La Trobe

File(s) stored somewhere else

Please note: Linked content is NOT stored on La Trobe and we can't guarantee its availability, quality, security or accept any liability.

The physiological and perceptual effects of plant extracts (Catha Edulis Forsk) during sustained exercise

journal contribution
posted on 2021-03-22, 02:45 authored by MA Sallam, KA Sheikh, R Baxendale, Mohammad Azam, M El-Setouhy
© 2016 Sallam et al. Background: Khat (Catha Edulis Forsk) is a natural psychoactive substance that contains addictive substances such as Cathine and Cathinone which have similar structure and action to amphetamine. This substance has been suggested that it can decrease perceived exertion and thus improve performance. There is no study in the literature regarding the effect of khat on exercise performance. Therefore, the aim of this study is to find out whether khat leaves can decrease perceived exertion in humans. Methods: This study is an experimental crossover study conducted at the Substance Abuse Research Centre in Jazan University, Saudi Arabia. Twenty one healthy volunteers were randomly assigned into two experiment trials. Each volunteer visited the lab three times. The first visit was a familiarization session about the nature of the study and the equipment. On the second visit, 45 min before the experiment volunteers ingested either 33 ml of fruit juice (placebo) or the juice mixed with 45 g of ground khat leaves. Then the participants were instructed to perform a 10 Km cycling on an ergometer and recorded the following physiological variables repeatedly on every 5 min of cycling: heart rate, time to complete 10 km cycling, tympanic temperature, and perceived exertion rate. On the third visit a crossover trial was conducted one week after the second visit; then the same cycling test was performed and the same variables were recorded as the second visit. The experimental protocol was reviewed and approved by Research Ethical Committee of the Medical Research Centre, Jazan University. Results: According to study results, khat dramatically decreased time taken to complete a 10 km cycling time trail (p < 0.05), and significantly increased heart rate (p < 0.05) and tympanic temperature (p < 0.01). However, khat did not reduce participant's perceived exertion during the physical trial. The Bonferrini simultaneous confidence intervals using multivariate Hotelling's T2 was performed to test the significance of the mean vectors for the placebo group and the Khat group and found that groups are statistically significant. Conclusions: Khat showed a clear enhancing effect on physical performance. The most parsimonious explanation for this effect is that, like the related amphetamines, cathine/cathinone act as stimulants to increase the capacity to perform exercise. Thus, khat produces the same effects which lead to the banning of amphetamine. These findings conform & endorse the recent prohibition of cathinone by the World Anti-Doping Agency (WADA, 2014).


This study was fully funded by the Substance Abuse Research Center (SARC) of Jizan University, and we gratefully acknowledge it (Project number SARC # 1004). The authors thank all the research assistants who collected and entered data, and the participants who filled out the study questionnaire.


Publication Date



Substance Abuse Treatment, Prevention, and Policy





Article Number



9p. (p. 1-9)


Springer Nature



Rights Statement

The Author reserves all moral rights over the deposited text and must be credited if any re-use occurs. Documents deposited in OPAL are the Open Access versions of outputs published elsewhere. Changes resulting from the publishing process may therefore not be reflected in this document. The final published version may be obtained via the publisher’s DOI. Please note that additional copyright and access restrictions may apply to the published version.