A rat study comparing different forms of exercise has found that running was much more effective than HIIT or resistence training in generating new brain cells.

Most exercise studies involving rats have used running wheels, and the benefits of these for the creation of new neurons in the hippocampus (adult neurogenesis) have been well-demonstrated. This study used two other (rather ingenuous) strategies to mimic high-intensity interval training and weights training.

Those animals given resistance training climbed a wall with tiny weights attached to their tails. Those given HIIT 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.

The exercise programs lasted seven weeks.

Those rats that had jogged on running wheels showed robust levels of neurogenesis in the hippocampus, with higher levels linked to higher levels of running. Those who did HIIT showed levels of neurogenesis that were somewhat better than the sedentary controls, but far less than that seen in the distance runners. The weight trainers, while much stronger, showed no more neurogenesis than the sedentary rats.

The findings are consistent with research showing weight training has little effect on the BDNF levels.

All this is not to say that HIIT and resistance training aren’t good for your brain! Exercise has a number of different benefits for the brain. This finding only speaks to the level of neurogenesis.

However, it does suggest that, whatever your exercise program, it should include aerobic exercise such as jogging or brisk walking (or even not-so-brisk, if that’s all you can do!).