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July 21, 2010
By Emily Roback

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Low back pain (LBP) is one of the most important health issues among rotary-wing aircrews at Mustang Helicopters Ltd.

Low back pain (LBP) is one of the most important health issues among rotary-wing aircrews at Mustang Helicopters Ltd. in Red Deer, Alberta. 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 and there has been an increase in the number of pilots 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 posture.1 Helicopter vibration has a peak power at frequencies around 5 Hz, which is within the range that the human upper body presents resonance frequency.2 Furthermore, there are several contact points between the pilot 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 forces and vertical are of the compression type. With this in mind, this region is under maximal strain but has minimal support.

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POSTURE ISSUES AND AIRCRAFT DESIGN
Awkward posture is also independently 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 flex forward at the trunk and towards the left to operate the controls. This appears to be the predominant in-flight seating posture for most helicopter pilots. This asymmetrical posture during prolonged flights tends to lead to musculoskeletal fatigue and fatigue often leads to pain. An average flight is four to six hours with three or four landings to refuel. 

SIMILARITIES TO NON-AVIATOR SEDENTARY WORK ENVIRONMENTS
The lifestyle of an aviator 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 extremities 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. Also, improper positioning of the pelvis creates excessive anterior tilt (top of the pelvis rotates forward), which is common among pilots during prolonged sitting in aircrafts.

 Prolonged unsupported sitting may also result in loss of flexibility in the hip joint and supporting muscle groups. The post-flight stretching routine must consist of exercises focusing on five important muscles 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, pilots that do not stretch, find themselves constantly shifting their body in their seat to minimize low back and leg discomfort.

A CHANGE IN PARADIGM?
For a typical rotary-wing operator, practising good health/fitness habits is not considered a priority unless there is a decrease in operational effectiveness and quality of life. But, an increase in body weight, decrease in energy levels, and increase in joint wear and tear causes the pilot to take more time off work and spend more time at the doctor’s office.

As we’ve said, flying a helicopter predisposes flight operators to low-back pain and degenerative joint disease.3 Not only are specific stretches for the lower body important, but it might also be necessary to progress to higher levels of exercise that include stability, muscle endurance/strength, power/agility, balance and co-ordination. By improving power, agility, balance and co-ordination, pilots have better eye/hand speed and co-ordination. 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, aviators could handle the aircraft effortlessly while maintaining good health/fitness levels.

Prevention is the best management strategy for LBP that is induced by steady mechanical vibrations, poor posture, lack of abdominal stability, loss of flexibility and poor health/fitness levels.  It is recommended that cushions be utilized to dampen the effects of vibrations that occur in a single flight. Each time there is an opportunity to land the aircraft, the aviator should do an extra set of stretches to extend the back and flex to the right side. Furthermore, while sitting for long periods, practise tilting the top part of the pelvis backwards and tightening up the abdominals for two minutes every 20 minutes.

By practising good exercise techniques as well as incorporating optimal eating habits daily, the overall quality of life and operational effectiveness of aviators would automatically improve. There would be a reduction in the number days taken off work, an increase in readiness to take on a flight, a decrease wear and tear of the body, and a decrease in health-care and veterans affairs costs.

References:

  1. Day, Nigel. Interview and Conversation. Mustang Helicopters Ltd. 9 April. 2009.
  2. De Oliveira, CG and Nadal, J. Transmissibility of helicopter vibration in the spines of pilots in flight. Aviation, Space and Environmental Medicine. Jun 2005; Vol. 76 (6), pp. 576-80.
  3. Harrison, D et al. Sitting Biomechanics, Part II: Optimal Car Driver’s Seat and Optimal Driver’s Spinal Model. Journal of Manipulative & Physiological Therapeutics; Jan 2000; Vol. 23 Issue 1; pp. 37-48.


Emily Roback, BSc, DC – Dr. Emily Roback is the founder of www.chirotrek.ca and works as a chiropractic rehabilitation consultant at the Downtown Integrative Health Group in Calgary. Her practice focuses on sport performance and rehabilitation, integrating chiropractic, nutrition and exercise. Dr. Roback can be contacted at www.chirotrek.ca .


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