Performance from the Inside Out Part 13:

Why Performance Is from the Inside Out

By Lillian So Chan with Manny W Radomski, PhD

Why Performance Is from the Inside Out

Physical activity and performance are manifested expressions of the energy and the life conditions in us. This is why physical activity is an internal matter and performance is from the inside out.

From our first steps to our best finishes, our movements are all intricate, orchestrated, total-body endeavors and experiences.

Our movements are poetry in motion—with notes and words contributed by every organ and system of our body, involving all of our physiological functions, and actively authored by our numerous cells and countless gut microbes.

Why are gut microbes maestros of our poetry in motion?

First, all forms of physical activity require energy to initiate, support, and sustain the movements. The energy to sustain life and for us to move around is derived from food. Our gut and gut microbes are directly and indirectly involved with food digestion, absorption and metabolism, and energy harvest and regulation.

Second, our gut with its resident microbiome regulates and influences numerous life functions including digestion, absorption, food metabolism, water and electrolyte uptake and balance, essential vitamin synthesis, energy harvest, use and homeostasis, immune response and inflammation, hormonal balance, stress response, brain function, emotions, and even social behaviors.

The fundamental and interconnected nature of these functions place gut function and gut microbes in the center of virtually all aspects of human physiology, including exercise physiology and sports performance.

In the last few years, mounting scientific evidence has demonstrated the significant yet previously unappreciated roles of gut function and gut microbes in physical activity and sports performance.

Research Findings

Many studies in the past decade have confirmed that moderate exercise and gut microbiome impact each other. Regular, moderate exercise alters gut microbiome composition and function, providing physical and mental health benefits. On the other hand, in some animal studies, moderate exercise performance measurements were improved with a more diverse and healthier gut microbiome.

In terms of endurance sports performance, groundbreaking 2019 animal and human studies showed how gut microbes can enhance endurance sports performance:

  • Gut microbes turn an exercise by-product into performance-enhancing molecules, improving marathon running performance by modulating lactate homeostasis.
  • Gut microbes help activate genes for shifting energy source in muscle from glucose to fat, improving endurance performance by preserving glucose consumption.

By interplaying, interacting, and communicating with other body systems and organs, and by modulating or influencing almost all body functions, our gut and gut microbes impact all adaptations to stressors of endurance sports, especially marathon running, and ultimately, performance.

They help us meet many physiological challenges in endurance sports performance, including: avoiding bonking; regulating inflammation; preventing infection; reducing exercise-induced GI symptoms; optimizing hydration status, balancing water and electrolytes; and optimizing redox balance (the balance between oxidative stress that causes fatigue, and muscle and tissue damage, and antioxidant defense of our body).

In exploring the roles of our gut and gut microbes in facilitating movements and influencing exercise and endurance sports performance, it is clear that our gut with its resident gut microbiome is an important exercise-and-sports-performance organ.


Mental focus, mood, emotional and psychological, and sleep challenges in endurance sports are also important for performance. How gut function and gut microbes help us meet these challenges to enhance performance will be explored in an upcoming issue.

References and Links

See the Full List of References for this Series

Table of Contents

Link: WellnessOptions Website

About the Authors

Lillian So Chan is the founding editor of WellnessOptions, a print magazine and website, and author of the book WellnessOptions Guide to Health published by Penguin Books. With over thirty years of experience in journalism and editing, Lillian has established unique editorial directions for several award-winning publications. She has worked for Maclean’s, Canada's largest news magazine, and served as a Governor and Deputy Chairperson of the Board of Governors at the Simon Fraser University, British Columbia, Canada.

Dr. Manny W Radomski, PhD
is the former Director General of the Defence and Civil Institute of Environmental Medicine (DCIEM) of Defence Canada. He was a professor in the Departments of Physiology and Community Health in the Faculty of Medicine, and in the Faculty of Physical and Health Education at the University of Toronto, Canada.

He served as Scientific Advisor to the Chief of Air Staff, Defence Canada; Board Director of the Canadian Defence Research and Development Executive Committee; member on the NATO Research and Technology Agency’s Human Factors and Medicine Panel.

He is the former Editor-in-Chief of the Undersea Biomedical Research Journal and serves as a referee for the Aviation, Space, and Environmental Medicine Journal.

He has published on diving and aerospace medicine, human performance and protection, stress endocrinology, sleep, tropical medicine, and circadian disorders. Manny is a co-editor of WellnessOptions.

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