Effects of Training on Athletes. Sports physiology is the study of the long-and short-term effects of training and conditions on athletes. This specialized field of study goes hand in hand with human anatomy. Anatomy is about structure, where physiology is about function.
Visa and Mastercard always have 16 digits whereas American Express has 15 digits. The short answer is that American Express cards have a different PAN format than Visa, MasterCard and Discover because they offer a different kind of financial service.
For Visa, MasterCard, and Discover cards, the card code is the last 3 digit number located on the back of your card on or above your signature line. For an American Express card, it is the 4 digits on the FRONT above the end of your card number.