In a study published in the US national library of health: (http://www.ncbi.nlm.nih.gov/pubmed/25226328) , Massage was shown to improve muscular strength and proprioception in the gastrocnemius ( calf muscle) when performed after vigorous exercise. It was found to reduce EIMD or Exercise-induced muscle damage. The study showed that massage can help speed the recovery from muscle damage caused by vigorous exercise.
Why does this happen? Massage helps breakup adhesive tissue, reduce inflammation, stimulate circulation and aid in tissue healing and regeneration.
So what does this mean in English? If you work out hard and become sore or are in pain, massage by a trained professional can help you recover faster, grow your muscles faster, increase flexibility and decrease pain all at the same time.