The cause is frequently unknown. Hypertrophic cardiomyopathy is often and dilated cardiomyopathy in a third of cases, is inherited from a person's parents. Dilated cardiomyopathy may also result from alcohol, heavy metals, coronary heart disease, cocaine use, and viral infections.
Consider the number of reps. You can also confuse your muscles by increasing or decreasing the number of repetitions you do during any given exercise. For example, if you normally do 12 repetitions, do 15 or 18 repetitions, but with a lower weight than you would normally use.
If you're trying to lose weight, cardio exercise is just one of the things you need in your weight loss toolbox. What can be confusing is figuring out how much cardio you need, how hard you should work, and the best cardio exercises for your goals and fitness level. That may be confusing but the upshot to that is that you have a variety of choices and you don't have to do the same workouts at the same intensity day after day.