneer in the field of gender-specific medicine. She is a Professor Emerita of Clinical Medicine at Columbia University College of Physicians & Surgeons and an Adjunct Professor of Medicine at Johns Hopkins Medical School. Dr. Legato is also the Director of the Foundation for Gender-Specific Medicine, which she founded in 2006 as a continuation of her work with The Partnership for Gender-Specific Medicine at Columbia University. She received an honorary PhD from the University of Panama in 2015 for her work on the differences between men and women.
At its core, gender-specific medicine is the science of how normal human biology differs between men and women and how the diagnosis and treatment of disease differs as a function of gender. Dr. Legato’s discoveries and those of her colleagues have led to a personalization of medicine that assists doctors worldwide in understanding the difference in normal function of men and women and in their sex-specific experiences of the same diseases.
She began her work in gender-specific medicine by authoring the first book on women and heart disease, The Female Heart: The Truth About Women and Coronary Artery Disease, which won the Blakeslee Award of the American Heart Association in 1992. Because of this research, the cardiovascular community began to include women in clinical trials affirming the fact that the risk factors, symptoms, and treatment of the same disease can be significantly different between the sexes. Convinced that the sex-specific differences in coronary artery disease were not unique, Dr. Legato began a wide-ranging survey of all medical specialties and in 2004, published the first textbook on gender-specific medicine, The Principles of Gender-Specific Medicine. The second edition appeared in 2010 and the third edition, dedicated to explaining how gender impacts biomedical investigation in the genomic era, won the PROSE Award in Clinical Medicine from the Association of American Publishers in 2018. A fourth edition is forthcoming.
She also founded the first scientific journals publishing new studies in the field, The Journal of Gender-Specific Medicine, and a newer version, Gender Medicine, both listed in the Index Medicus of the National Library of Medicine. She has founded a third peer-reviewed, open access journal, Gender and the Genome, which focuses on the impact of biological sex on technology and its effects on human life.
Dr. Legato is the author of multiple works, including: What Women Need to Know (Simon & Schuster, 1997), Eve’s Rib (Harmony Books, 2002), Why Men Never Remember and Women Never Forget (Rodale, 2005), Why Men Die First (Palgrave, 2008), The International Society for Gender Medicine: History and Highlights (Academic Press, 2017), and most recently, The Plasticity of Sex (Academic Press, 2020). Her books have been translated into 28 languages to date.
As an internationally respected authority on gender medicine, Dr. Legato has chaired symposia and made keynote addresses to world congresses in gender-specific medicine in Berlin, Israel, Italy, Japan, Panama, South Korea, Stockholm, and Vienna. In collaboration with the Menarini Foundation, she is co-chairing a symposium on epigenetics, Sex, Gender and Epigenetics: From Molecule to Bedside, to be held in Spring 2021 in Italy. She maintains one of the only gender-specific private practice in New York City, and she has earned recognition as one of the “Top Doctors in New York.”