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.
The myth of toning is often tangled up in the myth of spot training. Fine...you can (and should) work your triceps muscles, but that isn't going to get rid of the fat around your triceps, which is what keeps you from seeing that muscle. If you reduce your calories, lift weights and do some cardio, you can lose body fat.