Monday, August 31, 2015

Latest Research On The ITB (Iliotibial Band)


Picture taken from my Canon Ixus 
Mention the ITB (or iliotibial band) and images of pain quickly crop up. IT band syndrome is a painful overuse injury usually at the lateral (or outer) portion of the knee in many runners and cyclists.

Latest research on the IT band from Daniel Lieberman's Harvard lab by his former student Carolyn Eng shows that the IT band may not function as what was formerly believed.

Another view
The ITB runs along the outer part of the thigh, originating from your Tensor Fascia Lata and Gluteus Maximus muscles just above your hip to attach just below the knee. It is made up of fascia, an elastic connective tissue found throughout our body. Fascia is a sheath of connective tissue that wraps our muscle, nerves and blood vessels. It also connects our muscles to bones.

The researchers used human cadavers to investigate how the IT band moves and stretches during walking and running. A computer model was then built to calculate the forces and strains involved and then compared to the equivalent structure in chimpanzees (published in another journal).

Previously, the IT band's primary function was believed to stabilize the hip during walking. Carolyn Eng's research suggested that the IT band actually acts like a spring, storing energy when you swing your leg back and releasing it as the leg swings forward.

This energy storage capacity is highly developed in humans, enabling it to store 15 to 20 times more energy than a comparable structure in chimpanzees.

Lieberman suggested that if we consider evolution and how humans are adapted not just for walking but running as well, then the IT band is looked at at a totally different perspective. The IT band looked like another elastic structure, similar to the Achilles tendon, and this may be important for saving energy during walking and especially running.

The researchers estimate the IT band stores about seven joules of energy during fast running compared to about the standard estimate of about 50 joules in the Achilles tendon.

The researchers hope that with this improved standing of how the IT band works, they can compare how much forces the IT band transmits in runners with and without IT band pain. This will then establish a scientific basis for treating IT band injuries.

References

Eng CM, Arnold AS, Liberman DE et al (2015). The Capacity Of The Human Iliotibal Band To Store Elastic Energy During Running. J Biomech. pii: S0021-9290 (15) 00354-1. DOI:10.1016/j.jbiomech.2015.06.017.

Eng CM, Arnold AS et al (2015). The Human Iliotibila Band Is Specialized For Elastic Energy Storage Compared With The Chimp Fascia Lata. J Exp Biol. 218(15): 2382-2393. DOI: 10.1242/jeb.117952.


Here's Carolyn Eng's (Harvard University) computer simulation of a human leg running from here.

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