Low-intensity exercise reduces negative affect via circulating endocannabinoid dynamics in healthy young adults

Area of Science:

• Exercise physiology
• Neuroscience
• Mental health research

Background:

• Mental health disorders are a significant societal challenge.
• Low-intensity exercise is a potential mood-enhancement strategy.
• The precise mechanisms linking exercise and mood, particularly involving endocannabinoids (eCBs), require clarification.

Purpose of the Study:

• To investigate if increased circulating eCB levels during low-intensity exercise correlate with reduced negative affect.
• To test the hypothesis that exercise-induced eCB changes contribute to mood improvement.

Main Methods:

• A randomized crossover trial involving 30 healthy participants.
• Two 60-minute cycling sessions at low (30% HRR) and moderate (50% HRR) intensities.
• Measurement of plasma N-arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG) at multiple time points, alongside mood assessment using the Physical Activity Affect Scale.

Main Results:

• Plasma eCB concentrations exhibited significant inter-individual variability and did not change uniformly.
• Low-intensity exercise significantly reduced negative affect.
• No significant correlation was found between cumulative plasma AEA/2-AG and mood changes during exercise; however, a negative correlation between plasma AEA and negative affect was observed across time points in the low-intensity condition.

Conclusions:

• Low-intensity exercise improves negative affect, independent of consistent aggregate changes in AEA and 2-AG.
• Dynamic, intra-individual changes in plasma AEA, rather than cumulative levels, are implicated in the mental health benefits.
• Exercise-induced AEA dynamics represent a potential novel mechanism for exercise-mediated mood improvement.