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.
Discover/Visa/MasterCard: On the back of the card, you should see a 16-digit credit card number followed by a special 3-digit code. This 3-digit code is your CID. American Express: There is a 4-digit code printed on the front of your card just above and to the right of your main credit card number.