Exercise training device. (A) For young and adult flies, vials were vertically loaded in the exercise device, and rotated 180° to make flies constantly climb (just as Power Tower, overcoming weight = total body weight). (B) For aged flies (categorised as 4-week to 5-week-old flies in this study), vials were loaded in the exercise device, their long axis is at an angle of 45° to the horizontal plane (overcoming weight = total body weight×sin45°). When aged flies climbed and reached the top of vial, the vial was rotated 90° to make flies constantly climb.