muscle soreness is your body reacting to you wrecking it
the same reason when you are in a car accident you are sore, or when you fall off a bicycle, etc.
so the more you train your body the less sore you will be.. BUT when you change up your workouts it is completely normal to be sore cause you are shocking your body (yeah Rich Piana was right)
you can reduce soreness by getting SLEEP. ironically NOT eating and fasting will actually speed up recovery, because your body can focus less on digesting food and more on repair.. this is why people who intermittent fast (not eating 18 hours straight) have such better results than guys who eat 18 hours a day straight.. plus your body uses up 50% of its energy digesting food