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Exercise Effects on Bed Rest-induced Brain Changes

1School of Kinesiology, University of Michigan, Ann Arbor, MI, USA.
2Departments of Psychiatry and Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
Publication Date:
PLoS One
Volume Number:
Issue Number:
PLoS One. 2018 Oct 11;13(10):e0205515.
PubMed ID:
Appears in Collections:
P41 EB015902/EB/NIBIB NIH HHS/United States
UL1 RR029876/RR/NCRR NIH HHS/United States
UL1 TR000071/TR/NCATS NIH HHS/United States
Generated Citation:
Koppelmans V., Scott J.M., Downs M.E., Cassady K.E., Yuan P., Pasternak O., Wood S.J., De Dios Y.E., Gadd N.E., Kofman I., Riascos R., Reuter-Lorenz P.A., Bloomberg J.J., Mulavara A.P., Ploutz-Snyder L.L., Seidler R.D. Exercise Effects on Bed Rest-induced Brain Changes. PLoS One. 2018 Oct 11;13(10):e0205515. PMID: 30308004. PMCID: PMC6181401.
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PURPOSE: Spaceflight negatively affects sensorimotor behavior; exercise mitigates some of these effects. Head down tilt bed rest (HDBR) induces body unloading and fluid shifts, and is often used to investigate spaceflight effects. Here, we examined whether exercise mitigates effects of 70 days HDBR on the brain and if fitness and brain changes with HDBR are related. METHODS: HDBR subjects were randomized to no-exercise (n = 5) or traditional aerobic and resistance exercise (n = 5). Additionally, a flywheel exercise group was included (n = 8). Exercise protocols for exercise groups were similar in intensity, therefore these groups were pooled in statistical analyses. Pre and post-HDBR MRI (structure and structural/functional connectivity) and physical fitness measures (lower body strength, muscle cross sectional area, VO2 max, body composition) were collected. Voxel-wise permutation analyses were used to test group differences in brain changes, and their associations with fitness changes. RESULTS: Comparisons of exercisers to controls revealed that exercise led to smaller fitness deterioration with HDBR but did not affect brain volume or connectivity. Group comparisons showed that exercise modulated post-HDBR recovery of brain connectivity in somatosensory regions. Posthoc analysis showed that this was related to functional connectivity decrease with HDBR in non-exercisers but not in exercisers. Correlational analyses between fitness and brain changes showed that fitness decreases were associated with functional connectivity and volumetric increases (all r >.74), potentially reflecting compensation. Modest brain changes or even decreases in connectivity and volume were observed in subjects who maintained or showed small fitness gains. These results did not survive Bonferroni correction, but can be considered meaningful because of the large effect sizes. CONCLUSION: Exercise performed during HDBR mitigates declines in fitness and strength. Associations between fitness and brain connectivity and volume changes, although unadjusted for multiple comparisons in this small sample, suggest that supine exercise reduces compensatory HDBR-induced brain changes.