The Effect of High-Intensity Interval Training on Executive Function in Adolescents Hospitalized for a Mental Illness

Abstract

Introduction: Impaired inhibitory control, one of the core executive functions, is common among individuals with mental illness. However, inhibitory control is essential for successful treatment and recovery. Inhibitory control is extremely vulnerable to developmental disruption during adolescence, a time when mental illness is first diagnosed. An acute bout of exercise has been shown to improve inhibitory control in healthy adolescents, however, to our knowledge there are no studies evaluating this effect in adolescents with mental illness. Purpose: The primary goal of this project was to examine the effect of an acute bout of high-intensity interval training on inhibitory control immediately, and 30 minutes following exercise in adolescents hospitalized for mental illness. The secondary goal was to assess the feasibility of using this type of exercise as an adjunct to current treatment. Methods: Participants were recruited through the inpatient mental health unit at the Children’s Hospital of Eastern Ontario. They performed exercise and control conditions in a randomized, counterbalanced manner. The Colour-Word Stroop Task was assessed pre, post, and 30-minutes-post on both days. The exercise condition included a 12 minute HIIT circuit, consisting of body weight exercises performed in a 1:1 work to rest ratio. The control condition involved reading magazines. Repeated-measures ANOVA evaluated changes in Interference Cost, the reaction time cost of responding to trials where the ink and colour do not match, and overall accuracy. Feasibility was assessed through recruitment and completion rates, as well as changes in affect and acceptability of the high-intensity interval training. Results: There was a significant interaction between condition and time for the Interference Cost measure, F(1.6,43.3)=13.6, p<.0001, η2=.34. Interference Cost was similar for both conditions at baseline (Mdiff = 12.4±11.11, p=.28). Interference Cost was significantly reduced immediately (Mdiff = 78.8±14.91, p<.001) and 30-minutes post-exercise (Mdiff = 59.6±15.14, p=.001) compared to control. Response accuracy did not differ by time, F(2,54)=.14, p<=.87, η2=.01 nor condition, F(1,27)=2.25, p=.15, η2=.08. After exercise, participants increased positive affect (mean difference = 4.3±8.09, p=.009) and were willing to perform the exercise before therapy sessions (rating = 6.4±2.75 out of 10). Conclusion: These findings suggest that high-intensity interval training could be used to improve inhibitory control in adolescents with mental illness, which has the potential to enhance the efficacy of their treatment. Future research should determine the impact of individual factors, such as diagnosis, medication, age of illness onset, length of hospitalization, and treatment history, on inhibitory control improvement after exercise.