Muscle oxygenation and intramuscular pressure related to posture and load in back muscles

Abstract Background context There is little information about the simultaneous changes of intramuscular pressure (IMP) and oxygen saturation (StO2 ) of the paraspinal muscle under various conditions of posture and load. Purpose To measure simultaneously and compare IMP and StO2 across a range of static trunk postures commonly observed during normal work tasks. Study design A prospective study using a repeated-measure design in clinical setting. Patient sample Sixteen healthy young men with no history of back pain. Outcome measures Simultaneous measurements of IMP by a flexible slit catheter and StO2 by near infrared spectroscopy of the multifidus muscle were performed. Methods The two measures were taken in six static posture tasks: standing upright and bending forward with and without load (20 kg), bending backward and during a sustained isometric contraction (ie, Sorensen test). To compare the influence of the tasks on IMP and StO2 variables, a one-way variance analysis with repeated measures was used. Spearman's rank correlation coefficient (rho) was determined between the two variables for each posture task. Results We observed only a moderate but significant correlation between IMP and StO2 values in upright standing and a trend in bending forward positions with load (p