GLYCOLYSIS is the step of cellular respiration that converts each of her glucose molecules into pyruvic acid.
Glycolysis is also the first step in cellular respiration. This happens inside the cytoplasm. During this process the glucose is broken down into 2 and becomes 2 pyruvic acid.
The 650 skeletal muscles in the human body contract when they receive signals from motor neurons, which are triggered from a part of the cell called the sarcoplasmic reticulum. Motor neurons tell your muscles to contract and the better you become at having those signals tell your muscles to contract, the stronger you can get.