The “Firming & Toning” Myth

High rep extremely light weight routines designed to ‘firm and tone’ are a fallacy. In physiology tonus refers to the muscle in a steady partially contracted state caused by the successive flow of nerve impulses.Having a higher level of tonus causes the muscle to remain steadily contracted. A motor unit consists of a motor neuron and the muscle fibers it innervates(v. to supply nerves). Increasing tone means stimulating these motor units to fire therefore to contract muscle. Slow movements at light weight is not effective in doing this based on the size principal which basically states that more motor units need to fire in order to lift heavier objects. So the best ways to improve “muscle tone” are to engage in strength and power exercises which require large amounts of motor units to work. Power is most effectively by moving heavy objects fast or lighter objects faster (power=force * distance / time). Olympic weightlifting, kettlebell lifting, and strength (strength= force * distance) training are the most effective ways to “tone” muscles. The overload and threshold principles also comes into play meaning a minimum intensity must be met in order to drive adaptation. This adaptation is muscle growth and increased tonus that results in ‘firming’.

The ‘firm & tone’ myth usually coincides with the myth that lifting weights causes women to get “huge” muscles. Generally two things cause this: extreme volume of training and the more likely culprit, steroids. See Jocelyn’s article on this here Resistance Training Myths of Female Athletes.


Kaminsky, Leonard A.. (Eds.) (2006) ACSM’s resource manual for Guidelines for exercise testing and prescription /Baltimore, MD : Lippincott Williams & Wilkins

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