BDNF is associated with brain health and positively modulated by exercise; however, the influence of physical fitness status on BDNF is incipient. This study investigated the BDNF response after acute-exercise sessions performed at low, moderate, and high intensities and the relationship between physical fitness status and BDNF response. Twenty-eight men, divided according to physical fitness status (<50th or >50th percentile for VO2max), performed three randomised acute exercise sessions at low (90% of VT1), moderate (midpoint between VT1-VT2), and high (midpoint between VT2-Wmax) intensities until exhaustion or for up to 60 min. Lactate and BDNF were determined pre and post-exercises. For BDNF, there were main effects of time (p = 0.003) and interaction (p < 0.001), showing an increase post high-intensity exercise (p < 0.001). Changes in BDNF presented differences between conditions (p < 0.001) with greater increase in high-intensity compared with the others (p = 0.003). For lactate, there were main effects of time (p < 0.001), condition (p < 0.001), and interaction (p < 0.001) with greater concentration in high-intensity. High-intensity exercise exhibited inverse correlation between the changes in BDNF and lactate (r=-0.38, p = 0.044). There was significant correlation between BDNF and VO2max for moderate (r = -0.57, p = 0.002) and a trend for high-intensity condition (r = -0.37, p = 0.050) and when evaluating BDNF according to physical fitness level, it was observed that subjects with lower physical fitness levels had greater increases in BDNF in short-time high-intensity exercise (p = 0.041). In conclusion, short-time high-intensity exercise seems to be more efficient in increasing BDNF concentration, and physical fitness level influences this response, as healthy individuals with lower physical fitness levels were more responsive.
Keywords: BDNF; brain health; high-intensity training; lactate; neurotrophin.