Although both upright and recumbent stationary bikes provide a low-impact cardiovascular workout, these two machines differ in their details. While upright bikes mimic the form of a traditional bicycle, featuring simple saddle-like seats without backs, recumbent bikes provide back support with low, chair-like seats.he supportive seats of recumbent bikes put less stress on the lower back than the seats of upright stationary bikes, which is a key difference between the two exercise machines. Those who suffer from lower back pain or balance issues will typically find recumbent bikes more comfortable.
1 The body does not need these vitamins every day and stores them in the liver and adipose (fat) tissue when not used. 2  Most people do not need vitamin supplements. 3  Megadoses of vitamins A, D, E or K can be toxic and lead to health problems.  Requirements for vitamins may be expressed in different mathematical units.
Water-soluble vitamins travel freely through the body, and excess amounts usually are excreted by the kidneys. The body needs water-soluble vitamins in frequent, small doses.These vitamins are not as likely as fat-soluble vitamins to reach toxic levels.ater-soluble vitamins travel freely through the body, and excess amounts usually are excreted by the kidneys. The body needs water-soluble vitamins in frequent, small doses.