An interventional study of Lumbar ext. high intensity progressive resistance exercise and Low intensity core stabilization exercise in Lower Back Injury, sponsored by University of South Florida. Completed at 2 sites in United States. Open to participants aged 18 Years to 35 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2015-05-25.
Sponsored by University of South Florida · Not applicable, Interventional, and Prevention
The investigators will conduct a controlled clinical trial with U.S. Army soldiers training to become combat medics. The purpose of this study is to determine if a 11-week, high intensity exercise program targeting the low back muscles using specialized equipment will result in a 25% increase in low back muscular strength and endurance compared with a lower intensity general core stability exercise.
Background Low back injury is responsible for the largest percentage of non-battle injuries in the theater of operations and is a large contributor to non-expiration of active service attrition in the US Armed Forces. Weakness and poor endurance of the back muscles are associated with low back injury. Targeted, high intensity exercise approaches using specialized equipment to develop the strength and endurance of the "weak link" muscle group (the lumbar extensors) have been shown to reduce risk for low back injury in high-risk civilian workers, but have not been widely implemented in military settings.
Objective/Hypothesis Specific Aim: In a controlled clinical trial, the investigators will assess the effectiveness of a high intensity progressive resistance exercise training program targeting the lumbar extensors to improve lumbar extensor muscular strength and endurance in US Army soldiers.
Hypothesis: A high intensity progressive resistance exercise for the lumbar extensors will result in a 25% increase in lumbar extensor muscular strength and endurance compared with control following the 11-week intervention.
Study Design A mixed methods, two-arm, controlled clinical trial with cluster randomization will be conducted. The sampling frame will be soldiers training to become combat medics from one domestic US Army base. Soldiers will be randomly assigned (by platoon) to one of two interventions - experimental or control. All participants at a given platoon will receive the same intervention and all interventions will be carried out at the US Army base, in addition to the soldiers' usual physical fitness training program. Participants randomized to the experimental group (strengthening exercise) will perform lumbar extensor muscle progressive resistance exercise using standardized protocols. Exercise training will consist of 1 set of high intensity progressive resistance exercise for lumbar extensors on specialized equipment. Participants in the active comparator control group (stabilization exercise) will perform 5 minutes of low intensity core stabilization exercises on the floor. Interventions will be carried out 1X/week for 11 weeks. Outcome measures that will be utilized to test the hypothesis of Aim 1 include validated physical fitness tests for lumbar extension muscular strength and endurance. Fitness tests will be conducted at baseline and following the 11-week intervention period.
Relevance Soldiers preparing for deployment are in need of advanced technology to help improve and optimize the functional capacity of the lumbar extensor muscles. Assuming positive results from this study and confirmatory trials, implementation of this targeted exercise protocol will maximize resilience in soldiers at high risk for low back injury, thereby helping them become more physically fit to counteract the extreme physical demands required in combat.
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Exclusion Criteria:
Lumbar ext. high intensity progressive resistance exercise
Other: Lumbar ext. high intensity progressive resistance exercise
Low intensity core stabilization exercise
Other: Low intensity core stabilization exercise
1 active set of 1 exercise, 1x/week, 11 weeks
1 set of 5 exercises, 1x/week, 11 weeks
Isometric Lumbar Extension Muscular Strength at 11 Weeks
Isometric lumbar extension muscular strength (torque - Nm) as assessed by a validated physical performance test on the lumbar dynamometer
Time frame: 11 weeks
Isometric Core Muscular Endurance at 11 Weeks
Isometric core muscular endurance as assessed by a validated physical performance test (prone static plank test)
Time frame: 11 weeks
Dynamic Lumbar Extension Muscular Endurance at 11 Weeks
Dynamic lumbar extension muscular endurance (# repetitions at 50% peak torque) as assessed by a validated physical performance test on the lumbar dynamometer
Time frame: 11 weeks
Recruitment, enrollment, baseline assessments, and randomization procedures were completed during June 2012 through May 2013 at Fort Sam Houston, TX.
| Milestone | Strengthening Exercise | Stabilization Exercise |
|---|---|---|
| Started | 298 | 284 |
| Completed | 230 | 217 |
| Not completed | 68 | 67 |
| Withdrew: Withdrawal by subject | 3 | 2 |
| Withdrew: Academic reason | 4 | 1 |
| Withdrew: Changed companies | 20 | 34 |
| Withdrew: Discharged from us army | 3 | 4 |
| Withdrew: Invalid follow-up strength data | 1 | 4 |
| Withdrew: On profile | 9 | 5 |
| Withdrew: Other/unknown | 28 | 17 |
Isometric lumbar extension muscular strength (torque - Nm) as assessed by a validated physical performance test on the lumbar dynamometer
| Nm | Strengthening Exercise | Stabilization Exercise |
|---|---|---|
| Isometric Lumbar Extension Muscular Strength at 11 Weeks | 310.2 ± 6.1 | 282.7 ± 6.1 |
Isometric core muscular endurance as assessed by a validated physical performance test (prone static plank test)
| seconds | Strengthening Exercise | Stabilization Exercise |
|---|---|---|
| Isometric Core Muscular Endurance at 11 Weeks | 161.4 ± 7.2 | 160.2 ± 7.2 |
Dynamic lumbar extension muscular endurance (# repetitions at 50% peak torque) as assessed by a validated physical performance test on the lumbar dynamometer
| repetitions | Strengthening Exercise | Stabilization Exercise |
|---|---|---|
| Dynamic Lumbar Extension Muscular Endurance at 11 Weeks | 24.6 ± 1.0 | 21.9 ± 1.0 |
Collected over Adverse event information was collected for the time frame from baseline assessments through the 11-week intervention period through the follow-up assessments, up to 12 weeks.. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| Strengthening Exercise | — | 0/298 (0%) | 6/298 (2%) |
| Stabilization Exercise | — | 0/284 (0%) | 1/284 (0.4%) |
| Event | Strengthening Exercise | Stabilization Exercise |
|---|---|---|
| Back painMusculoskeletal and connective tissue disorders | 3/298 | 1/284 |
| Pain in extremityMusculoskeletal and connective tissue disorders | 1/298 | 0/284 |
| Musculoskeletal and connective tissue disorder - other: abdominal injuryMusculoskeletal and connective tissue disorders | 1/298 | 0/284 |
| Musculoskeletal and connective tissue disorder - other: groin injuryMusculoskeletal and connective tissue disorders | 1/298 | 0/284 |
All enrolled participants who were deemed eligible, completed baseline assessments, and were randomized.
| Age, Continuous(years) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| Mean | 21.8 ± 3.8 | 21.5 ± 3.6 | 21.7 ± 3.7 |
| Sex: Female, Male(Participants) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| Female | 67 | 68 | 135 |
| Male | 231 | 216 | 447 |
| Race/Ethnicity, Customized(participants) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| American Indian | 3 | 5 | 8 |
| American Indian, Asian, Hispanic, White/Cau | 1 | 0 | 1 |
| American Indian, Black/African American, White/Cau | 1 | 0 | 1 |
| American Indian, White or Caucasian | 3 | 2 | 5 |
| Asian | 12 | 14 | 26 |
| Asian, Black/African American, Hispanic, White/Cau | 1 | 0 | 1 |
| Asian, Black or African American, Other | 1 | 0 | 1 |
| Asian, Hispanic | 0 | 1 | 1 |
| Asian, Pacific Islander | 0 | 1 | 1 |
| Asian, White or Caucasian | 3 | 1 | 4 |
| Black or African American | 27 | 26 | 53 |
| Black or African American, Hispanic | 1 | 0 | 1 |
| Black or African American, White or Caucasian | 0 | 3 | 3 |
| Hispanic | 46 | 41 | 87 |
| Hispanic, White or Caucasian | 2 | 2 | 4 |
| Other/unknown | 6 | 10 | 16 |
| Other, White or Caucasian | 1 | 0 | 1 |
| Pacific Islander | 2 | 4 | 6 |
| Pacific Islander, White or Caucasian | 0 | 2 | 2 |
| White or Caucasian | 188 | 172 | 360 |
| Region of Enrollment(participants) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| United States | 298 | 284 | 582 |
| Isometric Lumbar Extension Muscular Strength(Nm) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| Mean | 275.4 ± 87.0 | 271.7 ± 92.8 | 273.7 ± 89.9 |
| Isometric Core Muscular Endurance(seconds) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| Mean | 169.0 ± 62.4 | 172.8 ± 64.1 | 170.8 ± 63.2 |
| Dynamic Lumbar Extension Muscular Endurance(repetitions) | Strengthening Exercise | Stabilization Exercise | Total |
|---|---|---|---|
| Mean | 21.8 ± 7.7 | 22.0 ± 8.0 | 21.9 ± 7.9 |
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