How does CBD affect the body’s response to aerobic exercise? Original paper

Cannabidiol (CBD) is a compound found in cannabis, but unlike THC, it is not intoxicating. CBD has shown clinical promise for its anticonvulsant effects and appears to have anti-inflammatory properties. Interest in CBD is increasing among athletes to improve recovery and sleep and reduce anxiety.^[1] However, few studies have investigated the effects of CBD on outcomes relevant to athletic performance.

In this randomized crossover trial, 9 endurance-trained men (average VO₂max of 57.4 mL/kg/min; average age of 33) were assigned to ingest either 300 milligrams of CBD or a placebo before completing a submaximal run (RUN 1; 60 minutes at 70% of VO₂max) and an incremental run to exhaustion (RUN 2). The treatment was ingested 90 minutes before RUN 1 and 180 minutes before RUN 2. Testing occurred at seven time points: baseline (pretreatment), before RUN 1 (60–90 minutes posttreatment), during RUN 1 (90–150 minutes posttreatment), after RUN 1 (155–170 minutes posttreatment), during RUN 2 (180–200 minutes posttreatment), after RUN 2 (205–220 minutes posttreatment), and 1 hour after RUN 2 (220–270 minutes posttreatment). The testing sessions were separated by a washout period of at least 7 days.

The outcomes assessed included time to exhaustion, VO₂max, oxygen consumption (VO₂), carbon dioxide production (VCO₂), blood lactate, blood glucose, respiratory exchange ratio (RER), tidal volume, minute ventilation, heart rate, blood pressure, gastrointestinal comfort, interleukin-1 beta (a marker of inflammation), myoglobin (a marker of muscle damage), anxiety (measured by the short-form State-Trait Anxiety Inventory), mood (measured by the short-form Profile of Mood States), ratings of perceived exertion, ratings of pleasure-displeasure (measured by the Feelings Scale), and sleep quality and muscle soreness the morning after each testing session.

The time to maximum CBD plasma levels was 206 minutes. CBD produced the following effects during RUN 1 compared to placebo:

• Higher blood lactate levels at minute 40
• Higher VO₂ at minutes 24 and 37
• Higher ratings of pleasure at minutes 20 and 40

CBD produced the following effects during RUN 2 compared to placebo:

• Higher average VO₂max
• Higher average VCO₂
• Higher average RER
• Higher average tidal volume

After RUN 2, CBD decreased interleukin-1 beta levels compared to placebo. CBD also increased myoglobin levels at 1 hour after RUN 2 compared to placebo. Additionally, after RUN 1, CBD decreased subjective fatigue compared to placebo but increased subjective fatigue at 1 hour after RUN 2.

This was a pilot study; it had a small number of participants, and it was not powered to detect a specific effect. The goal was to collect information to determine whether further investigations in a larger trial were warranted. Also, the researchers did not adjust for multiple comparisons, despite the inclusion of numerous outcomes, which increases the risk of false-positive results. Therefore, the findings should be considered exploratory.