Answer:
Contraction.
Explanation:
Muscle tissues are defined as they are elastic and extensible in nature. In other words it's also defined as they are able to stretched and returned to its original size and shapes. A unique feature of muscle tissue is they are able of contractile in nature. With the help of this contraction they are able to sliding myosin and actin filaments which are present in muscles tissues.
Basically muscle tissues are three types:
1) Skeletal muscle: They are strong and rapid in contraction.
2) Cardiac muscle: They are strong in contraction.
3) Smooth muscle tissues: They are slow and weak in contraction.
 
        
             
        
        
        
Smoking ruins your lungs making it harder to breath and get oxygen
you need oxygen when you exercise so you don't faint
smokers get less so it is harder for them, its like trying to exercise while breathing through a sponge or a straw os
        
                    
             
        
        
        
1. How many muscles are in the human body? 
2.What diseases affect the muscular system?
3. What are the functions of the muscular system?
4.what are two types of muscle fibre?
        
             
        
        
        
Its atomic mass determines its properties? hope this is correct