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 marathoner have trained for muscle endurance. The sprinter have trained for muscle strength. that's is what you can see when look at their appearance. Strength muscle(big muscle) will show how strong you are but it's get tired very fast. When you training for this you must limit repetition from 8-12reps.