Introduction

The sliding filament theory was first proposed by Jean Hansen and  Hugh Huxley in 1954 at Massachusetts Institute of Technology (MIT).

It is a theory that describes the mechanism by which striated muscles (cardiac and skeletal; not smooth) contracts.

• This site will concentrate on skeletal muscles

The striations in muscles are caused by sarcomeres (the repeating contractile units of the myofibril) which are composed of thick and thin filaments.

During contraction, the sarcomeres shorten.

According to the theory, the filaments do not shorten during contraction.

Instead, they slide over eachother so that the filaments overlap causing the sarcomere to shorten.

Numerous sarcomere shortenings will cause the myofibril to contract and the recruitment of more contracting myofibrils will cause the whole muscle to contract.