Since the fitness revolution, physical activity has been promoted as an effective way to combat obesity and heart disease. Currently, walking is the number one recommended activity among both the young and old. However, new research from the University of Bristol has found that running and jogging are also important for building strong bones in children. It has also found that gentle exercise like walking has little effect on bone strength, even over a longer period. Walking offers little protection against the risk of osteoporosis later in life.