John W Stauffer
University of Florida
Co-Authors: Joshua A Crow2, Jenessa L Bailey1, Robert L Cook1, Paul A Borsa1
1University of Florida, 2Augusta University
Background: Hemp-based supplements that use CBD-rich extracts have increased in popularity among physically active adults. Research indicates that CBD may have a promising therapeutic potential and is of particular interest due to its positive safety profile and non-intoxicating effects. However, very little is known about how CBD functions in the human body from both an efficacy and mechanistic perspective. Additionally, no published research has shown how CBD-rich hemp extracts may influence muscle fatigue and exercise performance.
Objective: Our objective was to investigate the impact of a controlled short-term trial of CBD supplementation on fatigue resistance following a bout of high intensity resistance exercise (HIRE).
Methods: A double-blind, randomized, two-arm study design was used with participants randomly assigned to either a CBD dose group or a placebo control group. Participants completed a 15-day study trial which included baseline testing, supplementation (CBD/placebo dosing regimen), and follow-up assessments in otherwise healthy men (n=9) and women (n=20) [age: 20.1 yrs, weight: 64.2±8.5kg, height: 169±5.3cm]. Participants self-administered the investigational product (CBD or placebo) under the tongue (sublingual) twice daily for 15 days. Daily dosage of CBD was 67mg. Participants completed a HIRE for the quadriceps muscle group on day 10 of supplementation with strength measurements (maximal voluntary contractions or MVCs) completed pre- and post-exercise to determine the level of strength loss and muscle fatigue (fatigue index). In addition, pre-exercise (day 10) and follow-up strength measurements were completed on days 11 through day 15 (24 to 96-hours post-exercise) to determine the rate of strength recovery. Results: Fatigue indices showed that participants who used CBD demonstrated less strength loss [CBD 28.1 v. PLA 41.2 Nm/Kg] and fatigue [CBD 21.8% v. PLA 32.6%] (F(1,28) =3.7, p=0.07) after exercise. No differences for the rate of strength recovery were demonstrated between groups post-exercise.
Conclusions: A CBD-rich extract administered sublingually may attenuate strength loss and reduce the onset of fatigue after strenuous exercise. Clinical studies using larger sample sizes are needed to confirm the reported trends in physically active adults.