Final answer:
The Principle of Specificity or SAID principle explains that our bodies adapt physiologically to the type of training, whether aerobic or anaerobic, leading to improved efficiency for the specific demands of the exercise.
Step-by-step explanation:
The principle that states our bodies will physiologically adapt to the type of exercise we perform, whether it be aerobic or anaerobic, is known as the Principle of Specificity or the Specific Adaptation to Imposed Demands (SAID) principle. When we engage in aerobic exercise, which is low-intensity and can be sustained over long periods, our body adapts by becoming more efficient at using oxygen to convert carbohydrates into energy, thus improving our endurance and heart efficiency. Conversely, during high-intensity, short-duration anaerobic exercise, our body relies on glycolysis for energy, resulting in adaptations such as increased muscle strength, power, and endurance due to the ability to manage higher levels of lactic acid.