Why is your back stiffer in the morning?

You may have noticed when you wake up in the morning that your spine is more stiff than it was before you went to bed.

I’d like to explain why this happens.

Why is my back stiffer in the morning?

The intervertebral discs between our vertebrae are made up of  multiple, strong, fibrous layers called the annulus fibrosis. The annulus encases the nucleus pulposus which is a jelly like substance. This jelly substance is attracted to water.

When we wake up in the morning our spine is approximately 19mm longer than it is at the end of the day. This is because when laying down the force of gravity on our spine is less than the force of attraction of the water to the nucleus pulposus. Therefore, water is drawn into the intervertebral disc.

This increase in water in the discs reduces the ability of the spine to bend forward by between 5 and 6 degrees.  Bending stresses on the spine are increased by 300% and stress on the ligaments is increased 80%.

Sadly, the muscles don’t seem to compensate for this stiffness by restricting the lumbar spine’s bending range of motion.  Therefore, when we bend forward this increased stress on the spine increases our chance of aggravating or injuring our spine.

Thankfully, approximately 50% of increased disc height is reduced within the first hour of the day.

Should I workout in the morning?

Based on this information it is highly recommended that if you want to exercise avoid spinal based movements that involve flexing the spine or bending within the first hour.

For those with chronic lower back pain this advice holds true as well.  Do your best to minimize the amount of bending that you perform within the first hour of the day. Plan your day out, the night  before, so that the first parts of your day involve less bending and heavy lifting.  Later in the day these activities would be more appropriate.

Dr Notley

P.S. You can watch more videos on Instagram TV and Youtube

 

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