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  • Author: Mark A. Sutherlin x
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Mark A. Sutherlin and Joseph M. Hart

Context:

Individuals with a history of low back pain (LBP) may present with decreased hip-abduction strength and increased trunk or gluteus maximus (GMax) fatigability. However, the effect of hip-abduction exercise on hip-muscle function has not been previously reported.

Objective:

To compare hip-abduction torque and muscle activation of the hip, thigh, and trunk between individuals with and without a history of LBP during repeated bouts of side-lying hip-abduction exercise.

Design:

Repeated measures.

Setting:

Clinical laboratory.

Participants:

12 individuals with a history of LBP and 12 controls.

Intervention:

Repeated 30-s hip-abduction contractions.

Main Outcome Measures:

Hip-abduction torque, normalized root-mean-squared (RMS) muscle activation, percent RMS muscle activation, and forward general linear regression.

Results:

Hip-abduction torque reduced in all participants as a result of exercise (1.57 ± 0.36 Nm/kg, 1.12 ± 0.36 Nm/kg; P < .001), but there were no group differences (F = 0.129, P = .723) or group-by-time interactions (F = 1.098, P = .358). All participants had increased GMax activation during the first bout of exercise (0.96 ± 1.00, 1.18 ± 1.03; P = .038). Individuals with a history of LBP had significantly greater GMax activation at multiple points during repeated exercise (P < .05) and a significantly lower percent of muscle activation for the GMax (P = .050) at the start of the third bout of exercise and for the biceps femoris (P = .039) at the end of exercise. The gluteal muscles best predicted hip-abduction torque in controls, while no consistent muscles were identified for individuals with a history of LBP.

Conclusions:

Hip-abduction torque decreased in all individuals after hip-abduction exercise, although individuals with a history of LBP had increased GMax activation during exercise. Gluteal muscle activity explained hip-abduction torque in healthy individuals but not in those with a history of LBP. Alterations in hip-muscle function may exist in individuals with a history of LBP.

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Mark A. Sutherlin, L. Colby Mangum, Jay Hertel, Susan A. Saliba and Joseph M. Hart

Ultrasound imaging has been used to assess muscle function of deeper muscles and to compare individuals with and without low back pain. These measures may be influenced by numerous factors requiring normalization for these comparisons. The purpose of this study was to assess anthropometric normalization variables with muscle thickness of the transversus abdominis and lumbar multifidus across multiple ultrasound testing positions. Numerous anthropometric variables were correlated with muscle thickness. Mass, body mass index, and height times mass show the best promise for normalization, but were not consistent for the transversus abdominis and lumbar multifidus muscles. Normalization strategies should be considered when comparing between groups.

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Mark A. Sutherlin, L. Colby Mangum, Shawn Russell, Susan Saliba, Jay Hertel and Joe M. Hart

Context: Reduced spinal stabilization, delayed onset of muscle activation, and increased knee joint stiffness have been reported in individuals with a history of low back pain (LBP). Biomechanical adaptations resulting from LBP may increase the risk for future injury due to suboptimal loading of the lower-extremity or lumbar spine. Assessing landing mechanics in these individuals could help identify which structures might be susceptible to future injury. Objective: To compare vertical and joint stiffness of the lower-extremity and lumbar spine between individuals with and without a previous history of LBP. Design: Cross-sectional study. Setting: Research laboratory. Participants: There were 45 participants (24 without a previous history of LBP—age 23 [8] y, height 169.0 [8.5] cm, mass 69.8 [13.8] kg; 21 with a previous history of LBP—age 25[9] y, height 170.0 [8.0] cm, mass 70.2 [11.8] kg). Interventions: Single-limb landing trials on the dominant and nondominant limb from a 30-cm box. Main Outcome Measures: Vertical stiffness and joint stiffness of the ankle, knee, hip, and lumbar spine. Results: Individuals with a previous history of LBP had lower vertical stiffness (P = .04), but not joint stiffness measures compared with those without a previous history of LBP (P > .05). Overall females had lower vertical (P = .01), ankle (P = .02), and hip stiffness (P = .04) compared with males among all participants. Males with a previous history of LBP had lower vertical stiffness compared with males without a previous history LBP (P = .01). Among all individuals without a previous history of LBP, females had lower vertical (P < .01) and ankle stiffness measures (P = .04) compared with males. Conclusions: Landing stiffness may differ among males and females and a previous history of LBP. Comparisons between individuals with and without previous LBP should be considered when assessing landing strategies, and future research should focus on how LBP impacts landing mechanics.

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Shandi L. Partner, Mark Alan Sutherlin, Shellie Acocello, Susan A. Saliba, Eric M. Magrum and Joe M. Hart

Context:

Individuals with low back pain (LBP) have reduced function of the transversus abdominis (TrA) and lumbar multifidus (LM) muscles. Biofeedback during exercise may increase the ability to contract the TrA and LM muscles compared with exercise alone.

Objective:

To compare TrA preferential activation ratio (PAR) and the percent change in LM-muscle thickness in patients with LBP history before and after exercise with or without biofeedback.

Design:

Controlled laboratory study.

Setting:

University research laboratory.

Patients:

20 LBP individuals, 10 exercise alone and 10 exercise with biofeedback.

Interventions:

Patients were allotted to tabletop exercises in isolation or tabletop exercises with visual, auditory, and tactile biofeedback.

Main Outcome Measures:

TrA PAR and percent change in LM-muscle thickness.

Results:

There were no differences between groups at baseline (all P > .05). Nonparametric statistics showed decreased resting muscle thickness for total lateral abdominal-wall muscles (P = .007) but not TrA (P = .410) or LM (P = .173). Percent TrA thickness increased from table to standing positions before (P = .006) and after exercise (P = .009). TrA PAR increased after exercise (pre 0.01 ± 0.02, post 0.03 ± 0.04, P = .033) for all patients and for exercise with biofeedback (pre 0.02 ± 0.01, post 0.03 ± 0.01, P = .037) but not for exercise alone (pre 0.01 ± 0.02, post 0.02 ± 0.05, P = .241). No group differences were observed for TrA PAR before (exercise 0.01 ± 0.02, exercise with biofeedback 0.02 ± 0.01, P = .290) or after exercise (exercise 0.02 ± 0.05, exercise with biofeedback 0.03 ± 0.01, P = .174). There were no group differences in LM percent change before exercise (P = .999) or after exercise (P = .597). In addition, no changes were observed in LM percent change as a result of exercise among all participants (P = .391) or for each group (exercise P = .508, exercise with biofeedback P = .575).

Conclusion:

TrA PAR increased after a single session of exercises, whereas no thickness changes occurred in LM.