Word for physical exercises

Do you mean an energizer?

Energizers are fun activities that get students up, out of their desks and moving around for 1-2 minutes before getting back to work. You can use them in transition times, to break up a long lesson or after a test.

http://www.realclassroomideas.com/167.html

Consider (in-class) activity breaks:

Are you thinking of implementing in-class activity breaks? Use these poll questions and ideas to create a customized poll that meets your needs.

Remember that your overall goal is to get more students to participate in physical activity during the day, beyond regular P.E. classes.

a. Mini-workout circuit in class
b. Stretching
c. Running or jumping in place
d. Strength-building activities like push-ups or calisthenics

(futpforms.com)

Another example:

In-Class Physical Activity Breaks

(www.fueluptoplay60.com)

Alternatively, consider movement break:

Regularly-scheduled movement breaks throughout the day and movement used within and between lessons results in better-behaved, more engaged students who can more easily focus on and retain what they are supposed to be learning.

Schools don’t need extra space and they don’t need special instructors in order to do this. They mostly need to change their mindset and accept that movement is beneficial. Movement breaks can be included between lessons very easily. Teachers can reduce the amount of instruction time per lesson from 40 to 30 minutes, and then use the remaining 10 minutes for movement breaks, so that children are clear and focused before the next lesson begins.

(www.creativitypost.com)