With my land personal training clients who are lifting weights, we change their programs every six weeks, if they have been exercising consistently 3 times a week. When the program changes, the client often works the same muscle groups in the new program, but in a different way. Adaptation to a given overload occurs quite rapidly if the exercise is done regularly. The body gets familiar with the movement pattern; the muscles recognize the way they are being challenged, and repetition of the exercise gets easier. As the trainer, I want the client to feel comfortable with the exercise, so that I can focus on increasing the weights each time the adaptation occurs. Over the six weeks, we try to keep increasing the weight, so that strength improves. With a general population, boredom does start to affect motivation to keep with the same exercises. Plus, general populations are going to reach a point where they just cannot lift more weight. Avoiding plateaus is important to keep a client coming back for more. When the program changes, the weights usually go back to a much lower number. The muscles are now being challenged a little differently, so they have to go through the new adaptation. It's all about specificity. If I do a leg press for 6 weeks, and then change to a squat, I will not be able to push the same weight even though many of the same muscles are involved. The specificity is different.

If you teach in the water using routines, the same principle can be applied. Change your routines every 6 weeks. Now that assumes that you have regular attendees, and that you have built resistance progressions in to those routines. In other words, they learned the moves and combinations. They know the routines inside out, and you have gradually added all the possible places where the intensity can be manipulated for further challenges. Then it is time to change! Let your class know that this is your method, and what it will do for them in terms of continuous fitness improvements. I wouldn't worry about a break in form or practice. There are only so many moves you can do in water, so the new routines are bound to include familiar exercises. For example, cross-country ski with quarter turns is a totally different challenge than doing it in place. Or, putting your hands on your shoulders while you do cross-country ski will set up many new stabilization challenges and technique refinements. Putting the same exercises in a different order is going to stimulate body awareness. JustLearning new movement patterns is a big part of being a better mover, and that is definitely a great benefit!