Vigorous-intensity Aerobic Exercise Promotes Greater Increase In Serum Serotonin Than Moderate

Serotonin is a neurotransmitter synthesized from the amino acid tryptophan. It is well known for its important role in many cognitive processes and mood, and the main candidate for mood improvement effect of exercise. PURPOSE: To compare the impact of moderate and vigorous-intensity aerobic exercise on serum serotonin levels in healthy adults. METHODS: Twenty-one male subjects (31.10 ± 5.2 yrs; 74.57 ± 9 kg; 173.95 ± 4.4 cm; 24.67 ± 2.5 kg/m2) underwent two exercise tests at intensities based on the Vpeak percentage of a treadmill maximal graded test separated by 7 days: 1) 60% Vpeak for 30 minutes (moderate intensity); 2) 85% Vpeak until volitional exhaustion (vigorous intensity). Blood samples were collected at baseline, immediately after, and 30 minutes after the end of the exercise. The means were compared using GLM (General linear models) repeated measures. When a significant effect was detected, post hoc comparisons were performed using Duncan’s multiple range test. Significance was set at p ≤ 0.05. The protocol was approved by UNIFESP Ethics Committee (#2.381.537). RESULTS: GLM analysis show effects for group and time (F(1,20) = 178.61; ηp2 = 0.90; p < 0.001). Duncan’s post hoc test showed an increase in serotonin immediately after exercise for vigorous (p < 0.001) and moderate intensities (p < 0.04) compared to baseline. However greater increase was observed in vigorous-intensity when compared to moderate-intensity (p = 0.03). Serum concentrations remained high 30 minutes after moderate intensity (p = 0.02) but returned to baseline levels 30 minutes after vigorous intensity. CONCLUSION: Moderate and vigorous aerobic exercise intensities can increase serum serotonin levels immediately after exercise. Although the effect appears to be longer lasting at moderate intensity, more pronounced increases are observed at vigorous intensity. These results are relevant to the use of different exercise intensities as an adjunctive strategy for the treatment of depression.