Question

Briefly construct a 3-week workout routine that incorporates the fitness principle of overload.

Answer 1

There are 3 fitness principles: overload, progression and specificity. 
According the principle of overload in order to improve, athletes must continually work harder as they their bodies adjust to existing workouts. This is the basic sports fitness training concept.
In the 3-week workout routine that incorporates the fitness principle of overload several things must be satisfied:loads should be gradually and progressively increased , the training loads should be  planed and monitored, the workout routine should include workouts that allow recovery (stretching for example), competition should be involved, and very important muscular failure should be avoided.

Answer 2

A sample response follows: Using the overload principle, you should plan on increasing a workout routine every day. The first routine will increase running pace over time. The second routine will increase the distance run every day.

Week 1: run 1 mile with a pace of 10 minutes/miles

Week 2: run 1.2 miles with a pace of 10 minutes/mile

Week 3: run 1.5 miles with a pace of 9.5 minutes/mile

or

Week 1: lift 50lbs for 15 reps

Week 2: lift 55lbs for 15 reps

Week 3: lift 60 lbs for 18 reps