Intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60 day bedrest

Abstract

BACKGROUND CONTEXT: Prolonged bedrest induces accumulation of intramuscular lipid concentration (ILC) in the lumbar musculature; however, spatial distribution of ILC has not been determined. Artificial gravity (AG) mitigates some adaptations induced by 60 day bedrest by creating a head-to-feet force while participants are in a supine position. PURPOSE: To quantify the spatial distribution of accumulation of ILC in the lumbar musculature after 60 day bedrest, and whether this can be mitigated by AG exposure. STUDY DESIGN: Prospective longitudinal study. PATIENT SAMPLE: Twenty-four healthy individuals (8 females) participated in the study: Eight received 30 min continuous AG (cAG); Eight received 6 £ 5 min AG (iAG), interspersed with rests; Eight were not exposed to AG (CRTL). OUTCOME MEASURES: From 3T magnetic resonance imaging (MRI), axial images were selected to assess lumbar multifidus (LM), lumbar erector spinae (LES), quadratus lumborum (QL), and psoas major (PM) muscles from L1/L2 to L5/S1 intervertebral disc levels. Chemical shift-based 2Àecho lipid and/or water Dixon sequence was used to measure tissue composition. Each lumbar muscle was segmented into four equal quartiles (from medial to lateral). METHODS: Participants arrived at the facility for the baseline data collection before undergoing a 60 day strict 6˚head-down tilt (HDT) bedrest period. MRI of the lumbopelvic region was conducted at baseline and Day-59 of bedrest. Participants performed all activities, including hygiene, in 6˚HDT and were discouraged from moving excessively or unnecessarily.

Morphology of paraspinal muscles in frail and non-frail older adults evaluated through FRAIL scale

“…Therefore, lacking exercise and motion, the process of muscle degeneration in frail patients would be more severe than in those not [ 25 ]. Martino et al found that intramuscular lipid concentration increased in localized regions of the lumbar muscles following 60-day bed rest [ 26 ]. Previous studies have shown nutritional risk factors were independently associated with physical pre-frail/frail condition [ 27 ].…”

The relationships between physical activity, lumbar multifidus muscle morphology, and low back pain from childhood to early adulthood: a 12-year longitudinal study

“…However, there is evidence that extreme sedentary behaviour may result in lumbar multifidus atrophy. For example, spaceflight 18 , 19 and prolonged head-down tilt bed rest 20 may reduce lumbar multifidus size and increase IMAT; changes that are potentially reversible with exercise training 21 . Our results do accord with studies reporting little to no relations between lumbar multifidus IMAT and lumbar multifidus function 22 , prognostic factors associated with exercise outcomes for patients with low back pain 23 , as well as lumbar multifidus size and tests of physical performance 24 .…”

Advances in the interaction between lumbar intervertebral disc degeneration and fat infiltration of paraspinal muscles: critical summarization, classification, and perspectives

“…The long-term effect makes the muscle gradually thin and degenerate, eventually replaced by adipose tissue ( 59 ). Previous studies have indicated a higher accumulation of adipose tissue in PSMs is related to physical inactivity ( 54 , 60 ). Movement and gravitational loading are essential for maintaining a healthy spine.…”

“…In response to decreased use, the lumbar spine undergoes adaptive remodeling ( 62 ). Adverse effects include lumbopelvic muscle atrophy, fat accumulation in PSMs, reduced lumbar lordosis, and altered disc hydration status ( 54 , 61 ). Surprisingly, Hides et al.…”