Heart Fit Brain Fit; A Study Of Intra-individual Variability In Older Subjects

Abstract

Studies in animals and humans have suggested that exercise training can positively affect cognitive abilities. Lower performance in cognition is associated with higher intra-individual variability on repeated cognitive tests. PURPOSE: To investigate whether a correlation exists between physical fitness and intra-individual variability in cognitive performance in older subjects. METHODS: 8 men and 7 women participated and completed three test sessions, at the same time of the day, following the same protocol, within fourteen days. One session consisted of (i) assessment of the physical fitness (maximal voluntary contraction of the quadriceps muscles, gait velocity, and a cycling test to estimate the maximal oxygen uptake (VO2-max)) and (ii) assessment of the cognitive task performance (Trail Making Test and Stroop colour word Test). RESULTS: Physical fitness was not correlated to intra-individual variability in cognitive performance. Correlations for cognitive tests variability with muscle strength are r=0.28; P=0.33, with gait velocity r=−0.06, P=0.8 and with estimated maximal oxygen uptake r=0.5, P=0.12. Due to a learning effect over the three sessions (ANOVA) it is questionable if the standard deviation and coefficient of variation calculated for cognitive tests represent intra-individual variability. CONCLUSION: This study did not show a correlation between physical fitness and intra-individual variability in cognitive task performance. A larger population and avoidance of a learning effect in testing should be applied to answer the question more properly.