This is because they train extremely hard in order to sustain stamina and endurance so, their bodies don't get the chance to build muscle because they burn more than they consume.
Answer:
In asexual reproduction there is no mating or mixing of genetics. Asexual reproduction results in a clone of the parent, meaning the offspring have identical DNA as the parent.
One way for an asexually reproducing species to get diversity is through mutations at the DNA level. If there is a mistake in mitosis, the copying of the DNA, then that mistake will be passed down to the offspring, possibly changing its traits. Some mutations do not change the phenotype—or observable characteristics—however, so not all mutations in asexual reproduction result in variations in the offspring.
Explanation:
The effects of the agricultural and industrial revolution on the environment is significant. The release of industrial waste into streams and rivers still is a major problem. The release of 
into the atmosphere has been shown as a major factor of climate change. Additionally, smog and other atmospheric pollutants create many issues. Finally, the use of industrial fertilizer and pesticides have caused algae blooms which are harmful to aquatic environments.
Diffusion has a major part in this. It has proteins embedded in it that allow molecules to diffuse in and out of the cell up and down its concentration gradient.
