Performance from the Inside Out Part 1:

From our first steps to our best finishes

By Lillian So Chan with Manny W Radomski, PhD


Performance from the Inside Out Part 1: From our first steps to our best finishes


Challenged to Perform

Most of us don’t remember when or how we took our first step and learned to walk. It was a courageous performance. Walking is actually a series of falls forward followed by getting back up on one foot after the other.

The simple, natural act of walking takes a lot of physical and physiological coordination, the courage to overcome the fear of falling, and many steps of practice. It is in this continuous struggle against a series of falls and in the continued victory of overcoming the challenges one footstep at a time that so much human potential is realized.

We have been moving forward since our first steps, challenging our bodies to stay fit and striving to better ourselves. Humans are the only animals that challenge their bodies with intentional physical and physiological stresses in exercise, pushing the limits of their physical and mental potential to triumph over themselves and others in endurance sports.

Today, more than 110 million Americans walk for fitness. Even though the mechanical repetitive forces on the body are about two times greater in running than in other endurance sports, running has become one of the most practiced sports worldwide.

The number of runners in the US alone has increased more than 50% in the last decade. It is fast approaching 65 million, about the population of France. The popularity of marathons has increased even more dramatically—from an estimated 25,000 marathon finishers in 1976 in the US to more than 507,000 in 2016, a twentyfold increase in four decades. With its historical and symbolic significance, marathons highlight the human desire to realize maximum potential against all internal and external odds.

Running and marathon races are also the most studied endurance sports, both in the laboratory setting on treadmills and in field events. Many scientific animal and human studies on the physiology of exercise and endurance sports are conducted using the running model.

But what facilitates those first forward steps and sustains our movements? What does our gut with its gut microbes have to do with movements and performance in exercise and in endurance sports?

Our Story

The physical, physiological, mental, and health benefits of regular, moderate exercise are well documented and scientifically indisputable. Recommendations of effective regular exercise routines for different populations with different needs have been developed and employed.

There is also mounting research on the science behind strenuous training for sports. Studies have resulted in the development of numerous training protocols and strategies.

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

Our gut, with its resident gut microbiome, is actually an important exercise- and sports-performance organ. It works hard with all our other organs and systems to facilitate our first steps and sustain our every movement.

It regulates and influences essential life functions, including digestion, absorption, food metabolism, water uptake, essential vitamin synthesis, energy use and homeostasis, immune response, hormonal balance, stress response, brain function, emotions, and even social behavior.

The fundamental and interconnected nature of these functions means that gut function and gut microbiome influence virtually all aspects of human physiology, including exercise physiology and sports performance.

Our story here is about what happens in our body during regular exercise and strenuous sports, the impact on (and of) our gut and gut microbes, and how our gut and gut microbiome facilitate movements and contribute to enhance performance.


Moving On and On

All forms of physical activity require energy to initiate, support, and sustain the movements.

Success in exercise and sports performance begins with adequate energy harvest to support energy consumption and to promote maintenance and improvements in strength, muscle mass, general health, and endurance.


References and Links

See the Full List of References for this Series

Table of Contents



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.


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 magazine and journal.

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