... . Introduction Sitting along with the back leaning,may extend the back muscle,exercise the muscle of waist ... up slowly,train your muscle of adbominal,the back board supportyour body,can let you make ... tiredness, train you abdominal muscle freelyJust lie your back on the chair , the exercises start .Spread ... 27 round massage points on the 4 arch back boards of the chair. Just imagine how comfortable ...