Kaizen is about continuous improvement which only has meaning if you have a goal you are improving toward.
Principle of specificity in exercise is one aspect of the process of continuous improvement.
Imagine that you are a martial artist planning to enter a competition.
How would you train? How would you improve your training? The simple answer is that you cannot train or improve your training without knowing the rules of the competition. The term martial arts is too general, too vague and ineffective.
Now imagine that you are planning to enter a Tae-Kwon-Do competition. The goals becomes more specific. Your training must focus on high kicks that give you more points and more hand defense to protect your head and to prevent losing high value points to your opponent.
The Tae-Kwon-Do competition becomes your “target activity.” Your training must be specific to that target activity. This is an example of specificity principle. The application of this principle is not limited to fitness or health.
Imagine that you are planning to improve your health. Just like the term martial arts, the word health is too general, too vague and ineffective. Now imagine that you want to reduce your resting heart rate and your blood pressure. Your activities become focused.
To reduce your resting heart rate, you need to increase the strength of your heart muscle so that with each beat, your heart forces more blood through out your body so that it can beat less and still provide the oxygen and nutrients your body needs. You also need to reduce or remove any restrictions within your circulatory system of veins and arteries so that your heart does not have to work against these restrictions.
Performing biceps exercises and doing crunches has nothing to do with the “target activity” of lowering your resting heart rate and your blood pressure.
To use principle of specificity effectively, you need to have a clear understanding of what your target activity is.