Effects of aerobic exercise intensity on brain-derived neurotrophic factor and affective states in patients with depression
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Background: Brain-derived neurotrophic factor (BDNF) is an important protein for neural growth and survival that is related to cognitive function and affective symptoms. Patients with depression have reduced levels of BDNF. Aerobic endurance training increase BDNF levels and is associated with improved positive affect and well-being, reduced distress and state anxiety. No study has compared changes in BDNF levels and affective states between high aerobic intensity training (HIT) and long slow distance training (LSD) in patients with depression. Aim: 1) To examine changes in serum BDNF levels after HIT compared to LSD in patients suffering from depression. 2) To examine changes in affective states after HIT compared to LSD. Methods: After determining maximum heart rate (HRmax) and familiarization to HIT and LSD, 16 patients with depression (ICD-10: F32-F33) performed one LSD and one HIT. HIT was warm up at 60-70 % of HRmax for 10 min, then 4x4 min intervals at 85-95 % of HRmax, intermitted by 3 min active rest periods at 60-70 % of HRmax. LSD was continuous running or walking for 45 min at 60-70 % of HRmax. Blood samples for measuring serum BDNF was taken 5-10 min before each training session and within 3 min after completing the last 4 min interval (HIT) or completing the whole 45 min (LSD). Self-evaluation questionnaires of state anxiety, positive affect, negative affect, well-being, distress, and fatigue were completed before training and 15 min after. Results: BDNF increased only after HIT (p = 0.001). After LSD there were improvements in negative effect (p = 0.022), well being (p = 0.006), distress (p = 0.017) and state anxiety (p = 0.001). After HIT there were improvements in negative effect (p = 0.034), well being (p = 0.002), distress (p = 0.019) and state anxiety (p = 0.004) and also improvements in positive affect (p = 0.013) and increase in fatigue(p = 0.019). The only pre- to post difference between the interventions was in fatigue (p = 0.009). Conclusion: Both HIT and LSD improves negative affect, well-being, distress and state anxiety. Only HIT improves BDNF levels. Thus, patients with depression should perform HIT in order to improve both affective states and BDNF levels.