A fundamental misconception about airspeed during turbulence is that it should never be the primary parameter of reaction. Flying attitude and maintaining wings level should be primary. It is never advisable to "chase" airspeed or altitude during an upset.
The Mach meter will roll forward and backwards during turbulence and its indication is not accurate because pitot and static ports are affected by the associated shear forces of turbulence. This is quite obvious as an airplane cannot physically change from M.84 indication to M.88 indication and reverse in 2 or 3 seconds. Most inexperienced pilots get flustered by instantaneous, momentary high Mach indications and immediately make large thrust reductions, only to realize later that the airspeed has dropped well below minimum [long range] cruise Mach.
In moderate or severe turbulence it is advisable to disconnect auto throttles and maintain speed and fly only attitude, with less emphasis on "chasing" altitude and airspeed. It is not advisable to engage speed brakes nor to retrim the stabilizer, nor to make any sudden or large control surface inputs.
