Lumbar muscle activity during common lifts: a preliminary study using magnetic resonance imaging.

The purpose of this preliminary study was to assess lumbar multifidus, erector spinae, and quadratus lumborum muscle activity during lifts as measured by changes in transverse relaxation time (T2) from magnetic resonance imaging (MRI). Thirteen healthy adults performed dynamic squat, stoop, and asymmetric stoop lifts at a standard load, with each lift followed by MRI. Increase in T2 for the multifidus and erector spinae was greater for the stoop than squat. No difference in T2 increase was noted between the multifidus and erector spinae for the squat or stoop. Increase in T2 for the contralateral multifidus was less for the asymmetric stoop than stoop. Future research using MRI and other biomechanical techniques is needed to fully characterize lumbar muscle activity during lifts for various populations, settings, postures, and loads.

The use of magnetic resonance imaging to evaluate lumbar muscle activity during trunk extension exercise at varying intensities.

STUDY DESIGN: Descriptive, repeated measures analysis of exercise-induced changes in lumbar muscle transverse relaxation time (T2). OBJECTIVES: To use muscle functional magnetic resonance imaging (MRI) to characterize the activity levels and recruitment patterns of the lumbar extensor muscles during trunk extension exercise over 3 intensities. SUMMARY OF BACKGROUND DATA: Contrast shifts in T2 are indicative of skeletal muscle activity during resistance exercise and are used to characterize the function of a variety of muscles. The use of muscle functional MRI for the lumbar muscles has been limited. METHODS: In 11 healthy participants, T2 was calculated for the lumbar quadratus lumborum, iliocostalis lumborum, longissimus thoracis, and multifidus at rest and following dynamic trunk extension exercise at 3 exercise intensities (40%, 50%, and 70% peak intensity). RESULTS: The multifidus displayed the largest T2 increase at each of the 3 exercise intensities, followed by the erector spinae and, finally, the quadratus lumborum. At the lowest intensity, the medial erector spinae (longissimus thoracis) displayed a higher T2 increase than the lateral group (iliocostalis lumborum), while at the higher intensities, this pattern was reversed. In general, the T2 increase was higher during exercise at 50% and 70% intensities than at 40%, while there was no difference in T2 increase between 50% and 70%. CONCLUSIONS: Muscle functional MRI can be used to characterize lumbar muscle function during trunk extension exercise. The levels and recruitment patterns of the lumbar extensors, as measured by muscle T2 shifts, vary with exercise intensity. Future research is needed to assess the mechanism of the nonlinear relationship between T2 shifts and exercise intensity, and to clarify the effects of fatigue and the order of exercise presentation on the T2 response of the lumbar extensors.

Can a patient educational book change behavior and reduce pain in chronic low back pain patients?

BACKGROUND CONTEXT: This study was prompted by 1) the almost universal use of patient education as an initial or at least an ancillary step in the treatment of patients presenting with low back pain, 2) the relative dearth of studies evaluating the effectiveness of patient education and 3) the complete lack of support in the few existing studies for the efficacy of education in improving patients' long-term health status. PURPOSE: A feasibility study to evaluate the efficacy of an individualized biomechanical treatment educational booklet to effect improvement in health status. STUDY DESIGN: A prospective, longitudinal cohort study. PATIENT SAMPLE: Sixty-two subjects (35 female, 27 male), average age 42.4 years, reported a mean duration of back pain before inclusion of 10.4 years. However, because of attrition, only 48 subjects had complete data across the 18-month follow-up period. OUTCOME MEASURES: Outcome measures included pain status, number of back pain episodes, subject compliance with self-care behaviors, knowledge and opinion of booklet content. METHODS: Volunteers with chronic low back pain were provided a copy of an individualized biomechanical treatment educational book and told they would undergo a written survey of its content 1 week after reading the book. Subjects' health status at 9 and 18 months was evaluated using a structured telephone interview. RESULTS: One week after the 62 subjects, with an average of 10.4 years of symptoms and extensive use of the medical system, finished reading the index book, 51.62% reported noticeable improvement in their pain, their content comprehension was good and opinions about the text were generally positive. At 9-month follow-up, there was statistically significant and clinically relevant improvement in reported pain magnitude (p< .03), number of episodes (p< .0001) and perceived benefit (p< .04). At 18-month follow-up, these gains held or demonstrated even further improvement. CONCLUSION: This study's results suggest that the Treat Your Own Back book may have considerable efficacy in helping readers decrease their own low back pain and reduce the frequency of, or even eliminate, their recurrent episodes. These findings also justify conducting a randomized controlled clinical trial to assess this book's efficacy in improving health status in subjects with low back pain with the study design including internal controls to minimize bias issues and a wider range of outcomes, including measures of pain, function, disability, patient satisfaction, utilization of health care services and psychosocial measures.

Quantitative Assessment of Lumbar Paraspinal Muscle Endurance.

OBJECTIVE: To evaluate the reliability and variability of repeated measurements of dynamic and static lumbar muscle endurance. DESIGN AND SETTING: Participants performed an isometric lumbar-extension strength test followed by 2 trials of 4 separate lumbar muscular-endurance tests (with a 24-hour rest period between tests). Data were collected at a university musculoskeletal research laboratory. SUBJECTS: Eight healthy, physically active volunteers (5 men, 3 women; age = 25.9 +/- 4.3 years; height = 169.0 +/- 4.6 cm; mass = 73.9 +/- 33.1 kg) participated in this investigation. MEASUREMENTS: We initially tested each participant's isometric lumbar-extension peak torque on a lumbar-extension dynamometer. Static (holding time) and dynamic (repetitions) lumbar-endurance tests were subsequently performed on the lumbar-extension dynamometer and a horizontal roman chair. RESULTS: Interclass reliability was high for all endurance tests completed (r = 0.91 to 0.96, P

Effect of Roman chair exercise training on the development of lumbar extension strength.

The purpose of this study was to determine the effect of 45 degrees Roman chair exercise training on the development of lumbar extension strength. Fifteen healthy volunteers (9 women, 6 men) were recruited from a university setting and were randomly assigned to 1 of 2 groups. One group (n = 9) performed progressive resistance back extension exercise on a 45 degrees Roman chair once weekly for 12 weeks. Training consisted of one set of 8-20 dynamic repetitions to volitional exhaustion using hand-held metal plates for additional resistance. The other group did not train (control, n = 6). Peak isometric lumbar extension torque was measured on a lumbar extension dynamometer before and after the 12-week program. Following training, peak isometric lumbar extension torque did not increase for the Roman chair group (before: 224.0 +/- 134.1 N x m; after: 240.3 +/- 137.4 N x m; p > 0.05) compared with the control group (before: 175.6 +/- 68.9 N x m; after: 178.2 +/- 69.9 N x m; p > 0.05), despite an increase in dynamic exercise load.

Electromyographic activity of the trunk extensor muscles: effect of varying hip position and lumbar posture during Roman chair exercise.

OBJECTIVE: To evaluate the effect of hip position and lumbar posture on the surface electromyographic activity of the trunk extensors during Roman chair exercise. DESIGN: Descriptive, repeated measures. SETTING: University-based musculoskeletal research laboratory. PARTICIPANTS: Twelve healthy volunteers (7 men, 5 women; age range, 18-35y) without a history of low back pain were recruited from a university setting. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Surface electromyographic activity was recorded from the lumbar extensor, gluteal, and hamstring musculature during dynamic Roman chair exercise. For each muscle group, electromyographic activity (mV/rep) was compared among exercises with internal hip rotation and external hip rotation and among exercises by using a typical lumbar posture (nonbiphasic) and a posture that accentuated lumbar lordosis (biphasic). RESULTS: For the lumbar extensors, electromyographic activity during exercise was 18% greater with internal hip rotation than external hip rotation (P< or =.05) and was 25% greater with a biphasic posture than with a nonbiphasic posture (P< or =.05). For the gluteals and hamstrings, there was no difference in electromyographic activity between internal and external hip rotation or between biphasic and nonbiphasic postures (P >.05). CONCLUSION: The level of recruitment of the lumbar extensors can be modified during Roman chair exercise by altering hip position and lumbar posture. Clinicians can use these data to develop progressive exercise protocols for the lumbar extensors with a variety of resistance levels without the need for complex equipment.

Electromyographic activity of the lumbar and hip extensors during dynamic trunk extension exercise.

OBJECTIVE: To evaluate the effects of exercise intensity and multiple sets on muscle activation patterns during trunk extension exercise. DESIGN: Descriptive, repeated measures. SETTING: University-based musculoskeletal research laboratory. PARTICIPANTS: Twenty volunteers recruited from a university setting. INTERVENTION: Not applicable. MAIN OUTCOME MEASURES: Electromyographic activity was recorded from the L3-4 paraspinal region, gluteus maximus, and biceps femoris muscles during multiple sets of trunk extension exercise at intensities representing 40%, 50%, and 70% of peak isometric force. RESULTS: As exercise intensity increased, the electromyographic activity of the gluteus maximus increased to a greater extent than the activity of the paraspinal region. At the 50% intensity level, biceps femoris electromyographic activity was significantly greater than the paraspinal region electromyographic activity, whereas at the 70% intensity no differences were found between muscles. During multiple sets of exercise at the same intensity a muscle by set interaction was observed. This interaction revealed that with respect to other muscle groups, the electromyographic activity of the gluteus maximus increased between sets 1 and 2, whereas electromyographic decrements occurred in the paraspinal region. During exercise at the 40% intensity level, biceps femoris electromyographic activity increased to a greater extent between sets 1 and 2 when compared with the paraspinal region. CONCLUSION: Exercise intensity and multiple sets result in alterations in muscle recruitment patterns of the lumbar and hip extensor muscles. These findings raise questions as to the efficacy of added loading and multiple sets during trunk extension exercise.

Back extension endurance and strength: the effect of variable-angle roman chair exercise training.

STUDY DESIGN: A pre- and postintervention randomized, controlled trial was conducted. OBJECTIVE: To evaluate the effect of progressive resistance exercise training using a variable-angle Roman chair on the development of lumbar extensor endurance and strength. SUMMARY OF BACKGROUND DATA: Progressive resistance exercise for the lumbar extensors has been used successfully for low back pain rehabilitation, but the limitations of currently available back exercise devices have negatively affected its use. METHODS: For this study, 36 healthy volunteers were randomized into one of two groups: a variable-angle Roman chair exercise group (n = 18) that performed one set of 15 to 25 repetitions of dynamic progressive resistance back extension exercise on a variable-angle Roman chair three times per week for 8 weeks or a control group (n = 18) that did not perform resistance exercise. Before training and after 4 and 8 weeks of training, static back extension endurance (seconds) and isometric lumbar extension strength (Newton.meters) were recorded. RESULTS: The variable-angle Roman chair exercise group displayed a 42% increase in static back extension endurance at the 4-week and 8-week tests relative to the pretraining measure (P < 0.05). The control group did not increase back endurance time at either the 4-week or 8-week tests (P > 0.05). Neither the variable-angle Roman chair exercise group nor the control group displayed an increase in lumbar extension strength at the 4-week or 8-week tests (P > 0.05). CONCLUSIONS: Dynamic progressive resistance exercise training on a variable-angle Roman chair is capable of developing back extension endurance. Future research is needed to determine the clinical applicability of variable-angle Roman chair exercise training for patients with low back pain patients.

Development of lumbar extension strength: Effect of pelvic stabilization during resistance training.

The purpose of this studywas to determine the effect of pelvic stabilization during resistance training on the development of isometric lumbar extension strength (torque output) when testing and training are conducted on a lumbar dynamometer. Eighteen healthy volunteers were randomly assigned to one of two groups that trained on a lumbar extension dynamometer: One trained with pelvic stabilization (n = 9) and the other trained without pelvic stabilization (n = 9). Peak isometric lumbar extension torque was measured on the dynamometer at seven angles over the full range of lumbar flexion, before and after a twelve-week, one time per week dynamic progressive resistance exercise program. Following training, peak isometric torque increased for the stabilization and without stabilization groups (average increase of 15.8 ± 11.8% and 20.6 ± ;17.2%, respectively; p ≤ 0.05), while there was no difference in torque production between the groups (p > 0.05). This study demonstrates that pelvic stabilization is not required during training to develop lumbar extension strength when testing and training are conducted on the same machine.

Quantification of the loading characteristics of the upper body and back extension strength on a variable angle Roman chair.

The purpose of this study was to quantify the loading characteristics of the upper body during variable angle Roman chair (VARC) exercise and to compare back extension strength outputs obtained from a VARC to a criterion measure (lumbar dynamometer). For twenty-four healthy volunteers (age, 22.7 ± 3.2 years), the load attributed to the upper body and isometric back extension strength were measured twice at six positions over a full range of lumbar flexion on a VARC. In addition, isometric back extension strength was measured at seven positions over a full range of lumbar flexion on a lumbar dynamometer. Test-retest reliability was high for measures of the load attributed to the upper body (r = 0.99) and isometric strength (r = 0.96 to 0.97) on the VARC. The load attributed to the upper body increased from the most flexed to most extended position, while isometric strength increased from the most extended to the most flexed position on the VARC. Average VARC and dynamometer strength values were highly correlated (r = 0.90), but were lower on the VARC than on the dynamometer (888.4 ± 249.8 N vs. 1050.0 ± 438.5 N, respectively; p < 0.05).

Comparison of different bioelectrical impedance analyzers in the prediction of body composition.

To investigate the influence of different bioelectrical impedance (BI) analyzers on the prediction of body composition from bioelectrical resistive impedance (R), 146 healthy white adults (73 men; 73 women) were studied at two independent laboratories: The University of Florida (UF) and the USDA, San Francisco. Whole body R was measured on each subject with three different BI analyzers. AT UF analyzers were: Valhalla Scientific model 1990-A (VH), RJL Systems model BIA-101 (RJL), and Medi-Fitness model 1000 (MF). At USDA analyzers were: VH, RJL, and Bioelectrical Sciences model 200Z (BES). The largest difference in R (36 ohms, P ⩽ 0.01) was noted between BES and VH at USDA. When applied to current BI prediction equations, the observed differences among analyzers resulted in differences in predicated % fat of up to 6.3% although most comparisons among mean values (79%) showed differences below 3%. Crossvalidation of the selected BI prediction equations with hydrostatistically determines body composition using the different R values revealed total errors of prediction (E) ranging from 3.6 to 9.8% fat. The prediction equations were most accurate when used with data collected on the same instrument that was to used to develop the equation (E = 3.6 to 5.3% fat). These findings indicate that different analyzers can be a significant source of variation when predicting body composition from R. To minimize this source of variation, it is recommended that BI prediction equations be used with the same type of instrument as that with which they were developed.