A study finds that resistance training generates memory gains in mice greater than those seen in resistance-free endurance training. The biochemical pathway appears to be a neurotrophic factor, BDNF.
In a recent post on Exercisemed.org, the effects of endurance training on memory was discussed. That paper, released in the spring of 2012, discussed the impact that brain derived neurotrophic factor (BDNF) had on memory in middle aged mice (Running throughout Middle-Age Improves Memory function, Hippocampal Neurogenesis, and BDNF Levels in Female C57BI/6J Mice, 2012; Michael W. Marlatt, et al.). The study found that the release of BDNF through endurance exercise improved the memory of middle-aged, female mice. The mechanism is likely brain plasticity, the ability of neurons to form new connections and pathways. A Japanese study published this month found that mice participating in a high-load resistance training program had an even stronger improvement in memory (Voluntary resistance running with short distance enhances spatial memory related to hippocampal BDNF signaling, 2012. Min Chul Lee, et al.).
The study used running wheels to exercise the mice. The mice were assigned to three groups: a sedentary control group (Sed), voluntary wheel running with no resistance (WR) and voluntary wheel running with increasing resistance. The mice were maintained with these controls for 30 days. As the figure below shows, the mice with resistance-free running wheels ran a greater distance than their counterparts with resistance running wheels. However, the work performed was higher in the resistance wheel group. Resistance is given as a percentage of body weight.
The mice were tested for memory capacity and general cognitive function with a water maze. The water maze has a hidden platform that the mice must find. The mice were placed in the maze four days in a row. On average, the mice became more efficient at finding the hidden platform each day. As the figure below demonstrates, the mice with running wheels performed better than the sedentary mice (Sed) regardless of whether or not they had resistance (RWR) or no resistance (WR) on their running wheels. The mice that did resistance training spent more time in the target quadrant, quadrant P (graph C).
Like other studies, the neurotropic factor BDNF was found to be higher in the wheel running groups. In addition, the protein p-CREB was found to be higher in the wheel running groups and significantly higher in the resistance wheel running group. BDNF and p-CREB have both been implicated by previous studies in brain plasticity and memory. The authors speculated that the gains in resistance training were observed because the training was voluntary. Thus, the negative affects of stress on the brain did not occur. This is the first study to suggest that quality over quantity is the rule for brain plasticity.
Exercise’s effect on brain plasticity is a very “hot” research subject right now. However, no research has been done on the biochemical affects of exercise in human subjects. While other studies have been focused on endurance training’s effect on brain plasticity, this is the first to look at how shorter resistance training affects the brain.