STUDY DESIGN: Longitudinal observational study. OBJECTIVES: To examine the relationship between severity of preseason hip, groin, and thigh (HGT) muscle injuries, and lumbopelvic muscle size, asymmetry, and function at the start and end of the preseason. BACKGROUND: In Australian Rules Football, HGT muscle injuries have the highest prevalence and incidence. Deficits within the lumbopelvic region, such as impaired muscle function and muscle asymmetry, could contribute to injuries in the preseason, and injury could, in turn, affect muscle size and function. METHODS: MRI examinations were performed on 47 male elite Australian Rules Football players at the start and at the end of the football preseason. The cross-sectional area (CSA) of multifidus, psoas major, and quadratus lumborum muscles was measured, as well as change in trunk CSA due to the function of voluntarily contracting the transversus abdominis muscle. Injuries occurring during each preseason training session were routinely recorded by the club's performance staff. RESULTS: Analysis of variance indicated that players with more severe preseason HGT injuries (more training sessions missed) had significantly smaller multifidus muscle CSA compared to players with no HGT injury (P = .006). No relationship was found for size or asymmetry of the quadratus lumborum or psoas major muscles, or ability to contract the transversus abdominis muscle through drawing in of the abdominal wall (P>.05). Small multifidus muscle size at L5 predicted 5 of 6 players who incurred a more severe HGT injury. CONCLUSIONS: An association between multifidus muscle size (relative to age, height, and weight) and preseason injury suggests a way to identify players at risk of severe HGT injuries. This result needs to be replicated in a larger sample before resources are committed to intervention efforts.

J Orthop Sports Phys Ther 2011;41(10):767-775, Epub 4 September 2011. doi:10.2519/jospt.2011.3755

KEY WORDS: hip, MRI, multifidus, pelvis

STUDY DESIGN: Clinical measurement, criterion standard. OBJECTIVES: To investigate the validity of real-time ultrasound imaging (USI) to measure individual anterior hip muscle cross-sectional area. BACKGROUND: The hip flexor muscles are important for hip joint function and could be affected by joint pathology or injury. Objectively documenting individual anterior hip muscle size can be useful in identifying muscle size asymmetry and monitoring treatment efficacy for patients with hip problems. USI offers a novel method of measuring individual muscle size in the clinic, but its validity in measuring the anterior hip muscles has not been investigated. METHODS: Nine healthy participants (5 males, 4 females) underwent imaging of their iliopsoas, sartorius, and rectus femoris muscles with USI and magnetic resonance imaging. Bilateral muscle cross-sectional areas were measured on images from both modalities. RESULTS: There was no significant difference (P>.05) in mean cross-sectional area measurements from USI and magnetic resonance imaging for each muscle. Agreement between measurements was high for the iliopsoas (left: intraclass correlation coefficient [ICC_3,1] = 0.86; 95% confidence interval [CI]: 0.51, 0.97; right: ICC_3,1 = 0.88; 95% CI: 0.57, 0.97), sartorius (left: ICC_3,1 = 0.82; 95% CI: 0.41, 0.96; right: ICC_3,1 = 0.81; 95% CI: 0.39, 0.95), and rectus femoris (left: ICC_3,1 = 0.85; 95% CI: 0.49, 0.96; right: ICC_3,1 = 0.89; 95% CI: 0.61, 0.97). Reliability of measuring each muscle with USI was high between 2 trials (ICCs_3,1 = 0.84 to 0.94). CONCLUSION: USI is a valid measure of iliopsoas, sartorius, and rectus femoris muscle size in healthy people, as long as a strict measurement protocol is followed.

J Orthop Sports Phys Ther 2010;40(9):577-581, Epub 13 May 2010. doi:10.2519/jospt.2010.3286

KEY WORDS: iliopsoas, MRI, rectus femoris, reliability, sartorius

STUDY DESIGN: Single-blinded quasi-experimental study. OBJECTIVE: To investigate the ability of elite football players with and without low back pain (LBP) to voluntarily draw-in the abdominal wall. BACKGROUND: While there has been considerable debate regarding the contribution of the transversus abdominis (TrA) muscle to control the lumbar spine and pelvis, there is evidence that retraining motor control of the deep trunk muscles is commensurate with decreases in LBP. Magnetic resonance imaging (MRI) has been used to assess the TrA muscle during the draw-in maneuver, with the contraction of the TrA muscle reducing the circumference of the trunk. Impairments in performance of the draw-in maneuver have been shown in people with LBP. METHODS: Forty-three elite players from a team in the Australian Football League were allocated to 3 groups: those with "no LBP," "a history of LBP but no current LBP," or "current LBP." MRI was used to image the cross-sectional area (CSA) of the trunk at the level of the L3-4 disc at the start and end of the draw-in maneuver. RESULTS: There was a significant decrease in the CSA of the trunk with the performance of the draw-in maneuver (P<.001). Subjects in the "no LBP" group were better able to "draw-in" the abdominal wall than subjects with current LBP (P = .015). CONCLUSIONS: This study provides evidence of an altered ability to draw-in the abdominal wall in footballers with current LBP. Retraining contraction of the TrA muscle may constitute one part of an exercise-therapy approach for athletes with current LBP.

J Orthop Sports Phys Ther 2010;40(1):4-10, Epub 3 December 2009. doi:10.2519/jospt.2010.3177

KEY WORDS: abdomen, lumbar spine, MRI

STUDY DESIGN: A single-blinded, pretreatment-posttreatment assessment. OBJECTIVES: To investigate, using ultrasound imaging, the cross-sectional area (CSA) of the lumbar multifidus muscle at 4 vertebral levels (L2, L3, L4, L5) in elite cricketers with and without low back pain (LBP) and (2) to document the effect of a staged stabilization training program on multifidus muscle CSA. BACKGROUND: Despite high fitness levels and often intensive strength training programs, athletes still suffer LBP. The incidence of LBP among Australian cricketers is 8% and as high as 14% among fast bowlers. Previous researchers have found that the multifidus muscle contributes to segmental stability of the lumbopelvic region; however, the CSA of this muscle has not been previously assessed in elite cricketers. METHODS AND MEASURES: CSAs of the multifidus muscles were assessed at rest on the left and right sides for 4 vertebral levels at the start and completion of a 13-week cricket training camp. Participants who reported current or previous LBP were placed in a rehabilitation group. The stabilization program involved voluntary contraction of the multifidus, transversus abdominis, and pelvic floor muscles, with real-time feedback from rehabilitative ultrasound imaging (RUSI), progressed from non-weight-bearing to weight-bearing positions and movement training. Pain scores (using a visual analogue scale) were also collected from those with LBP. RESULTS: The CSAs of the multifidus muscles at the L5 vertebral level increased for the 7 cricketers with LBP who received the stabilization training, compared with the 14 cricketers without LBP who did not receive rehabilitation (P = .004). In addition, the amount of muscle asymmetry among those with LBP significantly decreased (P = .029) and became comparable to cricketers without LBP. These effects were not evident for the L2, L3, and L4 vertebral levels. There was also a 50% decrease in the mean reported pain level among the cricketers with LBP. CONCLUSION: Multifidus muscle atrophy can exist in highly active, elite athletes with LBP. Specific retraining resulted in an improvement in multifidus muscle CSA and this was concomitant with a decrease in pain. LEVEL OF EVIDENCE: Therapy, level 2b.

J Orthop Sports Phys Ther. 2008;38(3):101-108, published online 7 December 2007. doi:10.2519/jospt.2008.2658

KEY WORDS: asymmetry, low back/lumbar spine rehabilitation, rehabilitative ultrasound imaging, therapeutic exercise, ultrasound imaging

STUDY DESIGN: Test-retest intrarater reliability study. OBJECTIVE: To examine reliability of abdominal musculature measurements across a broad range of conditions for a physical therapist newly trained in assessment using rehabilitative ultrasound imaging (RUSI). BACKGROUND: RUSI has previously been used to assess abdominal muscle function during a drawing-in maneuver of the anterior abdominal wall, and measurements conducted by an experienced assessor have been validated by comparison with magnetic resonance imaging. Few studies have examined the reliability of less experienced operators, and only in isolated measurement conditions. METHODS AND MEASURES: Nineteen subjects (11 female, 8 male) without a history of low back pain performed the abdominal drawing-in maneuver in a supine hook-lying position. RUSI was used bilaterally to assess the thickness of the internal oblique (IO) and transversus abdominis (TrA) muscles at rest and on contraction as well as changes in the length of the TrA muscle (indicated by slide of the anterior abdominal fascia). The reliability of a novice rater who received 8 hours of training was examined (a) across 3 measurements of the same ultrasound image, (b) across 3 separate ultrasound images (averaged for days and sides of abdomen), and (c) across 2 days (averaged for images and sides). RESULTS: Reliability of assessing muscle thickness was very high across 3 measurements of the same image (intrarater correlation coefficients [ICC_3,1] were all greater than 0.97), fair to high across 3 images (ICC_3,4 = 0.62-0.82), and fair to high across 2 days (ICC_3,6 = 0.63-0.85). Reliability of measuring the slide of the anterior abdominal fascia was very high across measurements from the same image (ICC_3,1 = 0.98) but very low across images (ICC_3,4 = 0.44) and across 2 days (ICC_3,6 = 0.36). CONCLUSIONS: High reliability of a novice rater was demonstrated for some measurement conditions. Measures of reliability for recapturing the image and repetition across days ranged from low to high. Inconsistencies in the pattern of results suggest that for a novice assessor using RUSI, training should be performed and reliability assessed for each abdominal muscle and measurement condition intended to be used for research and clinical practice.

J Orthop Sports Phys Ther. 2007:37(8):480-486; published online 30 May 2007. doi:10.2519/jospt.2007.2416

KEY WORDS: internal oblique muscle, real-time ultrasound imaging, sonography, transversus abdominis muscle

J Orthop Sports Phys Ther. 2007;37(10):608-612, published online 29 May 2007. doi:10.2519/jospt.2007.2418

KEY WORDS: back muscles, lumbar spine, muscle assessment, repeatability, ultrasonography