Sports and exercise science, sports medicine or exercise physiology is a discipline that studies how the healthy human body works during exercise, and how sport and physical activity promote health and performance from cellular to whole body perspectives. The study of sports science traditionally incorporates areas of physiology (exercise physiology), psychology (sport psychology), anatomy, biomechanics, biochemistry and biokinetics. Sports scientists and performance consultants are growing in demand and employment numbers, with the ever-increasing focus within the sporting world on achieving the best results possible. Through the study of science and sport, researchers have developed a greater understanding on how the human body reacts to exercise, training, different environments and many other stimuli. Sports Science can trace its origins to ancient Greece. The noted ancient Greek physician Galen (131-201) wrote 87 detailed essays about improving health (proper nutrition), aerobic fitness, and strengthening muscles. Assyrian Hunayn ibn Ishaq translated Galen's work, along with that of Hippocrates, into Arabic which led to the spread of Greek physiology throughout the Middle East and Europe. Between 776 BC to 393 AD, the ancient Greek physicians planned the training regimens and diets of the Olympic competitors.