The Locus of Age × Health-Related Physical Fitness Interactions in Serial Choice Responding as a Function of Task Complexity: Central Processing or Motor Function?

Abstract

The extent to which health-related physical fitness (HRF) attenuates age differences in psychomotor speed as a function of task complexity was examined in a sample of 48 men. Physiological measures were used to assign participants to fitness group (n 1-4 = 12): young less fit (mean age = 25.83 years), young fitter (mean age = 25.08 years), old less fit (mean age = 71.83 years), old fitter (mean age = 66.75 years). A serial choice reaction time (RT) task was used in which three conditions of two, four, or eight choices were administered. RTs for the choice and motor components of the task were recorded separately. A significant Age 2 HRF interaction was found in relation to choice RT but not motor time; older less fit individuals underperformed older fitter participants, and younger adults regardless of fitness level. This interaction remained significant having statistically controlled for motor function, suggesting benefits to central processing. The strength of this interaction did not increase as a function of task complexity. The findings suggest an association between HRF and psychomotor speed, and support the view that physically active lifestyles should be encouraged among older adults.