activity because the exercise includes both weight training and fast dynamic movement. Originally referred to as oxygen debt, this post exercise aerobic effect was first hypothesized by A.V. Hill and H. Lupton in 1922. They theorized that the body needs to replace the oxygen used by working muscles during mild to intense bouts of exercise. More recently, researchers have used the term 'excess post-exercise oxygen consumption' to describe the different events that occur as the body restores itself to homeostasis, or rest. The body’s metabolic rate will be raised for a longer period post- exercise from high intensity bouts of exercise. Depending on the level of stress and intensity of exercise, metabolic increase can be seen for up to 18–24 hours. Safety considerations Exercises with Bulgarian Bags, like any other plyometric shock-training exercises, involve an increased risk of injury due to the large forces that are generated during acceleration, and should only be performed by well-conditioned individuals or under supervision. For more information on risks involved in plyometric training, see safety considerations in plyometrics. Because the handles of the Bulgarian Bag are flexible and not rigidly fixed to the body of the equipment, it is harder for an athlete to transfer the weight of the equipment to his or her forearm and arm muscles than with traditional iron weights, and more load is carried by athlete's wrists. The use of wrist wraps may therefore be advisable for people with weaker wrists to provide additional support. For general information about the effects of physical exercise on human body and the physiological processes involved, see exercise physiology. See also Barbell Dumbbell Kettlebell Exercise equipment Weight training Strength training Resistance training Plyometric training References External links International Bulgarian Bag Confederation Weightlifting Weight training equipment Exercise equipment