who are likely to make New Yearís resolutions (actually 44% of Americans) and those who

are likely to resolve to exercise more (12% of those turning over a new leaf). So on New

Yearís day I downloaded a new app, obviously ëZombies, Run!í will help, and decided to

train for a race across the Sydney Harbour Bridge. Of course doing regular exercise is

good for your body, but the health benefits don't stop there. Physical exercise is also

good for your brain. One study split their participants into two groups, one that did

an aerobic exercise class every week for a year and another that did a stretching class.

Those in the exercise groupówho did 40 minutes of aerobic walking every weekóshowed improvements

on a spatial memory task, identifying where small dots flashed on a computer screen. This

improvement was directly related to some of their brain structures increasing in sizeójust

from exercising. Their hippocampus, the brainís memory and learning centre increased by an

average of 2%. But for those in the stretching group, their hippocampus decreased in size

by 1.42%- not surprising as peopleís brains can start deteriorating from as young as 30

years old. Data suggests thereís a significant positive relationship between physical activity

and cognitive functioning in children too. In one study, 9 and 10 year olds who performed

better on a fitness test had larger hippocampal volumes and a better performance on a memory

task. So as well as strengthening muscle cells, exercise strengthens brain cells. Researchers

believe some of these benefits come from a protein in your brain called BDNFóit stands

for Brain Derived Neurotrophic Factor. Exercise like running stimulates the production of

BDNF in the brain. BDNF promotes the growth of dendritesóthe branches of neuronís cell

bodiesóand the strengthening of synapses, structures that let neurons communicate with

each other. So BDNF increases the connectivity between your neurons in brain structures like

the hippocampus, which is crucial for some aspects of your memory, like spatial memory.

It makes sense from an evolutionary standpoint. If youíre going out on a runóor aerobic

walkóto find food or shelter, an increase in BDNF in your brain would promote the retention

of your memories of what you find. So jogging can actually jog your memory. Exercising your

brain cells might change the way you think about your New Yearís resolutions or your

morning run. Or, it might just change the way you think.