Injury Free Running: Gravity or Biomechanics?

I love research that has a large clinical impact! This month in JOSPT there was an interesting article looking at Lower Body Positive Pressure (LBPP) treadmills.

One of the factors that the researchers examined was the affect of running at different levels of body weight support (BWS) on gait characteristics and ankle/knee kinematics.

Some interesting findings during the stance phase of gait were that:

  • At 20% or < BWS, there was no change in arthrokinematics and gait characteristics (i.e. stride rate, Ground Contact Time, etc)
  • At 40% or > BWS there were significant changes in arthrokinematics and gait characteristic (Specifically an increase in stride duration and decrease in stride rate).

The first thing that popped in my head after reading this article is that LBPP treadmills may be very valuable, in the right situations.

My personal philosophy is that it is more beneficial to correct mechanics in order to put loads where they belong, rather than simply to allow for faulty mechanics with either a reduced load or an increased capacity to handle load.

It is important for professionals treating runners to understand how something changes gait characteristics, and if this is what you are intending to do. A study has yet to say that people will continue these changes after running on a LBPP treadmill, but my hypothesis would be that some evidence of these motor patterns will transfer into natural running.

It comes down to whether you think the patient will benefit more from reducing gravity or improving biomechanics. This may largely depends on how they got injured in the first place, and what your strategy is to get them running injury free.

If I was fortunate enough to have a LBPP treadmill, here is how I would use it.

  • Running Form: Like any other running drill, I could use a GPS watch with running dynamics to cue patients on maintaining normal gait characteristics while on the LBPP treadmill.
  • Off Season Mileage: Based on the article, keep it at 20% or < BWS for athletes who are at risk for or have a past history of volume related injuries.
  • Return to Running: The psychological benefits of getting someone back running as quickly (but as safely!) as possible are huge.

The take away is that LBPP treadmills can be great tools, and that clinicians should be aware of the effect on gait characteristics. Taking these characteristics into consideration will lead to better results and happier runners!

For those out there who use them, how have you seen LBPP treadmills effect running form?

Read the article here.