Efficacy and safety of cannabidiol (CBD) on reducing pain and functional impairment associated with exercise-induced muscle injury: a randomized placebo-controlled feasibility trial

Exercise and sports-related musculoskeletal injuries often result in pain, and the recovery process can be prolonged and challenging. Many physically-active Americans have begun using cannabidiol (CBD) for pain relief and improved recovery time, and CBD is of particular interest due to its positive safety profile, non-intoxicating effects, and therapeutic potential. Our objectives were threefold. First, to confirm the safety and tolerability of ingesting a CBD-rich hemp-extract. Second, we examined the feasibility and acceptability of our recruitment and blinding methods, and the tests and measures used to determine preliminary efficacy. Last, we planned to examine within-group effect sizes and observed power to make preliminary determinations of efficacy. A randomized, placebo-controlled, double-blind, two-arm parallel study design was used with participants randomly allocated to either a CBD or a placebo control group. Participants completed a 15-day study trial which included baseline testing, intervention (CBD/placebo dosing), and follow-up assessments on days 11 through day 15 (24 to 96-hrs post-injury). Outcomes included pain intensity, strength loss, and physical disability. Participants self-administered the investigational product (CBD or placebo) under the tongue twice daily for 15 days. Daily dosage of CBD was 67 mg. An experimental injury protocol for the quadriceps muscle group on day 10 induced pain and functional disability in otherwise healthy men (n = 9) and women (n = 20) [age: 20.1 yrs, weight: 64.2 ± 8.5 kg, height: 169 ± 5.3 cm]. There were no reports from participants of side effects or treatment-emergent adverse reactions from consuming the investigational products. Symptoms and functional deficits were most pronounced 24 to 48 h. post-injury and were least pronounced by 96-hrs post-injury. CBD users reported less peak pain at rest and with movement at 48-hrs post-injury. The CBD group showed less strength impairment and physical disability than placebo at 48-hrs post-injury. Sublingually administered CBD demonstrated a favorable safety profile and showed promise in reducing pain-related symptoms associated with exercise-induced muscle injury. Clinical studies using larger sample sizes are needed to confirm the reported estimates of efficacy in reducing pain and improving function post-injury. NCT04586712, registered on October 14, 2020.