Exposure-Related Differences on Neck and Trunk Musculoskeletal Characteristics in US ... · 2016....

Neuromuscular Research Laboratory University of Pittsburgh

Exposure-Related Differences on Neck and Trunk Musculoskeletal Characteristics in

US Army Helicopter Pilots

Nagai T*, Abt JP*, Sell TC*, Lovalekar M*, Smalley BW†, Wirt MD‡, Lephart SM**

Warrior Human Performance Research Center, Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA*

US Army School of Aviation Medicine, Fort Rucker, AL† US Army Institute of Surgical Research, Fort Sam Houston, TX‡

College of Health Sciences, University of Kentucky, Lexington, KY**


Disclosure Information 86th Annual Scientific Meeting

Takashi Nagai

Funding: the U.S. Army Medical Research and Materiel Command: W81XWH-11-2-0097. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the U.S. Army

I have no financial relationships to disclose I will not discuss off-label use and/or investigational use in my

presentation


Introduction: High Prevalence of Neck Pain and Low Back Pain in US Army Helicopter Pilots

1yr self-reported NP/LPB among the US Army Helicopter Pilots

Prevalence of NP: 37/123 (30.1%) • 78 Young Pilots: 16/78 (20.5%) • 32 Senior Pilots: 14/32 (43.8%) • 13 Master Pilots: 8/13 (61.5%)

Prevalence of LBP: 69/123 (56.1%) • 78 Young Pilots: 41/78 (52.6%) • 32 Senior Pilots: 18/32 (56.3%) • 13 Master Pilots: 11/13 (84.6%)

AR 600-105: 2010: Senior (7yr/1000hr) & Master (15yr/2000hr)


Vicious Cycle of NP/LBP in Helicopter Pilots

NP Potential Risk Factors • Previous injuries/NP

LBP Potential Risk Factors • Previous injuries/LBP



NP Potential Risk Factors • Previous injuries/NP • Total flight-hours/NVG-

hours • Exposure to whole-

body vibration

LBP Potential Risk Factors • Previous injuries/LBP • Total flight-hours • Exposure to whole-body

vibration





body vibration • Fatigue


vibration • Psychosocial factors • Fatigue





body vibration • Fatigue • Altered

musculoskeletal characteristics / posture

Salmon 2011


vibration • Psychosocial factors • Fatigue • Altered musculoskeletal

characteristics/posture Gaydos 2012



Non-Specific Neck Pain /

Low Back Pain

Total Flight / NVG Hours

Fatigue/Altered Proprioception

Altered Neuromotor

Control



body vibration • Fatigue • Altered

musculoskeletal characteristics/ posture

Salmon 2011


vibration • Psychosocial factors • Fatigue • Physical fitness,

BMI/obesity • Altered musculoskeletal

characteristics/posture Gaydos 2012

Potential for Interventions / Modifications – STOP THE BLEEDING!!!


Investigating the Musculoskeletal, Proprioception, and Posture Characteristics

Pilots with NP History • The NP pain group had significant

reductions in cervical extension and rotation range-of-motion (ROM)

• No differences in neck strength, upper quadrant posture, and neck proprioception

Nagai 2014


Investigating the Musculoskeletal, Proprioception, and Posture Characteristics

Pilots with NP History • The NP pain group had significant

reductions in cervical extension and rotation range-of-motion (ROM)

• No differences in neck strength, upper quadrant posture, and neck proprioception

Nagai 2014

Pilots with LBP History • The LBP group had significantly lower

trunk extension strength and trunk extension/flexion strength ratio

• The LBP group had less lumbar spine lateral flexion ROM and greater ROM asymmetry on lumbar spine lateral flexion and rotation

Nagai 2015


Non-Specific Neck Pain /

Low Back Pain

Total Flight / NVG Hours

Fatigue/Altered Proprioception

Altered Neuromotor

Control

Problem Statement • Few studies have evaluated

the musculoskeletal characteristics and compared them among groups of pilots with different flight-hours


Purpose Statement

• The purpose of the study was to examine and compare the neck/trunk strength, ROM, and posture among pilots with different total flight-hours


Clinical/Tactical Significance

• It is clinically significant to understand general patterns of the decrement of musculoskeletal characteristics so that clinicians and pilots can be aware of potential changes and participate intervention programs to reverse the trend

• Maintaining adequate strength, flexibility, and posture is essential to protect the spine so that a prevalence of NP/LBP or early progression of OA will be mitigated

• Experienced pilots play essential role in critical missions – their musculoskeletal characteristics can directly influence flight performance and readiness


Methods Subjects

• Helicopter pilots from the 101st Combat Aviation Brigade were recruited

• 115 male pilots participated in laboratory testing

• They were divided into 5 groups based on their total flight-hours 1. 0-999: n = 61 2. 1000-1999: n = 22 3. 2000-2999: n = 17 4. 3000-3999: n = 8 5. 4000+: n = 7

Laboratory Testing One-time visit (~2hr testing) • Neck strength (normalized to body weight) • Trunk strength (normalized to body weight) • Neck active range-of-motion • Lumbar spine range-of-motion • Hip rotation range-of-motion • Forward head posture • Forward shoulder posture • Pectoralis minor tightness

Statistical Analyses • Normality tests • One way ANOVA or Kruskal-Wallis • Post-hoc analyses for each group comparisons


Results: Demographics / APFT 0-999 1000-1999 2000-2999 3000-3999 4000+ p

Age (yr) 28.3 ± 3.8 34.6 ± 4.2 37.5 ± 4.9 40.3 ± 4.7 40.9 ± 5.8 0.001

Height (cm) 179.0 ± 8.0 177.5 ± 5.5 174.8 ± 6.4 177.2 ± 5.7 177.4 ± 5.4 0.480

Weight (kg) 82.9 ± 11.4 81.7 ± 10.8 85.6 ± 10.4 90.1 ± 7.1 88.8 ± 15.8 0.242

BMI 25.8 ± 3.1 25.8 ± 2.9 28.0 ± 3.3 28.6 ± 1.8 28.0 ± 3.8 0.010

APFT 266.2 ± 30.1 269.6 ± 23.7 255.0 ± 45.1 254.5 ± 35.9 271.5 ± 32.0 0.763

Total Flight-hrs 408.1 ± 252.1 1345.1 ± 285.4 2404.1 ± 339.7 3293.8 ± 302.9 4707.1 ± 809.5 0.001

NVG Flight-hrs 77.5 ± 62.9 375.1 ± 180.7 576.2 ± 304.8 664.4 ± 409.1 1195.0 ± 424.4 0.001

12-mon Flight-hrs 148.7 ± 98.4 177.6 ± 182.6 243.4 ± 254.5 253.2 ± 115.2 273.4 ± 174.0 0.047


Results: Neck and Trunk Strength (%BW) 0-999 1000-1999 2000-2999 3000-3999 4000+ p

Neck Flexion 17.8 ± 3.9 16.3 ± 3.9 18.8 ± 4.1 16.1 ± 3.6 20.0 ± 3.1 0.092

Neck Extension 31.5 ± 5.8 34.3 ± 3.0 31.8 ± 3.3 27.4 ± 7.2 32.0 ± 7.4 0.036

Neck Latflex R 25.4 ± 5.0 27.5 ± 3.2 26.3 ± 3.7 22.0 ± 3.6 25.6 ± 5.0 0.049

Neck Latflex L 26.8 ± 5.3 28.5 ± 4.6 26.9 ± 4.1 23.4 ± 4.0 26.3 ± 6.1 0.207

Neck Rot R 20.5 ± 3.5 22.5 ± 4.0 21.6 ± 3.6 18.3 ± 4.4 19.9 ± 4.2 0.051

Neck Rot L 21.2 ± 3.8 22.8 ± 5.1 22.2 ± 4.2 19.5 ± 4.4 21.4 ± 5.6 0.367

Trunk Flexion 249.3 ± 53.5 254.8 ± 32.8 245.8 ± 38.6 246.4 ± 43.1 246.6 ± 53.6 0.979

Trunk Extension 381.5 ± 94.7 389.6 ± 69.3 396.6 ± 63.3 331.7 ± 64.4 357.2 ± 94.6 0.400

Trunk Flex/Ext Ratio 67.4 ± 14.7 66.9 ± 12.3 63.5 ± 13.6 74.8 ± 6.1 73.1 ± 22.2 0.340

Trunk Rot R 147.1 ± 30.9 154.1 ± 21.9 153.9 ± 23.6 138.3 ± 23.8 150.7 ± 29.8 0.601

Trunk Rot L 141.3 ± 30.3 152.4 ± 21.8 147.6 ± 24.1 136.0 ± 14.2 146.4 ± 32.5 0.456

Trunk Rot R/L Ratio 104.7 ± 10.8 101.5 ± 8.2 105.0 ± 11.1 101.0 ± 9.6 104.1 ± 13.0 0.652


Results: Spine Range of Motion 0-999 1000-1999 2000-2999 3000-3999 4000+ p

Neck Flexion 58.7 ± 9.1 57.3 ± 10.2 56.4 ± 10.3 60.7 ± 5.0 61.9 ± 6.1 0.641

Neck Extension 70.8 ± 8.9 68.4 ± 6.5 62.3 ± 10.3 64.5 ± 5.3 63.1 ± 7.9 0.002

Neck Latflex R 53.5 ± 8.4 49.9 ± 5.7 46.0 ± 10.9 45.9 ± 11.7 50.4 ± 6.1 0.023

Neck Latflex L 55.2 ± 9.2 51.1 ± 6.6 48.1 ± 10.1 50.2 ± 11.2 50.3 ± 7.2 0.031

Neck Rot R 73.9 ± 8.5 71.8 ± 6.7 69.5 ± 11.4 68.6 ± 3.6 67.1 ± 7.1 0.085

Neck Rot L 73.4 ± 7.6 71.8 ± 6.5 68.6 ± 11.4 69.7 ± 3.6 68.7 ± 12.8 0.173

Back Flexion 20.4 ± 8.8 19.7 ± 8.4 19.0 ± 8.8 19.9 ± 8.4 15.4 ± 9.7 0.711

Back Extension 50.3 ± 7.9 48.2 ± 8.4 43.4 ± 8.2 42.7 ± 9.4 40.4 ± 7.2 0.001

Back Latflex R 25.8 ± 5.0 23.7 ± 5.5 24.2 ± 6.1 18.8 ± 4.5 20.3 ± 4.6 0.002

Back Latflex L 26.3 ± 5.2 24.9 ± 5.2 25.3 ± 5.7 21.5 ± 5.1 21.6 ± 3.4 0.040

Back Rot R 10.4 ± 3.9 11.8 ± 1.8 11.7 ± 3.9 11.1 ± 5.2 9.8 ± 2.9 0.159

Back Rot L 10.2 ± 3.4 11.4 ± 2.7 10.0 ± 3.1 11.4 ± 5.2 9.1 ± 3.0 0.372


Results: Hip Range of Motion and Forward Head/Shoulder Posture

0-999 1000-1999 2000-2999 3000-3999 4000+ p

Hip Int Rot R 48.0 ± 9.0 45.0 ± 9.7 40.7 ± 6.9 42.2 ± 5.2 39.9 ± 9.4 0.009

Hip Int Rot L 47.7 ± 8.8 44.7 ± 8.5 37.4 ± 8.8 41.5 ± 2.6 37.6 ± 8.1 0.001

Hip Ext Rot R 60.7 ± 8.6 57.8 ± 6.7 59.6 ± 9.4 58.0 ± 7.9 57.6 ± 6.8 0.598

Hip Ext Rot L 60.9 ± 9.3 59.1 ± 6.6 61.3 ± 11.3 58.0 ± 7.0 59.1 ± 4.8 0.816

Hip Int/Ext Rot R 108.7 ± 14.6 102.8 ± 10.4 100.3 ± 14.9 100.2 ± 8.0 97.5 ± 13.6 0.043

Hip Int/Ext Rot L 108.5 ± 15.0 103.8 ± 10.6 98.7 ± 17.8 99.5 ± 8.1 96.8 ± 9.9 0.033

Fwd Head Posture 21.6 ± 1.3 21.8 ± 1.2 22.4 ± 1.4 22.3 ± 0.8 22.6 ± 2.7 0.118

Fwd Shld R 16.2 ± 2.2 16.3 ± 1.8 16.7 ± 1.9 17.8 ± 2.2 17.7 ± 2.1 0.152

Fwd Shld L 15.7 ± 2.1 15.3 ± 1.9 16.4 ± 1.8 17.5 ± 2.8 16.6 ± 2.5 0.177

Pec Min R 6.8 ± 1.5 6.7 ± 1.5 7.0 ± 1.8 7.4 ± 1.5 7.4 ± 1.1 0.522

Pec Min L 6.3 ± 1.2 5.7 ± 1.3 6.9 ± 1.5 6.8 ± 1.2 7.3 ± 1.2 0.005


Discussion: Strength • Neck extension and lateral

flexion strength had a significant group difference

• Pilots in the 1000 group were stronger than those in the 3000-3999 group

• Early Retirement / Dropouts due to NP?

• No other strength variables were significant

Normalized Strength (based on the 0-999 group)


Discussion: Neck Range of Motion • Neck extension and lateral flexion

ROM had a significant group difference • Decreased neck extension ROM was

associated in the pilots with NP • Pilots in the 0-999 group were more

flexible than those in the 2000+ group • Early retirement/dropouts due to NP?


Discussion: Back Range of Motion

• Back extension and lateral flexion ROM had a significant group difference

• Pilots in the 0-999 group were more flexible than those in the 2000+ group

• Greater magnitude of decrement • Early retirement/dropouts due to

LBP?


Discussion: Hip Range of Motion

• Hip IR/ER ROM had a significant group difference

• Pilots in the 0-999 group were more flexible than those in the 2000+ group

• Early retirement/dropouts due to LBP / sciatic nerve involvement?


Discussion: Posture

• Pectoralis minor tightness on the left shoulder had a significant group difference

• Pilots in the 1000-1999 group were less tight than those in the 2000+ group

• Only on the left shoulder? – Halo Hunch


Recommendations

• Routine flexibility/ROM exercises pre/post flight

• Strengthening focusing neck/back extensors and lateral flexors

• Proper posture and stretching pec minor muscle

• Flexibility/ROM have downward trends throughout their career while strength may vary


Immediate Cares and Prehab

Anti-WBV / NVG Countermeasures

No Fatigue / No Pain / Good

Proprioception

Build the Body: Smart and

Specific

STOP THE BLEEDING!!!

SOF Truth: “Humans are more important than hardware”


Take Home Messages

1. Suboptimal musculoskeletal characteristics exhibited by the experienced pilots resemble those exhibited by the pilots with a history of NP/LBP

2. It is clinically important for pilots to focus on pre-flight warm-up and post-flight cool-down (stretching)

3. Scientifically designed and validated programs do work in our previous study (101st Div – ETAP), and similar programs should be implemented to reduce the NP/LBP burden among helicopter pilots


Questions?

Collaborative Opportunities?

Takashi Nagai University of Pittsburgh

[email protected]

Exposure-Related Differences on Neck and Trunk Musculoskeletal Characteristics in US ... · 2016....

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