Lumbar spine mechanics and boots

Your footwear can affect your hips and low back ? Yes.

If you have been with us even a short while, this study should be of zero new value to you. But this study looked at the ankle dorsiflexion restricting firefighting boots on the low back.
We know that there are several force dissipators in the lower limbs, those being hip flexion, knee flexion and ankle dorsiflexion not to forget the all important foot pronation. When one of those is compromised, the job of that joint complex typically gets shunted elsewhere, and often proximally into the body.
Obviously, above ankle boots will restrict ankle dorsiflexion. Imagine an ice skate laced up all the way, or a ski boot, the ankle dorsiflexion virtually disappears. The came can happen in an inappropriately laced hiking boot or high ankle trail running shoe.
This will hit home the posts earlier in the week on the "z-angle" we discussed and Gray Cooks video from the weekend.
It is possible if you dial back the ankle dorsiflexion you cheat hip extension, or you make the lumbar spine extend into more lordosis than it is happy to perform.
You just cannot rob Peter to pay Paul all the time. Eventually Peter is gonna get pretty pissed.

http://www.sciencedirect.com/…/article/pii/S0003687017301333

Boots make the Man (or the Woman)

If you had any doubts about shoes changing ground reaction forces (GRF’s), then read no further.GRF’s are one of the factors considered by some sources as being injurious.

Tennis shoes had the most ground reaction forces

Army boots came in a narrow second

Bare feet had the least forces by a significant amount

Incidently, the amount of the valgus in the knees on landing was not significantly different among the 3 cases.

Hmmm. We need to think before recommending a shoe.

Ivo and Shawn. The Gait Guys. Sifting through the literature so you don’t have to. Yes, we are still bald, middle aged and good looking….

J R Army Med Corps. 2011 Sep;157(3):218-21.

A kinematic and kinetic analysis of drop landings in military boots.

Oliver GD, Stone AJ, Booker JM, Plummer HA.

Abstract

OBJECTIVE:

The purpose of this study was to examine knee valgus in drop landings during three different footwear conditions and to examine the ground reaction forces exhibited during the drop landing in the three different footwear conditions.

METHODS:

Sixteen male and female Reserve Officer Training Corps (ROTC) university undergraduate cadets (21 +/- 3 yrs, 79 +/- 12 kg, and 172 +/- 10 cm) volunteered to participate in the study. Kinematic data were collected while participants performed drop landings in three conditions: bare feet, tennis shoes, and issued military boots.

RESULTS:

Significant differences among footwear for ground reaction forces (bare feet: 1646 +/- 359%, tennis shoe: 1880 +/- 379%, boot: 1833 +/- 438%; p < 0.05) were found, while there was no significant difference in knee valgus among footwear.

CONCLUSIONS:

Though footwear conditions did not affect knee valgus, they did affect ground reaction forces. Participants in this study had yet to receive any military training on how to land properly from a specified height. Further research should be completed to analyze the kinematics and kinetics of the lower extremity during different landing strategies implemented by trained military personnel in order to better understand injury mechanisms of drop landings in this population. It is likely that injury prevention landing techniques would be beneficial if these were employed by the military and not just in the sporting community.

Barefoot Winter Footwear: The mukluk.

In this, the latest of The Gait Guys videos, Dr. Shawn Allen talks about a neat product, the Steger Mukluk. It is about as close as you can get to a Minimalist Winter boot (in case you are chasing caribou in the north, or shoveling out from the Chicago Blizzard of 2011, or just working outside in the bitter cold). Some interesting principles of minimalist shoes apply here. Where do these guys come up with their ideas !