The purposes of this dissertation were to determine: 1) the relationship betweenmuscle thickness change (MTC) as measured by rehabilitative ultrasound imaging(RUSI) and EMG activity in the lumbar multifidus (LM), 2) if motor control changesproduced by experimentally induced pain are measurable with RUSI, 3) if a differenceexists in MTC between subjects with low back pain (LBP) classified in the treatmentbasedclassification system (TBC) system and controls, 4) if MTC improves followingintervention.Current literature suggests sub-groups of patients with LBP exist and responddifferently to treatment, challenging whether the majority of LBP is "nonspecific". TheTBC system categorizes subjects into one of four categories (stabilization, mobilization,direction specific exercise, or traction). Currently, only stabilization subjects receive anintervention emphasizing stability. Because recent research has demonstrated that motorcontrol impairments of lumbar stabilizing muscles are present in most subjects with LBP,it is hypothesized that impairments may be present across the TBC classifications.Study 1: Established the relationship between MTC as measured by RUSI andEMG in the LM. Study 2: Assessed MTC of the LM during control and painfulconditions to determine if induced pain changes in LM and transverse abdominis (TrA)are measurable with RUSI. Study 3: Measured MTC of the LM and TrA in subjects withLBP classified in the TBC system and 20 controls. Subjects completed a stabilizationprogram and were re-tested.The inter-tester reliability of the RUSI measurements was excellent (ICC3,3 =.91,SEM=3.2%). There was a curvilinear relationship (r = .79) between thickness changeand EMG activity. There was a significant difference (p andlt; .01) between control andpainful conditions on 4 of the 5 LM tasks tested and on the TrA task. There was adifference in MTC between subjects and controls on the loaded LM test which varied bylevel and category. All categories were different from control on the TrA. Followingintervention the TrA MTC improved (p andlt; .01). The LM MTC did not (p values from .13-.86).These findings suggest MTC can be clinically measured and that deficits existwithin TBC system. Significant disability and pain reduction were measured.

Muscle architecture, innervation pattern and fiber type distribution of lumbar multifidus (LMT) throughout its volume was quantified. Musculotendinous (n=10) and neural components (n=3) were dissected and digitized from thirteen embalmed cadaveric specimens. The data were imported into Autodesk® Maya® 2008 to generate 3D neuromuscular models of each specimen. Architectural parameters (fiber bundle length, FBL; fiber bundle angle, FBA; tendon length) were quantified from the models using customized software. The medial branch of the posterior rami (L1-L5) was traced through LMT to determine its distribution. Using immunohistochemistry, Type I/II muscle fibers were identified in 29 muscle biopsies from one fresh frozen specimen. The total area and number of each cell type was calculated using Visiopharm® (image analysis software). Architectural and fiber type data were analyzed using ANOVA with Tukey’s post-hoc test (p ≤ 0.05). From L1-L4, LMT had three architecturally distinct regions: superficial, intermediate and deep. At L5, intermediate LMT was absent. Mean FBL decreased significantly from superficial (5.8 ± 1.6cm) to deep regions (2.9 ± 1.1cm) as did volume (superficial, 5.6 ± 2.3ml; deep, 0.7 ± 0.3ml). In contrast, mean FBA increased from superficial to deep. The medial branch of the posterior ramus (L1-L5) supplied the five bands of LMT. Each medial branch in turn divided to supply the deep, intermediate and superficial regions separately. The area occupied by Type I fibers was significantly less (p< 0.01) in the deep (56%) compared with the superficial regions (75%). Based on architecture and morphology, superficial LMT with the longest FBL and relatively small FBA is well designed for torque production and controlling the lumbar lordosis. Intermediate LMT with significantly longer FBL compared with the deep region and with its caudal to cranial line of action may help to control intersegmental stability. Furthermore, the absence of intermediate LMT at L5 and may contribute to the higher incidence of instability observed at the lumbosacral junction. Deep LMT with its short FBL, large FBA and proximity to the axis of spinal rotation may function to provide proprioceptive input to the CNS rather than a primary stabilizer of the lumbar spine.

Muscle architecture, innervation pattern and fiber type distribution of lumbar multifidus (LMT) throughout its volume was quantified. Musculotendinous (n=10) and neural components (n=3) were dissected and digitized from thirteen embalmed cadaveric specimens. The data were imported into Autodesk® Maya® 2008 to generate 3D neuromuscular models of each specimen. Architectural parameters (fiber bundle length, FBL; fiber bundle angle, FBA; tendon length) were quantified from the models using customized software. The medial branch of the posterior rami (L1-L5) was traced through LMT to determine its distribution. Using immunohistochemistry, Type I/II muscle fibers were identified in 29 muscle biopsies from one fresh frozen specimen. The total area and number of each cell type was calculated using Visiopharm® (image analysis software). Architectural and fiber type data were analyzed using ANOVA with Tukey’s post-hoc test (p ≤ 0.05). From L1-L4, LMT had three architecturally distinct regions: superficial, intermediate and deep. At L5, intermediate LMT was absent. Mean FBL decreased significantly from superficial (5.8 ± 1.6cm) to deep regions (2.9 ± 1.1cm) as did volume (superficial, 5.6 ± 2.3ml; deep, 0.7 ± 0.3ml). In contrast, mean FBA increased from superficial to deep. The medial branch of the posterior ramus (L1-L5) supplied the five bands of LMT. Each medial branch in turn divided to supply the deep, intermediate and superficial regions separately. The area occupied by Type I fibers was significantly less (p< 0.01) in the deep (56%) compared with the superficial regions (75%). Based on architecture and morphology, superficial LMT with the longest FBL and relatively small FBA is well designed for torque production and controlling the lumbar lordosis. Intermediate LMT with significantly longer FBL compared with the deep region and with its caudal to cranial line of action may help to control intersegmental stability. Furthermore, the absence of intermediate LMT at L5 and may contribute to the higher incidence of instability observed at the lumbosacral junction. Deep LMT with its short FBL, large FBA and proximity to the axis of spinal rotation may function to provide proprioceptive input to the CNS rather than a primary stabilizer of the lumbar spine.

Activating the core muscles through exercise training programs is believed to be important for athletic performance. Considerable attention has been credited to the lumbar multifidus, transverse abdominis, and quadratus lumborum in designing exercise training programs. Numerous core exercise claims and recommendations abound in the fitness and physical therapy communities touting a superior core challenge for these muscles. The plethora of core activation literature with conflicting outcomes has convoluted the process of choosing exercises for an optimal core training approach. Although an abundance of research studies have quantified the muscle activity, collectively, a consensus on the type of exercise that elicits the largest muscle activity does not exist. Therefore, the objective of this investigation was to critically examine the literature and synthesize the muscle activity produced across various physical fitness exercises to determine which type of exercise elicits the largest amplitude for the core muscles in healthy individuals. PubMed, EMBASE, SPORTdiscus, CINAHL, (CCRT) and Web of Science databases were searched revealing 27 studies meeting the inclusion criteria measuring EMG activity during 202 exercises. In absence of research for the quadratus lumborum, no conclusions could be made and bring about concern for current recommendations. Furthermore, the methodological diversity significantly limited the quality of studies meriting standardization for future EMG research. Nonetheless, the current evidence suggests free weight exercises and non-core exercises using external resistances produce the largest EMG activity for the lumbar multifidus and transverse abdominis, respectively.