Relationships Between Physical Fitness, Demands of Flight Duty, and Musculoskeletal Symptoms Among Military Pilots

The Fascial Distortion Model in Military Aircrew with Chronic Neck Pain: A Case Study

Musculoskeletal pain can be a significant safety risk to aircrew. Flight surgeons are the primary care providers for aircrew and are responsible for safely treating musculoskeletal pain. Certain medical interventions can be used to treat pain while maintaining the ability to fly safely. A previous F-18 Naval Flight Officer presented to the flight surgeon with chronic neck pain seeking noninvasive and nonpharmacological therapy. After one Osteopathic Manual Treatment session using the Fascial Distortion Model (FDM), the patient had improved pain and function. The aircrewman reported an 83% reduction in pain and a 200% improvement in cervical Range of Motion (ROM) immediately following treatment. Neck pain is a common complaint in aircrew. This pain can become an in-flight distraction, thus increasing the risk of aviation mishaps. FDM can decrease pain and increase ROM quickly, without equipment or a large amount of space and without the use of medications that may prohibit an aircrew member from flying. This case study shows the ability to treat a uniformed aircrewman with neck pain while onboard an aircraft. FDM is a technique that can be taught to all flight surgeons. Teaching future flight surgeons FDM techniques can improve the U.S. Navy's resources by decreasing time away from work along with decreasing medical costs. The use of osteopathic manipulation treatment significantly reduced an aircrewman's pain and increased ROM with one treatment while maintaining flight status per current aeromedical waiver guidelines.

Exposomic Signatures of Cervical Pain

INTRODUCTION

We evaluated risk factors associated with cervical pain (CP) among officers and enlisted members of the U.S. Army and Marine Aviation community using an exposomic approach. Specifically, we aimed to determine the factors associated with reported CP.

MATERIALS AND METHODS

This is a retrospective cohort study that utilized the Medical Assessment and Readiness System housed at Womack Army Medical Center to evaluate the longitudinal data taken from medical and workforce resources. This study included 77,864 active duty AMAC members during October 2015-December 2019. Multivariable mixed-effects logistic regression was used to assess the relationship between the independent variables of rank, service time, deployment, Armed Forces Qualification Test score, tobacco use, alcohol use, age, gender, race, ethnicity, body mass index, marital status, and education level and the dependent variable, incidence occurrence of CP.

RESULTS

The total analysis included 77,864 individuals with 218,180 person-years of observations. The incidence rate of CP was 18.8 per 100 person-years, with a 12% period prevalence. Cervical pain was independently associated with rank, service time, Armed Forces Qualification Test score, and alcohol use (all P < .05).

CONCLUSIONS

Our longitudinal exposomic signatures-based approach aims to complement the outcomes of data science and analytics from Medical Assessment and Readiness System with validations of objective biochemical indicator species observed in Army and Marine Aviation community members suffering from CP. This initial approach using parallel track complementarity has the potential of substantiating the underlying mechanisms foundational to design prospective personalized algorithms that can be used as a predictive model. Finally, a specific evaluation of occupational risk factors may provide insight into factors not readily ascertained from the civilian literature.

Association between physical fitness and musculoskeletal health in firefighters

Introduction: Firefighters are often placed in situations that require high levels of physical exertion, leading to significant strain on firefighters' musculoskeletal system, predisposing them to musculoskeletal discomfort (MSD) and/or musculoskeletal injury (MSI). Physical fitness programs are often recommended and justified, in part, to prevent injuries. The aim of this study was to determine the association between physical fitness and musculoskeletal health (MSH) in firefighters. Methods: A total of 308 full-time firefighters took part in the study conducted in Cape Town, South Africa. Physical fitness tests encompassed a non-exercise estimation for cardiorespiratory fitness, grip and leg strength for upper and lower body strength, push-ups and sit-ups for muscular endurance, and sit-and-reach for flexibility. The Nordic Musculoskeletal Questionnaire and Cornell Musculoskeletal Discomfort Questionnaire were used to determine MSIs and MSD, respectively. A p-value <0.05 indicated statistical significance. Results: Every one-unit increase in AbVO2max, push-ups, sit-ups, and sit-and-reach decreased the odds of firefighters reporting MSIs by 5% (p = 0.005), 3% (p = 0.017), 3% (p = 0.006), and 3% (p = 0.034), respectively. Every one repetition increase in push-up capacity increased the odds of firefighters reporting neck, elbow and forearm, wrist and hand, and thigh discomfort by 3% (p = 0.039), 4% (p = 0.031), 5% (p = 0.002), and 5%` (p = 0.007), respectively. Every one repetition increase in sit-up capacity increased the odds of firefighters reporting upper back discomfort and thigh discomfort by 5% (p = 0.045) and 7% (p = 0.013), respectively. Conclusion: Maintenance of physical fitness is likely beneficial in reducing MSIs, which, however, may increase the feeling of MSD in firefighters. In addition, it may be noticed that there is an ideal level of physical fitness that is conducive to the reduction of MSIs and should be studied further.

An Evaluation Study of a New Designed Oscillating Hydraulic Trainer of Neck

In view of the importance of neck strength training and the lack of adequate training equipment, this study designed a new oscillating hydraulic trainer (OHT) of neck based on oscillating hydraulic damper. We used surface electromyography (sEMG) and subjective ratings to evaluate the neck OHT and compared the results with a simple hat trainer (HATT) and traditional weight trainer (TWT) to verify the feasibility and validity of the OHT. Under similar exercise conditions, 12 subjects performed a set of neck flexion and extension exercise with these 3 trainers. The sEMG signals of targeted muscles were collected in real time, and subjects were asked to complete subjective evaluations of product usability after exercise. The results showed that the root mean square (RMS%) of sEMG indicated that the OHT could provide two-way resistance and train the flexors and extensors simultaneously. The overall degree of muscle activation with OHT was higher than that with the other two trainers in one movement cycle. In terms of resistance characteristics exhibited by the sEMG waveform, duration (D) with OHT was significantly longer than HATT and TWT when exercising at a high speed, while Peak Timing (PT) was later. The ratings of product usability and performing usability of OHT were remarkably higher than that of HATT and TWT. Based on the above results, the OHT was proved to be more suitable for strength training, such as neck muscles, which were getting more attention gradually, but lacked mature and special training equipment.

Typical Cockpit Ergonomics Influence on Cervical Motor Control in Healthy Young Male Adults

INTRODUCTION: Neck pain and injury are common problems in military high-performance aircraft and helicopter aircrews. A contributing factor may be the reclined sitting position in cockpits. This study aimed to determine the effect of typical cockpit ergonomics on cervical proprioception, assessed by using the cervical joint position error (cJPE).METHODS: A total of 49 healthy male military employees (mean age 19.9 ± 2.2 yr) were examined. Measurements of the cJPE were obtained in the flexion, extension, and rotation directions in an upright and in a 30°-reclined sitting position. Each condition comprised three trials, with an additional 3-kg head load to mimic real world working conditions.RESULTS: A smaller cJPE was noted in the 30°-reclined sitting position (mean cJPE = 3.9 cm) than in the upright sitting position (mean cJPE = 4.6 cm) in the flexion direction. The cJPE decreased significantly in all movement directions across the three trials; for example, in the flexion direction in the 30°-reclined sitting position: Trial 1/2/3 mean cJPE = 5.0/3.8/3.1 cm.CONCLUSION: It seems that a reclined seating position has a positive influence on cJPE. However, the result is weak. In both sitting positions and all three directions, the first tests of the cJPE showed the highest values. Already after one or two further measurement runs, a significantly reduced cJPE was observed. This rapid improvement might indicate that an exercise similar to the cJPE test may improve the pilots' cervical proprioception and possibly reduce the risk of injury or pain.Heggli U, Swanenburg J, Hofstetter L, Häusler M, Schweinhardt P, Bron D. Typical cockpit ergonomics influence on cervical motor control in healthy young male adults. Aerosp Med Hum Perform. 2023; 94(3):107-112.

Pain in the Cervical and Lumbar Spine as a Result of High G-Force Values in Military Pilots-A Systematic Review and Meta-Analysis

Neck pain and lower back pain are commonly reported by military pilots. That is why the answers to the following questions are important: (1) which part of the back (neck or lumbar spine) is more likely to be painful in military pilots as a result of high G-force, and (2) what intervention methods do pilots use as countermeasures for back pain resulting from high G-force? To answer these questions, the literature was searched in the following online databases: MEDLINE, PubMed, and Embase. A meta-analysis of eleven studies on pain in the neck-spine in fighter pilots vs. transport pilots showed pooled pulled OR = 1.69 (95% CI 1.25 to 2.29, I² = 32%, p-value = 0.21); this outcome is consistent with most of the published results. A meta-analysis of five studies on pain in the lumbar spine (lower back) did not show a difference between fighter pilots vs. transport pilots with OR = 1 (95% CI 0.83 to 1.19, I² = 0%, p-value = 0.96). The meta-analysis showed that of the two spinal segments evaluated, it was the cervical spine that showed more soreness in tactical fighter pilots. Prevention of lumbar and neck injuries should be combined with individual lumbar and neck support, as well as increasing back muscle strength through training.

Physical exercise improved muscle strength and pain on neck and shoulder in military pilots

Purpose: To evaluate the effects of physical exercise on neck and shoulder muscle strength and pain in military pilots.

Method: Embase, PubMed, and Cochrane Library databases were searched studies published up to April 1, 2022. Studies that met the screening criteria were included in the final meta-analysis. We calculated neck and shoulder maximal voluntary isometric contractions (MVICs), prevalence of pain, and pain intensity. Heterogeneity was explored by subgroup and sensitivity analyses.

Result: A total of 15 studies with 907 participants were included. In the exercise group, muscle strength was significantly increased in four directions of neck motion: flexion (standardized mean difference (SMD) = 0.45; 95% CI, 0.08–0.82), extension (SMD = 0.63; 95% CI, 0.27–1.00), right lateral flexion (Rtflx) (SMD = 0.53; 95% CI, 0.12–0.94), and left lateral flexion (Ltflx) (SMD = 0.50; 95% CI, 0.09–0.91). Subgroup analysis showed that fighter pilots, strength plus endurance training, and a follow-up period <20 weeks exhibited more significant muscle strength improvements than helicopter pilots, simple strength training, and a follow-up period ≥20 weeks. Overall, the pooled odds ratio (OR) for the effect of physical exercise on the prevalence of neck pain was not statistically significant (I² = 60%). Sensitivity analysis revealed that the heterogeneity was restored after removing each of two studies (I² = 47%), and the pooled OR was statistically significant (OR = 0.46; 95% CI, 0.23 to 0.94, or OR = 0.47; 95% CI, 0.24–0.91). Furthermore, compared with observational studies (OS), the reduction in the prevalence of neck pain was more significant in randomized controlled trials (RCTs) (OR = 0.37; 95% CI, 0.18–0.78). No significant differences in the effects of exercise on shoulder muscle strength and neck and shoulder pain intensity were observed.

Conclusion: Physical exercise can improve neck muscle strength in military pilots. After removing studies that may be the source of heterogeneity, exercise showed a protective effect on neck pain, especially in RCTs. The conclusion that exercise had no effects on shoulder muscle strength and pain intensity should be taken with caution.

Changes in physical fitness and body composition of pilot cadets before and after a process of directed flight preparation

OBJECTIVES

The aim of the study was to check the changes in the level of physical fitness and body composition after a directed training process in cadets-pilots, in relation to control group.

MATERIAL AND METHODS

The study involved 29 cadets studying at the Air Force Military Academy in Dęblin. Group A (study group)-second year pilots (n = 17), male, with an average age of 19.94 ± 1.3 years, studying to become an aircraft pilot, who realized 35-h directed training process based on the Aviation Synthetic Efficiency Test (ASET) and group B (control group)-second year in the field of ground navigation (n = 12), male, with an average age of 19.83 ± 1.27 years, completing the standard physical education process. In both groups, the fitness tests and physiological studies were conducted twice time: before starting the training process-study I; after the training process-study II. Fat mass (FM), fat-free mass (FFM), muscle mass (MM), total body water (TBW), extracellular water (ECW) and intracellular water (ICW) were measurement with using the bioimpedance method with using body composition analyzer the AKERN 101 type BIA 101SE.

RESULTS

In group A in study II, fitness was at a good level, while in group B it was below the standard expected for pilots. There was statistically significant decrease in fat mass (FM) and increase in fat-free mass (FFM), muscle mass (MM), total body water (TBW) in group A compared to group B. In study II, group A showed no significant correlation between ASET and FM, FFM, MM, TBW while group B showed statistically significant correlations.

CONCLUSIONS

The results obtained in study II showed an increase in directed physical fitness in groups A and B, as measured by ASET. In both groups A and B, the training process decreased FM and increased FFM, MM, and TBW, but a greater effect of these changes was observed in group A.

+Gz Exposure and Flight Duty Limitations

BACKGROUND: High +G_z exposure is known to cause spinal problems in fighter pilots, but the amount of tolerable cumulative +G_z exposure or its intensity is not known. The aims of this study were to assess possible breaking points during a flight career and to evaluate possible determinants affecting pilots' spines.METHODS: Survival analysis was performed on the population who started their jet training in 1995-2015. The endpoint was permanent flight duty restriction due to spinal disorder. Then the quantified G_z exposure and possible confounding factors were compared between those pilots with permanent flying restriction and their matched controls. Cumulative G_z exposure was measured sortie by sortie with fatigue index (FI) recordings. FI is determined by the number of times certain levels of G_z are exceeded during the sorties.RESULTS: The linear trend of the survival curve indicates an annual 0.86% drop out rate due to spinal problems among the fighter pilot population. A conditional logistic regression did not find any difference in the FI between cases and controls (OR 0.96, 95%CI 0.87-1.06). No statistical difference was found for flight hours, a sum of intensive flying periods, fitness tests, or with nicotine product use. Additionally, a maximum +G_z limitation without airframe restriction was assessed and is presented as a useful tool to manage loading and developed symptoms.DISCUSSION: No particular breaking point during follow-up or individual factor was found for G_z induced spinal disorders. The results of the study outline the multifactorial nature of the problem. Thus, multifactorial countermeasures are also needed to protect pilots' health.Sovelius R, Honkanen T, Janhunen M, Mäntylä M, Huhtala H, Leino T. +Gz exposure and flight duty limitations. Aerosp Med Hum Perform. 2022; 93(4):390-395.

Factors associated with low back pain in air force fighter pilots: a cross-sectional study

INTRODUCTION

Low back pain in military pilots is a frequent condition which constantly leads to absences from work, decreased concentration and performance during flight, as well as changes in work functions.

METHODS

This is a cross-sectional analytical study including 28 fighter pilots who underwent an evaluation comprising muscle strength and fatigue resistance, trunk mobility and application of questionnaires to identify associated clinical factors.

RESULTS

It was observed that 68% of the pilots reported low back pain with an average pain intensity of 3.7 at numerical pain scale in the last week. No significant differences were observed regarding the range of motion and trunk muscle strength when pilots with low back pain were compared with asymptomatic pilots. However, lateral right trunk muscle (mean difference=16, 95% CI 0.6 to 33.0]) and lateral left trunk muscle (mean difference=22, 95% CI 1 to 44) fatigue sooner in pilots with low back pain when the two groups were compared (p=0.04 for both).

CONCLUSION

There was a high rate of low back pain complaints among fighter pilots. There was also a significant reduction in fatigue resistance of the lateral trunk muscles in symptomatic pilots when compared with asymptomatic pilots. These factors must be considered in the physical training of this population.

The effects of 12 weeks of functional strength training on muscle strength, volume and activity upon exposure to elevated Gz forces in high-performance aircraft personnel

BACKGROUND

Technological advancements in modern military and acrobatic jet planes have resulted in extraordinary psychophysiological loads being exerted upon flying personnel, including inducing neck and back pain. The purpose of this study was to examine the effects of 12 weeks of functional strength training on 1) the volume and strength of the neck and shoulder muscles and 2) muscular activity upon exposure to helmets of different masses and elevated G_z forces in a long-arm centrifuge in high-performance aircraft personnel.

METHODS

Eighteen participants underwent 12 weeks of functional strength training (n = 12) or the control protocol (n = 6) without additional strength training. Pre- and post-intervention tests included evaluations of isometric strength of the head extensor muscles, flexion, and lateral flexion and rotation, as well as magnetic resonance imaging (MRI) to measure the volume of the m. sternocleidomastoideus, m. trapezius, and deep neck muscles. Furthermore, during a long-arm centrifuge (+ 1.4 and + 3 G_z) protocol, the muscular activity levels of the m. sternocleidomastoideus, m. trapezius and m. erector spinae muscles were assessed without a flight helmet, with a helmet, and with a helmet and night vision goggles. Each participant's perception of muscular strain was noted immediately after the long-arm centrifuge protocol.

RESULTS

The maximal isometric strength in all exercises and muscle volumes increased in the training group but not the control group (P < 0.05). Relative muscle activity (%MVC) with a helmet decreased after the intervention in the training but not the control group (P = 0.01). Relative muscle activity while wearing a helmet and night vision goggles was higher after intervention in the control group than in the training group (P < 0.01). The perceived muscular strain of the neck muscles induced by the long-arm centrifuge did not differ between the groups.

CONCLUSION

Twelve weeks of functional strength training improves the maximal isometric strength and volume of neck and shoulder muscles and leads to lower relative muscle activation upon exposure to elevated G_z forces in a long-arm centrifuge.

Greater Fitness Is Associated With Improved Functional Movement Characteristics in Explosive Ordnance Disposal Technicians

Hernández, LM, Coffin, SD, and Taylor, MK. Greater fitness is associated with improved functional movement characteristics in explosive ordnance disposal technicians. J Strength Cond Res XX(X): 000-000, 2020-Low fitness and poor functional movement (FM) have been linked to higher musculoskeletal injury risk. The FM Screen (FMS) and Y-Balance Test (YBT) are useful indicators of potential injury risk in military personnel. U.S. Navy Explosive Ordnance Disposal (EOD) technicians are the premier combat force for countering explosive hazards and must operate in austere environments. To safeguard health and mission success, it is critical to assess factors related to injury risk in this specialized military population. This study evaluated the relationship between fitness and FM characteristics in 64 male EOD technicians (mean age ± SD = 34.2 ± 7.0 years). Body fat percentage (BF%), maximum volume of oxygen uptake (V[Combining Dot Above]O2max), muscular strength, and FM (i.e., FMS, YBT) were assessed. Body fat percentage and V[Combining Dot Above]O2max were associated with FMS and YBT scores (all p < 0.05). A nonlinear model further revealed that the group with the lowest V[Combining Dot Above]O2max values had the bottommost FMS and YBT scores (all p < 0.01), but FM scores did not differ among those with a higher V[Combining Dot Above]O2max, implying a "threshold" effect. No correlations were observed with muscular strength. By characterizing the unique and shared contributions of BF% and V[Combining Dot Above]O2max, and exploring the nonlinear relationship between V[Combining Dot Above]O2max and FM, this study expands on accruing data that indicate individuals who are more physically fit have better FM and lower injury risk. Although muscular strength is a critical element of overall fitness, body composition and cardiorespiratory fitness may more strongly influence FM and injury risk.

Musculoskeletal disorders and their associations with health- and work-related factors: a cross-sectional comparison between Swedish air force personnel and army soldiers

BACKGROUND

The high numbers of musculoskeletal disorders (MSD) among soldiers in the Swedish Armed Forces has led to the implementation of an effective prevention program, the musculoskeletal screening protocol (MSP), including questionnaires, physical tests and individual intervention of their MSD. A corresponding MSP for the Swedish Air Force is also needed due to earlier reported high prevalence of MSD. We therefore investigated the prevalence of MSD in Swedish Air Force personnel (AF) and compared this to Swedish Army deployed soldiers (DS). Individual, health- and work-related factors associated with MSD were also investigated.

METHODS

Cross-sectional questionnaire-based study on 166 male AF and 185 DS. AF consisted of fighter pilots, helicopter pilots and rear crew from one Swedish air base.

RESULTS

The one-year and point prevalence, respectively, of MSD were significantly higher for AF compared to DS with regard to both the upper quarter of the body (i.e. neck, shoulder and thoracic regions) (AF = 54.8 and 31.3%, DS = 26.1 and 13.6%, p = 0.01) and the lumbar region (AF = 38.0 and 18.7%, DS = 22.2 and 7.1%, p = 0.00). No significant differences were present between fighter pilots, helicopter pilots and rear crew regarding MSD prevalence. Factors significantly associated with having both upper quarter and lumbar regions MSD were group (i.e. greater odds for AF than DS) and self-reported physical health as less than excellent. Additionally, being older and taller were also factors associated with lumbar region MSD.

DISCUSSION

Despite a generally healthy lifestyle, MSD were commonly reported by AF and DS, with generally higher prevalence in AF who mainly reported MSD in the upper quarter of the body. The results from this study indicate that the MSP can be a meaningful tool to prevent MSD in air force personnel and that questions regarding general health and MSD in specific body regions should be included in screening protocols. The development of the preventive program MSP is therefore recommended for the Swedish Air Force.

Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots: a 5-year follow-up

Background

A small cross sectional area (CSA) of the paraspinal muscles may be related to low back pain among military aviators but previous studies have mainly concentrated on spinal disc degeneration. Therefore, the primary aim of the study was to investigate the changes in muscle CSA and composition of the psoas and paraspinal muscles during a 5-year follow up among Finnish Air Force (FINAF) fighter pilots.

Methods

Study population consisted of 26 volunteered FINAF male fighter pilots (age: 20.6 (±0.6) at the baseline). The magnetic resonance imaging (MRI) examinations were collected at baseline and after 5 years of follow-up. CSA and composition of the paraspinal and psoas muscles were obtained at the levels of 3–4 and 4–5 lumbar spine. Maximal isometric strength tests were only performed on one occasion at baseline.

Results

The follow-up comparisons indicated that the mean CSA of the paraspinal muscles increased (p < 0.01) by 8% at L3–4 level and 7% at L4–5 level during the 5-year period. There was no change in muscle composition during the follow-up period. The paraspinal and psoas muscles’ CSA was positively related to overall maximal isometric strength at the baseline. However, there was no association between LBP and muscle composition or CSA.

Conclusions

The paraspinal muscles’ CSA increased among FINAF fighter pilots during the first 5 years of service. This might be explained by physically demanding work and regular physical activity. However, no associations between muscle composition or CSA and low back pain (LBP) experienced were observed after the five-year follow-up.

Inter-rater and test-retest reliability of movement control tests for the neck, shoulder, thoracic, lumbar, and hip regions in military personnel

Strategies are needed to mitigate the high rates and related risks of musculoskeletal complaints and injuries (MSCI) in the military aviator community. Previous work on Swedish Armed Forces (SwAF) soldiers have shown that proper screening methods have been successful in reducing early discharge from military training. Research has pointed at the importance of optimal spinal movement control in military aviators. The aim of this work was to investigate the inter-rater and test-retest reliability of a battery of clinical tests for evaluating movement control in the neck, shoulders, thoracic, lumbar, and hip regions in a population of SwAF military personnel. Inter-rater and test-retest reliability of 15 movement control tests were assessed by crude and prevalence-adjusted kappa coefficient. The study included 37 (inter-rater) and 45 (test-retest) SwAF personnel and was performed with two physiotherapists simultaneously observing and rating the movements on the first occasion and repeated with one physiotherapist on the second occasion. For inter-rater reliability, the kappa coefficient ranged from .19 to .95. Seven tests showed substantial to almost perfect agreement (kappa > .60). With the adjusted kappa, three more tests reached the level of substantial agreement. The corresponding values for test-retest reliability ranged from .26 to .65. Substantial agreement was attained for two tests, three with adjusted kappa. The following tests can reliably be used when screening for biomechanically less advantageous movement patters in military aviators: Shoulder flexion, and rotation, Neck flexion in sitting and supine, Neck extension and rotation in sitting, Pelvic tilt, Forward lean and Single and Double knee extension tests. Grading criteria for tests in supine and quadruped positions need to be further elaborated.