Electric trikes can provide an excellent method of exercising. It is similar to that of riding a bike, working primarily your legs. The more weight you put on the back of your adult tricycle with the help of the basket will make it harder to move and therefore a better workout.
Some people might find the temptation of an electric motor too much to get a good workout; however. So, you'll need strong willpower to work your legs rather than giving up and using the motor.