US scientists discovered that dark chocolates are as useful to human health as regular athletic exercises. A study conducted by US researchers at Wayne University in Detroit, USA revealed that a substance found in dark chocolates caused a muscle reaction similar to that seen after athletic exercise. The researchers focused their study on mitochondria thread-like grains that contribute into the process of energizing the human body. Researchers carried out their studies on rats given a similar substance derived from coconuts over a period of 15 days. The researchers said a group of rats given the same substance and another group of rats who exercised on a jogging-machine have gained equal stamina. Usually aerobics, jogging and cycling help increase the energy-producing thread-like grains in the human body. The study showed that the substance also increased the number of thread-like grains specially in the heart.