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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Physiol. | doi: 10.3389/fphys.2019.01115

Neck Muscle Changes Following Long-Duration Spaceflight

 Kyle P. McNamara1, 2,  Katelyn A. Greene1, 2, Janet Tooze3, Jade Dang2, 4,  Karim Khattab2, 5, Leon Lenchik1 and  Ashley A. Weaver1, 2*
  • 1Wake Forest School of Medicine, United States
  • 2School of Biomedical Engineering and Sciences, Virginia Tech - Wake Forest University, United States
  • 3Department of Biostatistical Sciences, Wake Forest School of Medicine, United States
  • 4University of North Carolina at Chapel Hill, United States
  • 5Louisiana State University, United States

The effects of long-duration spaceflight on crewmember neck musculature have not been adequately studied. The purpose of this study was to evaluate the changes in the neck musculature on pre-flight and post-flight magnetic resonance imaging (MRI) examinations of six crewmembers on 4- to 6-month missions equipped with the advanced Resistive Exercise Device. The MRI images were resliced to remove variations in spinal curvature, and the cross-sectional area (CSA) and muscle fat infiltration (MFI) of neck musculature at the C1-C2, C4-C5, C7-T1, and T1-T2 intervertebral disc levels were measured bilaterally. Percent changes in the neck muscle CSA and fatty infiltration following spaceflight were calculated, and mixed models were used to assess significance of these changes. Crewmembers on missions equipped with the advanced Resistive Exercise Device experienced an average 25.1% increase in CSA for the trapezius muscle at C6-C7, an average 11.5% increase in CSA for the semispinalis capitis muscle at C4-C5, an average 9.0% increase in CSA for the sternocleidomastoid muscle at C4-C5, and an average 23.1% increase in CSA for the rhomboid minor at T1-T2. There were no significant changes in the CSA of the levator scapulae, splenius capitis, rectus capitis posterior major, scalenus anterior, scalenus posterior, scalenus medius, longissimus capitis, or obliquus capitis inferior muscles at the locations measured. None of the muscles analyzed experienced statistically significant changes in fatty infiltration with spaceflight. Our study indicates that long-duration spaceflight conditions are associated with preservation of cross-sectional area in most neck muscles, and significant increases in the cross-sectional areas of the trapezius, semispinalis capitis, sternocleidomastoid, and rhomboid minor muscles. This may indicate that cervical muscles are not subjected to the same degradative effects microgravity imparts on the majority of muscles.

Keywords: Advanced Resistive Exercise Device, Astronaut, Cosmonaut, Cross-sectional area, cervical muscle, microgravity, muscle hypertrophy, Magnetic resonace imaging

Received: 27 Feb 2019; Accepted: 12 Aug 2019.

Edited by:

Ginés Viscor, University of Barcelona, Spain

Reviewed by:

Debora Angeloni, Sant'Anna School of Advanced Studies, Italy
Daniel Belavy, Deakin University, Australia
Yoav Gimmon, Ben-Gurion University of the Negev, Israel  

Copyright: © 2019 McNamara, Greene, Tooze, Dang, Khattab, Lenchik and Weaver. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Ashley A. Weaver, Wake Forest School of Medicine, Winston-Salem, United States, asweaver@wakehealth.edu