The ability of the circulatory and respiratory systems to supply oxygen to skeletal muscles during sustained physical activity is known as cardiorespiratory fitness. Scott Hayes, from Boston University School of Medicine (Massachusetts, USA), and colleagues assessed a group of adults ages 18-31 years, and a group aged 55-82 years.
All participants underwent brain MRIs and were assessed for cardiorespiratory (heart and lung) fitness via treadmill test. Among the older adults, the team observed that cardiorespiratory fitness was positively linked to the structural integrity of white matter fiber bundles in the brain; no such association was observed in younger adults. The study authors observe that: “[cardiorespiratory fitness] is positively associated with neural white matter microstructure in aging. The association between peak VO2 and [fractional anisotropy – an indicator of white matter integrity] appears to be age-dependent.”