Danny M. O'Dell, MA. CSCS*D Strength coach
Danny M. O'Dell, MA. CSCS*D Strength coach


Explosivelyfit strength training builds powerful bodies!

Freedom is never free. ~Author Unknown

Explosivelyfit gym
Fitness Tools
Other Resources
Personal Training
Strength Basics
Strength Links
Strength Tips
Strength Workouts
The Ultimate Bench
Upcoming Events
Women's Health

Explosivelyfit Strength Training blog

Join me on LinkedIn

Official PayPal Seal


Email Newsletters & Email Marketing by YMLP.com 

Explosivelyfit Strength Training, LLC
PO Box 35
Nine Mile Falls,
WA. 99026

Contact Danny



Fatigue: Is it in the muscles, the mind, or the heart


Fatigue: Is it in the muscles, the mind, or the heart

Dr. Timothy Noakes, MD. postulates that fatigue originates within the structural makeup of the heart itself and is thus controlled by a ‘Central Governor’. This model of fatigue “proposes the existence of a governor that monitors the state of oxygenation of the heart and perhaps other organs (such as the brain and diaphragm) as well.” (1)

When the oxygenation levels to the heart approach a critical stage of what is deemed safe by the organism the motor cortex of the brain stops recruiting additional muscles to continue the activity at the present pace or intensity. Without new muscle fibers recruited into the activity, the body experiences fatigue. This sensation “is always sensed exclusively by the brain, even though it appears to be coming from(2) somewhere else. These signals of fatigue may manifest as muscular exhaustion or various degrees of discomfort in the musculature.

Following the lack of additional muscle fiber recruitment, the work output of both the heart and muscles begins to drop off. This leads to a reduced demand for oxygen at the heart. With this reduced demand for oxygen the heart is automatically protected from damage which would occur if it were to be without enough oxygen to function correctly.

Accordingly, “this model predicts that maximum exercise capacity is a process, coordinated subconsciously by the brain, limited by the maximum capacity of the coronary blood flow to supply oxygen to the heart, and regulated to prevent heart damage during maximal exercise.” (3)

With that out of the way here is a new definition of fatigue:

Recall that fatigue is traditionally defined as “the inability to sustain the desired or required force”(4). Some authorities hypothesize that fatigue is an emotion or sensation and not a direct physical phenomenon. These interpretations of fatigue seems to indicate that changes in the brain commands to the muscles signals the onset of the fatigue condition in our bodies. Added to this theory is the contribution from Noakes, T who believes that fatigue is the ‘manifestation of a change in pacing strategy’. 


Fatigue may not be what it appears, i.e. a physical deterioration of muscle and oxygen utilization. Instead according to this new theory it may well be controlled by the hearts ability to maintain the critical blood flow within the system, specifically to the actively engaged muscles.

(1) Lore of Running, Noakes, T, MD. Human Kinetics 2003
(2) Ibid
(3) Ibid
(4) Ibid




    We abide by the The CAN-SPAM Act of 2004

Copyright © 2003 to present Explosivelyfit.com
Site created by: Fire Creek Photography and Design Studio™

If You Can't See All Of This Page Please Update Your Browser, It's Free JAVA & Flash Player