Relationship between paraspinal muscle morphology and function in different directions in a healthy Chinese population at different ages: a cross-sectional study

BackgroundParaspinal muscle degeneration occurs with age; however, it is unknown whether strength and endurance change with muscle cross-sectional area (CSA) and fatty infiltration (FI) parameters in Chinese healthy individuals.MethodsA total of 94 asymptomatic Chinese volunteers were enrolled in this study. The participants were divided into three groups: young (20-39 years old, n = 27), middle-aged (40-59 years old, n = 49), and elderly (>= 60 years old, n = 18). CSA and FI of the psoas (PS), quadratus lumborum (QL), multifidus (MF), and erector spinae (ES) were measured using magnetic resonance imaging. The Bionix Sim3 Pro was used to evaluate the maximum isometric torque and the Ito test to evaluate endurance.ResultsThe CSA of the PS and ES in the elderly group was smaller than those in the other groups, while the CSA of QL in the young group was larger than that in the other groups. There were differences in the MF and ES FI among the three groups. The maximum isometric torque and endurance test time decreased with increasing age; however, these differences were not statistically significant. Maximum isometric torque positively correlated with the average paraspinal muscle CSA and negatively correlated with the torque and FI of the MF and ES muscles. The endurance test was found to be positively correlated with the FCSA of the MF and to be negatively correlated with the FI of the MF and ES. PS and QL can predict the maximum isometric torque, and MF and PS can predict the endurance time.ConclusionMF and ES showed earlier degeneration than PS and QL. MF is the first paraspinal muscle to undergo functional area atrophy, and it plays an important role in the endurance test. The maximum moment of equal length in all directions of the lumbar spine is not completely symmetrical, but it is correlated with the imaging parameters of the paraspinal muscles. QL and PS were more activated in the lumbar activity.Trial registrationThe study was registered in Chinese Clinical Trial Registry and the registration number is ChiCTR2000039073 on 15/10/2020 (https://www.chictr.org.cn/showproj.html?proj=62785). Ethical Approval was obtained from the Peking University Third Hospital Medical Science Research Ethics Committee (IRB00006761-M2020305).