Elliptical workouts are similar to cardio exercises, like running, walking, and biking. Krystal who is doing a cardio workout each day using the elliptical machine at the gym should increase strength and flexibility training. This makes the correct answer: D
Incorporating strength (lifting weights
, working with resistance bands, climbing) and flexibility exercises (yoga, stretching..) in her fitness routine will help Krystal increase muscle strength, maintain bone density, improve balance...
