Really? Regardless of your fitness levels, age, aerobic capacity, lactate tolerance, hormone balance, weight, experience or injury history? I disagree.
Only if you are extremely fit AND very experienced in any given type of exercise, do you have any chance of even surviving a 1000 kcal/hr workout.
Then why would anyone make these claims? What they might be trying to say is that maybe after weeks, months or years (or never) of training might you be fit and experienced enough to burn 1000 kcal/per hour. Unfortunately, people want results quickly and my explanation does not make for great marketing, just decent blogging.
Let’s take running for example. It is relatively common knowledge that approximately 1 mile of running (or walking) will burn about 100 kcal regardless of speed (for the most part). Therefore, you would need to run 10 miles/hr or 16 km/hour for one hour to get to 1000 kcal. This is very hard to do. Even if you have inefficient technique, you may be burn more calories for any given pace, but your pace will drop and you will still not be able to tap into the fat/fuel burning potential that fitness and experience provide.
It would take approximately 2.5 hours of brisk walking at 4 miles/hour to burn the same 1000 kcal.
Running doesn’t use the upper body much, you might say. So let’s try the rowing machine which uses almost all of the major muscle groups repeatedly. Try maintaining a 2:00 minute/500 meter pace for a full hour (equivalent of approx. 1000 kcal/hour) on a rowing machine. Actually, please don’t try it right away. Your back would likely snap like a twig without the fitness or rowing experience.
In summary, calorie burn has less to do with the type of exercise that you are doing as long as large muscle groups are worked repeatedly. Calorie burn has more to do with your current state of fitness, health and experience. The more you enjoy the exercise, the more you will do it and the more intensely you can do it and the more your calorie burn/metabolism will increase and even extend into hours after you complete the exercise. So please do what you enjoy, even if it is trying new exercises that burn 1 million billion kcal/hour.