White matter allow communication between different brain regions.

During the investigation, 88 people aged between 60 and 78 years with low cardiovascular fitness, but no other health problems, using accelerometers for a week to get track of your daily physical activity and the amount of time spent sitting.

The researchers conducted brain scans of the participants to see the structural integrity of white matter. This was achieved by finding lesions called "white matter hyperintensities" which are common in older people.

The results showed that people who performed moderate or vigorous exercise, had fewer white matter lesions.

The results could explain the links between exercise and improved cognitive function in elderly people found in previous studies. The study suggests that increasing physical activity and avoiding a sedentary lifestyle may be beneficial for brain health.

During the investigation it was also noted that any light physical activity, such as housework or gardening, is associated with a good structure of white matter in parts of the brain. People who perform light physical activity, have a structurally solid white matter in the temporal lobe, a part of the brain located behind the ears, involved in memory and language.

Conversely, the longer people spent sitting, there was a less robust structure in white matter tracts that connect the hippocampus, an area important for learning and memory brain.

We do not know quite how it protects the exercise the brain from aging, but it is possible that a good physical condition linked to physical activity counteract the vascular changes associated with age involved in the development of lesions in the white matter, the researchers conclude.

source: “Physical Activity and Cardiorespiratory Fitness Are Beneficial for White Matter in Low-Fit Older Adults”  Agnieszka Zofia Burzynska, Laura Chaddock-Heyman, Michelle W. Voss, Chelsea N. Wong, Neha P. Gothe, Erin A. Olson, Anya Knecht, Andrew Lewis, Jim M. Monti, Gillian E. Cooke, Thomas R. Wojcicki, Jason Fanning, Hyondo David Chung, Elisabeth Awick, Edward McAuley, Arthur F. Kramer