Study Shows Back Injury Secondary To Muscle Fatigue

A recent study funded by the National Institute for Occupational Safety and Health shows the relationship between muscle fatigue from repetitive lifting and back injury. It was conducted by an Ohio State industrial systems engineer and an MD who is studying biomechanics. The study which recently appeared in Clinical Biomechanics is the first to examine muscle oxygenation throughout the workday.

The Study
Ten people participated in the study; six had at least one year’s experience in a job that requires lifting, such as in stocking shelves. Four were considered novice lifters. Each person wore a Lumbar Motion Detector, a device that was designed to measure the spine’s movement. They wore oximeters, a gauge that measures the oxygen level of the muscles – just like the pulse oximeter, a device that clips onto a finger, measures oxygen level of the blood.

Activity
Study participants lifted a box from a waist high stand and set it on a chest-high conveyor belt. The box traveled on a conveyor belt to the next participant, who would lift the box and set on another conveyor belt. The boxes weighed 2 pounds, 11 pounds, and 26 pounds. Participants worked 8 hours with a half-hour lunch break and two 15 minute breaks.

Researchers said that the 26 pound box weighed less than half as much as loads that some workers are routinely required to lift in industry. The researchers studied the oxygen levels in the muscles. After 2 hours of lifting, the oxygen level gradually increased until it reached 11% above the resting level. During hours 2 to 4, it rose to 13%. During the lunch break, the oxygen level returned to the resting level but immediately rose to 11 % with lifting during hours 4 to 6. During the last 2 hours of the work day, the oxygenation level rose to 16%, the highest level of the day. This oxygen level indicates how hard the muscles were working and whether they were becoming fatigued. Citing his study, Professor Marras of Ohio State, says, “ Because the oxygen demand at the end of the day was so much higher, that’s when we’d expect people to get hurt on the job.” As muscles fatigue and begin to hurt, workers tense up and try to lift with other muscles that are not as painful.

Conclusion
Tense muscles constrict blood vessels, preventing the flow of oxygen and nutrients to the tissues and the removal of waste produced by muscle activity. While using different muscles may bring relief at first, it increases stress on the joints and the spine, increasing the chance of injury. The muscles of inexperienced lifters tensed up more quickly as they needed more oxygen. Injuries were most likely to happen during the last 2 hours of a shift when muscles were the most fatigued.

Professor Marras showed in the study that half-hour breaks were more effective in reducing muscle fatigue but agreed that this might not be practical in the industry. The study also concluded that people who are new to lifting need to take breaks more often than experienced workers.
• According to the US Bureau of Labor Statistics, in 2002, there were more than 345,000 on the job back injuries which required time off from work.

• In 2004, a Harvard Medical School Study showed that back pain was the reason for over 100 million lost work days per year.

Perhaps this latest study on muscle fatigue could be helpful in implementing some changes in the workplace where back injury is a constant factor.

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Good Habits Help You Avoid Back Injuries at Work

Most back injuries on the job are due to a combination of factors. Some of them can be affected by changing your lifestyle and taking a look at:
• Your weight
• Your degree of fitness
• Your muscle conditioning
• Your flexibility

There are four factors in the workplace which are related to the increased risk of back injury:
• Force - if your job is physical and you have to lift or move heavy objects often, exerting too much force on your back may cause an injury.
• Repetition refers to the number of times that you must perform a certain movement. This can lead to muscle fatigue or injury, especially if your body is positioned awkwardly or you are stretching to the end of your range of motion.
• Posture is the position in which you spend the most time. For instance, sitting at a desk or bending over a computer all day will bring aches and pains. On the average, your body can usually tolerate being in one position for about 20 minutes before you feel compelled to move.
• Stress is increased by pressures from home and work, leading to muscle tension and tightness, which may develop into back pain or result in an injury.

Making Your Workplace Safer
Minimize Hazards
• Remove boxes, stools, and other obstacles from your area that might cause you to trip or fall.
• Look at the setup of your office or workspace. What can you do to modify it to reduce the strain of repetitive tasks and reduce physical demands? The goal is to decrease force and repetition while maintaining safe posture.

Pay Attention To Your Posture
• Poor posture places stress on your back. When you slouch, stand slumped or swaybacked, the back’s natural curves are exaggerated and this can lead to muscle fatigue and possible injury. Good posture relaxes your muscles and minimal effort is required to maintain your balance.
• If you sit at a desk, get a chair that supports your lower back.
• If your chair does not support the curve in the lower back, tuck in a small towel roll or pillow.
• Do not sit with a wallet or bulky item in a rear pocket pressing on your back as this can create pain and disrupt balance in your lower back.
• Adjust the height of your chair so your feet stay flat on the floor.
• If you work at a computer, make sure the chair and the monitor are positioned properly.
• If you use the phone, do not cradle it between your ear and shoulder as this definitely contributes to neck and shoulder pain.
• If you stand for long periods, rest one foot on a stool or small box periodically to relieve the strain on your back.
• Hold reading material at eye level when you are standing.
• Try to avoid bending forward when using the computer, handling desk work or completing handwork. This helps relieve strain on neck, shoulders and upper back.

Adopt Healthy Habits
• Change your position often and take a stretch break. The Mayo Clinic recommends a 30 second timeout every 15 minutes or so to stretch, relax, or move.
• Wear sensible shoes. Low heeled shoes with non-slip soles are preferable to high heels.
• Work on your coordination and balance. Do exercises to improve your balance and keep you steady on your feet.
• Regular walking is good exercise for the back and helps with your balance.
• Try to minimize the sources of stress on the job and at home.
• Develop coping mechanisms when you feel especially stressed.
• Perform deep breathing exercises, take a brief walk, or talk to a trusted friend.

Plan Your Moves
• If you are carrying something heavy, know exactly where you are going to put it and clear the area of obstacles and clutter.
• Avoid carrying heavy bags, briefcases, and purses whenever possible. Try to lighten the load that you carry on a daily basis.
• Avoid unnecessary twisting, bending, reaching.
• Lift properly by letting your legs do the work and keeping a heavy weight close to your body.
• If your back hurts, stop the activity and give the muscles a rest. Evaluate what you are doing to determine whether there is a better way you can complete this task without discomfort.
• Ask for help if a load is too heavy.

You can avoid back pain and injury by first understanding the causes and then making necessary changes in your work environment and your habits. To protect your back and maintain your well being, your focus should be on prevention. Brought to you by Jupiter Spinal Decompression.

Facet Joint Syndrome

The facet joints are the connections between the vertebrae of the spine. Just like the knee or elbow or any other joint in the body, they allow the spine to bend and twist. They are also stabilizing joints that prevent excessive motion and help hold the body upright.

The joints are on the back of each vertebrae and they link one vertebra to the vertebrae directly above and below to form a working unit that allows movement. The surfaces of the joints are covered with a tissue called the articular cartilage. The joint itself is lined with a membrane called the synovium and the joint is enclosed in a fibrous sac, the joint capsule. Synovial fluid, a thick liquid which acts like lubricating grease and surrounds the joint, allows the bones to move without friction.

When these joints become inflamed secondary to injury or arthritis, pain and stiffness occur. If the joints in the neck or cervical spine are affected, these symptoms develop:

• Headaches
• Pain in the neck, shoulders, and upper back.
• Difficulty rotating the head
• Patients often complain that they have to turn their entire body to look to the right or left.

When Facet Joint Syndrome affects the lower back, there is:

• Pain in the lumbar area
• There may be referred pain to the buttocks and thighs
• Stiffness of back
• Difficulty getting out of a chair
• Difficulty standing up
• Complaints that the patient must walk hunched over

An injury or changes associated with aging may cause the cartilage cushion that covers the bones to wear away, resulting in pain as the bones in the joint rub together. Also, small nerves that branch off the larger spinal nerves can become irritated or pinched, causing pain. Facet Joint Syndrome is more common in people over 50 and is usually associated with aging.

Causes of Facet Joint Syndrome

• Whiplash Injury can cause the syndrome in the cervical area.
• Sports activities,such as gymnastics, where neck is extended
• Arthritis
• Poor posture which pushes the spine out of alignment
• Inflammation
• Infection
• Degeneration of the joint
  

Diagnosing Facet Joint Syndrome

• History and Physical should be done
• An X-ray, CT (computerized tomography) scan of the spine or an MRI (magnetic resonance imaging) will rule out fracture or herniated disc.
• Facet joint block would determine if the joints are the source of pain.
• A local anesthetic is injected into or near the nerves that supply the joint. If there is a significant decrease in pain, the diagnosis is confirmed.
  

Treatment

• NSAIDs (Non-steroidal Anti-inflammatory Drugs) such as ibuprophen, Naproxyn
• Muscle relaxants and narcotic pain relievers might be prescribed for more severe pain.
• Physical therapy
• Exercise program to improve flexibility and increase pain free movement
• Posture correction
• Activity Modification to avoid excessive lifting, stretching, bending
  

Approximately 80% of the patients who follow an active rehabilitation program and take NSAIDs become pain free. This usually lasts several months.

When conservative treatment fails, a surgical procedure called, Raiofrequency Rhizotomy, uses an electrical current to destroy the sensory nerves to the joint, resulting in pain relief.

(Brought to you by Jupiter Spinal Decompression)