Acknowledgements. Background. Background. Background. Objective 4/2/2014

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Effects of Lumbar Extensor Progressive Resistance Exercise Versus Core Stabilization Exercise on Low Back Strength and Endurance in Soldiers: Preliminary Results of a Randomized Clinical Trial John

1 Effects of Lumbar Extensor Progressive Resistance Exercise Versus Core Stabilization Exercise on Low Back Strength and Endurance in Soldiers: Preliminary Results of a Randomized Clinical Trial John Mayer, DC, PhD Lt Col John D. Childs PT, PhD, MBA (USAF) MAJ Shane Koppenhaver, PT, PhD (USA) CPT Will Pitt, PT, DPT (USA) Brett D. Neilson, PT DPT (Study Coordinator) William S. Quillen, PT, PhD, FACSM (USN-ret) Promoting Readiness Through Research Acknowledgements Funding DoD FY10 Congressional Special Interest Musculoskeletal Interdisciplinary Research Initiative (W81XWH ) IRB Approval - Brooke Army Medical Center Oct 2011 (C d) Registration: Background The lifetime prevalence of low back pain is up to 80%. 1 The recurrence rate of individuals with first-time low 23 back pain is high (40-60%). 2,3 10% low back injuries are not resolved within 6 months and account for 80% of all costs related to low back injuries. 4 Background LBP is responsible for the largest percentage of non-battle injuries among deployed warfighters. Military personnel are likely at higher risk for low back injury than civilians Low back injury was identified as the second most frequent reason for health care visits. Low back pain is a leading cause of medical evacuation. 5 Background While many treatment strategies for warfighters with LBP are available, many do not return to the line of duty after onset of LBP. LBP is the Silent Killer in the military Prevention is KEY! Objective Specific Aim: Assess the effectiveness of a progressive resistance exercise training program to improve lumbar extensor muscle strength and endurance in US Army Soldiers in training to become combat medics. Hypothesis: A high intensity progressive resistance exercise (HIPRE) for the lumbar extensors will result in a 25% increase in lumbar extensor muscular strength and endurance compared to core stabilization training following the 11-week intervention. 1

Research Design 592 (12 platoons, 3 companies) Army Soldiers from the 232 Medical Battalion Fort Sam Houston (AMEDD) 2 groups (experimental and control) 12 week intervention Pre and Post intervention

Cardiovascular contraindication, orthopedic complaints, systemic inflammatory disease, history of spinal surgery, etc.

2 Research Design 592 (12 platoons, 3 companies) Army Soldiers from the 232 Medical Battalion Fort Sam Houston (AMEDD) 2 groups (experimental and control) 12 week intervention Pre and Post intervention follow-up 1 year for recruitment Inclusion Criteria years of age English Speaking and Reading Exclusion Criteria Diagnoses of condition that would affect their ability to complete interventions Cardiovascular contraindication, orthopedic complaints, systemic inflammatory disease, history of spinal surgery, etc. Currently seeking or receiving treatment for LBP Currently performing progressive resistance exercise for the lumbar extensors (outside of standard military fitness programs) Randomization Due to military training and living environments individual randomization was unfeasible for risk of treatment contamination. Balanced cluster randomization by company was used. Lumbar Extensor HIPRE Training (n=298) Core Stabilization Exercise Training (n=284) Enrollment Assessed for eligibility (n=702) Data Collection Consented (n= 649) Randomized (n= 582) Excluded (n= 120) Not meeting inclusion criteria (n= 24) Declined to participate (n=43) Other reasons (n= 53) Baseline and 12 weeks Physical performance tests and questionnaires HIPRE Allocated to intervention (n= 298) Received allocated intervention (n= 265) Did not receive allocated intervention (n= 33) Allocation CORE Allocated to intervention (n= 284) Received allocated intervention (n= 257) Did not receive allocated intervention (n= 27) Follow-Up Assessed at follow-up (n=231) Lost to follow-up (n= 67) Assessed at follow-up (n=221) Lost to follow-up (n= 63) Analysis Intention to treat analysis (n=298) Evaluable data analysed for primary outcome at follow up (n= 230) Excluded from analysis for invalid test data (n= 2) Intention to treat analysis (n=284) Evaluable data analysed for primary outcome at follow up (n= 217) Excluded from analysis for invalid test data (n= 4) 2

Baseline Collection Intervention Subjective and Physical Exam Questionnaires Height and Weight Lumbar Extensor Strength th and

randomization Group 1 (experimental, HIPRE) - High intensity exercise program targeting the lumbar extensor muscles Group 2

VS Group 1(Experimental) Group 1 (Experimental) 1x per week for 11 weeks MedX, Welltek Inc, Orlando, FL Each session consisted of

Group 2 (Control) Group 2 (Control) 1x per week for 11 weeks 1 set of 6 repetitions of each exercise within 1 minute with no rest

3 Baseline Collection Intervention Subjective and Physical Exam Questionnaires Height and Weight Lumbar Extensor Strength th and Endurance Testing Lumbar dynamometer Timed prone plank test All participants underwent identical baseline tests prior to randomization Group 1 (experimental, HIPRE) - High intensity exercise program targeting the lumbar extensor muscles Group 2 (Control, CORE) Core Stability Exercises *interventions are in addition to normal military physical training. VS Group 1(Experimental) Group 1 (Experimental) 1x per week for 11 weeks MedX, Welltek Inc, Orlando, FL Each session consisted of one se of dynamic, full ROM isolated HIPRE training on dynamometer. One warm-up set was completed prior to training set. Group 2 (Control) Group 2 (Control) 1x per week for 11 weeks 1 set of 6 repetitions of each exercise within 1 minute with no rest between exercises 5 Core Stability Exercises Abdominal drawing-in crunch maneuver Horizontal side support Supine Sp shoulder bridge Quadruped alternating arm and leg Woodchopper 3

4 Outcome Measures Statistical Analysis Primary measure evaluated was lumbar extension strength defined as maximum voluntary lumbar extension isometric torque (ft-lb). Secondary measures Dynamic lumbar extension endurance (number of repetitions on dynamometer) Times prone plank test (seconds) Outcomes were assessed by raters blinded to group assignment. Performed using SAS software, version 9. Demographic and baseline variable compared using ANOVA. Primary analysis was conducted according to intention to treat principles using a mixed models approach. T-tests were performed using exercise compliance as a between group factor (compliance=completion of 11+ sessions) Alpha level was a priori set to 0.05 for all analyses. Baseline Characteristics Results - Lumbar Extension Strength CORE (n = 284) HIPRE (n = 298) TOTAL (n = 582) Continuous variables: Mean SD Mean SD Mean SD Age Height (m) Weight (kg) Categorical variables: % % % Sex (% male) History Low Back Pain (% Yes) All participants: At follow up, adjusted (by baseline) lumbar extension strength was 9.7% greater in HIPRE compared to Core (HIPRE: ± 6.1 Nm; Core: ± 6.1 Nm, respectively, p = 0.001) Significant improvements in lumbar extension strength were observed in both groups (HIPRE 13.3%, Core 3.3%, p < 0.05) Results - Lumbar Extension Strength Adjusted (by baseline) isometric lumbar extension strength values at follow up plotted by group and angle of measurement for all subjects Results - Lumbar Extension Strength Compliant participants: At follow up, lumbar exercise strength HIPRE was 11.9% greater in HIPRE compared to Core (HIPRE ± 99 Nm; Core ± 92.1 Nm, respectively, p = 0.004) Significant improvements in lumbar extension strength were observed in both groups (HIPRE 14.9%, Core 4.4%, p < 0.05) HIPRE (n = 231) CORE (n = 221) 4

5 Results - Lumbar Extension Endurance All participants: At follow up, adjusted (by baseline) lumbar extension endurance was 12.3% greater in HIPRE compared to Core (HIPRE 24.6 ± 1.0 repetitions, Core 21.9 ± 1.0 repetitions, p = 0.001) Significant improvements in lumbar extension endurance were observed in HIPRE (11.4%, p < 0.001), but not Core (p > 0.05). Results - Prone Plank All participants: At follow up, no significant between group differences or within group improvements were observed. Discussion HIPRE training results in significantly greater improvement in lumbar extension isometric strength and dynamic endurance compared to core stabilization exercise Previous research (Mayer 2002) among civilians ili had: Nearly identical baseline values 16% improvement was observed in the Mayer study which is similar to the 15% improvement observed in the current study Discussion Ceiling effect may have limited magnitude of improvement (10% instead of hypothesized 25%) due to high baseline endurance/strength Unlikely a ceiling effect occurred near the ranges of strength we observed In a previous study (Pollock, 1989), the average pre-training/posttraining strength values were 223 and 357 ft-lb, respectively Among compliant Soldiers in our HIPRE group, the average pretraining/post-training strength values were 202 and 232 ft-lb, respectively Likely a ceiling effect occurred with the timed prone plank test Consistent with previous literature regarding core muscular endurance in (Mayer, 2013 and George, 2011) Future Research Explore strategies for improving compliance Test hypothesis in injury prevention RCT of lumbar extensor HIPRE training to reduce the incidence/severity of low back injury during gpeacetime and theater of operations Explore benefits of HIPRE training in other highly active civilian populations as well (e.g., police, firefighters) Test whether effects of lumbar extensor HIPRE training are further enhanced in the most highly actively occupations within the military (ie. special ops forces) Conclusion Results suggest HIPRE training results in significant improvement in lumbar extension isometric strength and endurance compared to core stabilization exercise While the observed lumbar extensor strength and endurance gains were statistically significant, the clinical relevance of these gains is unclear Need for future research 5

6 Questions References 1. Nachemson A, Waddell G, Norlund A. Epidemiology of neck and back pain. In: Nachemson A, Jonsson E, eds. Neck and back pain: the scientific evidence of causes, diagnosis, and treatment. Philadelphia: Lippincott Williams & Wilkins; 2000: Croft P, Macfarlane G, Papegeorgiou A, Thomas E, Silman A. Outcome of low back pain in general practice: a prospective study. BMJ. 1998;316: Hides J, Richardson C, Jull G. Multifidus muscle recovery is not automatic after resolution lti of acute, first-episode i low back pain. Si Spine. 1996;21(23): Gatchel R, Mayer T. Occupational musculoskeletal disorders: introduction and overview of the problem. In: Gatchel R, Mayer T, Polatin P, eds. Occupational musculoskeletal disorders: function, outcomes, and evidence. Philadelphia: Lippincott Williams & Wilkins; 2000: Cohen S, Brown C, Kurihara C, Plunkett A, Nguyen C, Strassels S. Diagnoses and factors associated with medical evacuation and return to duty for service members participating in Operation Iraqi Freedom or Operation Enduring Freedom: a prospective cohort study. Lancet. 2010;375: Army-Baylor DPT Involvement Assist with study related procedures including but not limited to screening and intervention procedures, data collection and management, and other study related duties. Assist in carrying out fitness tests as part of baseline and 12 week measurements. Assist in delivering interventions to both study groups. 6

Effect of Lumbar Progressive Resistance Exercise on Lumbar Muscular Strength and Core Muscular Endurance in Soldiers

MILITARY MEDICINE, 181, 11/12:e1615, 2016 Effect of Lumbar Progressive Resistance Exercise on Lumbar Muscular Strength and Core Muscular Endurance in Soldiers John M. Mayer, DC, PhD*; Lt Col John D. Childs,