According to the law of conservation of energy, which statement must be true?
A. The total
energy
of a system can decrease only if energy leaves
the system
B. A system cannot take in additional energy.
C. There is only one form of energy.
D. Potential energy can only change to kinetic energy.
SUB

The muscles feels relaxed as the massage improves the blood circulation in the muscles.

Explanation: The  massage in the muscles aids in improving the blood circulation which helps in reducing the fatigue and stress in muscles.

It also in several problems of muscles such as muscle spasm, tenderness in muscles, et cetera.

Improved blood circulation in the muscles improve the oxygen content in it and also along with blood comes many nutrients which help the muscle cell grow better.

Muscle contraction also suppresses the nerves around them  which results in many problems. But with the help of massage the muscles feels relaxed and the suppressed nerve associated with the muscle also gets relaxed with proper supply of nutrients.