Neuroprotector Effect of Daily 8-Minutes of High-Intensity Interval Training in Rat Aβ Alzheimer Disease Model.

Background: Alzheimer's disease (AD) is the most common and irreversible neurodegenerative disorder, and amyloid peptide plays a central role in its pathogenesis. Physical training contributes as a beneficial adaptation to AD. However, these effects may be underestimated because much of the literature used fixed training prescription variables (intensity and volume) throughout the protocol. Moreover, researchers poorly understand whether chronic high-intensity interval training (HIIT) exerts similar effects on the brain tissue of individuals with AD.

Objective: This study evaluated the effect of 8 minutes of HIIT with incremental overload in an AD model.

Methods: Forty male Wistar rats were divided into four groups: an untrained Sham group, Sham trained group, Aβ (Alzheimer's) untrained group, and Aβ (Alzheimer's) trained group (n=10 rats per group). Animals underwent stereotactic surgery and received a hippocampal injection of Aβ or a saline solution. Seven days after surgery, two weeks of treadmill adaptation followed by a maximal running test (MRT) was performed. Then, animals were subjected to eight weeks of HIIT. Rats were sacrificed 24 h after the behavioral tests (open field and Morris water maze), hippocampal tissue was extracted to analyze the redox balance and BDNF/TrkB pathway, and neuritic plaques (NP) were detected by evaluating silver impregnation.

Results: The AD trained group presented a physical capacity amelioration every two weeks and locomotor, learning, and memory improvements (p<0.05). These effects were accompanied by increased CAT and SOD levels, followed by decreased lipid peroxidation (p<0.05). Furthermore, increased activation of the BDNF/TrkB (p<0.05) pathway and decreased NP was observed.

Conclusion: Based on these results, MRT was essential for an excellent chronic training protocol prescription and overload adjustment. Therefore, 8 minutes of HIIT daily for 8 weeks may reduce behavioral deficits by promoting a positive redox balance and increased activity of the BDNF/TrkB pathway that may contribute to NP attenuation.