Syeda Aa`ishah Siddiqa (Ra) narrates that Holy Prophet used to prolong the prostration to such an extent that one could recite fifty verses (of the Qur'an) before he would lift his head, (Bukhari). 

In another Hadeeth narrated by Anas bin Malik Holy Prophet (pbuh) advised Muslims to perform Ruku (bowing) and Sajdah properly. 

In another Hadeeth he advised to perform Sajdah and Bowing calmly and to get up only when the body has come to ease. 

In supplication for the victory. He also performed long bowing (Ruku) and Sajdah in the special prayers at the time of eclipse. Hence the first positive effect upon a person who prostrates or does Sajdah is that he comes nearest to Allaah and hence in that condition he can supplicate. This is a great psychological advantage and it gives relief to the person concerned as life is full of worries and in this position he gets at least a transient refuge from the agonizing problems. When a person goes to the position of prostration Sajdah his whole body is in active motion. This position can be considered as a mini dive as the musalli (one who offers prayer) goes to rest his forehead on the ground while his hands are placed at the sides. This brings most of the body muscles if not all in active motion and serves to give them some exercise.

The hands are then specifically stretched out and thence the forearm as well as arm muscles are supposed to bear the weight in the Sajdah position. It gives good exercise to the muscles of the upper limb. Holy Prophet (pbuh) in a hadeeth advised not to put the forearms flatly on the ground but to keep them elevated above ground and this is better for the forearm and arm muscles.

Sajdah is a unique position as this is the only position in which brain (or head) becomes lower than the heart and hence for the first time the blood gushes towards the brain with full force whereas in all other positions (even when lying) brain is above the heart when it has to work against gravity to send blood to the brain.

In the position of Sajdah due to the increased blood supply the brain receive more nourishment and it has good effect upon memory, vision, hearing, concentration, psyche and all other cognitive abilities. People who offer their prayers regularly have more will power and can cope with the difficulties of life in a much better manner. They have less incidence of headaches, psychological problems and other defects of cognitive function.

In the unique position of Sajdah the neck muscles get best exercise. They have to bear the load when the forehead lies at the ground hence the neck muscles become stronger. One can note the tense pressure at the neck muscles in the position of Sajdah specially the active motion of the neck and the facial muscles when the head is being lifted. (e.g. one inch above the ground) and it will be noticed that they are in a very active motion. 

More strong cervical muscles mean the cervical vertebra will be better protected. Strength of cervical muscles is important as the head rests upon cervical vertebra supported by cervical musculature.

Infact head performs rotator movements over the cervical vertebra. In any accident cervical neck examination is especially important to the physicians because of its extraordinary importance. 

It is uncommon that a person who offers his prayers regularly will get the usual neck myalgias or cervical spondylosis as the neck muscles particularly become very strong due to the 34 sajdahs offered daily in five prayers.

Position of Sajdah is also said to be a good treatment for the retroversion of uterus, a disease of women. 

Most of us do not know that the position of Sajdah is an excellent exercise for men (for manpower). It may be a good information to the Viagra dependents. While getting up from Sajdah the perinneal muscles are one of those muscles which have to pull the trunk back to sitting position and they contract actively. Similarly while standing up from Sajdah the perennial muscles are again actively mobilised and this gives much strength to the muscles important for manpower.

The unique position of Sajdah also has positive effects upon the back muscles as while going into Sajdah and getting up from it the back muscle contract actively and they become stronger. Probably it is because of this reason that a person who is regular in prayers will uncommonly get backache.

After performing Sajdah either the musalli stands up or he sits to pray Attahiyyat. In this position the person sits calmly while his hands rest at his thighs which are folded backwards. This is much similar to the relaxation position of Yoga and has soothing effect upon one's health and mentation.

Holy Prophet Muhammad used to elongate the position of Ruku (bending) and Sajdah positions and he advised to do so. In the light of the above facts it is appropriate to say that from medical point of view as well this advice is a golden rule for health.

Finally it must be reminded that prayer is not meant to be an exercise. However there are a lot of medical advantages associated with it. Still the best blessing is the peace of mind, which a person derives by the accomplishment of his duty to Allah by fulfilling an obligation.