Neurobehavioral mechanisms underlying the effects of physical exercise break on episodic memory during prolonged sitting.

BACKGROUND AND OBJECTIVE: Episodic memory is the ability that enables individuals to recall and re-experience previous events and usually includes information concerning the spatial and temporal context. This study examined the effects of a physical exercise break during a period of prolonged sitting on episodic memory. Furthermore, we aimed to investigate whether alterations of functional connectivity patterns might contribute to the exercise-induced changes in episodic memory. METHODS: Sixty healthy male college students were randomly assigned (1:1 ratio) to a prolonged-sitting group (PS group) or a physical-exercise-break group (PE group). The face-name paired-associate learning task was used to probe episodic memory. During the task, cortical hemodynamics in the prefrontal cortex were recorded using functional near-infrared spectroscopy (fNIRS). Changes in cortical hemodynamics were used to determine functional connectivity using graph-theoretical network analysis. RESULTS: There was no between-group difference in neurobehavioral outcomes at the pretest assessment. During the posttest assessment, compared with the PS group, higher nodal efficiency in the anterior prefrontal cortex (orbitofrontal and frontopolar cortices) was observed during the encoding phase (FDR corrected p values = 0.039), and higher nodal efficiency and degree centrality of orbitofrontal cortex were observed in the retrieval phase in the PE group (FDR corrected p values = 0.035). Moreover, the PE group showed closer temporal correlational interactions between the dorsolateral prefrontal cortex and the anterior prefrontal cortex in the left hemisphere during the episodic memory encoding phase (FDR corrected p values = 0.043), when compared to the PS group. Neither significant between-group difference in accuracy nor correlations between neural and behavioral outcomes were observed after the intervention. CONCLUSION: Our findings suggest that a physical exercise break during a prolonged sitting period has neither a beneficial nor a detrimental effect on behavioral performance concerning episodic memory. However, physical breaks do facilitate functional connectivity patterns of the prefrontal cortex while performing a episodic memory task.

The effects of an acute bout of exercise on neural activity in alcohol and cocaine craving: study protocol for a randomised controlled trial.

BACKGROUND: Numerous studies suggest that exercise may be an effective adjunct treatment for substance use disorders. It has been suggested that exercise-induced improvements in inhibitory control may reduce craving for the substance of abuse. However, this potential mechanism has seldom been researched. OBJECTIVES: The aim of the ExAlCo Study is to examine how acute bouts of exercise, at varying intensities, impact on craving for cocaine or alcohol. Cerebral haemodynamic responses during cognitive tests of inhibitory control, and exposure to substance-related cue imagery, will also be assessed using functional near-infrared spectroscopy. DESIGN: The study is a crossover randomised controlled trial. Participants will be recruited from inpatient and outpatient psychiatric treatment centres, on the approval of their treating physician. A healthy control group will be recruited using online advertising. All participants will undergo each of three conditions in randomised order: 20 min of cycle ergometry at 50-60% of maximum heart rate; 20 min of exercise at 70-80% of maximum heart rate; and 20 min of quiet reading. Immediately before and after each condition, participants will be asked to complete a computerised Stroop test, watch a film containing substance-related images and self-report craving levels. During the Stroop test and film viewing, participants' neural activity will be measured via functional near-infrared spectroscopy. OUTCOMES: The primary outcome measures are self-reported craving, inhibitory control and cerebral haemodynamic response to the Stroop test and a substance-related film. It is hoped that the findings from this study will shed more light on the role of exercise in the treatment of substance use disorders, particularly its scope in preventing relapse through reduced craving severity. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03502486 . Registered retrospectively on 5 April 2018.