Several times a day observant Jews will recite Tefillat Ahmida. What is not widely known are times and blessings during which one must bow. Chazal has already stated that one should bow several times during the Ahmida prayer.

The proper times to bow during the Ahmida are as follows: (1) At the beginning of “Magen Avraham” the end of (2) "Magen Avraham" (3) the beginning of “Modim Ankhnu Lakh*”, (4) upon reciting "Na'eh Le'Hodot" and lastly (5)"Oseh Shalom".

The proper Halakha is to not bow at the beginning or end of any other blessings in the Ahmida prayer.

How much must one bow? One should not suffice with a small bow; rather, one must bow to the extent that all of the vertebrae in one’s spine protrude. One should not keep one’s head straight while bowing; rather, one should bend one’s head while bowing as well, as the Rambam (Chapter 5 of Hilkhot Tefillah) states 'that while bowing, one must resemble and arc, meaning that besides for bowing until one’s vertebrae protrudes from one’s back, one must likewise bend one’s head'.

It was already taught by Chazal that one should not bow so excessively that the mouth is directly across one’s belt. Rather, it is customary to bow as prescribed by the above Halakha.

If one is elderly, ill and cannot bow until one’s vertebrae protrudes

due to medical reasons such as vertigo and the like, one need not bow to such an extent, many Rabbim and Poskim have ruled that it is sufficient for those individuals to nod the head slightly, for this shows that the desire is to bow fully and that not doing so is merely due to the pain or discomfort involved with bowing.

The custom of most Sephardic and other Middle Eastern (Edot Hamizrach etc.) communities is not to bend one’s knees at all. Rather we bow the body until one’s vertebrae protrudes. This is done while reciting the word “Barukh, Modim, etc.”

Shavua tov and Shabbat Shalom!