Effects of High-Intensity Interval Training on Physical and Cognitive Function in Middle-Aged Male Mice

Declining functional capacity, both physical and cognitive, is a consequence of aging. However, exercise is a promising intervention to mitigate normal age-related decline. While numerous studies have elucidated the benefits of exercise per se, less well-studied is the effect of high intensity interval training (HIIT) on a middle-aged population. Our primary purpose was to assess the effect of three months of HIIT on physical and cognitive performance in middle-aged (17-month-old) male C57BL/6J mice, compared to sedentary controls. We hypothesized that exercised mice would be resistant to any decline in cognitive and physical ability, both measured pre- and post-intervention. To measure physical function, we used the well-validated CFAB (comprehensive functional assessment battery) scoring system comprised of determinants including voluntary wheel running, inverted cling, grip test, treadmill max speed, and rotarod. We measured cognition with open field, novel object recognition, y-maze, and puzzle box. Further measures of sarcopenia/frailty included body composition (MRI) and in vivo contractile physiology (plantar flexor torque). Training resulted in significant aerobic capacity improvements for the HIIT group, increasing treadmill time by 28%, while the SED group demonstrated a 41.4% decline in treadmill time. However, no significant differences in cognitive function were determined. Contrary to our previous research in other age groups, the current study found a negligible effect of HIIT on body composition. We note that at 17 months old, mice did not experience any evidence of cognitive deterioration in either group over the three-month period, thus explaining the lack of exercise effect. We found that HIIT had less influence on either physical or cognitive function than we expected, which may be because function in this age group is stable. Future work will investigate older adult cognitive response to HITT at ages where there is well-documented cognitive decline.