Are Jumping Exercises Bad For Knees?

My short answer is yes. Exercises like squat jumps and jumping lunges have become really popular in HIIT workouts because they get the heart racing and create a lot of muscle soreness (thus giving the impression of effectiveness) but there is a price to pay.

Force = Mass x Acceleration.

Everytime you jump gravity accelerates your body back to earth magnifying total force when you land. The higher you jump, the greater the impacts. These high forces coupled with dodgy biomechanics and excessive repetitions create a perfect storm for long-term joint issues, particularly in the knees.

Using jumping exercises for cardio... bad idea.

On the flip side there is probably some value in learning, practising and refining the skill of jumping. The key here is low reps, fresh muscles and an utmost focus on good form. Using elevated surfaces to dampen the impact forces of the exercise seems like a good idea too.

As with so many things in health and fitness… context matters.