Does your busy schedule force you to workout late in the day? Do you find that late workouts cause more back pain or discomfort than those performed early in the day? Research in exercise science has actually confirmed that you are more vulnerable to suffer a back injury in the evenings and that inversion should be a part of prepping the spine for workouts.

Establishing the facts and hypothesis

A group of researchers in Liverpool performed a study to evaluate the effect of workouts on the loads of the spine. They began by establishing two important factors:

  1. During exercise, the spine is subjected to a variety of forces, including gravity, changes in motion, and muscle activity, and
  2. When the discs in the spine are under load, or compressed, water is lost through the disc wall, resulting in loss of disc height and loss of stature.

What they expected was that the amount of spinal shrinkage would be determined by the degree of loads placed on the spine. For their study, they looked at how weight-training and running loaded the spine.


The results showed that these activities did cause reductions in spinal height. While height change is normal throughout the day, the height loss experiencedexceeded the normal range by 18%!

The researchers noted that the spine may be more vulnerable to injury from loading in the evening when it has already lost considerable disc height (a normal effect of daily stature change). They went on to say that,

“Some form of reversing this prior shrinkage may be advisable before such exercise regimes are performed in the evening. These could include…the use of gravity inversion for unloading the spine.”

The Gist

  • During the day, gravity causes your discs to compress, expelling fluid and losing height
  • Disc height and fluid provides flexibility and shock absorption for your spine
  • Working out causes greater loads on your discs than gravity
  • With diminished disc height and hydration from daily natural compression, your spine is not properly “primed” to handle the loads of working out
  • Evening workouts, without unloading the spine beforehand to rehydrate the discs, are more likly to result in back pain and/or injury.

How to prep your back for your workout with Teeter inversion

  • While inverted on a Teeter Hang Ups Inversion Table or Gravity Boots:


Source: Leatt, P., T. Reilly, and J. G. Troup. “Spinal Loading during Circuit Weight-training and Running.” British Journal of Sports Medicine 20.3 (1986): 119-24. Print.
[1] By Mike Baird from Morro Bay, USA Mike Baird Canon 20D 100-400mm IS lens handheld from an outrigger canoe. (female-jogger-morro-bay-coleman-avenue) [CC-BY-2.0 (], via Wikimedia Commons
[2] By U.S. Navy photo by Photographer’s Mate 3rd Class Scott Phillips. [Public domain], via Wikimedia Commons