Effect of two different exercise regimens on trunk muscle morphometry and endurance in soldiers in training.

BACKGROUND: Limited evidence exists on how strength and endurance exercises commonly used to prevent low back pain affect muscle morphometry and endurance. OBJECTIVE: The purpose of this study was to analyze the effects of 2 exercise regimens on the morphometry and endurance of key trunk musculature in a healthy population. DESIGN: The study was designed as a randomized controlled trial. SETTING: The study was conducted in a military training setting. PARTICIPANTS: A random subsample (n=340; 72% men, 28% women; mean [±SD] age=21.9±4.2 years; mean [±SD] body mass index=24.8±2.8 kg/m2) from the larger Prevention of Low Back Pain in the Military trial (N=4,325) was included. INTERVENTION: The core stabilization exercise program (CSEP) included low-load/low-repetition motor control exercises, whereas the traditional exercise program (TEP) included exercises conducted at a fast pace, with the use of high-load, high-repetition trunk strengthening exercises. MEASUREMENTS: Baseline and follow-up examinations included ultrasound imaging of the trunk muscles and endurance tests. Linear mixed models were fitted to study the group and time effect and their interactions, accounting for the clustering effect. RESULTS: Symmetry generally improved in the rest and contracted states, but there were no differences suggestive of muscle hypertrophy or improved ability to contract the trunk muscles between soldiers receiving the CSEP or the TEP. Total trunk endurance time decreased over the 12-week period, but endurance performance favored soldiers in the CSEP group. Endurance time was not associated with future episodes of low back pain. LIMITATIONS: The lack of morphological changes may not be detectable in an already-active cohort, or a more intensive dose was needed. CONCLUSIONS: Although improved symmetry was noted, neither the CSEP nor the TEP resulted in muscle hypertrophy. Longer endurance times were noted in individuals who completed the CSEP but were not strongly predictive of future low back pain episodes.

Abdominal and lumbar multifidus muscle size and symmetry at rest and during contracted States. Normative reference ranges.

OBJECTIVES: The purpose of this study was to establish reference values for abdominal and lumbar multifidus muscles at rest and while contracted in a sample of active healthy adults. METHODS: Three hundred forty participants (mean age ± SD, 21.8 ± 3.9 years; 96 females and 244 males) completed the study. Ultrasound imaging was used to assess the thickness of the transversus abdominis, internal and external oblique, rectus abdominis, and lumbar multifidus muscles. Additionally, the cross-sectional area of the rectus abdominis was assessed. RESULTS: Although males had significantly thicker muscles than females (P < .05), the relative change in thickness during specified tasks was equivalent. Overall, relative muscle thickness and symmetry were similar to previous studies using smaller sample sizes. CONCLUSIONS: These findings provide a robust data set of muscle thickness values measured by ultrasound imaging and can be used for comparison to those with pain, abnormal function, and pathologic conditions.

The Functional Movement Screen: a reliability study.

STUDY DESIGN: Reliability study. OBJECTIVES: To determine intrarater test-retest and interrater reliability of the Functional Movement Screen (FMS) among novice raters. BACKGROUND: The FMS is used by various examiners to assess movement and predict time-loss injuries in diverse populations (eg, youth to professional athletes, firefighters, military service members) of active participants. Unfortunately, critical analysis of the reliability of the FMS is currently limited to 1 sample of active college-age participants. METHODS: Sixty-four active-duty service members (mean ± SD age, 25.2 ± 3.8 years; body mass index, 25.1 ± 3.1 kg/m2) without a history of injury were enrolled. Participants completed the 7 component tests of the FMS in a counterbalanced order. Each component test was scored on an ordinal scale (0 to 3 points), resulting in a composite score ranging from 0 to 21 points. Intrarater test-retest reliability was assessed between baseline scores and those obtained with repeated testing performed 48 to 72 hours later. Interrater reliability was based on the assessment from 2 raters, selected from a pool of 8 novice raters, who assessed the same movements on day 2 simultaneously. Descriptive statistics, weighted kappa (κw), and percent agreement were calculated on component scores. Intraclass correlation coefficients (ICCs), standard error of the measurement, minimal detectable change (MDC95), and associated 95% confidence intervals (CIs) were calculated on composite scores. RESULTS: The average ± SD score on the FMS was 15.7 ± 0.2 points, with 15.6% (n = 10) of the participants scoring less than or equal to 14 points, the recommended cutoff for predicting time-loss injuries. The intrarater test-retest and interrater reliability of the FMS composite score resulted in an ICC3,1 of 0.76 (95% CI: 0.63, 0.85) and an ICC2,1 of 0.74 (95% CI: 0.60, 0.83), respectively. The standard error of the measurement of the composite test was within 1 point, and the MDC95 values were 2.1 and 2.5 points on the 21-point scale for interrater and intrarater reliability, respectively. The interrater agreement of the component scores ranged from moderate to excellent (κw = 0.45-0.82). CONCLUSION: Among novice raters, the FMS composite score demonstrated moderate to good interrater and intrarater reliability, with acceptable levels of measurement error. The measures of reliability and measurement error were similar for both intrarater reliability that repeated the assessment of the movement patterns over a 48-to-72-hour period and interrater reliability that had 2 raters assess the same movement pattern simultaneously. The interrater agreement of the FMS component scores was good to excellent for the push-up, quadruped, shoulder mobility, straight leg raise, squat, hurdle, and lunge. Only 15.6% (n = 10) of the participants were identified to be at risk for injury based on previously published cutoff values.

Predictors of occurrence and severity of first time low back pain episodes: findings from a military inception cohort.

Primary prevention studies suggest that additional research on identifying risk factors predictive of low back pain (LBP) is necessary before additional interventions can be developed. In the current study we assembled a large military cohort that was initially free of LBP and followed over 2 years. The purposes of this study were to identify baseline variables from demographic, socioeconomic, general health, and psychological domains that were predictive of a) occurrence; b) time; and c) severity for first episode of self-reported LBP. Baseline and outcome measures were collected via web-based surveillance system or phone to capture monthly information over 2 years. The assembled cohort consisted of 1230 Soldiers who provided self-report data with 518 (42.1%) reporting at least one episode of LBP over 2 years. Multivariate logistic regression analysis indicated that gender, active duty status, mental and physical health scores were significant predictors of LBP. Cox regression revealed that the time to first episode of LBP was significantly shorter for Soldiers that were female, active duty, reported previous injury, and had increased BMI. Multivariate linear regression analysis investigated severity of the first episode by identifying baseline predictors of pain intensity, disability, and psychological distress. Education level and physical fitness were consistent predictors of pain intensity, while gender, smoking status, and previous injury status were predictors of disability. Gender, smoking status, physical health scores, and beliefs of back pain were consistent predictors of psychological distress. These results provide additional data to confirm the multi-factorial nature of LBP and suggest future preventative interventions focus on multi-modal approaches that target modifiable risk factors specific to the population of interest.

Brief psychosocial education, not core stabilization, reduced incidence of low back pain: results from the Prevention of Low Back Pain in the Military (POLM) cluster randomized trial.

BACKGROUND: Effective strategies for the primary prevention of low back pain (LBP) remain elusive with few large-scale clinical trials investigating exercise and education approaches. The purpose of this trial was to determine whether core stabilization alone or in combination with psychosocial education prevented incidence of low back pain in comparison to traditional lumbar exercise. METHODS: The Prevention of Low Back Pain in the Military study was a cluster randomized clinical study with four intervention arms and a two-year follow-up. Participants were recruited from a military training setting from 2007 to 2008. Soldiers in 20 consecutive companies were considered for eligibility (n = 7,616). Of those, 1,741 were ineligible and 1,550 were eligible but refused participation. For the 4,325 Soldiers enrolled with no previous history of LBP average age was 22.0 years (SD = 4.2) and there were 3,082 males (71.3%). Companies were randomly assigned to receive traditional lumbar exercise, traditional lumbar exercise with psychosocial education, core stabilization exercise, or core stabilization with psychosocial education, The psychosocial education session occurred during one session and the exercise programs were done daily for 5 minutes over 12 weeks. The primary outcome for this trial was incidence of low back pain resulting in the seeking of health care. RESULTS: There were no adverse events reported. Evaluable patient analysis (4,147/4,325 provided data) indicated no differences in low back incidence resulting in the seeking of health care between those receiving the traditional exercise and core stabilization exercise programs. However, brief psychosocial education prevented low back pain episodes regardless of the assigned exercise approach, resulting in a 3.3% (95% CI: 1.1 to 5.5%) decrease over two years (numbers needed to treat (NNT) = 30.3, 95% CI = 18.2 to 90.9). CONCLUSIONS: Core stabilization has been advocated as preventative, but offered no such benefit when compared to traditional lumbar exercise in this trial. Instead, a brief psychosocial education program that reduced fear and threat of low back pain decreased incidence of low back pain resulting in the seeking of health care. Since this trial was conducted in a military setting, future studies are necessary to determine if these findings can be translated into civilian populations. TRIAL REGISTRATION: NCT00373009 at ClinicalTrials.gov - http://clinicaltrials.gov/

Reliability of lower quarter physical performance measures in healthy service members.

INTRODUCTION: Measures of endurance, flexibility, strength, and power may be of value in predicting injury risk, but application to the military setting has been limited. The purpose of this study was to assess the reliability and precision of lower quarter physical performance measures among novice raters. METHODS: Sixty-four (53 male, 11 female) healthy active duty Soldiers (aged 25.2±3.8 years, 25.1±3.1 kg/m²) were recruited while in training at Fort Sam Houston, Texas. Subjects completed 13 lower quarter physical performance measures in a counterbalanced order. Measures included indicators of lumbopelvic endurance (trunk flexion, trunk extension, and trunk lateral flexion), lower extremity flexibility (gastrocnemius, soleus, iliotibial band, hamstring, and quadriceps), hip strength (hip external rotation, hip abduction), quality of movement (lateral step down), and lower extremity power (timed hop test and crossover hop test). Interrater test-retest reliability was assessed between baseline scores and those obtained 48 hours later using intraclass correlation coefficients (ICC) and standard errors of measurements (SEM). RESULTS: Measures of lumbopelvic endurance had ICC(2,1) values ranging from 0.77 to 0.79 with SEM ranging from 18.3 to 24.5 seconds. Measures of flexibility had ICC(2,2) values ranging from 0.27 to 0.59 with SEM ranging from 4.1° to 9.9°. Measures of hip strength had ICC(2,3) values ranging from 0.61 to 0.82 with SEM ranging from 1.3 kg to 3.0 kg. Measures of power had ICC(2,3) values ranging from 0.78 to 0.93 with SEM values of 0.2 seconds and 27.4 cm. CONCLUSIONS: The majority of measures assessed had adequate reliability in this sample of uniformed service members assessed by novice raters. The measures of strength and power had moderate to good reliability with small measurement error, indicating the possibility of these measures to detect change over time. Although the measures of lumbopelvic endurance had good reliability, they were associated with relatively large SEM values compared to the group mean, thus limiting the ability of these tests to detect change over time. The measures of flexibility had limited reliability which may be associated with a restriction in range of the underlying scores that could artificially underestimate reliability. These results can help inform which physical performance measures should be used in future research to assess injury prediction and human performance optimization among uniformed service members.

Inter-rater reliability of ultrasound imaging of the trunk musculature among novice raters.

OBJECTIVE: The purpose of this study was to determine the inter-rater reliability of ultrasound imaging for assessing trunk muscle morphologic characteristics at rest and while contracted among different pairs of novice raters. The secondary purpose was to compare 3 different measurement techniques for assessing lateral abdominal muscle thickness. METHODS: A single-group repeated measures reliability study was conducted on 21 healthy participants (mean ± SD, 21.5 ± 4.4 years; 5 female and 16 male) without low back pain. Ultrasound images of the transversus abdominis, internal oblique, rectus abdominis, and lumbar multifidus muscles were obtained by different pairs of novice raters in a counterbalanced order. All raters received a standardized training program before obtaining measurements. RESULTS: The intraclass correlation coefficient (1, 3) point estimates ranged from 0.86 to 0.94; the standard error of the measurement ranged from 0.04 to 0.16 cm for the thickness values and 0.67 cm(2) for the cross-sectional area of the rectus abdominis muscle. There was no meaningful difference between the different measurement techniques used to analyze the lateral abdominal muscles. CONCLUSIONS: Good to excellent reliability was obtained for all measures by novice raters. Minimal differences in reliability were noted between the different measurement techniques to assess lateral abdominal muscle thickness.

Effects of traditional sit-up training versus core stabilization exercises on short-term musculoskeletal injuries in US Army soldiers: a cluster randomized trial.

BACKGROUND: The US Army has traditionally utilized bent-knee sit-ups as part of physical training and testing. It is unknown whether the short-term effects of a core stabilization exercise program without sit-up training may result in decreased musculoskeletal injury incidence and work restriction compared with traditional training. OBJECTIVE: The objective of this study was to explore the short-term effects of a core stabilization exercise program (CSEP) without sit-up training and a traditional exercise program (TEP) on musculoskeletal injury incidence and work restriction. DESIGN: The study was designed as a cluster randomized trial. SETTING: The setting was a 16-week training program at Fort Sam Houston (San Antonio, Texas). PARTICIPANTS: The study participants were soldiers with a mean age of 22.9 years (SD=4,7, range=18-35) for whom complete injury data were available for analysis (n=1,141). INTERVENTION: Twenty companies of soldiers were cluster randomized to complete the CSEP (10 companies of 542 soldiers) or the TEP (10 companies of 599 soldiers). The CSEP included exercises targeting the transversus abdominus and multifidus musculature. The TEP comprised exercises targeting the rectus abdominus, oblique abdominal, and hip flexor musculature. MEASUREMENTS: Research staff recorded all injuries resulting in the inability to complete full duty responsibilities. Differences in the percentages of musculoskeletal injuries were examined with chi-square analysis; independent sample t tests were used to examine differences in the numbers of days of work restriction. RESULTS: Of the 1,141 soldiers for whom complete injury data were available for analysis, 511 (44.8%) experienced musculoskeletal injuries during training that resulted in work restrictions. There were no differences in the percentages of soldiers with musculoskeletal injuries. There also were no differences in the numbers of days of work restriction for musculoskeletal injuries overall or specific to the upper extremity. However, soldiers who completed the TEP and experienced a low back injury had more days of work restriction: 8.3 days (SD=14.5) for the TEP group and 4.2 days (SD=8.0) for the CSEP group. LIMITATIONS: A limitation of this study was the inconsistent reporting of injuries during training. However, the rates of reporting were similar between the groups. CONCLUSIONS: The incidence of musculoskeletal injuries was similar between the groups. There was marginal evidence that the CSEP resulted in fewer days of work restriction for low back injuries.

Effects of sit-up training versus core stabilization exercises on sit-up performance.

PURPOSE: Core stabilization exercises target abdominal and trunk muscles without the excessive loading that occurs during sit-ups. However, core stabilization exercise programs (CSEP) have not been widely adopted in the US Army partially because of the perceived deleterious impact they would have on performance during the Army Physical Fitness Test. The purpose was to determine whether performing CSEP in lieu of sit-ups during unit physical training would have detrimental effects on sit-up performance and passing rates on the fitness test. METHODS: Soldiers (N = 2616) between 18 and 35 yr of age were randomized to receive a traditional exercise program (TEP) with sit-ups or CSEP. Subjects with a previous history of low back pain or other injury precluding participation in training were excluded. The training programs were completed four times per week for 12 wk. Performance was assessed at baseline and after 12 wk. RESULTS: Both groups demonstrated significant improvements in sit-up performance and overall fitness scores over time (P < 0.001). There were no significant between-group differences in overall fitness scores (P = 0.142) or sit-up performance (P = 0.543). However, CSEP resulted in a significant improvement in sit-up passing rates by 5.6% compared with 3.9% for the TEP group (P = 0.004). CONCLUSIONS: CSEP did not have a detrimental impact on sit-up performance or overall fitness scores or pass rates. There was a small but significantly greater increase in sit-up pass rate in the CSEP (5.6%) versus the TEP group (3.9%). Incorporating CSEP into Army physical training does not increase the risk of suboptimal performance on the Army's fitness test and may offer a small benefit for improving sit-up performance.

Mental health symptoms in combat medic training: a longitudinal examination.

Mental health symptoms in military populations are rising and constitute a significant health concern. This study examined the prevalence of depression, anxiety, and suicidal ideation in soldiers (N = 3,792) undergoing combat medic training. At the start of training, 10.4%, 15.5%, and 4.1% of soldiers had clinically significant depression, anxiety, or suicidal ideation, respectfully. These percentages increased to 12.2%, 20.3%, and 5.7% at completion of training, respectfully. Worsening of depression, anxiety, and suicidal ideation occurred for 7.7%, 11.4%, and 4% of soldiers. Higher percentages of symptoms were associated with females, lower education, and lower income. Active duty personnel were more likely to worsen following training with respect to suicidal ideation (OR = 1.9, 95% CI = 1.2-2.9) compared to reservists. The identification of these significant predictors of mental health status may serve to identify individuals at risk. Additional work to examine the relative contribution of anticipatory (impending deployment) factors vs. training-related factors is warranted.

Psychosocial education improves low back pain beliefs: results from a cluster randomized clinical trial (NCT00373009) in a primary prevention setting.

The general population has a pessimistic view of low back pain (LBP), and evidence-based information has been used to positively influence LBP beliefs in previously reported mass media studies. However, there is a lack of randomized trials investigating whether LBP beliefs can be modified in primary prevention settings. This cluster randomized clinical trial investigated the effect of an evidence-based psychosocial educational program (PSEP) on LBP beliefs for soldiers completing military training. A military setting was selected for this clinical trial, because LBP is a common cause of soldier disability. Companies of soldiers (n = 3,792) were recruited, and cluster randomized to receive a PSEP or no education (control group, CG). The PSEP consisted of an interactive seminar, and soldiers were issued the Back Book for reference material. The primary outcome measure was the back beliefs questionnaire (BBQ), which assesses inevitable consequences of and ability to cope with LBP. The BBQ was administered before randomization and 12 weeks later. A linear mixed model was fitted for the BBQ at the 12-week follow-up, and a generalized linear mixed model was fitted for the dichotomous outcomes on BBQ change of greater than two points. Sensitivity analyses were performed to account for drop out. BBQ scores (potential range: 9-45) improved significantly from baseline of 25.6 +/- 5.7 (mean +/- SD) to 26.9 +/- 6.2 for those receiving the PSEP, while there was a significant decline from 26.1 +/- 5.7 to 25.6 +/- 6.0 for those in the CG. The adjusted mean BBQ score at follow-up for those receiving the PSEP was 1.49 points higher than those in the CG (P < 0.0001). The adjusted odds ratio of BBQ improvement of greater than two points for those receiving the PSEP was 1.51 (95% CI = 1.22-1.86) times that of those in the CG. BBQ improvement was also mildly associated with race and college education. Sensitivity analyses suggested minimal influence of drop out. In conclusion, soldiers that received the PSEP had an improvement in their beliefs related to the inevitable consequences of and ability to cope with LBP. This is the first randomized trial to show positive influence on LBP beliefs in a primary prevention setting, and these findings have potentially important public health implications for prevention of LBP.

Rationale, design, and protocol for the prevention of low back pain in the military (POLM) trial (NCT00373009).

BACKGROUND: There are few effective strategies reported for the primary prevention of low back pain (LBP). Core stabilization exercises targeting the deep abdominal and trunk musculature and psychosocial education programs addressing patient beliefs and coping styles represent the current best evidence for secondary prevention of low back pain. However, these programs have not been widely tested to determine if they are effective at preventing the primary onset and/or severity of LBP. The purpose of this cluster randomized clinical trial is to determine if a combined core stabilization exercise and education program is effective in preventing the onset and/or severity of LBP. The effect of the combined program will be compared to three other standard programs. METHODS/DESIGN: Consecutive Soldiers participating in advanced individual training (AIT) will be screened for eligibility requirements and consented to study participation, as appropriate. Companies of Soldiers will be randomly assigned to receive the following standard prevention programs; a core stabilization exercise program (CSEP) alone, a CSEP with a psychosocial education (PSEP), a traditional exercise (TEP), or a TEP with a PSEP. Proximal outcome measures will be assessed at the conclusion of AIT (a 12 week training period) and include imaging of deep lumbar musculature using real-time ultrasound imaging and beliefs about LBP by self-report questionnaire. We are hypothesizing that Soldiers receiving the CSEP will have improved thickness of selected deep lumbar musculature (transversus abdominus, multifidi, and erector spinae muscles). We are also hypothesizing that Soldiers receiving the PSEP will have improved beliefs about the management of LBP. After AIT, Soldiers will be followed monthly to measure the distal outcomes of LBP occurrence and severity. This information will be collected during the subsequent 2 years following completion of AIT using a web-based data entry system. Soldiers will receive a monthly email that queries whether any LBP was experienced in the previous calendar month. Soldiers reporting LBP will enter episode-specific data related to pain intensity, pain-related disability, fear-avoidance beliefs, and pain catastrophizing. We are hypothesizing that Soldiers receiving the CSEP and PSEP will report the longest duration to first episode of LBP, the lowest frequency of LBP, and the lowest severity of LBP episodes. Statistical comparisons will be made between each of the randomly assigned prevention programs to test our hypotheses related to determining which of the 4 programs is most effective. DISCUSSION: We have presented the design and protocol for the POLM trial. Completion of this trial will provide important information on how to effectively train Soldiers for the prevention of LBP.