Research Article: Strength exercise weakens aerobic exercise-induced cognitive improvements in rats

Date Published: October 10, 2018

Publisher: Public Library of Science

Author(s): Yongsheng Lan, Zhaoyuan Huang, Yanjie Jiang, Xuehua Zhou, Jingyu Zhang, Dianyu Zhang, Bo Wang, Guangqing Hou, Robert Blum.

http://doi.org/10.1371/journal.pone.0205562

Abstract

Aerobic exercise improves cognitive function and adult hippocampal neurogenesis. However, the effects of aerobic exercise combined with strength exercise on cognitive function and adult hippocampal neurogenesis are still unknown. In this study, we established exercise paradigms in rats to mimic aerobic exercise combined with low- and high-intensity strength exercise. We found that aerobic exercise improved spatial learning and memory as well as adult hippocampal neurogenesis, whereas strength exercise suppressed aerobic exercise-induced cognitive improvements and adult hippocampal neurogenesis in an intensity-dependent manner. Furthermore, the levels of β-hydroxybutyrate (β-HB) and its downstream effector brain-derived neurotrophic factor (BDNF) were increased in the aerobic exercise group, and strength exercise impaired the aerobic exercise-induced increases in β-HB and BDNF mRNA levels. Taken together, these results demonstrated that strength exercise weakened aerobic exercise-induced cognitive improvements and adult hippocampal neurogenesis in rats.

Partial Text

Aerobic exercise is well known for its beneficial effects on cognitive performance [1–4]. Aerobic exercise refers to the use of aerobic metabolism to adequately meet energy demands during exercise. This process reflects the delivery of oxygen in the blood, which is pumped by the heart and transported to muscles. Increasing aerobic exercise ability means expanding the capacity of the heart and cardiovascular system to perform the task, supplying more oxygen and energy to the entire body, including the brain [5].

All data represent mean ± the standard error of the mean (s.e.m.). ANOVA was used to determine statistical significance (*p < 0.05, **p < 0.01, and ***p < 0.001). All statistical analyses were performed using GraphPad Prism 6.0. Aerobic exercise combined with strength exercise is composed of both aerobic exercise and strength exercise. The results obtained in our study suggest that aerobic exercise improves cognitive function and promotes adult hippocampal neurogenesis, which is consistent with the findings of previous studies [4, 15, 16]. In the Morris water maze test, the rats in the AER group required less time to find the platform and spent more time in the target quadrant (Fig 3). Adult hippocampal neurogenesis was increased in the AER group, as revealed by BrdU labeling and Ki67 immunostaining (Fig 4). Intriguingly, cognitive function and adult hippocampal neurogenesis were improved in both the AER group and the AER&LST group, but AER&LST exhibited a less significant effect than AER (Figs 3 and 4). Furthermore, the rats in the AER&HST group did not show any aerobic exercise-induced improvements in cognitive function or adult hippocampal neurogenesis (Figs 3 and 4), demonstrating that strength exercise weakened these aerobic exercise-induced benefits in an intensity-dependent manner.   Source: http://doi.org/10.1371/journal.pone.0205562