Governor Theory: A Role for the Brain in Endurance Performance
In the 2026 Cocodona 250 mile ultramarathon, Rachel Entrekin delivered a coronating performance, winning in a time of 56 hours and 9 minutes. She not only took over 7 hours off of her previously held women’s course record; she also bested the overall course record by over 2 hours. During the race, Entrekin slept for a total of 19 minutes.
Chasing Entrekin for a place on the women’s podium was Heather Jackson, a former Ironman World Championship medalist. Within 10 miles of the finish, Jackson’s fatigue got the better of her. A wrong turn led to 4th place woman Meg Eckert overtaking Jackson, and hobbling into the final aid station, 4 miles from the finish, Jackson decided to stop and sleep for 3 hours. She would finish 4th in the women’s race with a time of 69 hours and 36 minutes. How did Entrekin’s nervous system enable her performance in spite of intense sleep deprivation while Jackson’s urged her to stop?
This question strikes at the core of an enduring, controversial theory in sports neuroscience: Governor theory. Coined by exercise scientist Tim Noakes, Governor theory suggests there exists a network within the central nervous system that monitors signals of fatigue and compares what those signals indicate about an athlete’s current state against their own performance expectations (Noakes, 2011). If this calculation returns a negative judgment about the ability to persist, this governing system produces a state of fatigue in an act of preservation to cease activity and return the body to a resting state (Tornero-Aguilera et al., 2022).
The theory emerged in part as a reaction from Noakes to the work of exercise scientist and running coach Jack Daniels. Daniel’s training system was developed from his research on VO2max, one’s maximum rate of oxygen consumption, and held that velocity at VO2max was the ultimate differentiator in elite distance running performance (Daniels, 1998/2022). While his 8 national championships at SUNY Cortland deemed Daniels’ training effective, Noakes remained frustrated that Daniels’ methodology left little room for the nervous system. It was from this that Noakes developed Governor theory, first Central Governor theory to emphasize the central nervous system, as a way to integrate findings from affective neuroscience with exercise physiology.
Perhaps the most important concept from affective neuroscience for understanding Governor theory is interoception, the nervous system’s ability to create perceptions of our internal states from physiological signals. By taking in information about our heart rate, sweat rate, and muscle damage, our interoceptive system can help us understand whether we may be tired, hungry, or dehydrated.
Within its understanding of the role interoception plays in endurance performance, Governor theory makes a distinction between two categories of fatigue signals based on their relationship to the nervous system. Fatigue affecting largely non-neuronal processes, dubbed peripheral fatigue, comprises much of what are commonly thought of as fatigue signals, such as blood pH levels and inflammatory responses (Tornero-Aguilera et al., 2022). Noakes was more interested in the category of central fatigue, that is the central nervous system’s degrading ability to execute motor functions with intense exercise (Tornero-Aguilera et al., 2022). While the neurochemistry of central fatigue remains somewhat murky relative to the study of peripheral fatigue, serotonin has emerged as a promising culprit.
The central nervous system experiences an increase in serotonin with exercise as the bloodstream’s concentration of tryptophan, an amino acid used for serotonin synthesis, increases in tandem with blood flow to the brain (Tornero-Aguilera et al., 2022). The resulting accumulation of serotonin downregulates motor neurons which are abundant in 5HT1A receptors, a serotonin receptor that is inhibitory when bound (Pearcey & Heckman, 2020). This inhibition is read by the interoceptive system’s main processor, the insular cortex, as a sign of increasing central fatigue, and can be compared with information about muscle damage to make a judgment about whether to continue the effort.
In addition to this serotonin-related motor system inhibition, there is evidence of compounding downregulation of the motor system from afferent neural fibers located near the skeletal muscles (Sidhu et al., 2017). If this inhibition is significant enough, there may be a noticeable decline in the athlete’s power output as the efficiency of the motor system gets compromised. In extreme cases, the motor system may even fail to execute movements as was seen when ultramarathoner John Kelly terminated his 2025 attempt at the Fastest Known Time on the Appalachian Trail due to a loss of mobility in his feet.
Governor theory is not without its critics. Among coaches, there is confusion about how one designs protocols to train the Governor system. In a time when endurance training in Western Europe and North America is fixated on blood lactometers and VO2max tests, it remains frustratingly opaque how one measures an athlete’s Governor system. This has in turn sown frustration among other scientists over the theory’s logical foundation (Inzlicht & Marcora, 2016): How does one compare the merits of Noakes’ theory to that of Daniels? Or any other exercise scientist?
Particularly in endurance contexts like ultramarathons, where emotional regulation is critical to success on race day, the need for a theory of endurance that includes the central nervous system appears essential. Governor theory is merely one attempt to unify two fields that have long talked past each other and hold great potential for synthesis.
ABOUT THE WRITER
Maggie Dochnal
Guest Writer
Maggie Dochnal is a recent graduate from George Washington University with interests in cognitive psychology and sports neuroscience. She has been a Guest Writer for Remember Magazine since August 2026.
References
Daniels, J. (2022). Daniels’ Running Formula (4th ed.). Human Kinetics. (Original work published 1998)
Inzlicht, M., & Marcora, S. M. (2016). The central governor model of exercise regulation teaches us precious little about the nature of mental fatigue and self-control failure. Frontiers in Psychology, 7. https://doi.org/10.3389/fpsyg.2016.00656
Noakes, T. D. (2011). Time to move beyond a brainless exercise physiology: The evidence for complex regulation of human exercise performance. Applied Physiology, Nutrition, and Metabolism, 36(1), 23–35. https://doi.org/10.1139/H10-082
Pearcey, G. E. P., & Heckman, C. J. (2020). Serotonin affects our perception of fatigue when performing submaximal efforts – but is it all in our heads? The Journal of Physiology, 598(13), 2533–2534. https://doi.org/10.1113/JP279883
Sidhu, S. K., Weavil, J. C., Mangum, T. S., Jessop, J. E., Richardson, R. S., Morgan, D. E., & Amann, M. (2017). Group III/IV locomotor muscle afferents alter motor cortical and corticospinal excitability and promote central fatigue during cycling exercise. Clinical Neurophysiology, 128(1), 44–55. https://doi.org/10.1016/j.clinph.2016.10.008
Tornero-Aguilera, J. F., Jimenez-Morcillo, J., Rubio-Zarapuz, A., & Clemente-Suárez, V. J. (2022). Central and peripheral fatigue in physical exercise explained: A narrative review. International Journal of Environmental Research and Public Health, 19(7), 3909. https://doi.org/10.3390/ijerph19073909
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