Physical activity exerts its greatest anti-aging effects on the brain when performed in conjunction with a cognitive activity (such as sightseeing, as these cyclists are doing on the right).
Numerous studies have shown exercise reduces age-related brain degeneration. Many of these studies have been discussed on Exercisemed, including the effects of physical activity on Alzheimer's and our telomeres. Furthermore, physical activity has been found in mouse models to enhance cognitive ability and memory. However, new research is finding that other factors can confound the cerebral effects of exercise. One of the problems with good scientific experiments is that every outside variable is fully controlled. By controlling these outside variables, researchers are able to isolate changes to the single, experimental variable. In exercise physiology research this means that physical activity is performed under strict supervision on a mundane treadmill. This is true for both human and animal studies.
Yet in the natural world, animals (humans are the one exception) never find themselves exercising on a treadmill. Physical activity is performed in conjunction with cognitive tasks, such as scouring for food or exploring unknown territory. A recent review appearing in the Journal of Sleep Medicine highlights importance of "getting out and about" on maintaining neuroplasticity (Exercise benefits for the aging brain depend on the accompanying cognitive load: insights from sleep electroencephalogram, 2013. Jim Horne).
Researchers can use sleep electroencephalogram (EEG) to measure various markers of neuroplasticity in subjects while they sleep. Neuroplasticity is a measure of how malleable the brain is. For example, new synaptic connections are made to generate memories in the hippocampus. As we age, neuroplasticity decreases, which is one potential explanation for why the elderly have impaired memory capabilities. The research presented in the aforementioned paper suggests that physical activity performed with cognitive tasks that require curiosity and analysis can have a greater effect on the aging brain than physical activity or cognitive challenges by themselves.
In a world where physical activity is increasingly being pursued in static environments (i.e. on a treadmill or cycling machine), it may be advisable to move our exercise habits in the opposite direction. There are many ways for achieving a simultaneous physical and mental workout. Instead of sightseeing from the car, explore a new place while on your bike. Go trail running, kayaking, hiking, even window shopping. Please share how you like to challenge yourself physically and mentally in the comments section to the left.