The term emotion is a little misleading here. Baron was really referring to a continuum of comfort and discomfort. Through training and racing experiences, endurance athletes learn how much discomfort they ought to feel at any given point in a maximum effort of a certain distance or duration. Thereafter, they can feel their way to the optimal pace in each specific effort. But the maximum amount of suffering that an athlete is able to tolerate before slowing down is not fixed. It is influenced by a variety of factors, including experience and motivation. Baron used the term affective load (AL) to refer to the quantity of discomfort an athlete experiences during individual training and racing efforts.
He wrote: If the object of training is to improve the physiological responses in order that a greater physiological stress can be sustained during exercise, in the same way training could also be designed to insure that a more demanding emotional loading could also be accepted by the athlete. Hence, it might be proposed that the athlete should be trained also to accept high levels of AL during training and competition. In other words, exposing yourself to intense sufferingin a controlled and sensible way, of coursewill increase the amount of suffering you can tolerate in races and thereby increase your sustainable speed.
That’s right: no pain, no gain. In his memoir Every Second Counts, Lance Armstrong described this phenomenon brilliantly in lay terms: Pain is good because it teaches your body and your soul to improve. It’s almost as though your unconscious says, I’m going to remember this, remember how it hurt, and I will increase my capacities so the next time, it does not hurt so much. The body literally builds on your experiences, and a physique and a temperament that have gone through a Tour de France one year will be better the next year, because it has the memory to build on.