In Paul Turner's Blog by Paul Turner

Q:  A parishioner wants the pastor to ask the assembly to all raise their arms in an outstretched position at the time of the epiclesis so that they too can join in in calling for the Spirit. She feels it would be very meaningful not only for her but for others.  Please comment on this.

A:  Not a good idea. In fact, the Vatican discourages the faithful from imitating the gestures of the priest. http://www.vatican.va/roman_curia/pontifical_councils/laity/documents/rc_con_interdic_doc_15081997_en.html. I believe that this pertains especially to the Eucharistic prayer.

People definitely should join in the act of calling for the Spirit, but quietly in their hearts together with the priest as he recites the words.