Endogenous Opioids and Runner’s high

Endogenous Opioids and Runner’s high



Endogenous Opioids and Runner’s high

Runner’s high refers to a phenomenon whereby an athlete experiences a state of euphoria with energy burst, enabling the athlete to perform exceedingly well (Boecker, 2008). However, the phenomenon has been a biological mystery for many years, with scientist extending their research to unravel the mystery. Currently, there is no consensus on the definition of runner’s high and its causes. However, most researchers suggest that the phenomenon comes as a result of release of pain-blocking endorphins by the body in response to the intense exercises. Endogenous opioids refer to amino acids that bind on opioid receptors in the brain. These amino acids play a critical role in motivation, response to pain and stress, and emotion. This paper seeks to extend the available literature on the relationship between endogenous opioids and runner’s high, by conducting an in-depth literature review on the topic.

Koneru (2009), in his investigation of endogenous opioids in regards to their physiological roles and receptors, argued that, the complex effects of opioid analgesics can be traced by the analysis of their interaction with the whole system of the endogenous opioids. Opioid receptors and compounds are found entirely on the peripheral and nervous system, where they are mainly involved in the control and influence of many homeostatic functions and the control of processing of sensory inputs such as noxious inputs (Koneru, 2009). Moreover, the opioid system is mainly vital in the modulation of pain in a system that is very complex.  Koneru (2009) further argues that the body produces four types of opioid peptides namely; endorphins, enkephalins, dynophins, and endomorphins, and each family of the opioid peptide derive its name from a specific precursor protein. However, of the four endogenous opioids, endorphins play critical role in analgesia, and, therefore, informing runner’s high. Endorphins are produced in the hypothalamus and pituitary glands of human beings to respond to pain, excitement, strenuous activities, and orgasm. Endorphins acts as pain relievers, and are found in different parts of the body in four types; sigma (ό), alpha (α), gamma (γ), and beta (β) (Koneru, 2009). The differences amongst the four types of endorphins are found in the type and number of amino acids in each, which ranges from 16 to 31. Beta endorphins are the most prevalent types of endorphins, and are largely released by pituitary gland in times of stress and pain. The endorphins induce analgesic effect during times of pain and stress, and, more so, produce a feeling of euphoria for lessening the pain. Physical exercises increases the production of endorphins, and the more an athlete exercises, the more endorphins are released, bringing in the effect of analgesia and euphoria, which results to runner’s high.

Boecker (2008) set out to investigate the opioidergic mechanism in the human brain in relation to runner’s high, by conducting 2 scans on 10 athletes. The scan was conducted when the athletes were at rest and another after two hours of strenuous exercise. The study results indicated that, significant increase of euphoria was registered by athlete after the two hours strenuous exercise. The brain scans indicated a reduction in the number of opioid receptors in the limbic and prefrontal structures of the brain. For Years, scientists have claimed that, strenuous activities induce the number of psychophysical effects on human bodies, which includes pain and stress reduction and the feeling-good effects (Boecker, 2008). Using a PET ligand activation study, the researcher showed that after two hours of strenuous exercise, changes in the athletes’ brains in regard to the psychophysical changes were indentified. Strenuous activities alter the volume and release of endogenous opioids by pituitary gland and hypothalamus (Boecker, 2008). Boecker further reveals previous studies involving rats. The author noted that the opioidic pathways in regards to changes in the rat’s behavior after a strenuous activity was investigated and revealed the complex changes in the binding of opioidic receptors in the brain during and after the activity. Forced swimming of rats in cold water was shown to reduce diprenorphine binding. Those study results revealed that, beta-endorphin levels increased in the blood plasma by five folds after the exercise. The changes in the brain structure and the receptor bonding were attributed to the changes in physical and emotional states of the athletes (Boecker, 2008). However, the study could not conclude which type of endorphin was solely or mostly responsible for the changes registered in the athletes. Therefore, the study suggested further research to indentify the specific role and contribution played by each type of endorphin during runner’s high episodes.

The opioidic system of human body exercises control of addictive behavior and pain in the human bodies (Klein and Thorne, 2007). Three opioidic receptors are critical in the pharmacological control of opioids. These receptors include; kappa, delta, and mu. Each of the receptors in the brain is activated by peptides of different families, which include; dynophins, endorphins, and enkephalins. Using genetically modified rats, one can be able to pin point the brain function and the functioning of these receptors in regard to the runner’s high phenomenon. Klein and Thorne (2007) argue that, of all the receptors induced by endogenous opioid peptides, mu-opioid receptors play a critical role in the analgesia effect and addictive activities. Analysis of the brain imaging of the athletes after strenuous exercises can indicate increment in mu-receptors in the prefrontal lobe of the brain, which induces analgesia and euphoric effects on the athletes after strenuous exercises. Endogenous opioidic system has been a commonly studied area in the pursuit of understanding of the innate pain-relieving abilities in vertebrates (Klein and Thorne, 2007). Although the mechanisms of the pain relieving abilities of human beings remained a mystery for decades Klein and Thorne (2007) revealed that scientists have now established that pain relieving ability is brought about by endogenous opioids. These transmitters play the role of neural modulator, and neurotransmitter to produce analgesia.

Scientists have associated sustained exercise with positive health outcomes such as slowing down cognitive decline as a result of age, and improving mental functions for centuries (Holden, 2005). However, the concept of runner’s high came into focus in 1970s, when scientists set out to investigate the causes of the phenomena.  This pursuit followed the development of many theories for explaining the phenomena, but each theory had its own flaws. According to Holden (2005), recent studies involving genetically modified mice have identified endogenous opioids as the cause behind runner’s high. Endogenous opioid peptides have been shown to play a critical role in human cognitive functions, emotions, motivation, and pain reliever (Holden, 2005). The neuron peptide inhibitory transmitters control the transmissions of receptors on several neuronal circuits setting standards, and limits of the psychophysical experiences. However, although endogenous opioids play a vital role in the pain relieve and improving individual motivation and emotions, these protein compounds have been linked with addictive behaviors. The opioids are linked with increasing addiction of heroin and morphine in individuals (Holden, 2005). Moreover, alcohol addiction in individuals is also linked with these vital protein compounds.

Runner’s high is a phenomenon most athletes yearn to achieve during their careers. However, most athletes have never experienced the phenomena, despite their undertakings on intense strenuous exercise. A review from various researches suggests that, endogenous opioids are responsible for the runner’s high phenomenon, which an athlete experiences after intense exercise. The hypothalamus and pituitary glands are critical in the production of endogenous opioids, which have a direct effect on motivation, mood, and pain reliever.  Although research identifies four types of opioidic peptides, endorphins play a significant role in analgesia. Equally, there exists four types of endorphins; alpha, sigma, beta, and gamma, which are critical in analgesia. However, the particular role played by each type of endorphin remains unclear. Therefore, further research to identify the particular contributions of each of the endorphins is called for.


Boecker, H. (2008). The Runner’s High: Opioidergic Mechanisms in the Human Brain. Oxford Journal of Sport Medicine , 2523-2531.

Holden, J. F. (2005). The endogenous opioid system and clinical pain management. American Association of Critical-Care Nurses , 291-301.

Koneru, A. (2009). Endogenous Opioids: Their Physiological Role and Receptors. Global Journal of Pharmacology, Vol 3(3) , 49-153.

Klein, S. B., & Thorne, B.M. (2007). Biological Psychology. London: Worth Publishers.


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