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The capacity of the human iliotibial band to store elastic energy during running

updated

Tags: IT band pain, movement, anatomy, biomechanics, running, knee, leg, limbs, pain problems, overuse injury, injury, exercise, self-treatment, treatment, tendinosis, etiology, pro

Two articles on PainSci cite Eng 2015: (1) The Complete Guide to IT Band Syndrome(2) IT Band Stretching Does Not Work

PainSci summary of Eng 2015: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible.

This paper presents the abstract and speculative “results” of a thought experiment aided by a fancy model of the leg, so it can’t be taken too seriously, and in particular it has no clear clinical implications. But it is interesting! Mostly it purports to show that the IT band stores elastic energy, much like the achilles tendon, just a lot less: “1J of energy per stride during slow running and 7J during fast running,” which is “approximately 14% of the energy stored in the Achilles tendon at a comparable speed.”

If that’s how it actually works, it’s a handy biological adaptation that makes running a little more efficient: more evidence that we are “born to run” (Bramble).

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

The human iliotibial band (ITB) is a poorly understood fascial structure that may contribute to energy savings during locomotion. This study evaluated the capacity of the ITB to store and release elastic energy during running, at speeds ranging from 2-5m/s, using a model that characterizes the three-dimensional musculoskeletal geometry of the human lower limb and the force-length properties of the ITB, tensor fascia lata (TFL), and gluteus maximus (GMax). The model was based on detailed analyses of muscle architecture, dissections of 3-D anatomy, and measurements of the muscles' moment arms about the hip and knee in five cadaveric specimens. The model was used, in combination with measured joint kinematics and published EMG recordings, to estimate the forces and corresponding strains in the ITB during running. We found that forces generated by TFL and GMax during running stretch the ITB substantially, resulting in energy storage. Anterior and posterior regions of the ITB muscle-tendon units (MTUs) show distinct length change patterns, in part due to different moment arms at the hip and knee. The posterior ITB MTU likely stores more energy than the anterior ITB MTU because it transmits larger muscle forces. We estimate that the ITB stores about 1J of energy per stride during slow running and 7J during fast running, which represents approximately 14% of the energy stored in the Achilles tendon at a comparable speed. This previously unrecognized mechanism for storing elastic energy may be an adaptation to increase human locomotor economy.

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