Which Type of Exercise Is Best for the Brain?

 

Some forms of exercise may be much more effective than others at bulking up the brain, according to a remarkable new study in rats. For the first time, scientists compared head-to-head the neurological impacts of different types of exercise: running, weight training and high-intensity interval training. The surprising results suggest that going hard may not be the best option for long-term brain health.

As I have often written, exercise changes the structure and function of the brain. Studies in animals and people have shown that physical activity generally increases brain volume and can reduce the number and size of age-related holes in the brain’s white and gray matter.

Exercise also, and perhaps most resonantly, augments adult neurogenesis, which is the creation of new brain cells in an already mature brain. In studies with animals, exercise, in the form of running wheels or treadmills, has been found to double or even triple the number of new neurons that appear afterward in the animals’ hippocampus, a key area of the brain for learning and memory, compared to the brains of animals that remain sedentary. Scientists believe that exercise has similar impacts on the human hippocampus.

These past studies of exercise and neurogenesis understandably have focused on distance running. Lab rodents know how to run. But whether other forms of exercise likewise prompt increases in neurogenesis has been unknown and is an issue of increasing interest, given the growing popularity of workouts such as weight training and high-intensity intervals.

So for the new study, which was published this month in the Journal of Physiology, researchers at the University of Jyvaskyla in Finland and other institutions gathered a large group of adult male rats. The researchers injected the rats with a substance that marks new brain cells and then set groups of them to an array of different workouts, with one group remaining sedentary to serve as controls.

Some of the animals were given running wheels in their cages, allowing them to run at will. Most jogged moderately every day for several miles, although individual mileage varied.

Others began resistance training, which for rats involves climbing a wall with tiny weights attached to their tails.

Still others took up the rodent equivalent of high-intensity interval training. For this regimen, the animals were placed on little treadmills and required to sprint at a very rapid and strenuous pace for three minutes, followed by two minutes of slow skittering, with the entire sequence repeated twice more, for a total of 15 minutes of running.

These routines continued for seven weeks, after which the researchers microscopically examined brain tissue from the hippocampus of each animal.

They found very different levels of neurogenesis, depending on how each animal had exercised.

Those rats that had jogged on wheels showed robust levels of neurogenesis. Their hippocampal tissue teemed with new neurons, far more than in the brains of the sedentary animals. The greater the distance that a runner had covered during the experiment, the more new cells its brain now contained.

There were far fewer new neurons in the brains of the animals that had completed high-intensity interval training. They showed somewhat higher amounts than in the sedentary animals but far less than in the distance runners.

And the weight-training rats, although they were much stronger at the end of the experiment than they had been at the start, showed no discernible augmentation of neurogenesis. Their hippocampal tissue looked just like that of the animals that had not exercised at all.

Obviously, rats are not people. But the implications of these findings are provocative. They suggest, said Miriam Nokia, a research fellow at the University of Jyvaskyla who led the study, that “sustained aerobic exercise might be most beneficial for brain health also in humans.”

Just why distance running was so much more potent at promoting neurogenesis than the other workouts is not clear, although Dr. Nokia and her colleagues speculate that distance running stimulates the release of a particular substance in the brain known as brain-derived neurotrophic factor that 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 extremely beneficial for muscular health, has previously been shown to have little effect on the body’s levels of B.D.N.F., Dr. Nokia said, which could explain why it did not contribute to increased neurogenesis in this study.

As for high-intensity interval training, its potential brain benefits may be undercut by its very intensity, Dr. Nokia said. It is, by intent, 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 weight training and high-intensity intervals probably lead to different types of changes elsewhere in the brain. They might, for instance, encourage the creation of additional blood vessels or new connections between brain cells or between different parts of the brain.

So if you currently weight train or exclusively work out with intense intervals, continue. But perhaps also thread in an occasional run or bike ride for the sake of your hippocampal health. 

The health benefits of exercise are known to all; it reduces the risk of heart disease and extends lifespan. New research sets out to understand, in the world of sports, which ones are best for staving off illness.

All sports are healthful, but which sport is the most healthful?

A raft of studies over the last few decades has unequivocally shown that physical activity benefits health.
Sports participation has been shown to decrease mortality in middle-aged and older individuals.
In particular, vigorous sporting activity is considered to hold the most benefits. However, to date, exactly which activities are best for longevity has not been thoroughly investigated.
Previous studies addressing the question have lacked strength.
Research, published this week in the British Journal of Sports Medicine, set out to examine the relationship between sports and mortality (including cardiovascular-based mortality).
They designed their study to investigate which types of sporting activity provided the strongest beneficial effect.
Taking data from 11 annual health surveys for England and Scotland between 1994-2008, the team used data from 80,306 adults with an average age of 52. Each participant was asked which activities they had carried out in the previous 4 weeks, and whether the activity had been intense enough to make them sweaty and breathless.
The types of activities that were collected included chores, such as DIY and gardening. They also collated information about the types of sports they had been involved in. The six most popular were cycling; swimming; aerobics/keep fit/gymnastics/dance; running/jogging; football/rugby; and racquet sports - badminton/tennis/squash.
Overall, just 44 percent of respondents met the recommended levels of physical activity.
On average, each individual was tracked for 9 years. During that time, 8,790 died, and 1,909 of them died from heart disease or stroke.

Breaking the data down by sports type

Once the analysis had accounted for potentially influential factors, differences could be measured between the various sporting activities. Compared with participants who had done no exercise, risk of death was:

• 47 percent lower in those who played racquet sports
• 28 percent lower in swimmers
• 27 percent lower in aerobics
• 15 percent lower in cyclists.

Perhaps surprisingly, cycling, running/jogging, and football/rugby were not associated with any kind of protection from cardiovascular disease. When joggers and runners were compared with those who did not run or jog, there was a 43 percent decrease in risk of death from all causes and a 45 percent reduction in cardiovascular risk; however, when confounding variables were adjusted for, this effect disappeared.
Few of the respondents said that they played football or rugby frequently, this may account for its lack of apparent influence on health outcomes. Additionally, because these sports tend to be seasonal, even an avid football or rugby player might have long periods where they do not play a match.

The effects of intensity

When the intensity of the exercise was investigated, for some sports, the higher the intensity, the greater the positive influence on longevity. But, for other activities, there was a U-shaped curve - lesser intensity was more beneficial than higher intensity or no activity at all.
Although the intensity findings are intriguing, the authors warn that this part of the analysis included only a small number of deaths, making the findings tentative; further investigation is necessary to firm them up.
Also, the findings are based on an observational study, meaning that cause and effect can not be concluded. Regardless of this, the findings add further weight to the already weighty hypothesis that exercise reduces mortality and that any sport is better than no sport.