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OCCUPATIONAL HEALTH AND SAFETYVertical Spin
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Low back pain (LBP) is one of the most important health issues noticed among rotary-wing aircrew members at Mustang Helicopters Ltd. in Red Deer, Alberta. This health issue also affects many air search and rescue members throughout Canada. The flight sitting posture and vibrations produced by the aircraft are identified as high risk factors for LBP.
The primary causes of LBP include steady mechanical vibrations, poor posture, lack of abdominal stability, loss of flexibility and poor health/ fitness levels. With this in mind, an aviator experiencing LBP while controlling an aircraft compromises flying safety. Until recently, there had been an increase in the number of pilots, navigators, and spotters reporting difficulties concentrating during flights, as well as achieving low back and leg comfort while airborne in a helicopter.
According to Nigel Day, Safety Officer at Mustang Helicopters Ltd, the incidence of lower back and right-sided sciatic pain in helicopter pilots is attributed to the steady horizontal and vertical vibrations and the in-flight pilot’s posture1. Helicopter vibration has a peak power at frequencies around 5 Hz, which is within the range that the human upper body presents resonance frequency2. This means that not only the pilot may experience low back pain, but also the navigator and spotters as well.
Furthermore, there are several contact points between the aircrew and the aircraft, hands, feet, low back and pelvis regions. The lumbopelvic (low back and pelvis) region accepts all horizontal and vertical forces. The horizontal forces are shear and vertical are compression. With this in mind, low back and pelvis are under maximal muscle strain and minimal joint support due to the vibrations produced by the aircraft.
Asymmetrical Posture
Awkward posture is also connected with the presence of LBP and sciatica. In the Eurocopter Astar, one of the most innovative helicopters at the Red Deer Regional Airport, the pilot must bend the trunk forward and towards the left to operate the controls. This appears to be the main in-flight seating posture for most helicopter pilots. As a spotter, one must bend the trunk to the side towards the nearest window to do a ground search. This asymmetrical posture during prolonged flights tends to lead to muscle fatigue which often leads to pain. An average flight lasts between four and six hours with three or four landings to refuel.
The workstation of a pilot, navigator, and spotter is quite similar to that of an office worker. The special relationship of the extremities (arms and legs) with the abdominals is defined as core stability. The more stable the spine is, the easier it is to move the arms and legs effortlessly.
The ideal positioning of the core involves aligning the arms and legs with the spine where minimal mechanical stress is applied to the soft tissues (i.e. muscles, ligaments, tendons, capsule, etc), bones, and joints. Incorrect alignment produces additional mechanical demands on the supporting structures and creates wear and tear in the joints. Improper positioning of the pelvis also creates excessive anterior tilt (top of the pelvis rotates forward), which is common among individuals during prolonged sitting in aircrafts.
Importance of Stretching
Prolonged unsupported sitting may also result in loss in flexibility in the hip joint and supporting muscle groups. The post-flight stretching routine must consist of exercises that focus on five important muscle groups, namely, the hip flexors (iliopsoas and rectus femoris), hip lateral rotators (piriformis), hip adductors (iliotibial band and tensor fasciae latae), hip extensors (hamstrings, gluteals, and calves) and upper chest (pectoralis major/ minor). More often than not, individuals that do not stretch find themselves constantly shifting their body in their seat to minimize low back and leg discomfort.
For a typical rotary-wing crew member, practicing good health/ fitness habits are not considered a priority unless there is a decrease in the quality of life and effectiveness of the searches. An increase in bodyweight, decrease in energy levels, and increase in joint wear and tear encourages the member to take more time off work and spend time at the doctor’s office. Flying a helicopter predisposes flight operators to low-back pain and degenerative joint disease3.
Specific stretches for the lower body are important, but it is also primordial to progress to higher levels of exercise that include stability, muscle endurance/strength, power/agility, balance and coordination. By improving power, agility, balance and coordination, pilots have better eye/hand speed and coordination. An increase in muscle mass, vitamins/minerals, healthy food/beverage intake, and bone density leads to higher metabolism and lower body fat percentages. As a result, the crew can handle the aircraft effortlessly and maintain good health/fitness levels.
Foresight is better than hindsight
Prevention is the best method for the management of LBP induced by steady mechanical vibrations, poor posture, lack of abdominal stability, loss of flexibility and poor health/ fitness levels. It is recommended to utilize cushions that dampen the effects of vibrations that occur in a single flight. Each time there is an opportunity to land the aircraft, do an extra set of stretches to lengthen the back muscles.
While sitting for long periods, practice tilting the top part of the pelvis backwards and tightening up the abdominals for two minutes every twenty minutes. By practicing good exercise techniques and eating habits daily, the overall quality of life and the effectiveness of the searches will automatically improve. There will be a reduction in the number of days taken off work, increase readiness, decrease wear and tear of the body, and decrease in health care and veterans affairs costs.
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