“Generally speaking, if we look at sports we find that their strong point is that because they are competitive they are interesting, and young people are likely to be attracted to them. No matter how valuable the method of physical education, if it is not put into practice, it will serve no purpose — therein lies the advantage of sports. But, in this regard there are matters to which we must also give a great deal of consideration. First, so-called sports were not created for the purpose of physical education; one competes for another purpose, namely, to win. Accordingly, the muscles are not necessarily developed in a balanced way, and in some cases the body is pushed too far or even injured. For that reason, while there is no doubt that sports are a good thing, serious consideration must be given to the selection of the sport and the training method. Sports must not be undertaken carelessly, over-zealously, or without restraint. However, it is safe to say that competitive sports are a form of physical education that should be promoted with this advice in mind. The reason I have worked to popularize sports for more than twenty years and that I have strived to bring the Olympic Games to Japan is entirely because I recognize these merits. However, in times like these, when many people are enthusiastic about sports, I would like to remind them of the adverse effects of sports as well. I also urge them to keep in mind the goals of physical education—to develop a sound body that is useful to you in your daily life — and be sure to consider whether or not the method of training is in keeping with the concept of”

http://www.judoinfo.com/seiryoku2.htm seiryoku zenyo
"Judo and Physical Training" in Mind Over Muscle : Writings from the Founder of Judo (2006) edited by Naoki Murata, p. 57