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

Authors:
  • Finnish Institute of Occupational Health, Oulu

Abstract and Figures

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). 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. 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. 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.
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RESEARCH ARTICLE
Trampoline Exercise vs. Strength Training to Reduce
Neck Strain in Fighter Pilots
Roope Sovelius,Juha Oksa,Harri Rintala,
Heini Huhtala,Jari Ylinen, and Simo Siitonen
SOVELIUS R, OKSA J, RINTALA H, HUHTALA H, YLINEN J, SIITONEN S.
Trampoline exercise vs. strength training to reduce neck strain in
fighter pilots. Aviat Space Environ Med 2006; 77:20–5.
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 G
z 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. Intro-
duced 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.
Keywords: trampoline, strength training, G
z loading, neck injury pre-
vention, neck injuries.
T
HE MANEUVERABILITY of a modern high perfor-
mance combat aircraft may exceed the pilot’s capa-
bilities to tolerate high G
z acceleration. High Gz load
with high onset rate may produce neck pain and more
serious injuries (11). Especially in the lateral neck, peak
strain with magnitude well above the maximal volun-
tary contraction has been measured, thus presenting a
potential risk for negative health effects and injuries
(19). The level of peak strain episodes means that fighter
pilots’ muscular strength and endurance, particularly in
the neck and shoulder area, are subjected to demands
clearly higher than those of the average population.
When sorties are repeated several times per day, aerial
combat maneuvering exercises cause fatigue, especially
in the neck muscles (20). Fatigued muscles perform
with less power, leading to increased strain under
equivalent loading, which may in turn increase the risk
for neck injuries.
Individual factors affecting the pilot’s muscle G
z
load tolerance include strength and motor skill. It has
been reported in the literature that increased muscle
strength may reduce muscle strain under G
z loading
(2,6,7) and thus diminish the incidence of acute in-flight
neck pain (10,13,18). Portero (21) reported the beneficial
effect of a strength-training program which increases
neck muscle size and strength during lateral flexion,
and decreases the fatigability of the superficial muscles
of the neck. The training effects were evaluated in their
study in three ways: strength; muscles’ cross-sectional
area in computerized tomography; and fatigability
evaluated with a decrease in mean power frequency of
the electromyogram.
Trampoline training has been considered as a tool to
create a “G environment” for fighter pilots’ physical
training. The purpose of trampoline training is to im-
prove general motor skills and to enhance muscle bal-
ance. However, as relatively low-intensity, repetitive
muscular loading, it has the potential to improve mus-
cle tone and endurance. Muscular fatigue and post-
exercise muscular soreness in the neck/shoulder, fore-
neck, and abdominal area have also been reported
when we evaluated users’ experiences with this new
training method.
The aim of this study was to compare two different
training methods for reducing fighter pilots’ neck strain
under Gz loading and to evaluate how permanent the
possible effects of the training methods were after a
3-mo follow-up. The question was: is it more efficient to
do exercises that increase the general muscle strength or
those that improve motor skill and muscle balance?
From the Training Air Wing, Finnish Air Force, Kauhava (R. Sove-
lius); the Oulu Regional Institute of Occupational Health, Oulu (J.
Oksa); Finnish Air Force Headquarters, Tikkakoski (H. Rintala, S.
Siitonen); the School of Public Health, University of Tampere (H.
Huhtala); and the Department of Physical and Rehabilitation Medi-
cine, Central Hospital, Jyva¨skyla¨ (J. Ylinen); Finland.
This manuscript was received for review in July 2005. It was
accepted for publication in October 2005.
Address reprint requests to: Roope Sovelius, Training Air Wing,
P.O. Box 5, FIN-62201 Kauhava, Finland; roope.sovelius@mil.fi.
Reprint & Copyright © by Aerospace Medical Association, Alexan-
dria, VA.
20 Aviation, Space, and Environmental Medicine Vol. 77, No. 1 January 2006
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METHODS
Materials
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).
Mean age was 22.1 0.6 yr in the STG and 22.6 0.9 yr
in the TTG, height 178.5 4.6 cm and 177.5 4.9 cm,
weight 77.4 6.5 kg and 76.3 6.8 kg, and body mass
index 24.3 1.1 kg m
2
and 24.2 1.5 kg m
2
,
respectively. The subjects were informed of the details
of the experimental protocol and the study was granted
approval by the Finnish Defense Force Medical Re-
search Register, the Finnish Air Force Headquarters
Research License, and the Ethical Committee of Central
Finland Hospital District.
The program was part of the cadets’ physical training
program. Prior to starting the training period all sub-
jects took part in an introduction phase when training
methods and exercises were practiced to ensure that all
subjects had appropriate skills when the actual training
was performed. The training program lasted for 6 wk
and consisted of 2–3 exercise sessions per week. Train-
ing assessments were held to evaluate the successful-
ness of the training program. The STG did cervical
dynamic flexion and extension exercises and isometric
rotation exercises. Each training session consisted of
2–4 sets of each exercise. Sets were 20 40 reps with the
resistance of approximately 15–30% of the measured
maximal isometric force in the neutral position. Reps
and resistance were increased progressively in each
successive training week. The program consisted of two
3-wk periods of easy, moderate, and hard training
weeks. Endurance type, relatively low exercise intensity
was chosen to achieve increased endurance strength of
the muscle groups exercised and to avoid over-training
or cervical discomfort caused by too heavy loading.
The trampoline training program consisted of basic
trampoline exercises including basic, hand and knee,
and back bouncing. A round trampoline with a diam-
eter of 4.3 m (JumpKing, Inc., Portland, OR) was used.
Exercises were performed up to subjectively evaluated
fatigue, normally in 30 60 s in one set, and there were
similar 30 60-s recovery times between the sets. In the
beginning of the training period, the set was performed
twice, and after 2 wk, it was repeated three times. On a
separate occasion, vertical acceleration measurements
(n 4) during bouncing were performed with a MoTec
ADL Datalogger and triple axis G-sensor (Printsport
Oy, Lievestuore, Finland) fixed to the flying helmet.
All subjects flew test flights with a BAe Hawk MK 51
jet trainer at the beginning and on completion of the
training period. The flights were similar training sorties
and consisted of aerobatics and basic tactical maneu-
vering. They were performed according to the sortie
charts where the order of maneuvering and their per-
formance values (e.g., v
i,Gz, etc.) were stated com-
pletely. The number of times the levels of 0.25, 2.5,
3.5, 4.5, 5.5, and 7.0 G
z were exceeded during the
flight was recorded by the aircraft’s G
z-meter coder.
In addition to in-flight measurements, muscle strain
was also measured during a cervical loading test (CLT).
In this test, cervical flexor and extensor muscles were
loaded separately. Lateral loads were not tested due to
a higher injury risk since a loaded vertebral column and
muscles have less range of movement in that direction.
Each neck movement, or strain against a load, involves
multiple muscles working together, and the same mus-
cle is participating in various different types of move-
ment. Thus all muscles involved in anterior flexion
movement or in straining against a posterior load have
been considered flexors and all muscles involved in
extension or strain against an anterior load have been
considered extensors. In the test, each subject lay supine
on the test table with shoulders on the edge of the test
table wearing a helmet with an external load hanging
on an 8-cm long elastic rope. The load for each subject
was 25% of the maximal cervical extension force and
10% of the maximal cervical flexion force. The load was
dropped from the frontal level (extensors) or from the
occipital level (flexors) 15 times. The rope stretched
approximately 6 cm when the load was dropped, and it
incurred impact loading on the muscle group involved.
The test was also performed 3 mo later (during a fol-
low-up period) after a period of intensive flight training
with high G
z loading. The purpose of using the CLT
was to exclude the effect of learning and improved
Fig. 1. The subject is seated in a standard position. The head is
automatically centralized by tightening the pads (C) simultaneously from
both sides by a screw system traveling the same distance, so that the
sagittal plane comes into the middle. The frontal plane along the rotation
axis of the apparatus (y) is verified to run through the opening of both ear
canals by two sights (D). The pads can be moved (B) for comfort on the
skull. The cheek is supported (F) to prevent head movement. The chest
(G) and waist (H) are tightly fixed to the bars with wide straps at the level
of the iliac spine and above the lower border of the scapula. Rotational
forces are recorded from the load cell of the device (A). The load cell (F)
is moved upwards and placed against the forehead with the lower edge
located midway between the inner canthus of both eyes to measure
neck flexion force.
REDUCING NECK STRAIN—SOVELIUS ET AL.
21Aviation, Space, and Environmental Medicine Vol. 77, No. 1 January 2006
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flying skills during the training period and follow-up.
One subject had an in-flight neck injury prior to the
scheduled test day, another was rejected from flight
training during follow-up, and these two did not per-
form the follow-up measurements.
During the test flights and CLT, EMG activity of the
right and left sternocleidomastoid, cervical and thoracic
erector spinae, and trapezius muscles were measured
using bipolar surface electrodes. Measured EMG was
proportional to maximal voluntary contraction (MVC)
EMG level and muscle strain was determined as a
percent of MVC (%MVC). Muscle strain was deter-
mined using a portable eight-channel EMG device
(ME3000P, Mega Electronics Ltd., Kuopio, Finland).
The bipolar EMG recordings were made using pre-
gelled surface electrodes (Medicotest M-OO-S, Ol-
stykke, Denmark). The electrodes were placed longitu-
dinally on the muscles; the distance between the
measurement surfaces of the electrodes was 2 cm. The
ground electrodes were placed on inactive tissue. The
measured signal was preamplified 1000 times. The sig-
nal-band between 20 and 500 Hz was full-wave rectified
and averaged with a 100-ms time constant. The sites of
the electrodes were marked on a clear plastic film with
the aid of anatomical marks (moles, scars, etc.), thus
ensuring that the electrodes were replaced in exactly
the same place after the training period and for fol-
low-up measurements.
The muscle strength of the cervical flexor, extensor,
and rotator muscles was measured with an isometric
neck strength measurement system (INSMS, Kuntova¨-
line Oy, Finland) (25) before and after the training pe-
riod (pre- and post-test). The subject was seated facing
toward the apparatus while testing rotation and flexion
forces (Fig. 1). While testing extension forces the subject
was seated facing away from the apparatus. The load-
cell was placed against the occipital at the same height
as it was while measuring flexion force. After warm-up,
the subject was asked to push/turn with maximal force
three times in each direction with a pause of 45 s
between each effort. The best one of three efforts was
chosen for data analysis.
Statistics
Mean differences with 95% CI are given as descrip-
tive statistics. A t-test was used to compare in-flight
G
z loads between training groups or Flight 1 and
Flight 2. ANOVA with repeated measures were used to
determine training effects, i.e., muscle strain after the
training period and between training groups. In all
tests, p 0.05 was considered statistically significant.
RESULTS
Vertical acceleration during basic trampoline bounc-
ing varied between 0 and 4Gz. A sample of the
acceleration curve as a function of time is shown in Fig.
2. Comparison of G
z loading during the test flights is
shown in Fig. 3. G
z loading was similar between
training groups (p 0.21) and between flights in the
beginning and on completion of the training period
(p 0.23).
Maximal muscle force was increased in both groups
in all measured directions after the training period. All
test subjects enhanced their flexion and extension forces
during the training period. Improvement in flexion
force was significantly better in the TTG; otherwise
statistically significant differences between the training
groups were not seen (Table I).
In-flight muscle strain (%MVC) decreased after the
training period in both groups and most significantly in
the cervical muscles, especially in the sternocleidomas-
toid muscles. In the trapezoid and thoracic erector spi-
nae muscles, the effect of training was not so clearly
seen. There was no statistically significant difference in
Fig. 2. Vertical acceleration during basic trampoline bouncing.
Fig. 3. Gz loading during test
flights. The aircraft’s Gz-meter coder
recorded the number of times the
given Gs were exceeded during the
flight.
REDUCING NECK STRAIN—SOVELIUS ET AL.
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in-flight muscle strain between the training groups (Ta-
ble II).
Results were similar in the CLT measurements. Both
training methods decreased muscle strain in the cervi-
cal muscles, in both the sternocleidomastoid and in the
cervical erector spinae. In the lower muscles such a
clear difference was not seen. Again, between training
groups there was no statistically significant difference
in any measured muscle (Table III).
There was a tendency toward reduced EMG activity
during the CLT in all muscles from the beginning to the
end of the follow-up period (Fig. 4). The positive effects
of the training period in muscle loading was sustained
in the cervical area in both training groups (STG and
TTG), but in the thoracic erector spinae muscles the
results were not so clear. No statistically significant
difference was seen between the training groups.
DISCUSSION
The results of this study indicate that training de-
creased muscle strain in-flight and during the CLT,
especially in the lateral neck area. Both methods
seemed to be efficient and their effect was still seen after
a 3-mo follow-up period. The in-flight measurements
were taken during ordinary flight training sorties. It is
not possible to reach the accuracy of a centrifuge in Gz
loading when a human is piloting an aircraft, but anal-
ysis of the Gz loading during flights evinced compa-
rable loads between training groups as well as between
the before and after training periods. Therefore, the
results obtained in this study can be considered as
reliable and as reflecting changes in the functional ca-
pacity of the pilots rather than in differences in external
loading.
Training intervention was short, but it has been re-
ported that with 6 wk training it is possible to increase
muscle force (1,14,17), and improved muscle force has
been reported to diminish in-flight strain or neck pain
under G
z loading (2,6,10,18,21). The improvement in
maximal muscle force in this study was small but sta-
tistically significant in both training groups, thus con-
firming previous findings. However, because the mea-
surements were isometric and performed in the neutral
position, the maximal forces measured probably did not
show the entire increase in muscle power. Muscle force
can vary greatly depending on the phase of movement
(15,23,24).
Since both these training methods included rather
low-intensity exercises, the increase in maximal muscle
force was relatively small. It should also be considered
that every training method is site- and intensity-spe-
cific, and that the accuracy of the measurements may
cause small changes in the measured results. However,
in this study all test subjects increased their flexion and
extension forces during the training period. This sup-
ports the presumption that the changes seen in maximal
forces are due to the training. In the literature, submaxi-
mal strength training or endurance training has also
been reported to have a positive effect on maximal
strength (3,4,12). In fact, it is likely that due to low-
intensity training (both the STG and TTG), the submaxi-
mal endurance and motor coordination of the neck/
shoulder area muscles were enhanced. It may be
assumed that strength training would have more effect
on submaximal endurance and trampoline training on
motor coordination than vice versa. However, based on
these results this remains a speculation. Training may
cause adaptations to the many neural elements that are
involved in the control of movement. Increased neuro-
muscular performance and intermuscular coordination
may increase mechanical efficiency in maintaining cer-
vical stability and thus have a beneficial effect in de-
creasing in-flight and CLT muscle strain. In this sense
both training methods were successful. Even a small
TABLE I. THE EFFECT OF TRAINING PERIOD ON MAXIMAL FORCES PERFORMED.
Cervical Force
STG TTG
Pre- vs.
Post-test STG vs. TTG
Pretest
(N)
Change
(%) CI (95%)
Pretest
(N)
Change
(%) CI (95%) p p
Flexion 316 2.3 1.8 to 2.8 337 3.2 2.9 to 3.5 0.001 0.005
Extension 155 6.0 5.4 to 6.6 200 6.4 5.9 to 6.9 0.001 0.250
Rotation 160 6.5 0.2 to 12.5 176 3.1 2.5 to 8.7 0.052 0.423
STG strength training group; TTG trampoline training group.
TABLE II. THE EFFECT OF TRAINING ON MUSCLE STRAIN (aEMG) DURING TEST FLIGHTS DESCRIBED AS CHANGES IN %MVC.
Muscles
STG TTG
Flight 1 vs.
Flight 2 STG vs. TTG
%MVC CI (95%) %MVC CI (95%) p p
SCM 50.3 54.0 to 12.4 40.8 43.4 to 13.2 0.049 0.637
CES 2.6 13.1 to 5.1 30.5 39.4 to 18.8 0.053 0.080
TRA 4.3 36.2 to 3.0 20.0 26.0 to 8.6 0.428 0.675
TES 7.9 25.4 to 94.2 6.1 38.6 to 10.0 0.933 0.637
STG strength training group; TTG trampoline training group.
SCM sternocleidomastoid; CES cervical erector spinae; TRA trapezius; TES thoracic erector spinae.
REDUCING NECK STRAIN—SOVELIUS ET AL.
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decrease in muscle strain during flight sorties may di-
minish muscle fatigue. Less fatigued muscles need
shorter recovery times after contraction, i.e., when
loaded. This also aids maintenance of muscles’ safety
margins during high onset rate Gz loading.
Both training methods were successful in reducing
in-flight muscle strain. Training was most effective in
the cervical area (sternocleidomastoid and cervical erec-
tor spinae), but a positive effect was also seen in the
lower muscles (trapezius and thoracic erector spinae
muscles). This may be due, in part, to the exercises. In
the strength training program, both dynamic and iso-
metric exercises were performed, mostly with cervical
muscles, so the effect was naturally greatest in the
muscle groups specifically practiced. Then again, there
were neck flexor (back bouncing) and neck extensor
specific exercises (hand and knee bouncing) in the tram-
poline training program, too.
In this study the muscles’ in-flight %MVC levels were
not very high, which differs from some other reports
(8,9,16,19). This may be due to the nature of the test
flights. The sorties were basic aerobatics and maneuver-
ing with single aircraft. During air combat flights pilots
need higher Gz maneuvering and move their heads to
follow the other aircrafts’ moves. This increases the
load on the cervical muscles, especially the sternoclei-
domastoid muscles that also rotate, bend laterally, and
resist extension of the head from the neutral position.
However, both training methods had a positive effect
on these critical muscles. A slight increase in strength
resulted in a slight decrease of strain in the cervical
erector spinae muscles. In the lower part of the spine,
where the muscles stabilize the posture rather than
perform movements against Gz loading, the results
were more variable.
A similar change in muscle strain was seen in the
CLT as during in-flight EMG-measurements. This sup-
ports the hypothesis that improved muscular capacity
due to training decreases muscle strain under Gz load-
ing. The test also excluded the effect of cadets’ im-
proved flying skills during the training period as a
factor of change to muscle strain: improved flying skills
or learning had no effect on loading in the CLT. The
%MVC levels were higher in the CLT than during test
Fig. 4. EMG activity during CLT in all muscles in the beginning (pretest), on completion of the training period (post-test), and after 3 mo
(follow-up).
TABLE III. THE EFFECT OF TRAINING ON MUSCLE STRAIN (aEMG) IN THE CERVICAL LOADING TEST (CLT) DESCRIBED AS
CHANGES IN %MVC.
Muscles
STG TTG
Pretest vs.
Post-test STG vs. TTG
%MVC CI (95%) %MVC CI (95%) p p
SCM 17.3 21.7 to 8.7 6.7 29.7 to 3.1 0.059 0.291
CES 15.7 25.8 to 8.8 22.0 38.6 to 10.0 0.001 0.555
TRA 30.0 91.9 to 20.3 9.5 29.9 to 14.5 0.347 0.688
TES 23.7 41.8 to 1.8 26.4 39.0 to 11.8 0.013 0.582
STG strength training group; TTG trampoline training group.
SCM sternocleidomastoid; CES cervical erector spinae; TRA trapezius; TES thoracic erector spinae.
REDUCING NECK STRAIN—SOVELIUS ET AL.
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flights, which may be due to the more impulsive and
impact type loading in the CLT than the moderate,
more sustained in-flight accelerations during the flights.
On the other hand, in-flight recorded data also included
flying between maneuvers. Even though %MVC values
were higher in the CLT, these results indicate that the
CLT is a sensitive method for simulation of in-flight
loading over the cervical area. It is an inexpensive and
simple on-site alternative to test flights and centrifuge
tests, and especially useful in follow-ups.
On completion of the 3-mo follow-up period, the
muscles’ electrical activities during the CLT were sim-
ilar to those after the training period. Decreased muscle
strain in the cervical muscles was still seen, and there
was no statistically significant difference between train-
ing methods. During the follow-up period, the cadets
had an intensive air combat training phase with 3–4
high Gz sorties per day. Due to strenuous flying ac-
tivities, the cadets recuperated after flight with little
additional physical activity and no specific training pro-
gram. What the training effect of flying itself was dur-
ing follow-up remains to be discussed. It has been
reported that the overall muscular neck strength 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 (5,22). Still, those
results may reflect the difficulty of measuring out all the
specific changes in muscular tone and strength in the
complex cervical column rather than the ineffectiveness
of Gz loading on musculature.
In conclusion, neither of the described training meth-
ods was superior to the other, but both had positive
results. Trampoline training seems to be a suitable
method for diminishing in-flight muscle strain in the
neck area. Exercises enhance the motor control ability of
the cervical muscles, and thus pilots do not need to use
as much of their muscle strength as previously. Train-
ing improves the skills related to the maintenance of
situational balance, control of movement, and muscular
stabilization, and this may cause a positive effect to
in-flight muscle strain. In addition, strength training,
even with a slight increase in maximal muscle force, has
a positive effect on neck muscle strain under Gz load-
ing. Both training methods expand the muscles’ capac-
ity in different ways. The greater the muscle capacity
between maximum capacity and capacity needed dur-
ing Gz loading, the smaller the risk of cervical injuries.
A combined strength and trampoline training program
has been included in fighter pilots’ physical education
programs in Finland.
ACKNOWLEDGMENTS
The study was supported by a grant from the Work Environment
Fund of the Ministry of Finance.
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REDUCING NECK STRAIN—SOVELIUS ET AL.
25Aviation, Space, and Environmental Medicine Vol. 77, No. 1 January 2006
... In primary school children, participating in trampoline park activities resulted in higher heart rate and energy expenditure than traditional sports clubs of soccer and netball (Budzynski- Seymoure et al., 2019). Trampoline-based training has been shown to successfully improve the functional outcomes of children with developmental coordination disorder ( Giagazoglou et al., 2015), improve balance ability in stroke patients (Hahn, Shin, & Lee, 2015) and the elderly (Aragao et al., 2011), improve neck muscles strength in fighter pilots ( Sovelius et al., 2006), and reduce body fat percentage and improve anaerobic fitness in high school students (Aalizadeh, Mohammadzadeh, Khazani, & Dadras, 2016). ...
... Each session lasted for approximately 30 minutes, including 10 min warm-up (calisthenics and stretching) and 20 min training. The 6-week training duration was similar to other studies in the literature ( Hahn et al., 2015;Heitkamp et al., 2001;Kidgell, Horvath, Jackson, & Seymour, 2007;Sovelius et al., 2006). For good consistency throughout the entire study period, all training sessions for both TT and RT groups were supervised in a 1:1 ratio by the same, trained personnel. ...
... Future studies can measure muscle activation and rate of torque development during the early phase of maximal voluntary isometric contraction to confirm if neural adaptation takes place. While current study quantified the possible gain in knee extensors and flexors after training, previous studies showed that trampoline exercises also had positive effects on other muscles groups (Aragao et al., 2011;Sovelius et al., 2006). For example, Sovelius et al. (2006) compared the effects of 6-week trampoline exercise versus strength training on neck strength in fighter pilots and reported significant improvement in neck flexion force. ...
Article
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Purpose: Trampoline parks are becoming popular in many countries, providing recreational facilities for children and adults. This study investigated the effects of trampoline training on knee muscles strength and balance in young adults. Methods: Twenty-six participants (14 males, 12 females) were randomized into trampoline training (TT) and resistance training (RT) groups to undergo a 6-week supervised intervention program (2 × 30 min per week). TT group performed basic trampoline exercises while the RT group performed resistance training targeting lower extremities muscles. Peak knee extension and flexion torque, postural sway characteristics, and Y balance test (YBT) performance were evaluated before and after the intervention. A mixed model analysis of variance (group × time) was applied. Results: After training there were significant improvements in knee extension torque (mean differencepost-pre [95% CI], TT: 0.27 [0.00, 0.54] N∙m/kg, RT: 0.31 [0.09,0.54] N∙m/kg, p = .001), knee flexion torque (TT: 0.25 [0.17,0.33] N∙m/kg, RT: 0.21 [0.08,0.34] N∙m/kg, p < .001), and dynamic balance (YBT composite scores, mean differencepost-pre [95% CI], TT: 4.9 [-0.3, 10.2]%, RT: 5.2 [2.4,8.0]%, p = .001). No difference between groups was found. Conclusion: Trampoline training can be as effective as resistance training for improving knee muscles strength and dynamic balance in young men and women.
... Other novel interventions have been proposed including trampoline training which is suggested to provide low-intensity, repetitive muscular endurance exercise (Sovelius et al., 2006;Posch et al., 2019). In a study of fighter pilots, trampoline training was found to be equally effective as strength training in reducing in-flight neck strain (Sovelius et al., 2006;Posch et al., 2019). ...
... Other novel interventions have been proposed including trampoline training which is suggested to provide low-intensity, repetitive muscular endurance exercise (Sovelius et al., 2006;Posch et al., 2019). In a study of fighter pilots, trampoline training was found to be equally effective as strength training in reducing in-flight neck strain (Sovelius et al., 2006;Posch et al., 2019). Alternatively, one study in HPJA pilots demonstrated application of traction as a daily home-based intervention using a commercially available unit to mitigate pain (Chumbley et al., 2016). ...
Article
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Aviation and space medicine face many common musculoskeletal challenges that manifest in crew of rotary-wing aircraft (RWA), high-performance jet aircraft (HPJA), and spacecraft. Furthermore, many astronauts are former pilots of RWA or HPJA. Flight crew are exposed to recurrent musculoskeletal risk relating to the extreme environments in which they operate, including high-gravitational force equivalents (g-forces), altered gravitational vectors, vibratory loading, and interaction with equipment. Several countermeasures have been implemented or are currently under development to reduce the magnitude and frequency of these injuries. Cervical and lumbar spine, as well as extremity injuries, are common to aviators and astronauts, and occur in training and operational environments. Stress on the spinal column secondary to gravitational loading and unloading, ± vibration are implicated in the development of pain syndromes and intervertebral disk pathology. While necessary for operation in extreme environments, crew-support equipment can contribute to musculoskeletal strain or trauma. Crew-focused injury prevention measures such as stretching, exercise, and conditioning programs have demonstrated the potential to prevent pre-flight, in-flight, and post-flight injuries. Equipment countermeasures, especially those addressing helmet mass and center of gravity and spacesuit ergonomics, are also key in injury prevention. Furthermore, behavioral and training interventions are required to ensure that crew are prepared to safely operate when faced with these exposures. The common operational exposures and risk factors between RWA and HPJA pilots and astronauts lend themselves to collaborative studies to develop and improve countermeasures. Countermeasures require time and resources, and careful consideration is warranted to ensure that crew have access to equipment and expertise necessary to implement them. Further investigation is required to demonstrate long-term success of these interventions and inform flight surgeon decision-making about individualized treatment. Lessons learned from each population must be applied to the others to mitigate adverse effects on crew health and well-being and mission readiness.
... Basically, exercise training may increase individual capacity and reduce the relative workload on the cervical musculature, by further reducing the risk of developing neck pain [50]. Sovelius et al. found a benefit of trampoline training as relatively low-intensity and repetitive muscular loading improves muscle balance and motor skills [51]. Trampoline training was shown to be effective in reducing muscle strain during in-flight, especially in the cervical muscles [51]. ...
... Sovelius et al. found a benefit of trampoline training as relatively low-intensity and repetitive muscular loading improves muscle balance and motor skills [51]. Trampoline training was shown to be effective in reducing muscle strain during in-flight, especially in the cervical muscles [51]. Recapped, the hypothesis specific to helicopter pilots and crewmembers suggests training programs focus on muscular endurance and general fitness to limit the effects of cumulative exposure to multiple factors that contribute to neck pain [44]. ...
Article
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Background Flight-related neck, shoulder and low back pain are the most common musculoskeletal disorders among helicopter pilots and their crewmembers, thus becoming a growing concern. Information on the combined prevalence of these types of pain and related risks are scarce. The aim of this study was therefore to estimate pain prevalence and to evaluate potential risk factors for neck pain among helicopter pilots and crewmembers within the armed forces, the airborne police and airborne rescue organizations in Austria. Methods Among a cohort of 104 helicopter pilots and 117 crewmembers (69.8% compliance), demographics, flying experience, use of Night Vision Goggles (NVG), helicopter type flown, prevalence and intensity of musculoskeletal symptoms (pain was defined as any reported pain experience, ache or discomfort) were collected by an online-based questionnaire. Results For helicopter pilots the 12-month prevalence of neck pain was 67.3%, followed by low back (48.1%) and shoulder pain (43.3%). Among crewmembers, the 12-month pain prevalence were 45.3, 36.8 and 30.8% among the neck, lower back and shoulder, respectively. During this period, 41.8% of these helicopter pilots had experienced 8–30 pain days in the areas of neck (45.7%), shoulder (37.8%) and lower back (42.0%) whereas 47.8% of crewmembers self-reported 1–7 days of neck (54.7%), low back (44.2%) and shoulder (44.4%) pain in the previous year. The 3-month prevalence of neck pain was 64.4% followed by low back (42.3%) and shoulder pain (38.5%) for helicopter pilots. Among crewmembers, 41.9% suffered from neck, 29.9% from low back and 29.1% from shoulder pain the previous 3 months. Multivariate regression analysis revealed NVG use (OR 1.9, 95% CI, 1.06–3.50, p = 0.032), shoulder pain (OR 4.9, 95% CI, 2.48–9.55, p < 0.001) and low back pain (OR 2.3, 95% CI, 1.21–4.31, p = 0.011) to be significantly associated with neck pain. Conclusions The 12- and 3-month prevalence of neck, shoulder and low back is considerably high among both, helicopter pilots and crewmembers confirming the existence of this growing concern. The use of NVG devices, shoulder and low back pain in the previous 12 months represent independent risk factors for neck pain. These findings highlight the need for longitudinal studies.
... As the duration of exercises increase glucose and non-esterified fatty acids are utilized and with the continuation of the exercises, non-esterified fatty acids become the major fuel. The accumulative effects of these metabolic reactions with the repetitive vertical propulsion of the body possibly facilitate an 'insulin-like' action for glycaemic control [23]. Additionally, the elastic nature of muscles, tendons, enhanced neurological responses and reflex processes occurring in muscles renders rebound exercises, with its low-impact elastic surface, springs and gravity-assisted movements an alternate mode of cardio-respiratory exercise compared to jogging and treadmill exercises. ...
... Additionally, the elastic nature of muscles, tendons, enhanced neurological responses and reflex processes occurring in muscles renders rebound exercises, with its low-impact elastic surface, springs and gravity-assisted movements an alternate mode of cardio-respiratory exercise compared to jogging and treadmill exercises. The repeated "bouncing" alternates G-forces from 0 to 4 Gz by vertical acceleration and deceleration with an increase in heart, respiratory and blood flow and repetitive loading and unloading of muscles creates a "training" effect thereby increasing energy expenditure and improving BMI data [22,23]. Together with participants adhering to counselling for diet and reducing the intake of fatty foods these would also improve BMI values. ...
... The whiskers demarcate the 5 th to the 95 th percentile. *P < 0.05 Sovelius et al. [25] subjected 16 to two different 6-week training programs (a strength endurance training program and a trampoline training program) and measured the influence on muscle activity during inflight measurements. The authors concluded that both programs reduced the activity of the neck muscles. ...
Article
Full-text available
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 Gz 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 Gz) 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 Gz forces in a long-arm centrifuge.
... 24 Th e prevalence of neck pain within the global community is 4.9%, where 90% of cases are attributed to injuries of the intervertebral discs, 80% to anterior spinal ligaments, and 40% to facet joints following vehicle collisions. 9 Neck pain can result in lost workdays and reduced fl ying capacities for fast jet pilots. 37 , 51 Given that $15.2 million is required to train one pilot for an F/A-18 Hornet aircraft , 36 days lost from fl ying are expensive to defense forces 48 and informed risk strategies are required. Th is issue has gained international focus and is supported by a specialized North Atlantic Treaty Organization (NATO) Research Task Group: HFM 252. ...
Article
BACKGROUND: During flight, fast jet pilots frequently move their heads into extreme positions while withstanding large amounts of stress on their cervical spines. These factors are thought to contribute to episodes of neck pain. METHODS: We conducted a systematic review and meta-analysis of previous neck pain prevalence data in fast jet pilots to determine an overall pooled prevalence. Subgroup analyses were performed according to when pilots complained about their neck pain, whether these same pilots sought treatment, and if they lost time from flying. Four research databases were searched. Studies were eligible for inclusion if they were written in English, involved a group of fast jet pilots who were actively flying high performance aircraft, and reported quantitative prevalence data about neck pain in these pilots. These eligibility criteria were independently applied by two reviewers and risk of bias was evaluated. MetaXL software was used to conduct the meta-analysis. RESULTS: In total, 8003 fast jet pilots across 18 eligible studies were included in the review. The overall pooled prevalence of neck pain in fast jet pilots was 51%. It was found that 39% of subjects lost time from flying, while only 32% sought medical treatment. DISCUSSION: Neck pain in fast jet pilots adversely affects operational capabilities of defense forces. The prevalence of neck pain varies according to the definitions or thresholds of complaints used across the literature. Further research is required to standardize the definition of neck pain.
... Moreover, research has supported the recommendation of the safe use of trampoline in school environment as a tool to minimize injury risk (Johnson et al., 2011). According to studie (Sovelius et al., 2006) try to compare the effects of two different training methods in reducing muscular loading during inflight and cervical loading testing (CLT). Both training methods were found to be effective in reducing muscle strain during in-flight and CLT, especially in the cervical muscles. ...
Article
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Backgroundː Mini-trampoline exercise is becoming a very popular form of training. The purpose of this study is to examine the effects of 15-week trampoline training on vertical jump parameters in boys who do not exercise regularly. Methodsː The subjects (13 years +/-6 months) old boys were randomly allocated to one of two groups: trampoline training group (TG, N=23) and control group (CG, N=29) to examine effects of 15-week trampoline training (1 time per week). Optojump we measure the following variables: time of flight phase (s), height of jump (cm), specific energy (J/kg) and total energy (J). Sixteen variables were used to estimate the explosive power of lower extremity: DJ drop jump 20cm, DJ drop jump 40cm, SJ squat jump and CMJ countermovement jump. The t-test was used to compares the means of two groups. For this analysis, the significance level is 0.05. Resultsː As a result; whereas 15 weeks of trampoline exercise improved vertical jump preformance of subjects. Differences between the pre-test and post-test in TG are statistically significant (P<0.05). TG in regards to CG differs in the height of the jump DJ20cm for 1.161 cm, DJ40cm for 0.580 cm, SJ for 0.141 cm and CMJ for 0.313 cm in benifit of TG. Conclusionsː The trampoline training used in our study may form an example for the sports educators for improving the explosive strength of the lower extremities in children. Using a mini trampoline offers a variety of health benefits for the body.
Article
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Cukrzyca to choroba stanowiąca jeden z głównych problemów zdrowia publicznego. Szacuje się, że około 15% pacjentów z cukrzycą – w wyniku neuropatii obwodowej oraz niewydolności naczyń obwodowych – zagrożonych jest zespołem stopy cukrzycowej (ZSC). Obydwa powikłania prowadzą do degradacji struktur anatomicznych stopy, tj.: układu kostno-stawowego, ścięgien i więzadeł oraz mięśni. Dysfunkcje i wady powstające w przebiegu cukrzycy powodują wadliwą dystrybucję sił i nacisków w obrębie stóp, co jest istotnym czynnikiem sprzyjającym powstawaniu ran przeciążeniowych, złamań zmęczeniowych itd. Obecnie strategie profilaktyczne ukierunkowane są głównie na profilaktykę nawrotów oraz na leczenie w celu uniknięcia amputacji. Mając na uwadze patofizjologię, ważnym aspektem wczesnej profilaktyki jest obserwacja kondycji układu neurologicznego oraz naczyniowego, co praktycznie realizowane jest przez zespoły interdyscyplinarne poprzez: obserwację, badanie czucia powierzchownego oraz przepływów (np. ABI), a tym samym znajduje odniesienie w licznych rekomendacjach. Niezbędną procedurą wczesnego wykrywania zagrożeń jest ocena stóp i kończyn dolnych w ujęciu anatomicznym oraz funkcjonalnym, uwzględniając w szczególności ocenę dystrybucji nacisków. Profilaktyczne znaczenie mają również niemedyczne usługi podologiczne. Istniejące rekomendacje i zalecenia w zakresie profilaktyki i terapii oraz edukacji pacjentów z grupy ryzyka, dotyczące wczesnej prewencji powstawania zmian przeciążeniowych, są zbyt ogólne, co wynika zarówno z doświadczenia praktycznego, jak i naukowego Autorów niniejszej publikacji. Natomiast obowiązujące przepisy oraz dokumenty normatywne w tym obszarze są wystarczające do wdrożenia procedur szczegółowych, co jest czynnikiem pozytywnym w procesie wdrożeniowym. Cel Wskazanie wczesnych i wtórnych procedur diagnostycznych, terapii oraz edukacji pacjenta, mających zastosowanie w profilaktyce ZSC.
Technical Report
A significant proportion of fixed- and rotary-wing aircrew in NATO air forces experience flight-related neck pain that is exacerbated by additional head-mounted equipment and non-ergonomic aircraft crew spaces. Thus, aircrew neck pain solutions must be found. Research Task Group (RTG) Human Factors and Medicine (HFM) Panel 252 on Aircrew Neck Pain had a mandate to study this problem and evaluate proposed mitigating solutions. The objective of this NATO RTG was to seek and recommend evidence-based administrative, procedural, ergonomic, engineering, preventative, and treatment solutions for the problem of aircrew neck pain. RECOMMENDATIONS Human Factors: NATO air forces should implement aircrew conditioning programmes that emphasise physiotherapy support, education, total lifestyle health promotion, individual guidance, cost and benefit assessments, and sufficient rest and recovery time to reduce the risk of developing or aggravating neck pain. Aviation medicine team members should provide personalized flying duty fitness recommendations, including gradual return to flying duties and appropriate, temporary, or permanent G-exposure limitations. Body-Borne Equipment: The mass and inertia of future helmet systems (helmet, night vision goggles, and other peripherals) should not exceed those of current in-service systems, and remain balanced during critical aircrew tasks. Aircrew should have their helmets fitted properly and regularly to reduce neck pain, helmet slippage, hot spots, and pressure points. Procurement agencies must consider all helmet system requirements such as aircrew performance, impact protection, aircraft life support equipment integration, as well as aircrew neck pain. Behaviours and Tasks: Aircrew should adopt biomechanically advantageous postures and aircraft should include ergonomic handles and supports whenever possible to reduce neck joint loading and muscle strain. Aircraft Workspace: Recognising that aircraft modifications come with significant costs and airworthiness recertification requirements, certain aircraft displays and controls should be repositioned to promote biomechanically advantageous postures and reduce neck loading. For helicopters, track-and-balance maintenance and seat cushions can reduce vibration at head level. Organisation: Neck pain should not be ignored. It is a problem shared by aircrew, clinicians, and command, and may require a shift in organisational culture. There is no ‘quick fix’ for the aircrew neck pain problem. Solutions must work synergistically and be implemented as soon as possible to minimise the risk of developing or aggravating neck pain. A cost-benefit analysis is essential to justify long-term comprehensive solutions. Future Studies: Future studies include refining the HFM-252 neck pain survey, validating electromyography standards, updating helmet system mass properties guidelines, maturing seat vibration mitigation solutions, developing business case templates, and developing evidence to support the effectiveness of aircrew neck pain solutions in NATO air forces.
Thesis
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Die hier vorliegende Arbeit hatte in einem ersten Schritt das Ziel, die physiologische Beanspruchung ausgewählter Muskeln des Hals-, Nacken – und Schulterbereiches unter positiven Beschleunigungskräften zu ermitteln und den Einfluss unterschiedlicher Helmsysteme sowie Bewegungen des Kopfes zu analysieren. Dafür wurde die Methode der Oberflächenelektromyographie genutzt, eine Technik, welche myoelektrische Signale, die Muskeln bei ihren Kontraktionsvorgängen erzeugen, erfassen kann. Im Speziellen wurde die Normalisierungsmethode der maximalen Willkürkontraktion (MVC-Normalisierung) gewählt, bei der das mikrovoltbasierte Signal zu einer vorher durchgeführten Maximalkontraktion der zu messenden Muskulatur (Referenzwert = 100%) in Relation gesetzt wird. Somit wird ein prozentualer, quantifizierbarer Wert generiert. In der Humanzentrifuge der Bundeswehr, die am Zentrum für Luft- und Raumfahrtmedizin der Luftwaffe in Königsbrück bei Dresden steht, wurden 18 Probanden unterschiedlich hohen Beschleunigungsexpositionen ausgesetzt. Dabei wurden die muskulären Aktivitäten bilateral des M. sternocleidomastoideus, des M. trapezius Pars descendens und des M. erector spinae ermittelt. Im Anschluss daran wurden die Daten mit vorhandener Literatur im flugmedizinischen Kontext verglichen. Weiterhin wurde das subjektive Belastungsempfinden der Probanden während der Beschleunigungsexpositionen erhoben. Diese Studie zeigt, dass die muskuläre Beanspruchung der HWS-Muskulatur, während positiver Beschleunigung, im Wesentlichen durch die Beschleunigung selbst und durch Kopfbewegungen beeinflusst wird. Weiterhin erhöhen zusätzliche Helmsysteme in Verbindung mit Beschleunigung und Bewegung die muskuläre Beanspruchung signifikant. Auch das subjektive Belastungsempfinden nahm mit zunehmender Beschleunigung und Gewichtszunahme durch die Helmsysteme zu und war im Nackenbereich am höchsten. Insgesamt erwies sich die Methode der Oberflächenelektromyographie als valide Messmethode zur Bestimmung der physiologischen Beanspruchung der Muskulatur unter Beschleunigungskräften, allerdings nur, sofern sich die Halswirbelsäule in einer neutralen Position befand. In einem weiteren Schritt, sollte nun überprüft werden, ob die physiologische Beanspruchung im Bereich der Halswirbelsäule unter positiven Beschleunigungskräften durch ein - speziell für das Umfeld der Jet-Fliegerei konzipiertes - Trainingsprogramm verringert werden kann. Dafür wurden die 18 Probanden in eine Trainings- (12 Personen) und Kontrollgruppe (6 Personen) unterteilt und mit Hilfe unterschiedlicher Validierungskriterien wurde ein 12-wöchiges funktionelles Ganzkörpertraining - mit Schwerpunkt des Muskelaufbaus im Hals-, Nacken- und Schulterbereich - in einem Pre-Posttest-Design überprüft. Die Validierungskriterien setzten sich sowohl aus qualitativen als auch quantitativen Methoden zusammen. Es wurden grundsätzliche anthropometrische Daten erhoben, Fragebögen erarbeitet als auch Maximalkraftmessungen in allen Bewegungsrichtungen der Halswirbelsäule durchgeführt. Zusätzlich zu den „gängigen“ Methoden wurden die schon beschriebenen Oberflächenelektromyographiemessungen in der Humanzentrifuge angewandt, um zu analysieren, ob objektiv nachgewiesen werden kann, dass ein Training einen positiven Einfluss auf die physiologische Beanspruchung der Muskulatur unter positiven Beschleunigungskräften haben kann. Diese Validierungsmethode wurde in der gesichteten Literatur im flugmedizinischen Kontext in diesem Umfang noch nicht angewandt. Weiterhin wurden die analysierten Muskeln vor als auch nach der Interventionsphase mit Hilfe der Magnetresonanztomographie volumetriert. Somit konnte auch die autochthone schwer zu analysierende Nackenmuskulatur untersucht werden. Insgesamt konnte mit allen gewählten Methoden nachgewiesen werden, dass durch das Training die physiologische Beanspruchung der Muskulatur subjektiv als auch objektiv verringert wurde. Speziell unter Beschleunigung wurden in der Trainingsgruppe - während die Probanden einen Helm trugen - signifikante Abnahmen der muskulären Aktivität im Posttest festgestellt. Auch das Muskelvolumen nahm in der Trainingsgruppe bei allen untersuchten Muskeln signifikant zu. Die hier vorliegende Studie stellt eine validierte Möglichkeit dar, die Gesunderhaltung des fliegenden Personals nachweislich zu unterstützen und leistet einen Beitrag in der komplexen Thematik zur Verringerung von Wirbelsäulenbeschwerden bei Luftfahrzeugbesatzungen.
Article
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 sure 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.
Article
Introduction: Specific mechanisms leading to acute neck injury in flight as a result of +Gz exposure remain unclear. In this study, head positions adopted by aircrew in air combat have been quantified, and the associated levels of cervical muscle activation have been determined. Method: Six fast jet aircrew subjects were instrumented with surface electromyography (EMG) electrodes, and activation potentials from neck erector spinae (ES) and sternocleidomastoid (SC) muscles were logged on a data recorder. EMG signal was normalized to preflight maximum voluntary contraction (MVC). All subjects flew a one-on-one air combat sortie in a Hawk T1 aircraft comprising at least four air combat engagements. In-cockpit video and +Gz acceleration were recorded. Time-synchronized analysis of video, EMG, and acceleration were conducted for head position and normalized muscle activation (%MVC). Results: During air combat, the head was away from neutral for 68% of the time, predominantly in extension, or rotation plus extension. During neck extension under G, 40-80% MVC occurred in the ES: this was reduced by half when the canopy was used as a support. Similar activation occurred in the SC in neck extension plus rotation. The ES was activated at over 40% MVC for 25% of the engagement duration. Post-sortie, 35% reduction in neck muscle strength occurred. Conclusions: Extreme neck extension +/- rotation is very common in air combat and is associated with high levels of muscle activation and fatigue. This information can be used to help devise targeted neck conditioning and positioning strategies in order to reduce injury risk.
Article
To evaluate the repeatability of an advanced method of measuring the strength of functionally different groups of neck muscles using an isometric apparatus. A repeated measures design was used within and between sessions. Chronic neck pain has been associated with poor isometric neck strength. In rehabilitation, strength measurements may thus help to evaluate the basic condition and show whether or not treatments and exercises have been beneficial for improving strength. Previous tests have concentrated on testing strength while trying to bend forwards and backwards, but no biomechanics device, able to test rotator muscles, has been presented. The new isometric measurement device was used to test flexion, extension and also rotation strengths of normal subjects (n = 33). Intratester repeatability was good with regard to all measured parameters. With both tests performed on the same day and test comparisons between days, intratest repeatability was good with regard to all measured parameters.
Article
The purpose of this study was to quantify the neuromuscular cervical adaptations to an 8week strength training programme. Seven healthy men, with no pathological conditions of the neck, performed a lateral flexion isometric resistance-training programme three times a week. The training sessions consisted of one set of ten contractions, each of 6s duration, at 60% of the predetermined maximal voluntary isometric torque (MVTim) (warm-up) and two sets of eight contractions, each of 6s duration, at 80% MVTim. The training effects were evaluated in three ways: muscle size, strength and fatigability. The cross-sectional areas (CSA) of the trapezius (TRP) and sternocleidomastoideus (SCM) muscles were determined using a computerised tomographic scanner. Results showed an increase in the CSA of TRP and SCM muscles after training, 8.8% at C5 level and 6.4% at C7 level for SCM muscle and 12.2% at C7 level for TRP muscle. Strength increased significantly under both isometric and isokinetic conditions (35% and 20%, respectively). Muscle fatigability in lateral flexion was quantified during a sustained isometric contraction at 50% of MVTim. The shift of the mean power frequency of the electromyogram power spectrum density function of SCM muscle toward lower frequencies was less after training (14.6% compared to 6.8%). These results indicate the beneficial effect of a strength-training programme which increases neck muscle size and strength during lateral flexion, and decreases the fatigability of the superficial muscles of the neck.
Article
This study investigated the effects of concurrent endurances and low velocity resistance training (LVR) on measures of strength and aerobic endurance. One group (ES) performed concurrent endurance training 3 days a week and LVR training on alternate days, 3 days a week for 12 weeks. The other group (S) performed only LVR training 3 days a week for 12 weeks without any endurance training. Measurements and increases in training volume were made every three weeks in both groups. Group ES exhibited increases in submaximal exercise responses after 3, 9 and 12 weeks (p less than 0.05). Knee extension peak torque and total work as well as cross-sectional area of quadriceps femoris were significantly increased after 6 and 9 weeks of training in both groups. These findings indicate that no significant differences in strength gains were observed between subjects performing concurrent endurance and resistance training or resistance training only. However, the time-course of adaptations between groups was somewhat different.
Article
Changes in body fat, cardiovascular endurance, muscular endurance, flexibility and strength were assessed in 22 women and 16 men after 6 weeks sequence training. It was found that two training sessions per week were sufficient to cause a significant increase in the majority of measurements made. The extent of the improvement in women was inversely related to the starting value, with most measurements, whereas this was not found in men. The measurements in this small group were comparable to those found in a large series in Canada, with the exception of the proportion of body fat which was lower in this UK series.
Article
The influence of physical conditioning on tolerance to a centrifugation profile called the Simulated Aerial Combat Maneuvering (SACM)--was determined using 24 young men as subjects. These subjects were assigned to groups as controls (no physical training, C), runners (R), and weight trainers (W). They followed a 12-week protocol of specified physical training. During this study, tolerance to the SACM, maximum oxygen consumption, muscle strength, and body composition were periodically determined. SACM tolerance was defined as the total time that a subject could withstand continuous exposure to a 4.5 and 7.0 +Gx centrifugation profile as determined by his voluntary endpoint of fatigue. The +Gx tolerance of the runners and controls increased at an average rate of 4 s/week during the course of the experiment. On the other hand, the weight trainers increased their G tolerance at an average rate of 15 s/week. The difference between group W compared with groups C and R was statistically significant at the 5% level. Fatigue scores indicate that group W subjects take longer to reach a given level of fatigue than did the subjects of the other groups. It appears therefore that a physical conditioning program of weight training will improve human tolerance to aerial combat maneuvers.
Article
A special preamplifying system was designed to record electrophysiological signals on fighter aircrew in flight. The system is composed of two elements worn by the pilot in a specially designed jacket. The first element is a preamplifying device for ECG or EMG signals, which includes one or two accelerometer channels, according to the needs of the studies. All recorded signals may thus be correlated with the accelerations actually sustained by the pilot. Accelerometers are new generation equipment. Accelerometer and preamplifier performances have been measured and are reported. The recorder performance has been tested on a centrifuge under high acceleration. The results show that up to +10 G, no frequency shift and no change in the harmonic distortion between acceleration and resting stages have been measured. An example of surface EMG recording on two neck muscles during head movements under high-G loading in flight is given.
Article
The introduction of the F-15 Eagle to the Japan Air Self Defense Force (JASDF) in the early 1980's seemed to increase musculoskeletal problems of the spinal column among pilots. The neck is the body part most vulnerable to high-G force injuries, and serious cases of neck injury have been reported. We surveyed 129 F-15 pilots from different air bases by means of a questionnaire. The occurrence rate of musculoskeletal problems in different types of aircraft was analyzed according to the pilots' flying experience. Of the surveyed pilots, 115 (89.1%) reported muscle pains related to flying. Of those who experienced pain, each averaged 7.6 events, 95% of which occurred in the F-15. Of these 115, 30% experienced pain in the F-4 and 15% in the F-1. The "checking six" position was the most common posture at the time of injury, followed by "forward bend." Of the 115 pilots, 44 stated that their symptoms adversely affected flight duty performance, and 50 pilots stated that their symptoms adversely affected daily life. The effectiveness of muscle training as a preventive measure was supported by 62%. Some oriental therapeutic methods (acupuncture, moxa cautery, and finger-pressure massage) were preferred by pilots for pain treatment. G-related problems of the spinal column still exist as a major medical concern in JASDF.
Article
This paper reports three cases of bulging cervical disks among fighter pilots flying high-performance aircraft who experienced acute in-flight neck pain during aerial combat maneuvers under high +Gz forces. Radiographic investigations (magnetic resonance imaging/computed tomography/myelography) revealed that disk bulges were the cause of the pain. One pilot underwent decompressive surgery, and two were treated conservatively. Acute in-flight neck pain and related problems, such as bulging cervical disks, may become more common, since the modern fighter aircraft of the future will be better able to create and sustain high +Gz forces than the fighter aircraft in use today. Further, the increasing number of helmet-mounted devices will make flight helmets heavier, thus placing increased stress on cervical structures.