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.
In some cases, supplements and fortified foods may actually cause you to exceed safe levels of intake of nutrients. People over age 50 should consume vitamin B12 in its crystalline form, that is, from fortified foods (like some fortified breakfast cereals) or as a supplement.