Trampoline exercise vs. strength training to reduce neck strain in fighter pilots

INTRODUCTION: Fighter pilots' muscular strength and endurance are subjected to very high demands. Pilots' fatigued muscles are at higher risk for injuries. The purpose of this study was to compare the effects of two different training methods in reducing muscular loading during in-flight and cervical loading testing (CLT). METHODS: There were 16 volunteer Finnish Air Force cadets who were divided into 2 groups: a strength training group (STG) and a trampoline training group (TTG). During the 6-wk training period, the STG performed dynamic flexion and extension and isometric rotation exercises, and the TTG performed trampoline bouncing exercises. During in-flight and CLT, muscle strain from the sternocleidomastoid, cervical erector spinae, trapezius, and thoracic erector spinae muscles was recorded with EMG. RESULTS: In-flight muscle strain in the STG after the training period decreased in the sternocleidomastoid 50%, cervical erector spinae 3%, trapezius 4%, and thoracic erector spinae 8%. In the TTG, the decrease was 41%, 30%, 20%, and 6%, respectively. In CLT, the results were similar. After a 3-mo follow-up period with intensive high +Gz flying, EMG during CLT was still lower than in baseline measurements. CONCLUSION: Both training methods were found to be effective in reducing muscle strain during in-flight and CLT, especially in the cervical muscles. There was no statistically significant difference between the training groups. Introduced exercises expand muscles' capacities in different ways and the authors recommend both strength and trampoline training programs to be included in fighter pilots' physical education programs.     

Acceleration effects on neck muscle strength: pilots vs. non-pilots

BACKGROUND: Conditioning of neck muscles, if any, due to repeated exposures to +Gz forces has received little research attention. OBJECTIVE: This study was conducted to evaluate and compare the neck muscle strength of test volunteers representative of the general populations of fighter aircraft pilots and non-pilots. METHODS: The tests were performed using a special attachment device on a computerized dynamometer. Ten pilots and ten non-pilots volunteered as test subjects. Each individual's maximal isometric neck muscle strength was evaluated in the extension, flexion, and left and right lateral bending directions in a single day. Peak values from the measurements were used for data analysis. Overall neck strength was calculated as the mean values for the four directions in each group. RESULTS: The overall muscular strength of the necks of pilots did not differ significantly from that of non-pilots, nor did exposure to +Gz forces lead to specific changes in isometric muscle strength across any of the four principal directions. Neck muscle strength in the four measured directions pooled across the two subgroups were statistically significant. The widespread practice of adopting protective head-positioning strategies to minimize neck strains, coupled with results from this research study, suggest that the neck muscles are subjected to reduced in-flight strengthening workouts during exposures to +Gz forces. CONCLUSIONS: To maximize in-flight performance and minimize +Gz-induced neck injuries, fighter pilots should be encouraged to perform on-land neck muscle strengthening exercise and in-flight head-positioning techniques. More research is needed to fine-tune this countermeasure strategy against cervical spine injury.     

Neck muscle activity in helicopter pilots: effect of position and helmet-mounted equipment

BACKGROUND: Helicopter pilots usually work in unfavorable ergonomic positions, often with bulky head-worn equipment during flying missions. The purpose of this study was to evaluate and compare immediate muscle response in the dorsal neck muscles to different positions with a variety of head-worn equipment. METHODS: Fourteen healthy male helicopter pilots volunteered for this study. EMG activity in the upper and lower dorsal neck muscles and the trapezius muscle was measured in a laboratory situation for 5 s in different sitting positions (neutral, trunk inclined 20 degrees, neck flexed 20 degrees), including registration of a 30 degrees left and right rotation in every position; all measurements were performed while wearing a helmet, a helmet and night vision goggles (hNVG), and a helmet, night vision goggles, and counterweight (hCW), in random order. RESULTS: There was significant higher EMG activity in the upper neck with hNVG and hCW than with the helmet only when comparing the mean activity level of all positions. However, there was no significant difference in EMG activity between any variations of head-worn equipment when comparing activity levels during each position separately. In the upper and lower neck, respectively, there was significantly higher muscle activity during the ipsilateral rotated positions plus neck flexion and trunk inclination than in most other positions. CONCLUSION: The increased load caused by different positions seems to have a greater influence on muscle activity than the increased load of the head-worn equipment, which must be considered when designing helicopter work-places.     

Flight-training effect on the cervical muscle isometric strength of trainee pilots

External stimulus/loading initiates adaptations within skeletal muscle. It has been previously found that the cervical area has the highest loading while performing flying maneuvers under +Gz. The first purpose of this study was to examine the neck muscle response to the physical environment associated with flight training, incorporating limited exposure to +Gz force, in a Pilatus PC-9 aircraft. The second purpose was to examine the short-term range of movement (ROM) response to flight training. Isometric cervical muscle strength and ROM was monitored in 9 RAAF pilots completing an 8-mo flight-training course at Pearce Airbase in Western Australia, and in 10 controls matched for gender, age, height, and weight. Isometric cervical muscle strength and ROM were measured at baseline and at 8 mo using the multi-cervical rehabilitation unit (Hanoun Medical, Downsview, Ontario, Canada). Results indicated that an increase in pilot neck strength was limited to flexion while in a neutral position. No strength changes were recorded in any other site in the pilots or for the controls. These findings suggest that short-term exposure to the physical environment associated with flight training had a limited significant effect on increasing isometric cervical muscle strength. No significant changes were observed in pilot ROM, indicating that short-term exposure to flight does not effect ROM.     

Quantitative electromyography: response of the neck muscles to conventional helmet loading

Experiments were conducted to quantify the fatigue of neck muscles which occurs during loading of these muscles by: the head itself (CON), the conventional SPH-4 helmet (HEL), and a combination of the SPH-4 helmet with Night Vision Goggles (H/NVG). Two exercise periods of 5 min and 35 min duration, respectively, were performed by the 5 subjects, during which a subject would rotate the head laterally (from side-to-side) in the CON, HEL, or H/NVG configuration. Immediately thereafter, the subject would position his head in an isometric head dynamometer and exert a sustained right lateral (LAT) neck contraction, or forward (FOR) neck contraction at 70% of his maximum strength, during which his endurance time to fatigue was recorded, and the EMG over the right sternocleidomastoid (SCM) muscle, and over the posterior trapezius/splenius muscles was continuously recorded. The root-mean-squared (RMS) amplitude of the electromyogram (EMG) continuously increased during the fatiguing contraction, being 78% greater (on the average) by the time of fatigue, and the center frequency of the EMG power spectrum continuously decreased, being 27% less (on the average) at the fatigue end-point. Some variability with head loading configuration and contraction mode was observed. These results are significant since they demonstrate that the EMG of neck muscles can be used as a noninvasive, objective and quantitative index of the neck muscle fatigue.     

Neck muscle strain when wearing helmet and NVG during acceleration on a trampoline

INTRODUCTION: The helmet-mounted equipment worn by military pilots increases the weight of the helmet system and shifts its center of gravity, increasing the loads on neck structures, especially during acceleration. The aim of this study was to determine neck muscle strain with different head-loads during trampoline-induced G loads (0 to +4 G). METHODS: Under three conditions [no helmet, helmet, helmet with night vision goggles (NVG)], 14 subjects performed trampoline exercises including basic, hand-and-knee, and back bouncing. EMG activity was measured for the sternocleidomastoid (SCM), cervical erector spinae (CES), trapezoid (TRA), and thoracic erector spinae (TES) muscles. Muscle strain was determined as a percentage of maximal voluntary contraction (%MVC). RESULTS: For the three exercises combined, the following significant changes were found: compared to control, the helmet increased muscle strain by 18%, 28%, and 18% in the SCM, CES, and TRA, respectively; NVG produced a further increase of 11% in the SCM and 6% in the CES. During back bouncing, the helmet increased muscle strain by 14% in the SCM and 19% in the CES, and NVG further increased this strain by 14% in the SCM. Hand-and-knee bouncing loaded extensors: the helmet caused increases of 46% in the CES and 29% in the TES, while NVG produced a further 13% increase in CES activation. CONCLUSION: Helmet weight alone had a large effect on muscular workload. The additional frontal weight of the NVG caused a further increase in the activity of cervical muscles that were already subjected to high strain.     

Muscle fatigue caused by repeated aerial combat maneuvering exercises.

BACKGROUND: Little is known about the development of in-flight muscular fatigue during repeated flights. HYPOTHESIS: This study was conducted to evaluate muscular fatigue in different upper body and neck muscles during repeated aerial combat maneuvering exercises. METHODS: Six pilots volunteered as test subjects. They performed one-to-one dog fight exercise three times (1 pilot, four times) in one day. During the flights, the pilots' electromyographic activity (EMG) was measured from the abdomen, back, neck and lateral neck. The mean muscular strain for each muscle was calculated. Before the first flight and after each flight, the maximal isometric strength of each muscle was measured. RESULTS: The results showed that maximal isometric strength between the first and last measurement decreased in the back, neck (p < 0.05) and lateral neck muscles. While the G-stress remained the same, the muscular strain during exercises increased in every muscle, but was significant only in neck and lateral neck (p < 0.05-0.01). Due to these changes, the fatigue index in the neck and lateral neck muscles was 2.0-2.1, and 1.3-1.4 (1.0 = no fatigue) in the abdomen and back muscles. CONCLUSIONS: Repeated aerial combat maneuvering exercises caused fatigue in every muscle studied. The fatigue was greater in the neck area, which may increase the risk for neck injuries, and may reduce mission effectiveness. The fighter pilots' muscular strength and endurance in the neck area are subjected to very high demands, especially if exercises are repeated several times. The recovery of the neck muscles from fatigue after repetitive exercises should receive special attention.     

Neck muscle strength and endurance in fighter pilots: effects of a supervised training program

INTRODUCTION: Cervical discomfort is common among pilots of high performance aircraft. An exercise program was introduced to increase the strength and endurance of the neck muscles. The purpose of this study was to analyze whether coaching or reinforcement strategies by a physical therapist was associated with improvement in neck muscle strength, endurance, and neck complaints in two cohorts of fighter pilots performing regular neck muscle exercises. METHODS: A reinforced group (RG) of 20 pilots (24-40 yr) at an Air Force base received weekly encouragement to perform their standardized exercise program three times per week. A non-reinforced reference group (NRG) of 20 pilots (23-37 yr) from another Air Force base carried out the same program without any supervision. Both groups performed the training program for 6-8 mo. Before and after the training period, isometric measurements of the neck flexors and neck extensors were performed in both groups. RESULTS: After the completion of the 6-8 mo training period, the RG pilots significantly increased their neck muscle strength (flexors: M = 3.9 nm, p = 0.000 and extensors: M = 5.0 nm, p = 0.001) as well as endurance in their neck extensors (M = 53 s, p = 0.000). The NRG pilots significantly decreased both strength (M = 11.5 nm, p = 0.0001) and endurance (M = 33 s, p = 0.003) of their neck extensors. Furthermore, the NRG pilots did not show any significant change of their neck flexor strength. No significant changes in the frequency of neck complaints were reported in either group throughout the entire study period. CONCLUSION: The reinforced training program increased the strength and endurance of the appropriate muscle groups. In order to draw any further conclusions concerning reducing neck complaints, a longer observation period with a larger group of pilots might be needed. However, it is likely that there is an individual correlation between strength and endurance of the neck muscles and neck pain, which means that any rehabilitation program should be tailored for each individual.     

Physiological effects of night vision goggle counterweights on neck musculature of military helicopter pilots

Increased helmet-mounted mass and specific neck postures have been found to be a cause of increased muscular activity and stress. However, pilots who use night vision goggles (NVG) frequently use counterweight (CW) equipment such as a lead mass that is attached to the back of the flight helmet to provide balance to counter the weight of the NVG equipment mounted to the front of the flight helmet. It is proposed that this alleviates this stress. However, no study has yet investigated the physiological effects of CW during an extended period of time during which the pilots performed normal operational tasks. Methods: Thirty-one Canadian Forces pilots were monitored on consecutive days during a day and a NVG mission in a CH-146 flight simulator. Near infrared spectroscopy probes were attached bilaterally to the trapezius muscles and hemodynamics, i.e., total oxygenation index, total hemoglobin, oxyhemoglobin, and deoxyhemoglobin, were monitored for the duration of the mission. Pilots either wore CW (n = 25) or did not wear counterweights (nCW, n = 6) as per their usual operational practice. Results: Levene's statistical tests were conducted to test for homogeneity and only total oxygenation index returned a significant result (p < or = 0.05). For the near infrared spectroscopy variables, significant differences were found to exist between CW and nCW pilots for total hemoglobin, deoxyhemoglobin, and oxyhemoglobin during NVG flights. The CW pilots displayed less metabolic and hemodynamic stress during simulated missions as compared to the nCW pilots. Conclusion: The results of this study would suggest that the use of CW equipment during NVG missions in military helicopter pilots does minimize the metabolic and hemodynamic responses of the trapezius muscles.     

Neck strength and myoelectric fatigue in fighter and helicopter pilots with a history of neck pain

INTRODUCTION: Flight-induced neck pain at high Gz loads or during sustained rotary-wing missions may be caused by limitations in neck muscle function. A better understanding of the contributing factors of excessive external load and internal neck-stabilizing mechanisms would improve the ability to prevent and treat such pain. The aim of this single-blinded cross-sectional study was to evaluate neck neuromuscular function in fighter and helicopter pilots who suffered from frequent neck pain. METHODS: Subjects with pain were 16 fighter pilots (FP-P) and 15 helicopter pilots (HP-P) with frequent neck pain episodes who were compared with pain-free controls (FP-C and HP-C). In all groups, neck extensor and flexor muscles were studied by measuring 1) the strength of maximum voluntary contraction (MVC), and 2) fatigue due to a submaximal isometric contraction. The decline (slope) of the electromyogram (EMG) median frequency power spectra was used as an index of fatigue, while initial median frequency (fi) was taken from the intercept of the regression line. RESULTS: Two-way analysis of variance (ANOVA) revealed interaction effects for extensor MVC. Post hoc testing showed that FP-P had significantly lower extensor MVC (p = 0.03) than FP-C, while there was no such difference for the HP-P vs. HP-C or between the two control groups. There were no significant effects for MVC-balance (flexors/extensors); nor were there any fi or extensor EMG-slope effects. However, there were interaction effects for flexor EMG-slopes: HP-P showed lower slopes than did HP-C (p = 0.02). CONCLUSIONS: To protect and stabilize the head and neck in high Gz environments, higher neck muscle strength is needed; less muscle strength in FP-P may cause further pain and perhaps reduced mission effectiveness. Less localized steep slopes for HP-P might reflect impaired muscle functioning. Specific preventive and clinical attention may be warranted for different types of pilot.     

A method for comparing manual muscle strength measurements with joint moments during walking

This paper describes a protocol for dynamometer assisted manual muscle testing of the major muscle groups of the lower extremity and its application to 11 able-bodied children who also had conventional gait analysis to obtain joint kinetics. Data from the manual muscle testing was processed in such a way that the results for maximum muscle strength (grade 5) and resistance against gravity alone (grade 3) were presented in N m/kg allowing direct comparison with conventional joint kinetics. The strength measurements of the hip muscles and the knee extensors were between two and three times the moments exerted during normal walking. Those of the knee flexors and dorsiflexors were about five times the joint moments. Measured plantarflexor strength was only just greater than the moment exerted during walking. These results, particularly those for the plantarflexors, question how valid it is to use measures of isometric muscle strength as indicators of muscle function during activity. The study also compares grade 3 muscle strength with both grade 5 strength and the maximum joint moments. For all muscle groups tested grade 3 muscle strength was less than the maximum moment exerted during normal walking. For the plantarflexors it was less than 1% of that moment. The study demonstrates that reliable isometric muscle testing is possible in able-bodied children but requires considerable care and is time consuming. More work is required to understand how measurements made in this way relate to how muscles function during activity.     

Fatigue is not a necessary stimulus for strength gains during resistance training

BACKGROUND: High resistance training enhances muscular strength, and recent work has suggested an important role for metabolite accumulation in this process. OBJECTIVE: To investigate the role of fatigue and metabolite accumulation in strength gains by comparing highly fatiguing and non-fatiguing isotonic training protocols. METHODS: Twenty three healthy adults (18-29 years of age; eight women) were assigned to either a high fatigue protocol (HF: four sets of 10 repetitions with 30 seconds rest between sets) to maximise metabolic stress or a low fatigue protocol (LF: 40 repetitions with 30 seconds between each repetition) to minimise changes. Subjects lifted on average 73% of their 1 repetition maximum through the full range of knee extension with both legs, three times a week. Quadriceps isometric strength of each leg was measured at a knee joint angle of 1.57 rad (90 degrees ), and a Cybex 340 isokinetic dynamometer was used to measure the angle-torque and torque-velocity relations of the non-dominant leg. RESULTS: At the mid-point of the training, the HF group had 50% greater gains in isometric strength, although this was not significant (4.5 weeks: HF, 13.3 (4.4)%; LF, 8.9 (3.6)%). This rate of increase was not sustained by the HF group, and after nine weeks of training all the strength measurements showed similar improvements for both groups (isometric strength: HF, 18.2 (3.9)%; LF, 14.5 (4.0)%). The strength gains were limited to the longer muscle lengths despite training over the full range of movement. CONCLUSIONS: Fatigue and metabolite accumulation do not appear to be critical stimuli for strength gain, and resistance training can be effective without the severe discomfort and acute physical effort associated with fatiguing contractions.     

蹬力测量系统在载人离心机上的应用

目的 观察一套安装在载人离心机上的蹬力测量系统使用效果. 方法 蹬力测量系统包括蹬力的传导及信号处理两个部分.蹬力传导部分包括左、右两套带气囊的踏板和1个充气组件.蹬力信号处理部分由5502型压力传感器、5B系列隔离信号调理模块、DaqBoard/2005TMA/D板及DASYLab 5.6 软件等组成.将该系统安装在AMST-HC-4E型载人离心机上,进行了以9名歼击机飞行员为受试者的3组+Gz暴露试验. 结果 不同载荷时的气囊内压力差异显著(F=11.63,P=0.000).气囊内压力与载荷呈正相关,其线性回归方程为:气囊内压力P=4.5×载荷+4.2(r=0.915,P<0.01).根据气囊内压力曲线形态,可判断飞行员在作抗荷动作时的下肢用力方式. 结论 该测量系统能够实时监测加速度作用时受试者的蹬力变化.在加速度耐力检查及离心机训练时可利用该系统监测受试者的下肢用力情况.     

Centrifuge training increases presyncopal orthostatic tolerance in ambulatory men

INTRODUCTION: Exposure to spaceflight or simulations of microgravity reduce human postflight orthostatic tolerance. Exercise training and volume loading can reduce associated losses of plasma volume and muscle strength, but are not successful in maintaining postflight orthostatic tolerance. A preliminary study (16) indicated that short bouts of artificial gravity (AG) training on a centrifuge could increase orthostatic tolerance in healthy, ambulatory volunteers. We tested the same AG protocol for its tolerance effect on 14 men who underwent a 3-wk exposure to Gz acceleration training on NASA-Ames' (Moffet Field, CA) human-powered centrifuge. METHODS: Subjects trained supine (head near the center of rotation) and in pairs (one subject rode passively while the other provided power to operate the 1.9-m centrifuge). The acceleration profile consisted of 7 min at 1 Gz before alternating between 1 and 2.5 Gz at 2-min intervals for 28 min. Each subject's presyncopal orthostatic tolerance limit (to a combination of 70 degrees head-up tilt and increasing lower body negative pressure) was determined before and after training. RESULTS: There were no significant differences between training groups, but presyncopal orthostatic tolerance time was improved 17 +/- 10% (p < 0.05) for the combined groups. Mechanisms associated with increased tolerance included: increased cardiac output (p < 0.04), stroke volume (p < 0.01) and low-frequency spectral power of arterial pressure (p < 0.006), and decreased arterial pressure (p < 0.05) and vascular resistance (p < 0.04). Artificial gravity training in this group of men appears to increase orthostatic tolerance through a combination of decreased vascular resistance and enhanced cardiac function.     

Acceleration effects on manual performance with isometric and displacement joysticks

BACKGROUND: We have shown before that novice human subjects produce exaggerated isometric forces when exposed to three times normal terrestrial acceleration (+3 Gz), and that this deficit is compensated by intensive training in +3 Gz. We now investigate whether training in normal terrestrial gravity (normal G) is also effective. We further examine whether subjects in +3 Gz produce not only exaggerated forces, but also exaggerated hand displacements. METHODS: Experiments were conducted in the stationary (normal G) or rotating (+3 Gz) gondola of a man-rated centrifuge. With their dominant hand, subjects produced either forces using an isometric joystick, or hand displacements using a regular joystick. Response directions and magnitudes were prescribed visually. In practice trials, subjects received continuous visual feedback about their performance, while in test trials they did not. RESULTS: Subjects produced exaggerated forces in +3 Gz, whether or not they previously practiced the task in normal G. In contrast, subjects did not produce exaggerated hand displacements in +3 Gz. DISCUSSION: Exaggerated force production in +3 Gz is not overcome by task practice in normal G, as opposed to task practice in +3 Gz. This might be an indication that pilot training should contain extended practice of force production during phases of increased gravity (+Gz) to avoid motor deficits during flight maneuvers inducing +Gz. Furthermore, the control of isometric and regular joysticks seems to be based on partly distinct neural mechanisms, with different +Gz dependence. Thus, against the background of motor performance during +Gz, regular sticks might be favorably compared to isometric sticks in high-performance aircrafts.     

Effect of Gz forces and head movements on cervical erector spinae muscle strain.

A portable surface-integrated EMG (IEMG) device was used to investigate the strain caused by low and high Gz forces and head movements on the cervical erector spinae muscles during flight missions. The obtained IEMG activities were normalized by comparing them with activities representing maximal voluntary contraction (MVC) of the cervical erector spinae muscles in each subject. The muscular strain increased with increasing Gz forces and head movements. Under +7.0 Gz the mean muscular strain was 5.9-fold compared with +1.0 Gz and was 37.9% of the MVC. In some individuals, the muscular tolerance (100% of the MVC) was ipsilaterally reached already under +4.0 Gz with concomitant movements and twisted positions of the head. Pilots are susceptible to acute neck injury when the protection afforded by their neck muscles is insufficient.     

Prevention of disuse muscular weakness by restriction of blood flow

PURPOSE: The aim of the present study was to compare the effects of periodic restriction of blood flow to lower extremities with those of isometric exercise on disuse muscular atrophy and weakness induced by immobilization and unloading. METHODS: The left ankle of each of 15 healthy males was immobilized for 2 wk using cast, and subjects were instructed to walk using crutches with non-weight bearing during this period. Subjects were divided into three groups: a restriction of blood flow (RBF) group (application of external compressive force of 200 mm Hg for 5 min followed by 3 min of rest, repeated five times in a single session, two sessions per day for 14 d); an isometric training (IMT) group (20 "exercises" of 5-s isometric contraction of the knee extensor, flexor, and ankle plantar flexor muscles followed by rest, twice a day, daily for 2 wk); and a control (CON) group (no intervention). We measured changes in muscle strength, thigh/leg circumferences, and serum growth hormone levels. RESULTS: Immobilization/unloading resulted in significant decreases in muscle strength of knee extensor and flexor muscles (P < 0.01 and < 0.05, respectively) and thigh and leg circumferences (P < 0.05, each) in the CON group, and significant decreases in muscle strength of the knee flexor muscles, ankle plantar flexor muscles, and leg circumference (P < 0.05) in the IMT group. RBF protected against these changes in muscle strength and thigh/leg circumference (P < 0.01 and < 0.05, respectively). No changes in serum growth hormone levels were noted. CONCLUSION: Our results indicate that repetitive restriction of blood flow to the lower extremity prevents disuse muscular weakness.     

Neck strength and EMG activity in fighter pilots with episodic neck pain

INTRODUCTION: Neck pain is common in fighter pilots due to repeated exposure to high +Gz loads, but studies comparing neck function in symptomatic and healthy fighter pilots are lacking. This study compared neck strength and EMG activity during maximal isometric contractions in a sitting position in the sagittal and coronal planes in neck pain (SP), asymptomatic fighter pilots (AP), and healthy, male, non-pilot subjects (NPS). METHODS: There were 9 SP, 10 AP, and 8 NPS, all males, who performed maximal isometric neck contractions on a specific dynamometer. Surface EMG activity was recorded bilaterally over the sternocleidomastoid and paraspinal muscles. EMG amplitude during side bending was normalized to that measured in the sagittal plane. RESULTS: SP exhibited lower side-bending strength than AP (17-19%, P < 0.05). In addition, SP and NPS exhibited lower left side-bending-to-extension torque ratios (20% and 14%, respectively, P < 0.05) than AP. Similar activation level of neck flexors and extensors during side bending was found in SP and AP, whereas EMG activity of the extensors was higher than the flexors in NPS (+48%, P < 0.05). In addition, antagonistic EMG activity was higher in AP compared to NPS (26% vs. 41%, respectively, P < 0.05). CONCLUSION: Our results suggest altered muscle function in SP compared with AP in the coronal but not in the sagittal plane. Further, AP appeared to be more efficient in the coronal plane with reference to neck extension than NPS, suggesting that some adaptations occurred due to flight exposure. These findings may have clinical implications for the management and the follow-up of neck pain in fighter pilots.     

Neck exercises compared to muscle activation during aerial combat maneuvers

INTRODUCTION: Performing specific neck strengthening exercises has been proposed to decrease the incidence of neck injury and pain in high performance combat pilots. However, there is little known about these exercises in comparison to the demands on the neck musculature in flight. METHODS: Eight male non-pilots performed specific neck exercises using two different modalities (elastic band and resistance machine) at six different intensities in flexion, extension, and lateral bending. Six Royal Australian Air Force Hawk pilots flew a sortie that included combinations of three +Gz levels and four head positions. Surface electromyography (EMG) from selected neck and shoulder muscles was recorded in both activities. RESULTS: Muscle activation levels recorded during the three elastic band exercises were similar to in-flight EMG collected at +1 Gz (15% MVIC). EMG levels elicited during the 50% resistance machine exercises were between the +3 Gz (9-40% MVIC) and +5 Gz (16-53% MVIC) ranges of muscle activations in most muscles. EMG recorded during 70% and 90% resistance machine exercises were generally higher than in-flight EMG at +5 Gz. DISCUSSION: Elastic band exercises could possibly be useful to pilots who fly low +Gz missions while 50% resistance machine mimicked neck loads experienced by combat pilots flying high +Gz ACM. The 70% and 90% resistance machine intensities are known to optimize maximal strength but should be administered with care because of the unknown spinal loads and diminished muscle force generating capacity after exercise.