This outdated notion has absolutely no place in a sound training program. Your body, in an effort to avoid pain, will force the body to compensate with less-than-optimal posture and the wrong groups of muscles, ultimately leading to tissue overload, decreased neuromuscular efficiency, muscle imbalances, and often injury. Furthermore, while exercise can sometimes be uncomfortable, a workout that leaves a person sore for several days is potentially hazardous for your body and can exacerbate or create movement compensations that also place an individual at greater risk for injury. Pain in a workout is not a prerequisite or a requirement for improving strength or endurance or any other such relevant objective. On the contrary, that level of discomfort is the body’s way of indicating that something is terribly amiss.
Now, pain and discomfort are not one and the same. I’ve had a client, on many the occasions, exclaim dramatically (while perhaps very real and true for them in that particular moment), “This hurts everywhere!!” In these cases, if what is more accurate is something along the lines of- this is accomplishing a great deal at one time- let us consider staying the course for a reasonable duration. True pain, however, is not something one ought to push through. On the contrary, depending upon the manifestation, this variety of grief should be immediately addressed if it is within the scope of the personal trainer’s knowledge or should otherwise be examined by a physician.
Don’t allow yesterday’s ignorant presumptions fan the flames of today’s woes or create a problem where one does not already exist.