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ON “MUSCLE ACTION” VS “MUSCLE CONTRACTION”

Peter Cavanagh

Surprisingly, even as of today researchers, clinicians and coaches erroneously make widely use of the term “eccentric contraction”. In 1988 Prof. Peter Cavanagh (Pictured), Penn State University, wrote a small piece on this subject in the Journal of Biomechanics, challenging this misuse. Here we have selected a few quotes from Prof. Cavanagh.

The word “contraction” – used in relation to muscle activity is so deeply rooted in the literature of muscle biomechanics and muscle physiology that we now use it instinctively in a wide varpiety of contexts – several of which seem to be singularly inappropriate. One example is the term “eccentric contraction” to describe the situition where the net tensile force acting on the muscle is greater than the force produced by the tension generating mechanism of the muscle itself. The net result is that the ends of the muscle tend to move apart rather than together.
The term “eccentrics” derives from the Greek “ekkentros” – “out of center” – while the word “contraction” is derived from the Latin “contrahere” – “to draw together” (Webster’s 1979).
All that said by Prof. Cavanagh and to make a long story short, most experts today agree we should use the term “eccentric action” rather than “eccentric contraction”.