A new study on rats has indicated that certain types of exercise may be more effective than others at maintaining and even building up brain health.
In a new first, scientists compared the neurological impacts of different types of exercise, including running, weight training and high-intensity interval training. The results suggest that high impact training may not be the best choice to maintain long-term brain health.
Exercise has been shown to change the structure and functioning of the brain. Studies in animals and people have shown that physical activity usually increases brain volume and can reduce the frequency and size of age-related holes in various parts of the brain.
Exercise also augments adult neurogenesis, (the creation of new brain cells in an already mature brain). In studies of animals, exercise involving running wheels or treadmills can double or even triple the number of new neurons that appear in the animals’ hippocampus, which is a key area of the brain associated with learning and memory. This result was apparent when comparing the brains of animals that remain sedentary with those that underwent exercise. Although not proven many scientists believe that the human hippocampus would be similarly affected.
These studies of exercise and neurogenesis have focused on distance running. Lab rodents of course know how to run. But the question still remains whether other forms of exercise would also prompt increases in neurogenesis.
The current study, which was published this month in the Journal of Physiology, involved researchers at the University of Jyvaskyla in Finland (and other institutions) injecting rats with a substance that marks new brain cells. These researchers then set groups of rats a variety of different workouts, with one group remaining sedentary to serve as a control group.
Some groups of rats were given running wheels in their cages, allowing them to run at will. Most jogged moderately every day for several miles.
Other groups began resistance training, which involved climbing a wall with weights attached to their tails.
There was also the rodent equivalent of high-intensity interval training. For this the animals were placed on small treadmills and required to sprint at a very rapid and strenuous pace for three minutes, followed by two minutes of slow activity, with the entire sequence repeated twice more, for a total of 15 minutes.
The study continued for seven weeks. At the end of the time period the researchers examined brain tissue from the hippocampus of each animal.
There were differing levels of neurogenesis, dependant on how each animal had exercised.
Those rats that had jogged on wheels showed robust levels of neurogenesis, far more than in the brains of the sedentary animals. The greater the distance that the animal had covered during the experiment, the more new cells its brain grew.
There were far fewer new neurons in the brains of rats that had completed high-intensity interval training. They showed somewhat higher amounts than in the sedentary animals but less than in the distance runners.
And the weight-training rats showed no discernible augmentation of neurogenesis, although their strength levels had increased. Their hippocampal tissue looked just like that of the animals that had not exercised at all.
According to Miriam Nokia, a research fellow at the University of Jyvaskyla “sustained aerobic exercise might be most beneficial for brain health also in humans.”
Dr. Nokia and her colleagues theorise that distance running stimulates the release of brain-derived neurotrophic factor which is known to regulate neurogenesis. The more miles an animal runs, the more B.D.N.F. it produces.
Weight training, on the other hand, while beneficial for muscular health, has previously been shown to have little effect on the body’s levels of B.D.N.F.
According to Dr. Nokia high-intensity interval training, is much more physiologically draining and stressful than moderate running, and “stress tends to decrease adult hippocampal neurogenesis,” she said.
These results do not mean, however, that only running and similar moderate endurance workouts strengthen the brain, Dr. Nokia said. Those activities do seem to prompt the most neurogenesis in the hippocampus. But the other types of exercise may lead to different types of changes in the brain. They could encourage the creation of additional blood vessels or new connections between brain cells or between different parts of the brain.
So if you’re at the gym doing weight training perhaps you should also think about mixing it up a bit more. Get on your bike or hit the cardio circuit a bit more often.