All exercise is good for you, but some forms of physical activity may yield higher benefits to the brain than others, according to a new study published in the Journal of Physiology.
For the first time, scientists compared the neurological effects of different types of exercise — running, weight training and high-intensity interval training — on the brain.
Studies on animals and people have found physical exercise leads to an increase in brain volume and can reduce the number and size of age-related holes in the brain's white and gray matter, according to The New York Times. It also enhances adult neurogenesis — the creation of new brain cells in an already mature brain, according to the report.
In studies where animals are put on treadmills or running wheels, exercise has been found to double or even triple the number of new neurons that appear in its hippocampus, the area of the brain that is closely associated to learning and memory, compared to those that remain sedentary. Scientists believe exercise produces a similar effect on the human hippocampus, according to the report.
While past studies have focused on running, a new study, led by researchers as the University of Jyvaskyla in Finland, compared the impact of different workouts on rats' brains. A control group of rats remained sedentary.
Some rats ran on wheels while others did resistance training — which involved climbing a wall with tiny weights attached to their tails — and others were assigned to high-intensity interval training. The rats in this group were placed on little treadmills and required to sprint at a very rapid pace for three minutes, followed by two minutes of slow jogging, with the sequence repeated for a total of 15 minutes.
After seven weeks, the researchers microscopically examined tissue from the hippocampus of the rats' brains. They found significantly different levels of neurogenesis.
The rats that jogged on the wheels showed the most neurogenesis, with a positive correlation between the number of miles run and the number of new neurons produced. There were substantially fewer new neurons in the brains of the animals that completed high-intensity training, though there were somewhat more than in the sedentary rats. Finally, the rats who did weight training showed no discernable augmentation of neurogenesis, though their bodies were stronger.
Miriam Nokia, PhD, a research fellow at the University of Jyvaskyla who led the study, said she and her colleagues speculate distance running produced the most new neurons because the activity stimulates the release of brain-derived neurotrophic factor that is known to regulate neurogenesis, according to NYT. Weight training, on the other hand, has been shown to have little impact on the body's levels of brain-derived neurotrophic factor. And, because high-interval training is more physiologically demanding and stressful, "stress tends to decrease adult hippocampal neurogenesis," Dr. Nokia said.