Abdominal exercises are a type of strength exercise that affect the abdominal muscles (colloquially known as the stomach muscles or "abs"). Human abdominal consist of four muscles which are the rectus abdomens, internal oblique, external oblique, and transversus abdominis. When performing abdominal exercises it is important to understand the effects, functions, the types of exercises, and think about how to perform this exercise safely. Effects Abdominal exercises are useful for building abdominal muscles. This is useful for improving performance with certain sports, back pain, and for withstanding abdominal impacts (e.g., taking punches). According to a 2011 study, abdominal muscle exercises are known to increase the strength and endurance of the abdominal muscles. It has been highly disputed whether or not abdominal exercises have any reducing effect on abdominal fat. The aforementioned 2011 study found that abdominal exercise does not reduce abdominal fat; to achieve that, a deficit in energy expenditure and caloric intake must be created—abdominal exercises alone are not enough to reduce abdominal fat and the girth of the abdomen. Early results from a 2006 study found that walking exercise (not abdominal exercise specifically) reduced the size of subcutaneous abdominal fat cells; cell size predicts type 2 diabetes according to a lead author. Moderate exercise reduced cell size by about 18% in 45 obese women over 20 weeks; diet alone did not appear to affect cell size. Functions of abdominal muscles Abdominal muscles have many important functions, including breathing, coughing, and sneezing, and maintaining posture and speech in a number of species. Other abdominal functions are that it helps "in the function of support, containment of viscera, and help in the process of expiration, defecation, urination, vomiting, and also at the time of childbirth." The anterior abdominal wall is made up of four muscles—the rectus abdominis muscle, the internal and external obliques, and the transversus abdominis."The two internal muscles, the internal oblique, and the transverse abdominis, respond more to increases in chemical or volume-related drive than the two external muscles, the rectus abdominis and external oblique; the basis for this differential sensitivity is unknown". Core training Not only can a one-sided preference for abdominal muscles (lack of exercise focused on other core muscles) result in creating muscle imbalances, but the effectiveness of exercise is also far from what could be achieved with a balanced workout planning. Core training frequently utilizes balance exercises, such as training of transverse abdomens and