Mitchell Ulrike H, Johnson A Wayne, Owen Patrick J, Rantalainen Timo, Belavy Daniel
Department of Exercise Sciences, Brigham Young University, Provo, Utah, USA.
Institute for Physical Activity and Nutrition, Deakin University, Burwood, Victoria, Australia.
BMJ Open Sport Exerc Med. 2019 Sep 6;5(1):e000556. doi: 10.1136/bmjsem-2019-000556. eCollection 2019.
The transversus abdominis muscle (TrA) is active during running as a secondary respiratory muscle and acts, together with the multifidus, as trunk stabiliser. The purpose of this study was to determine size and symmetry of TrA and multifidus muscles at rest and with contraction in endurance runners without low back pain.
Cross-sectional study.
A medical imaging centre in Melbourne, Australia.
Thirty middle-aged (43years±7) endurance-trained male (n=18) and female (n=12) runners without current or history of low back pain.
MRI at rest and with the core engaged. The TrA and multifidus muscles were measured for thickness and length (TrA) and anteroposterior and mediolateral thickness (multifidus). Muscle activation was extrapolated from rest to contraction and compared with the same and contralateral side. Paired t-tests were performed to compare sides and contraction status.
Left and right TrA and multifidus demonstrated similar parameters at rest (p>0.05). However, with contraction, the right TrA and multifidus (in mediolateral direction) were 9.2% (p=0.038) and 42% (p<0.001) thicker, respectively, than their counterparts on the left. There was no TrA thickness side difference with contraction in left-handed participants (p=0.985). When stratified by sex, the contracted TrA on the right side remained 8.4% thicker, but it was no longer statistically significant (p=0.134). The side difference with contraction of the TrA became less with increasing training age.
Right-handed long-term runners without low back pain exhibit a greater right side core muscle activation when performing an isometric contraction. This activation preference diminishes with increasing training age.
腹横肌（TrA）在跑步过程中作为辅助呼吸肌发挥作用，并与多裂肌一起起到稳定躯干的作用。本研究的目的是确定无下背痛的耐力跑者在休息和收缩状态下腹横肌和多裂肌的大小及对称性。
横断面研究。
澳大利亚墨尔本的一个医学影像中心。
30名中年（43岁±7岁）耐力训练的男性（n = 18）和女性（n = 12）跑者，无当前或既往下背痛病史。
休息时及核心激活时的MRI。测量腹横肌和多裂肌的厚度和长度（腹横肌）以及前后径和内外侧厚度（多裂肌）。从休息状态外推至收缩状态的肌肉激活情况，并与同侧和对侧进行比较。采用配对t检验比较两侧及收缩状态。
左右腹横肌和多裂肌在休息时表现出相似的参数（p>0.05）。然而，在收缩时，右侧腹横肌和多裂肌（内外侧方向）分别比左侧厚9.2%（p = 0.038）和42%（p< = 0.001）。左利手参与者收缩时腹横肌厚度无侧别差异（p = 0.985）。按性别分层时，右侧收缩的腹横肌仍厚8.4%，但不再具有统计学意义（p = 0.134）。随着训练年龄的增加，腹横肌收缩时的侧别差异减小。
无下背痛的右利手长期跑者在进行等长收缩时，右侧核心肌肉激活程度更高。这种激活偏好随着训练年龄的增加而减弱。
