The human body is incredibly complex and far too intricate for muscle isolation loading to have any benefits whatsoever. To the contrary, isolation training will harm the body. 

Movement requires the co-ordinated contraction of many different muscles. In addition, fascia, ligaments and tendons work in unison with muscles and together create efficient movement. 

There are multiple co-ordinated contractions and co-operation between different parts of the human body including the synergistic action of 4 different groups of soft tissue that are commonly referred to as anatomical slings, myofascial slings or sling systems. These sling systems include muscle, fascia and ligaments that are interconnected to one another to provide stability and mobility. When these structures are working effectively and efficiently we move better, produce more force, speed and power. In addition we become energy efficient and more robust, with less wear to our structures and reduced chances of injury. Essentially, these sling systems of the body, when functioning well, assist in transferring force between our upper and lower limb whilst providing a stable core. 

A weak component in a sling system will create dysfunction, which will not only reduce performance but also add additional stressors to our structures, increasing the chance of injury. 
Therefore, it is crucial to ensure that these sling systems are working optimally. 

The body is designed to work as a unit