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Dose-response relationship between intensity of exercise and cognitive performance in individuals with Down syndrome: a preliminary study.

BACKGROUND
Cognitive performance has been shown to be relevant to the early onset of Alzheimer's disease in individuals with Down syndrome. This study was aimed at investigating the dose-response relationship between acute exercise intensity and cognitive performance in this population.


METHODS
In the current study, we measured information processing speed and two aspects of executive function (i.e. attention shifting and inhibitory control). Participants were assigned to high-intensity exercise (i.e. 75-85% of predicted maximum heart rate) (N = 6), moderate-intensity exercise (i.e. 50-75% of predicted maximum heart rate) (N = 6) or attentional control (N = 6) groups. Two exercise groups walked on a treadmill using an incremental intensity walking protocol, and the attentional control group watched a video for 20 min. Measures of information processing speed and executive function were tested pre-intervention and post-intervention.


RESULTS
Our results indicated that the performance in choice reaction time test was impaired in the high-intensity exercise, whereas improved performance was observed in the moderate-intensity exercise. However, moderate-intensity and high-intensity exercises were beneficial for inhibitory control aspect of executive function. Further, inconsistent with previous studies, a quadric trend was seen in information processing speed, and a liner trend was evident in inhibitory control.


CONCLUSIONS
Future research is needed to examine with a larger sample size, and more physiological measures are necessary to explore the underlying mechanisms in the relationship between exercise intensity and cognitive performance in individuals with Down syndrome.