The Role of Cannabidiol in Sport: Mechanistic Insights, Ergogenic Potential, and Regulatory Implications

Cannabidiol (CBD), a non-intoxicating constituent of the Cannabis Sativa plant, has gained popularity amongst athletes for its purported therapeutic potential related to analgesia, inflammation and anxiety. In 2018, CBD was removed from the World AntiDoping Agency’s (WADA) list of prohibited substances, igniting widespread interest in its use in sport. However, scientific insight into its efficacy, mechanisms of action and safety – remain elusive. This thesis aimed to investigate CBD from three distinct, yet interrelated perspectives: (i) its mechanistic influence on skeletal muscle, (ii) its ergogenic effects, and (iii) its safety from an anti-doping perspective. Preliminary in vitro investigations revealed that acute CBD exposure might influence myogenesis at higher doses. These findings were extended through transcriptomic analyses offering insights into the molecular and biological pathways modulated by CBD. In parallel, a human investigation demonstrated that three-weeks of broad-spectrum CBD supplementation did not enhance performance in a 10-minute cycling time trial. Perhaps most importantly, a final study explored the implications of prolonged (10- week) supplementation. This study demonstrated that broad-spectrum CBD led to the appearance of prohibited cannabinoids in urine. Notably, moderate-intensity exercise appeared to amplify this risk in both males and females, highlighting a previously underappreciated interaction between exercise metabolism and contaminant exposure to cannabinoids. Taken together, these findings add important context to the emerging discourse on CBD in sport. While further work is required to elucidate its mechanisms of action, the anti-doping implications are unequivocal: off-the-shelf, broad-spectrum CBD supplements pose a significant risk to athletes. This thesis contributes novel evidence to inform athlete decision-making, guide regulatory policy, and support future education, whilst laying the foundation for further exploration into cannabinoids through the lens of sport and exercise.