Notice the differences in running (top) vs sprinting (bottom) activation patterns?

This picture (along with the MIchaud muscular firing pattern ones) are becoming some of my favorite ones to talk about. I just stare at them and look for differences and similarities. 

Check out that the abs do not seem to fire in running (in this study at least), but do in sprinting. Note also that most muscles fire longer (and we wil assume harder) during sprinting. Also check out the peroneals, which fire just as the foot touches down in sprinting, probably to make up for the instrinsics not firing, and assist in creating a rigid lever for push off. 

from: Mann et al 1986

The mighty Gluteus Medius, in all its glory!

Perhaps the delayed action of the gluteus medius allows an adductory moment of the pelvis, moving the center of gravity medially. This could conceivably place additional stress on the achilles tendon  (via the lateral gastroc) to create more eversion of the foot from midstance on

“The results of the study demonstrate altered neuromuscular control of the GMED and GMED in runners with Achilles Tendonitis. During running, GMED typically activates before heel strike so as to stabilize the hip and the pelvis. In runners with Achilles Tendonitis, GMED is activated with a delay, which consequently might affect the kinematics of knee and ankle resulting in rear foot inversion. Similarly, GMAX is activated with a delay and for a shorter duration in runners with Achilles Tendonitis. GMAX is the primary hip extensor and via a kinetic chain, a decreased hip extension moment might be compensated by an increased ankle plantarflexion moment which could potentially increase the load on the Achilles tendon.”

Franettovich Smith MM1, Honeywill C, Wyndow N, Crossley KM, Creaby MW. : Neuromotor control of gluteal muscles in runners with achilles tendinopathy.
Med Sci Sports Exerc. 2014 Mar;46(3):594-9.

Foot “core” anyone?

And a good time was had by all. Day 1 of the event in Vancouver. Lots of info and a bonus exercise session. Thanks to all who attended and looking forward to another great day tomorrow!

We spent a great deal of time talking about muscular firing sequences and the reasoning as to why things fire when.

Take a look at the picture and focus on the tib posterior, flexor digitorum longus, and flexor hallucis longus. They fire from loading response and fire through terminal stance. Up to midstance, they act eccentrically to slow pronation and after midstance, they fire concentrically to assist in supination. Note the sequence starts with the tib posterior (more proximal attachments in the foot) and ends with the flexor hallucis longus, more distal attachements (because in “ideal” gait, the hallux is the last to leave the party (or the ground, in this case)). Stability is a priority, so the central or “core” of the foot needs to fire before adding on peripheral (appendicular) muscles. Remember the foot intrinsics fire from midstance to pre swing, further stabilizing the foot “core”

The Gait Guys