Kickboxing may be performed in a variety of venues. Whether you work out in gym with a bag, spar against an opponent or participate in an aerobic kickboxing class, you burn significant calories in 45 minutes.
In 45 minutes of kickboxing, a 135-lb. woman burns about 482 calories. The American Council on Exercise notes that the calorie burn for a 135-lb. person may between 350 and 450 calories for a 50-minute kickboxing class featuring a warm-up, cardio portion, and cool-down.
The number of calories you ultimately burn depends on your size, the intensity of your workout and your efficiency at the exercise. The larger you are, the more calories you burn in 45 minutes of kickboxing. Working at a greater intensity also burns a greater number of calories. If you are efficient at the movements, you will probably burn fewer calories during the 45-minute session.
Some kickboxing programs claim you burn between 500 and 800 calories during their workout. ACE notes that this is unlikely unless you are extremely large and are working at extreme intensities.