Training for Muscle Strength and Mass vs Tone and Endurance
One of the most prevalent myths that pervade the field of exercise science is that an individual should strength train using a particular set/rep/modality scheme in order to produce a specific response. Consult the vast majority of personal trainers, physical therapists, university exercise science faculty, physicians, or body-building enthusiasts on the topic and you will receive the same response:
High weight, low reps, and free weights produce muscle mass
Low weight, high reps, and machines produce muscle tone
And...
High weight, low reps, free weights produce muscle strength
Low weight, high reps, machines produce muscle endurance
Examples of this methodology abound...
We all have a female friend who strength trains and uses very light weights for a lot of reps because she wants long lean muscles and doesn't want to bulk up.
We also all have a male friend or know some one who insists on using only free-weights and performs multiple sets with a lot of weight and a low number of reps.
The truth is that the design of the strength training program does not determine the results an individual experiences. An individual's genetic predisposition determines results to a training program. The facts about the relationship between strength training and mass, tone, strength, and endurance are as follows:
Muscle endurance and muscle strength improve in a linear fashion. If you improve your ability to lift a heavy weight five times, you also improve your ability to lift a lighter weight many times. Muscle endurance and muscle strength are not separate entities that need to be trained separately. If you improve one, you improve the other.
If you have the genetic pre-disposition to develop large amounts of muscle mass, and you train with a high level of intensity - you will develop large amounts of muscle mass. If you do not have the genetics to look like a bodybuilder - no amount of training will allow you to look like a body-builder. Arnold Schwarzenegger looks like he does because of his genetics... not his training program. If you follow his training program - you will not look like him. 20 reps performed to muscle failure on the leg press will build the same amount of muscle mass as 6 reps performed to failure.
There is really no such physiological phenomenon known as "tone." In order to have a more "toned" appearance, a person should strength train intensely as well as decrease caloric intake and increase aerobic exercise in order to create a caloric deficit and lose body fat. The muscles themselves are not more "toned"... there is just less fat surrounding the muscle.