Exploring the acute effects of running on cerebral blood flow and food cue reactivity in healthy young men using functional magnetic resonance imaging

Figures

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  FIGURE 1. Schematic of the study protocol. (a) Timeline of the trial procedures and functional magnetic resonance imaging (fMRI) scan protocol. Scans were conducted before and after 60 min of running and rest and involved iterations of the following sequences: (1) 3D sagittal T1‐weighted fast spoiled gradient echo (FSPGR) anatomical; (2) pseudo‐continuous arterial spin labelling (pCASL); (3) task‐based blood‐oxygen‐level‐dependent (BOLD) fMRI; and (4) spin‐echo echo‐planar imaging (SE EPI). Ratings of perceived appetite were measured using visual analogue scales (VAS). (b) Block design of the task‐based BOLD fMRI scan. Participants viewed eight blocks containing visually matched images of high‐ and very high‐energy density foods (HED) (total n = 40), very low‐ and low‐energy density foods (LED) (total n = 40), non‐food objects (total n = 40) and scrambled images of the two food categories (total n = 80). Images were presented in a random order for 2.5 s with a 0.5 s inter‐stimulus interval when a central fixation cross was displayed. Images were obtained from a freely available database (Blechert et al., 2014, 2019).

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  FIGURE 2. Ratings of perceived (a) hunger, (b) fullness, (c) satisfaction and (d) prospective food consumption (PFC) in the control and exercise trials (n = 23). On left‐hand panels, data presented as mean ± SD, open rectangles indicate functional magnetic resonance imaging scan and grey rectangle denotes the 60 min exercise or rest period. On right‐hand panels, the left‐hand y axis displays the time‐averaged area under the curve (AUC) for the intervention period (70–190 min) in the control and exercise trial. Bars and error bars represent the mean ± SD and circles with connecting lines show the individual participant data values. The right‐hand y axis displays the between‐trial difference (exercise minus control) in appetite. Horizontal lines represent the mean difference (95% confidence interval [CI] of the mean absolute difference) and the triangles indicate the between‐trial difference for each participant. For each rating, the p value, 95% CI of the mean difference and standardized effect size (Cohen's d) is presented for the main effect of trial which was adjusted for the pre‐intervention AUC (0–70 min).

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  FIGURE 3. Differences in regional cerebral blood flow (CBF) measured using pseudo‐continuous arterial spin labelling (pCASL) in the (a) amygdala, (b) hippocampus and (c) insula between the exercise and control trial (n = 23). Data analysed with a 2 × 5 (condition × time‐point) ANOVA in Randomise (threshold‐free cluster enhancement, family‐wise corrected p value of p < .05). Brain maps are presented for the main effect of trial representing an average of the five pCASL scans in each trial and are shown in radiological convention with the right hemisphere shown on the left. Red‐yellow clusters represent voxel clusters showing higher CBF in exercise versus control (p ≤ .001). Panels adjacent to brain maps depict the extracted CBF data values for the peak of each identified cluster. Data plotted for each CBF scan presented as mean ± SD and grey rectangle denotes the 60 min exercise or rest period. Bar plots represent the mean ± SD for the average of the five pCASL scans in each trial and circles with connecting lines show the individual participant data values. Brain co‐ordinates are presented in MNI space for the peak statistical voxel. MNI, Montreal Neurological Institute.

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  FIGURE 4. Differences in regional cerebral blood flow (CBF) measured using pseudo‐continuous arterial spin labelling (pCASL) in the (a) orbitofrontal cortex (OFC) and (b) striatum between the exercise and control trial (n = 23). Data analysed with a 2 × 5 (condition × time‐point) ANOVA in Randomise (threshold‐free cluster enhancement, family‐wise corrected p value of p < .05). Brain maps are presented for the main effect of trial representing an average of the five pCASL scans in each trial and are shown in radiological convention with the right hemisphere shown on the left. Blue clusters represent voxel clusters showing higher CBF in control versus exercise (p ≤ .018). Panels adjacent to brain maps depict the extracted CBF data values for the peak of each identified cluster. Data plotted for each CBF scan presented as mean ± SD and grey rectangle denotes the 60 min exercise or rest period. Bar plots represent the mean ± SD for the average of the five pCASL scans in each trial and circles with connecting lines show the individual participant data values. Brain co‐ordinates are presented in MNI space for the peak statistical voxel. MNI, Montreal Neurological Institute.

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  FIGURE 5. Voxel clusters showing greater blood‐oxygen‐level‐dependent (BOLD) activity in the pre‐to‐post change between the exercise versus control trial during a food cue reactivity task for the contrasts (a) food (HED + LED) versus non‐food cues and (b) HED versus non‐food cues (n = 23). The hippocampus cluster (a) was identified in the regions of interest analysis performed in Randomise (threshold‐free cluster enhancement, family‐wise corrected p value of p < .05); all other regions were detected in the whole brain analysis performed in FMRIBs Expert Analysis Tool (z > 3.1, corrected cluster significance threshold of p < .05). Brain maps presented in radiological convention with the right hemisphere shown on the left. Figures adjacent and underneath brain maps show the extracted BOLD signal change in the exercise (post–pre) and control (post–pre) trial for each identified cluster. Bars and error bars represent the mean ± SD and circles show the individual participant data values. Brain co‐ordinates are presented in MNI space for the peak statistical voxel. HED, high‐ and very high‐energy density foods; LED, very low‐ and low‐energy density foods; MNI, Montreal Neurological Institute.

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  FIGURE 6. Correlation between the exercise‐induced change in (a) hippocampus and (b) striatum cerebral blood flow (CBF) measured using pseudo‐continuous arterial spin labelling (pCASL) and the exercise‐induced change in fullness time‐averaged total area under the curve (AUC) in 23 healthy men. Grey shaded area represents the 95% confidence interval of the regression line (black solid line).